Polyunsaturated fatty acids in spinal cord injury.
Abstract
Spinal cord injury (SCI) is an important pathology leading to possibly fatal consequences. The most common repercussions are those affecting motor and sensitivity skills. SCI-damage occurs in its first phase—as a result of the lesion mechanism (contusion, compression, transection, and primary lesion). After this primary damage, there is a second phase with further deleterious effects on neural degeneration and tissue restoration. At the moment, several investigation groups are working on developing therapeutic strategies to induce neuroprotection. This chapter pretends to introduce the reader to a wide range of these therapies, particularly those with promising results and tested in preclinical and clinical studies. In the first section, physiopathology of SCI will be addressed. Afterwards, the chapter will review neuroprotective strategies such as cyclooxygenase, calpain, and apoptosis inhibitors. Finally, the effect of immunophilin ligands, neural-derived peptides, antioxidants, hypoglycemic agent, gonadal hormones, Na channel blockers, and transplant of cultured cells will also be reviewed.
Keywords
- neuroprotection
- SCI
- therapies
- acute phase
1. Introduction
Spinal cord injury (SCI) can be defined as damage to the spinal cord (SC). It causes anatomical and physiological changes that result in permanent or temporary alterations in its function [1]. The injury causes ionic deregulation, edema, ischemia, bleeding, free radicals production, and a generalized inflammatory response that will cause partial or total loss of sensitive and motor function below the site of injury [2, 3].
In the United States, there are around 17,500 new cases of SCI per year, with an approximate prevalence of 280,000 people [4]. SCI is found most frequently in men (79.8%) than women (20.2%) and the age distribution reflects a bimodal performance with a peak between 15 and 29 years of age and another one on ages above 50 years [4, 5, 6]. Traffic accidents are the main cause of traumatic SCI (38%), and they are most prevalent in young people. The low impact accidents like falls are the second cause of SCI (31%), and they are more common among people older than 60 years old [5]. In Mexico, the estimated annual incidence of SCI is about 18.1 per million inhabitants. Statistically, the number of people involved rises each year [7].
2. Pathophysiology
The Spinal Cord Injury could be divided by its etiology in traumatic and nontraumatic. The traumatic type is caused by physical damage (traffic accident, sportive, and fall), whereas nontraumatic is occasioned by an illness/sickness, such as tumors, infections or degenerative diseases which directly affect the SC [8]. In addition, SCI can be divided into primary and secondary injury [1, 9].
Primary injury is caused at the moment of physical damage and leads to irreversible affection on gray matter during the first hour post-lesion. There are three main mechanisms of injury: contusion, when there is not a visible alteration in its morphology, producing a necrotic region at the injury area; laceration or transection, when there is an extreme trauma or penetration, affecting SC conduction of nervous impulses depending on whether the tissue is partial or totally transected; compression from vertebral fractures leading ischemic damage in the area where blood flow was disrupted [10, 11].
After injury, superficial blood vessels undergo to vasospasm which provokes damage in the microvasculature of gray matter [12]. Reduction in the perfusion has two important implications: hypoxia and ischemia; which may involve to neurogenic shock characterized by arterial hypotension, bradycardia, arrhythmia, and intraparenchymal hemorrhage that causes neuronal death by necrosis. Afterwards, primary injury provokes the rupture of blood brain barrier and a cascade of destructive secondary phenomena leading to a further damage in SC and neurological dysfunction [1, 13]. Therefore, the primary lesion results in the development of a succession of cellular and molecular changes that alter gene expression patterns, which are processes that are already part of the secondary injury [11, 12]. During the acute phase, injury to the blood vessels and severe hemorrhages cause massive influx of inflammatory cells, cytokines, and vasoactive peptides. This phase is almost characterized by ionic deregulation that leads to edema, thus interrupting the conduction of nerve impulses. Following, subacute phase involves a sequence of events like ischemia, vasospasm, thrombosis, inflammatory response, free radicals (FR) production, lipid peroxidation (LPO), and activation of autoimmune responses causing apoptosis. The huge inflammatory responses after the acute and subacute phase, together with the disruption of the blood-brain barrier (BBB), contribute to the progressively swelling of the SC. This generalized edema may increase the mechanical pressure of the SC, aggravating the injury [1, 11, 14].
To counteract all these acute effects after SCI, neuroprotective strategies have been investigated to rapidly intervene decreasing the neuronal death occurring after damage mechanisms. Many pharmacological and nonpharmacological therapies have been developed, and others are still under investigation, this in order to improve the quality of life of patients.
3. Neuroprotective therapy after acute SCI
As we review previously, SCI leads to motor and sensory dysfunction, first with the primary mechanical injury and then with the complex cascade of secondary damaging events [15]. For several years, basic science, preclinical, and clinical studies are focused in overcoming elements involved in accurate recovery from SCI [1]. An ideal neuroprotective therapy must reduce neurological symptoms including degenerative changes; starting from there, we can discriminate between potential clinical therapies, which could have a better effect [16]. While these therapies are being searched, there are many preclinical and clinical investigations exploring pharmacological and nonpharmacological treatments.
3.1 Preclinical pharmacological therapies
This range of therapeutic approaches includes: ionic channel blockers, inhibitors of NMDA and AMPA-kainate receptors, inhibitors of FR and LPO, anti-apoptotic drugs, calpain inhibitors, immunosuppressive or immunomodulatory drugs, immunophilin ligands, immunomodulatory peptides, hypoglycemic agents, and gonadal hormones.
3.1.1 Ionic channel blockers
3.1.1.1 Sodium
3.1.1.1.1 Tetrodotoxin
Tetrodotoxin (TTX) is a low-molecular-weight guanidine neurotoxin that acts as a specific blocker of voltage-gated sodium (NaV) channel [17]. TTX has neuroprotective properties by blocking NaV channels, preventing neuronal death by diminishing depolarization, cellular Na+/Ca+2 exchange, and neuronal glutamate release [18].
The beneficial effects of TTX in preclinical studies include a reduction of white matter loss after SCI [17, 18, 19], promoting a motor function restoration. The effect of TTX is time-dependent [20]. The administration of TTX 15 minutes after a SCI helps to restore the function of hindlimbs [21]. Despite these promissory effects, there are some limitations for the use of TTX in patients, one of them is its toxicity. This may appear as a consequence of its systemic distribution and it can involve the blocking of diaphragmatic nerves ending in respiratory tract paralysis [17]. Even with previous findings, current studies are needed to improve its use in SCI.
3.1.1.1.2 Riluzole
Riluzole is a benzothiazole anticonvulsant drug with neuroprotective effects in the SCI [22]. One of the mechanisms by which riluzole operates is the inhibition in the presynaptic terminals of glutamate, and this helps to limit the glutamate-induced toxicity [23]. In addition, riluzole blocks the NaV-gated channels, avoiding swelling and neuronal acidosis. Riluzole blocks the entry of H+ to the neurons through the Na+/H+ exchanger; this prevents the Ca+2 from inducing the release of glutamate and excitotoxicity [22]. Investigations have shown that the interruption of events associated with glutamate release on the presynaptic space by reducing Ca+2 influxes provokes a glutamate-mediated LPO reduction [23, 24]. Administration of riluzole within 12 hours of SCI was well tolerated and suggests that it may have a beneficial effect on motor outcome [25].
3.1.1.2 Calcium
3.1.1.2.1 Nimodipine
Nimodipine is a dihydropyridinic Ca+2 channel antagonist that boosts the brain’s blood flow, without compromising metabolism [26, 27]. It reduces malondialdehyde (MDA) levels, ED-1 markers for activated macrophages and myeloperoxidase (MPo). Studies have shown that nimodipine helps reducing FR, oxidative damage, resulting in the reduction of the damaged area and the infiltration of the inflammatory cells to the region, allowing SCI restoration [26]. Furthermore, the effect of inhibiting Ca+2 flux by nimodipine reduces apoptosis and tissue damage after SCI, increasing cell viability [27].
3.1.2 Inhibitors of NMDA and AMPA-kainate receptors
3.1.2.1 Memantine
Memantine is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, which through the inhibition of hypoxic or ischemic damage/necrosis helps to prevent the secondary damage in SCI [28, 29]. The use of an NMDA antagonist limits neuronal glutamate exposure caused by excitatory amino acid neurotransmitters [29]. The use of memantine with anti-apoptotic agents like Q-VD-OPh boosts the neuroprotective effect through the reduction in apoptosis and necrosis mechanisms. Moreover, it provides better clinical and histological outcomes by limiting neuronal necrosis [28, 29].
3.1.2.2 Gacyclidine
Gacyclidine is a noncompetitive NMDA antagonist that is able to reduce the extension of ischemic lesions in SCI. It has been proven that gacyclidine is efficient in enhancing the functional and histological condition of the injury, but their neuroprotective effects are time and dose-dependent [30, 31].
3.1.2.3 NBQX (2,3-dihydroxy-6-nitro-7-sulfamoylbenzoquinoxaline)
NBQX is an AMPA/kainate antagonist that during acute SCI improves mitochondrial function and diminishes reactive oxygen species (ROS) formation as well as LPO production [32, 33]. The treatment with NBQX reduces white matter loss following SCI. Further studies are needed to know more about its efficacious effects in acute SCI.
3.1.3 Inhibitors of free radicals and lipid peroxidation
3.1.3.1 Polyunsaturated fatty acids (PUFAs)
Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are structural compounds of the phospholipid membrane. They produce beneficial effects in neurodegenerative diseases by its anti-inflammatory, antioxidant, and membrane stabilizing properties [34]. ω-3 PUFAs, particularly docosahexaenoic acid (DHA), exert profound anti-inflammatory effects on the central nervous system (CNS), confer significant protection to the white matter, and help to increase neurite growth and synapse formation. DHA acts on cyclooxygenases (COX), cytosolic phospholipase A2 (cPLA2), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) [35, 36]. Deficiencies of lipids affect neural responses in CNS injuries, and this must predispose nerve cells to dysfunction [37]. According to previous findings, there are some investigations (Table 1) that have previously shown the effects of PUFAs in preclinical models.
Treatment outcome | Ref. |
---|---|
α-linolenic acid (ALA) and DHA reduce lesion size and increase motor recovery and neuronal survival. | [34] |
DHA reduces microglia activation in both ventral and dorsal horns and increases motor recovery, promoting beneficial functional effect in SCI. | [38] |
ALA, combined with DHA, protects against neuronal necrosis and apoptosis. | [39] |
DHA induces a reduction in neutrophil number in SC epicenter. The administration confers histological protection and improves motor recovery. | [40] |
Prophylactic therapy with ω-3 has shown a reduction in cellular vulnerability. Supporting functional recovery, there is also an increase in levels of protein kinase B/Akt and CREB. | [37, 41] |
DHA plus rehabilitation enhance a functional, anatomical, and synaptic plasticity in cervical SCI. | [42] |
3.1.3.2 Glutathione
Glutathione (GSH) is a tripeptide compound constituted by glutamine, glycine, and cysteine. The reduced form of GSH is glutathione-monoethyl-ester (GSHE), which is an endogenous, rechargeable antioxidant. Besides its anti-oxidant functions, GSHE plays a role in regulation of apoptosis, and it is important for cellular defense against ROS [43, 44]. Some studies have reported that GSHE diminishes SC LPO after SCI, while also acting as a vasodilator under conditions of oxidative stress [44, 45]. In addition, GSHE plays an anti-excitotoxic role by inhibiting the binding ligands to ionotropic glutamate receptors under redox modulation, which have been involved in excitotoxicity after SCI. As a consequence of the reduction of GSH after an injury, there is neuronal loss in the SC, probably due to oxidative stress and mitochondrial dysfunction. Combined therapy of GSHE with A91 resulted in a better motor recovery and axonal sparing associated with a higher axonal myelination [46]. The use of GSHE could be an interesting alternative for SCI therapy; however, it should be strongly evaluated before its use in clinical trials.
3.1.4 Anti-apoptosis therapy
3.1.4.1 Zdevd-fmk
Caspase inhibitor Z-DEVD-fmk is a selective caspase-3 inhibitor that also has anti-inflammatory properties. Anti-apoptosis compounds are used to block apoptotic cell death but also to inhibit cytokine production. Treatment of SCI with z-DEVD reduces secondary tissue damage, ischemic injury, preserves motor function, and provides neuroprotection via the inhibition of cell death in all of cell types in the SC [47, 48]. Low doses of z-DEVD-fmk combined with basic fibroblast growth factor (bFGF) reduce neurological deficit in ischemia, therefore providing neuroprotection [49].
3.1.4.2 z-LEHD-fmk
Caspase inhibitor z-LEHD-fmk acts as a selective caspase-9 inhibitor with anti-apoptotic properties. This drug helps decreasing levels of apoptosis biochemical markers, reducing lesion size and remaining active during treatment to maintain its therapeutic effect. Treatment with z-LEHD-fmk helps to prevent apoptosis in a variety of cell types like neurons, astrocytes, oligodendrocytes, and microglia populations [50]. Further studies are needed to understand more about its effects and benefits in acute SCI.
3.1.5 Calpain inhibitors
Calpains belong to the family of calcium-dependent nonlysosomal cysteine proteases, which can be found expressed through the CNS. They are involved in neurodegeneration, degradation of cytoskeleton, and apoptosis via caspase-3 due to its proteolytic activities, in SCI. The influx of Ca+2 stimulates Ca+2-dependent enzymes, within them are calpains, which seem to play a role in proteolysis by contributing to apoptosis in CNS cells. The cell death decreases mRNA expression and transcription of myelin basic protein (MBP) and proteolipid protein (PLP), which are axonal neurofilament proteins [49, 51, 52]. The administration of a calpain inhibitor such as E-64-d (1 mg/kg) to injured rats blocks apoptosis and helps to re-establish MBP and PLP genes [51]. The administration of other calpain inhibitors such as SJA 6017 and calpeptin has demonstrated their ability to induce neuroprotection after SCI [53, 54]. Despite the study efforts and the promising therapeutic effects for functional neuroprotection, there are no clinical trials testing these drugs, so further studies are needed for the use of calpain inhibitors in patients.
3.1.6 Immunosuppressive or immunomodulatory drugs.
3.1.6.1 Inhibitors of cyclooxygenase
3.1.6.1.1 Indomethacin
Indomethacin, a nonsteroidal anti-inflammatory (NSAID) drug, acts as a nonselective cyclooxygenase inhibitor. It has shown that it inhibits the synthesis of prostaglandins and ameliorates the effects of secondary injuries like tissue necrosis in SCI [55, 56, 57]. RhoA is a convergent intracellular pathway that limits axonal growth; its inhibition with indomethacin prevents oligodendrocyte loss and induces myelination across damaged white matter [58]. Nevertheless, the administration of nonselective cyclooxygenase inhibitors is a controversial issue since these compounds could inhibit platelet aggregation and may produce gastrointestinal ulceration [55]. Moreover, there is evidence that a single injection of indomethacin in SCI had a minimal effect on functional recovery and anatomical repair [57].
3.1.6.1.2 Meloxicam
Meloxicam is a drug derived from enolic acid, which inhibits prostaglandin biosynthesis under inflammatory conditions via the inhibition of COX-2. It has minimal gastric toxicity. Meloxicam has shown to reduce SCI-induced oxidative stress and exert neuroprotection by inhibiting LPO, GSH depletion, and DNA fragmentation [59, 60]. Despite these interesting results, meloxicam has not been further studied. Therefore, more studies are needed to know about its clinical management in SCI.
3.1.7 Immunophilin ligands
3.1.7.1 Cyclosporine A
Cyclosporine A (CsA) is an immunosuppressant agent compound formed by 11 amino cyclic peptides, and it is obtained from
3.1.7.2 Tacrolimus
Tacrolimus or FK506 is an immunosuppressant macrolide drug, isolated from
3.1.8 With neural derived peptides
Immunization with neural derived peptides (INDP) such as A91, a peptide derived from the 87–99 immunogenic sequence of myelin basic protein has shown to induce neuroprotection and motor recovery after SCI [68]. Its mechanism of action is related to the activation of T-lymphocytes inducing an anti-inflammatory Th2 response that allows microglia to differentiate into a M2 phenotype. Th2 response is capable of producing brain-derived neurotrophic factor (BDNF), a molecule strongly related to tissue protection [69]. INDP has shown that anti-A91 T-lymphocytes promote tissue protection by inhibiting the expression of iNOS, reducing ON production [68] and decrease LPO after SCI [70]. On the other hand, it has been shown that all these beneficial effects contribute to the preservation of neural tissue by preventing apoptosis [71], the survival of neurons in rubrospinal tract [72] and promoting a better neurological recovery in models of SCI [46]. Studies suggest that A91 might be an immune modulating treatment for SCI.
3.1.9 Metformin
Metformin is a hypoglycemic agent used for therapy of type 2 diabetes mellitus; it is an AMP-activated protein kinase (AMPK) agonist. Metformin also acts through signaling pathway of mTOR and p70S6K causing an inhibition of apoptosis and inflammation. This drug is also capable of stimulating autophagy and reducing expression of NF-kB-mediated inflammation [73, 74]. Studies indicate that long-term use of metformin has been proved effective as a pharmacological treatment for some CNS disorders like Parkinson’s disease, Huntington’s disease, and ischemic brain injury. Using a rat model of traumatic SCI, the administration of metformin helps restoring the dysfunctional autophagy-lysosome pathways providing neuroprotection, decreasing neuronal death and mitigating apoptosis [75, 76]. The immediate administration of metformin after the injury showed diminishing complications, reflecting a decrease on histopathological signs of neuroinflammation, including TNFα and IL-1β inflammatory cytokines in the SC [73]. Although these outcomes are promising, subsequent studies are required to determine the risk ad optimal doses for the use of metformin on clinical studies.
3.1.10 Gonadal hormones
Androgens and estrogens are multi-active steroidal hormones that have neuroprotective effects in neural injuries; both testosterone and estradiol improve safeguard against apoptosis and promote motor and sensitive recovery. Also, reduce inflammation and FR generation and have been involved in regulating the expression of cytoskeletal proteins, promoting them as an increasing in neurite outgrowth [77, 78]. Studies in rats treated with estradiol have shown a reduction in the lesion size, an increase in white matter sparing, and an improving in motor function [77, 79, 80]. On the other hand, testosterone has shown to exert similar but not identical effects; it is neuroprotective against apoptosis in oxidative stress [77, 78]. A study with young adult female rats implanted with testosterone-filled silastic capsules reported regressive changes in motoneuron and muscle morphology after a SCI providing the possibility of improving motor function [81]. A study with administration of progesterone in rats improves neurological deficits and reduces inflammatory response. Prevents degeneration of motor neurons and reestablishes proliferation and differentiation of oligodendrocytes [82]. At the moment, investigations on the field conclude that gonadal hormones could be an effective alternative after SCI.
3.2 Clinical pharmacological therapies
Methylprednisolone, minocycline, GM-1-ganglioside, and glyburide are some of the most investigated pharmacological therapies in clinical settings.
3.2.1 Methylprednisolone
Methylprednisolone (MP) is a synthetic glucocorticoid, with anti-inflammatory and anti-oxidant effects [83, 84]. MP blocks the inflammatory cascade and disrupts neuron regeneration by inhibiting immunological cells [85, 86]. The potential neuroprotective effects of MP have been reported especially in the acute phase of SCI. According to some investigations, MP is capable of reducing FR production, Ca+2 influx, excitotoxicity, and immune-mediated phagocytosis over the course of hypoperfusion of SCI [87]. In addition, MP appears to have effect in apoptosis and autophagy regulation; however, the mechanisms are not clear [84]. While it remains the only option for acute SCI treatment in clinical settings, a debate regarding optimal dose, time of administration, efficacy, and adverse effects has dominated the field for years. There are three National Acute SCI Studies (NASCIS) and other clinical or biomedical investigations, in which the safety and efficacy of MP were assessed (Table 2) [88]. Despite the intense investigation, currently there is an important controversy regarding the real utility of this drug.
Treatment outcome | Ref. |
---|---|
NASCIS I: Treatment with a dose 1.0 g daily promotes neurological recovery. The morbidity and mortality is increased. | [89] |
NASCIS II: Administration of (30 mg/kg intravenous bolus plus 23 hour infusion of 5.4 mg/kg) during the first 8 hours after injury causes neurological recovery seen from 6 weeks after the SCI. | [86] |
NASCIS III: Administration within 8 hours from the SCI, should maintain the administration for 48 hours to improve neurological function. | [90] |
Combination of riluzole and MP improves functional recovery and tissue sparing. In addition, beneficial effects on oxidative stress were observed. | [91] |
MP may cause acute corticosteroid myopathy, at doses recommended by the NASCIS. | [92] |
High-dose MP inhibits glucocorticoid receptors as well as having effects in LPO; however, their beneficial effects are independent of LPO inhibition. | [55] |
Administration of MP for treatment of SCI is not recommended. There is evidence that high-dose steroids are associated with harmful side effects including death. | [93] |
A comparative study of MP vs. A91-immunization showed that A91-immunization has a better efficiency promoting motor recovery. Combining MP with A91-immunization allowed to observe that MP has a transient immunosuppressive effect that eliminated the beneficial actions of A91-immunization. | [94] |
3.2.2 Minocycline
Minocycline is a second generation tetracycline, a semi-synthetic antibiotic able to cross blood brain barrier, and it can be used to treat rheumatoid arthritis [95, 96]. Minocycline has neuroprotective effects when administered during the acute neural trauma. Current data suggest that minocycline has anti-inflammatory, immunomodulatory, and neuroprotective effects. These beneficial actions are achieved as a result of the inhibition of iNOS matrix metalloproteinases (MMPs), PLA2, TNF-α, caspase-1, and caspase-3. Moreover, minocycline enhances Bcl-2 and thus, reduces apoptosis, also, it decreases p38 mitogen-activated protein kinase (MAPK) phosphorylation and inhibits PARP-1 [97, 98, 99, 100]. Other studies report that minocycline can bind to Ca+2 and Mg+, reduces reactive astrocytes to increase oligodendrocyte viability in white matter, and inhibits the activation of microglial cells [101, 102]. A multi-center phase II trial was performed to explore the neuroprotective effect of minocycline; however, the results of the study did not establish a real improvement in SCI. Authors suggest further investigations in a multi-center phase III trial [103].
3.2.3 GM-1-ganglioside
Gangliosides (GM-1) are sialic acid-containing glycosphingolipids, present in cell membranes of CNS cells, specifically in the external leaflet of plasma membranes. They participate in the repair and maintenance of CNS [104, 105]. A randomized placebo-controlled (Phase II) trial with administration of GM-1 within 24 hours after injury was realized in 37 patients with SCI. The results of this study showed that GM-1 enhances the recovery of neurologic function after 1 year [104]. Further studies should be designed in order to provide more evidence about the efficacy of GM-1.
3.2.4 Glyburide
Glyburide (glibenclamide) is a FDA approved sulfonylurea drug widely used to treat type 2 diabetes; it has the ability to target receptor (SUR1) regulated Ca+2 activated [ATP] cation (NCCa-ATP) channels [96, 106]. After SCI, there are small hemorrhagic lesions at the epicenter of gray matter. Glyburide diminishes the progressive hemorrhage necrosis by jamming the interaction between SUR-1 and preforming subunits of NCCa-ATP channels located in endothelial cells. In addition, improves neurological function [107]. Actually, a phase I/II clinical trial is currently under way to test the safety and neuroprotective effectiveness of glyburide in patients with SCI [88].
4. Nonpharmacological therapies (preclinical interventions)
The most common preclinical nonpharmacological therapies in the acute phase of SCI are antioxidants, growth factors, and transplant of cultured cells like neural stem cells (NSCs), bone marrow stem cells (BMSCs), olfactory ensheathing cells (OECs), and Schwann cells (SCs).
4.1 Antioxidants
First damage in the acute phase of injury is generated in membranes, membranes which are susceptible to the attack of ROS and reactive nitrogen species (RNS). ROS are produced in metabolic and physiological processes of cells; however, they are overproduced by inflammatory response. ROS and RNS induce LPO, which leads to demyelinating processes. Among the nonpharmacological therapies to prevent damage from FR are nonenzymatic antioxidants like vitamins.
4.1.1 Vitamins
Vitamins are one of the main natural antioxidants. Table 3 shows some vitamins and their neuroprotective effect after SCI.
Treatment | Neuroprotection mechanism | Ref. |
---|---|---|
Vitamin E | Increases functional recovery. Reduces cavitation and decreases FR, LPO, and glutathione peroxidase and improves functional recovery. |
[108, 109, 110, 111, 112] |
Vitamin C | Stops lipid hydroperoxyides formation and decreases membrane damage. Reduces necrotic tissues and improves functional recovery in rats. Inhibits ROS generation and LPO. Decreases levels of proteins like NF-kB, iNOS, and COX-2. Down-regulates the levels of TNFα and IL-1β. Modulates antioxidant status and MPO activity |
[113, 114] |
Vitamin C + fluoxetine | Co-treatment with vitamin C + fluoxetine inhibits the blood-SC barrier disruption after SCI. Inhibits capillary fragmentation by reducing mRNA levels of MMP-9. Prevents degradation of tight-junction proteins, inhibits infiltration of neutrophils and macrophages. Inhibits apoptotic cell death and improves functional recovery. |
[115] |
Vitamin A | Increases the expression of IL-1β, IL-6, and TNFα after SCI. Systemic administration reduces early transcript levels of IL-1β, IL-6, and TNFα. Reduces blood-SC-barrier permeability and improves functional recovery |
[116] |
Decreases levels of β-catenin, P120 catenin, occluding, and claudin5. Inhibits endocytoplasmic reticulum stress and caspase-12 expression. |
[117] |
4.1.2 Resveratrol
Resveratrol is a natural polyphenolic compound that has exhibited beneficial health properties as well as antioxidant, anti-inflammatory, and antitumor effects. Resveratrol exerts a neuroprotective effect by regulating apoptosis [118]. Studies have shown that the anti-inflammatory effects of resveratrol are mediated mainly by sirtuin (SIRT) 1 [119, 120]. Resveratrol enhances locomotor recovery [121, 122, 123]. Furthermore, resveratrol increases nuclear factor erythroid 2-related factor (Nrf-2) activation, providing antioxidant effects [121]. Further investigation is needed in order to provide more evidence about the efficacy of this treatment.
4.2 Growth factors
The use of growth factors like BDNF, transforming growth factor-β (TGF-β), and insulin-like growth factor-1 (IGF-1) as a therapy to improve morphological and behavioral outcomes after SCI has been topic of study of many investigations.
4.2.1 Brain-derived neurotrophic factor
BDNF exerts a relevant function in the repair of neural tissue and plasticity in CNS [124, 125]. Nevertheless, recent studies have also shown that BDNF is capable of exerting neuroprotective effects. In acute phases of injury, several reports indicate that both, BDNF alone [126, 127] or in any combination [128, 129] has improved functional recovery, neuronal survival, and tissue preservation. Moreover, BDNF has potent antioxidant effects and may be involved in regulation of immune responses after an SCI [130]. BDNF after SCI requires careful selection to consider the location, mode, and time of application after an injury.
4.2.2 Transforming growth factor-β
TGF-β is a pleiotropic molecule with specific key functions in cell differentiation, proliferation, migration, immunosuppression, and extracellular matrix metabolism [131]. TGF-β could also be contributing to neuroprotective mechanisms after SCI since it participates in the regulation of neuronal survival and orchestrates repairing processes in the CNS [132]. It has been previously observed that TGF-β administration reduces microglial activation and increases neuronal survival [133]. The early induction of TGF-β after SCI modulates the acute immune response, the formation of glial scar and improves functional recovery [134].
4.2.3 Insulin-like growth factor-1
IGF-1 belongs to the family of insulin-related peptides, and it is the mediator of the anabolic and mitogenic activity of the growth hormone [135]. Aside from this, IGF-1 acts as a strong antioxidant [136] and pro-survival [137] factor in the CNS since it diminishes caspase-9 and elevates Bcl2 [138]. Experimental studies have shown that IGF-1 reduces edema and the upregulation of iNOS after SCI [139]. In the same way, it has been suggested that IGF-1 and erythropoietin protect against ischemic SCI in rabbits [140]. Therefore, the beneficial properties of IGF-1 make this molecule an interesting neuroprotective strategy in the acute phase of SCI.
4.3 Stem cells
Stem cells have also been the focus of several investigations. Table 4 summarizes some of the neuroprotective effects exerted by stem cells like NSCs, BMSCs, OECs, and SCs.
Therapy | Neuroprotective effects | Ref. |
---|---|---|
NSCs | Increase functional recovery. Reduction in neutrophils and M1 macrophages. Downregulation of TNFα, IL-1 β, IL-6, and IL-12. Improve functional recovery and reduce neuronal apoptosis, microglia activation, reduce pro-inflammatory cytokines like TNFα, IL-1β, and IL-6. Improve locomotor and sensory function and increase mRNA expression of BDNF. |
[141, 142, 143, 144] |
BMSCs | Improve locomotor function and tissue protection. Increase the neurotrophic growth factor. Stimulate M2 macrophage activation. Reduce cystic cavities size and suppress glial scar formation. |
[145, 146, 147, 148] |
BMSCs + SCs | Reduce the formation of the glial scar, remyelinate the injured axons, and promote functional recovery | [149] |
BMSCs + IGF-1 | Induce modulation of inflammatory cytokines and oxidative stress. Increase functional recovery and reduce activation of glial fibrillary acidic protein and increase myelination 4 weeks following SCI. |
[150] |
BMSCs + OECs | Reduce apoptosis and increase locomotor recovery. | [151] |
OECs | Reduce cavity size, increase the neurofilaments sprouting and serotonin axons, and improve functionality. | [152] |
OECs + SCs | Diminish astrocyte number, microglia/macrophage infiltration and expression of CCL2 and CCL3. | [153] |
SCs | Upregulate the expression of NOS, activate the NO-dependent cyclic-GMP pathway, which enhances neuronal survival. Stimulate the expression of neural growth factor and BDNF. Reduce inflammatory cytokines and ROS. |
[154, 155] |
SCs + NSCs | Promote neuronal differentiation, increase axonal regeneration/myelination, reduce neuronal loss, and improve functional recovery. | [156] |
5. Nonpharmacological therapies (clinical trials)
Nonpharmacological therapies with clinical studies are hence limited in acute phases of the injury.
5.1 Stem cells neural stem cells
Pilot studies cover the acute phase of SCI.
5.1.1 Neural stem cells
Transplants with human NSCs in phase I/IIa assessed the safety and neurological effects after SCI. Of 19 treated subjects, 17 were sensorimotor complete and two were motor complete and sensory incomplete. They demonstrated that 1 year after cell transplantation, there was no evidence of SC damage, syrinx or tumor formation, neurological deterioration, and exacerbating neuropathic pain or spasticity [157]. Additional studies should be designed in order to afford more evidence about the efficacy of NSCs.
5.1.2 Bone marrow stem cells
Regarding bone marrow stem cells (BMSC), an interesting study reported data from 20 patients with complete SCI who received transplants of BMSC. They showed improvement in motor and sensory functions [158]. In addition, a study with autologous BMSCs in three patients in the sub-acute phase of injury (<6 months of disease) demonstrated that, these cells could be safely administered through intrathecal injection in SCI patients [159]. Other study showed that 45.5% of transplanted patients presented improved neurological function. They showed some degree of improvement in sensitivity and motor function as well as in sexual function. In two patients, neuropathic pain disappeared and bladder and bowel control increased [160]. Nevertheless, more investigation through clinical trials is required with a larger population of patients before further conclusions can be drawn.
5.1.3 Olfactory ensheathing cells
Transplants with autologous OECs in three patients indicated that there were no adverse effects 1 year after transplantation. The neurosurgical process did not lead to any negative sequelae either during the operation or postoperatively. Additionally, they demonstrated the possibility of taking a nasal biopsy and reliably generating enough cells for transplantation within 4 weeks [161]. These observations suggest that autologous transplantation is safe but further researches are needed.
5.1.4 Schwann cells
A Phase I clinical trial with autologous human SCs was conducted to evaluate the safety of transplantation into the injury of six subjects with subacute SCI. There was no evidence of additional SC damage, mass lesion or syrinx formation. They conclude that it is feasible to identify eligible candidates, appropriately obtain informed consent, perform a peripheral nerve harvest to obtain SCs within 5–30 days of injury, and perform intra-spinal transplantation of highly purified autologous SCs within 4–7 weeks of injury [162]. Studies in acute phases using SCs are very few: therefore, more studies are needed in this area.
5.2 Physical therapy
Timing as a specific prognostic factor in rehabilitation results and confirms that early specific rehabilitation treatment is associated with greater improvement. Several studies investigate the early rehabilitation as a therapeutic strategy to improve locomotor function, some of them have even shown physical functional independence [163, 164, 165]. Other studies indicated that in acute SCI physical therapy of body weight support on a treadmill and defined overground mobility therapy did not produce different results [166]. Further studies are required to afford conclusive results.
6. Conclusions
In conclusion, there are several pharmacological and nonpharmacological treatments that have been tested in preclinical and clinical phases. However, so far have not yielded fully satisfactory results; even using combined therapies. Further studies are needed in order to identify novel therapeutic targets and strategies that provide a better medical care avoiding complications.
Acknowledgments
We gratefully acknowledge to Universidad Anáhuac México Norte for the support to this chapter.
References
- 1.
Ahuja CS, Wilson JR, Nori S, Kotter MRN, Druschel C, Curt A, et al. Traumatic spinal cord injury. Nature Reviews. Disease Primers. 2017; 3 :17018 - 2.
Rowland JW, Hawryluk GW, Kwon B, Fehlings MG. Current status of acute spinal cord injury pathophysiology and emerging therapies: Promise on the horizon. Neurosurgical Focus. 2008; 25 (5):E2 - 3.
Zhou Y, Wang Z, Li J, Li X, Xiao J. Fibroblast growth factors in the management of spinal cord injury. Journal of Cellular and Molecular Medicine. 2018; 22 (1):25-37 - 4.
Lenehan B, Street J, Kwon BK, Noonan V, Zhang H, Fisher CG, et al. The epidemiology of traumatic spinal cord injury in British Columbia, Canada. Spine (Phila Pa 1976). 2012; 37 (4):321-329 - 5.
Chen Y, He Y, DeVivo MJ. Changing demographics and injury profile of new traumatic spinal cord injuries in the United States, 1972-2014. Archives of Physical Medicine and Rehabilitation. 2016; 97 (10):1610-1619 - 6.
van den Berg ME, Castellote JM, Mahillo-Fernandez I, de Pedro-Cuesta J. Incidence of spinal cord injury worldwide: A systematic review. Neuroepidemiology. 2010; 34 (3):184-192; discussion 92 - 7.
Estrada-Mondaca S, Carreon-Rodriguez A, Parra-Cid del C, Leon CI, Velasquillo-Martinez C, Vacanti CA, et al. Spinal cord injury and regenerative medicine. Salud Pública de México. 2007; 49 (6):437-444 - 8.
Rouanet C, Reges D, Rocha E, Gagliardi V, Silva GS. Traumatic spinal cord injury: Current concepts and treatment update. Arquivos de Neuro-Psiquiatria. 2017; 75 (6):387-393 - 9.
Kim YH, Ha KY, Kim SI. Spinal cord injury and related clinical trials. Clinics in Orthopedic Surgery. 2017; 9 (1):1-9 - 10.
Dalbayrak S, Yaman O, Yilmaz T. Current and future surgery strategies for spinal cord injuries. World Journal of Orthopedics. 2015; 6 (1):34-41 - 11.
Dumont RJ, Okonkwo DO, Verma S, Hurlbert RJ, Boulos PT, Ellegala DB, et al. Acute spinal cord injury, part I: Pathophysiologic mechanisms. Clinical Neuropharmacology. 2001; 24 (5):254-264 - 12.
Mautes AE, Weinzierl MR, Donovan F, Noble LJ. Vascular events after spinal cord injury: Contribution to secondary pathogenesis. Physical Therapy. 2000; 80 (7):673-687 - 13.
Hilton BJ, Moulson AJ, Tetzlaff W. Neuroprotection and secondary damage following spinal cord injury: Concepts and methods. Neuroscience Letters. 2017; 652 :3-10 - 14.
Oyinbo CA. Secondary injury mechanisms in traumatic spinal cord injury: A nugget of this multiply cascade. Acta Neurobiologiae Experimentalis (Wars). 2011; 71 (2):281-299 - 15.
Hulsebosch CE. Recent advances in pathophysiology and treatment of spinal cord injury. Advances in Physiology Education. 2002; 26 (1-4):238-255 - 16.
von Euler M, Li-Li M, Whittemore S, Seiger A, Sundstrom E. No protective effect of the NMDA antagonist memantine in experimental spinal cord injuries. Journal of Neurotrauma. 1997; 14 (1):53-61 - 17.
Melnikova DI, Khotimchenko YS, Magarlamov TY. Addressing the issue of tetrodotoxin targeting. Marine Drugs. 2018; 16 (10):352 - 18.
Liu WM, Wu JY, Li FC, Chen QX. Ion channel blockers and spinal cord injury. Journal of Neuroscience Research. 2011; 89 (6):791-801 - 19.
Rosenberg LJ, Teng YD, Wrathall JR. Effects of the sodium channel blocker tetrodotoxin on acute white matter pathology after experimental contusive spinal cord injury. The Journal of Neuroscience. 1999; 19 (14):6122-6133 - 20.
Rosenberg LJ, Wrathall JR. Time course studies on the effectiveness of tetrodotoxin in reducing consequences of spinal cord contusion. Journal of Neuroscience Research. 2001; 66 (2):191-202 - 21.
Teng YD, Wrathall JR. Local blockade of sodium channels by tetrodotoxin ameliorates tissue loss and long-term functional deficits resulting from experimental spinal cord injury. The Journal of Neuroscience. 1997; 17 (11):4359-4366 - 22.
Wilson JR, Fehlings MG. Riluzole for acute traumatic spinal cord injury: A promising neuroprotective treatment strategy. World Neurosurgery. 2014; 81 (5-6):825-829 - 23.
Wang SJ, Wang KY, Wang WC. Mechanisms underlying the riluzole inhibition of glutamate release from rat cerebral cortex nerve terminals (synaptosomes). Neuroscience. 2004; 125 (1):191-201 - 24.
Mu X, Azbill RD, Springer JE. Riluzole improves measures of oxidative stress following traumatic spinal cord injury. Brain Research. 2000; 870 (1-2):66-72 - 25.
Grossman RG, Fehlings MG, Frankowski RF, Burau KD, Chow DS, Tator C, et al. A prospective, multicenter, phase I matched-comparison group trial of safety, pharmacokinetics, and preliminary efficacy of riluzole in patients with traumatic spinal cord injury. Journal of Neurotrauma. 2014; 31 (3):239-255 - 26.
Jia YF, Gao HL, Ma LJ, Li J. Effect of nimodipine on rat spinal cord injury. Genetics and Molecular Research. 2015; 14 (1):1269-1276 - 27.
Cai Y, Fan R, Hua T, Liu H, Li J. Nimodipine alleviates apoptosis-mediated impairments through the mitochondrial pathway after spinal cord injury. Current Zoology. 2015; 57 (3):340-349 - 28.
Aydoseli A, Can H, Aras Y, Sabanci PA, Akcakaya MO, Unal OF. Memantine and Q-VD-OPh treatments in experimental spinal cord injury: Combined inhibition of necrosis and apoptosis. Turkish Neurosurgery. 2016; 26 (5):783-789 - 29.
Ehrlich M, Knolle E, Ciovica R, Bock P, Turkof E, Grabenwoger M, et al. Memantine for prevention of spinal cord injury in a rabbit model. The Journal of Thoracic and Cardiovascular Surgery. 1999; 117 (2):285-291 - 30.
Gaviria M, Privat A, d'Arbigny P, Kamenka J, Haton H, Ohanna F. Neuroprotective effects of a novel NMDA antagonist, gacyclidine, after experimental contusive spinal cord injury in adult rats. Brain Research. 2000; 874 (2):200-209 - 31.
Gaviria M, Privat A, d'Arbigny P, Kamenka JM, Haton H, Ohanna F. Neuroprotective effects of gacyclidine after experimental photochemical spinal cord lesion in adult rats: Dose-window and time-window effects. Journal of Neurotrauma. 2000; 17 (1):19-30 - 32.
Liu S, Ruenes GL, Yezierski RP. NMDA and non-NMDA receptor antagonists protect against excitotoxic injury in the rat spinal cord. Brain Research. 1997; 756 (1):160-167 - 33.
Mu X, Azbill RD, Springer JE. NBQX treatment improves mitochondrial function and reduces oxidative events after spinal cord injury. Journal of Neurotrauma. 2002; 19 (8):917-927 - 34.
King VR, Huang WL, Dyall SC, Curran OE, Priestley JV, Michael-Titus AT. Omega-3 fatty acids improve recovery, whereas omega-6 fatty acids worsen outcome, after spinal cord injury in the adult rat. The Journal of Neuroscience. 2006; 26 (17):4672-4680 - 35.
Zendedel A, Habib P, Dang J, Lammerding L, Hoffmann S, Beyer C, et al. Omega-3 polyunsaturated fatty acids ameliorate neuroinflammation and mitigate ischemic stroke damage through interactions with astrocytes and microglia. Journal of Neuroimmunology. 2015; 278 :200-211 - 36.
Ward RE, Huang W, Curran OE, Priestley JV, Michael-Titus AT. Docosahexaenoic acid prevents white matter damage after spinal cord injury. Journal of Neurotrauma. 2010; 27 (10):1769-1780 - 37.
Figueroa JD, Cordero K, Llán MS, De Leon M. Dietary omega-3 polyunsaturated fatty acids improve the neurolipidome and restore the DHA status while promoting functional recovery after experimental spinal cord injury. Journal of Neurotrauma. 2013; 30 (10):853-868 - 38.
Lim SN, Huang W, Hall JC, Michael-Titus AT, Priestley JV. Improved outcome after spinal cord compression injury in mice treated with docosahexaenoic acid. Experimental Neurology. 2013; 239 :13-27 - 39.
Lang-Lazdunski L, Blondeau N, Jarretou G, Lazdunski M, Heurteaux C. Linolenic acid prevents neuronal cell death and paraplegia after transient spinal cord ischemia in rats. Journal of Vascular Surgery. 2003; 38 (3):564-575 - 40.
Hall JC, Priestley JV, Perry VH, Michael-Titus AT. Docosahexaenoic acid, but not eicosapentaenoic acid, reduces the early inflammatory response following compression spinal cord injury in the rat. Journal of Neurochemistry. 2012; 121 (5):738-750 - 41.
Figueroa JD, Cordero K, Serrano-Illan M, Almeyda A, Baldeosingh K, Almaguel FG, et al. Metabolomics uncovers dietary omega-3 fatty acid-derived metabolites implicated in anti-nociceptive responses after experimental spinal cord injury. Neuroscience. 2013; 255 :1-18 - 42.
Liu ZH, Yip PK, Priestley JV, Michael-Titus AT. A single dose of docosahexaenoic acid increases the functional recovery promoted by rehabilitation after cervical spinal cord injury in the rat. Journal of Neurotrauma. 2017; 34 (9):1766-1777 - 43.
Dringen R, Gutterer JM, Hirrlinger J. Glutathione metabolism in brain metabolic interaction between astrocytes and neurons in the defense against reactive oxygen species. European Journal of Biochemistry. 2000; 267 (16):4912-4916 - 44.
Guizar-Sahagun G, Ibarra A, Espitia A, Martinez A, Madrazo I, Franco-Bourland RE. Glutathione monoethyl ester improves functional recovery, enhances neuron survival, and stabilizes spinal cord blood flow after spinal cord injury in rats. Neuroscience. 2005; 130 (3):639-649 - 45.
Santoscoy C, Rios C, Franco-Bourland RE, Hong E, Bravo G, Rojas G, et al. Lipid peroxidation by nitric oxide supplements after spinal cord injury: Effect of antioxidants in rats. Neuroscience Letters. 2002; 330 (1):94-98 - 46.
Martinon S, Garcia E, Flores N, Gonzalez I, Ortega T, Buenrostro M, et al. Vaccination with a neural-derived peptide plus administration of glutathione improves the performance of paraplegic rats. The European Journal of Neuroscience. 2007; 26 (2):403-412 - 47.
Barut S, Unlu YA, Karaoglan A, Tuncdemir M, Dagistanli FK, Ozturk M, et al. The neuroprotective effects of z-DEVD.fmk, a caspase-3 inhibitor, on traumatic spinal cord injury in rats. Surgical Neurology. 2005;64(3):213-220. discussion 20 - 48.
Yakovlev AG, Knoblach SM, Fan L, Fox GB, Goodnight R, Faden AI. Activation of CPP32-like caspases contributes to neuronal apoptosis and neurological dysfunction after traumatic brain injury. The Journal of Neuroscience. 1997; 17 (19):7415-7424 - 49.
Ray SK, Hogan EL, Banik NL Calpain in the pathophysiology of spinal cord injury: Neuroprotection with calpain inhibitors. Brain Research. Brain Research Reviews. 2003; 42 (2):169-185 - 50.
Colak A, Karaoglan A, Barut S, Kokturk S, Akyildiz AI, Tasyurekli M. Neuroprotection and functional recovery after application of the caspase-9 inhibitor z-LEHD-fmk in a rat model of traumatic spinal cord injury. Journal of Neurosurgery. Spine. 2005; 2 (3):327-334 - 51.
Ray SK, Matzelle DD, Sribnick EA, Guyton MK, Wingrave JM, Banik NL. Calpain inhibitor prevented apoptosis and maintained transcription of proteolipid protein and myelin basic protein genes in rat spinal cord injury. Journal of Chemical Neuroanatomy. 2003; 26 (2):119-124 - 52.
Sun JF, Yang HL, Huang YH, Chen Q , Cao XB, Li DP, et al. CaSR and calpain contribute to the ischemia reperfusion injury of spinal cord. Neuroscience Letters. 2017; 646 :49-55 - 53.
Schumacher PA, Siman RG, Fehlings MG. Pretreatment with calpain inhibitor CEP-4143 inhibits calpain I activation and cytoskeletal degradation, improves neurological function, and enhances axonal survival after traumatic spinal cord injury. Journal of Neurochemistry. 2000; 74 (4):1646-1655 - 54.
Arataki S, Tomizawa K, Moriwaki A, Nishida K, Matsushita M, Ozaki T, et al. Calpain inhibitors prevent neuronal cell death and ameliorate motor disturbances after compression-induced spinal cord injury in rats. Journal of Neurotrauma. 2005; 22 (3):398-406 - 55.
Resnick DK, Graham SH, Dixon CE, Marion DW. Role of cyclooxygenase 2 in acute spinal cord injury. Journal of Neurotrauma. 1998; 15 (12):1005-1013 - 56.
Resnick DK, Nguyen P, Cechvala CF. Selective cyclooxygenase 2 inhibition lowers spinal cord prostaglandin concentrations after injury. The Spine Journal. 2001; 1 (6):437-441 - 57.
Popovich PG, Tovar CA, Wei P, Fisher L, Jakeman LB, Basso DM. A reassessment of a classic neuroprotective combination therapy for spinal cord injured rats: LPS/pregnenolone/indomethacin. Experimental Neurology. 2012; 233 (2):677-685 - 58.
Xing B, Li H, Wang HY, Mukhopadhyay D, Fisher D, Gilpin CJ, et al. RhoA-inhibiting NSAIDs promote axonal myelination after spinal cord injury. Experimental Neurology. 2011; 231 (2):247-260 - 59.
Ogino K, Hatanaka K, Kawamura M, Katori M, Harada Y. Evaluation of pharmacological profile of meloxicam as an anti-inflammatory agent, with particular reference to its relative selectivity for cyclooxygenase-2 over cyclooxygenase-1. Pharmacology. 1997; 55 (1):44-53 - 60.
Hakan T, Toklu HZ, Biber N, Celik H, Erzik C, Ogunc AV, et al. Meloxicam exerts neuroprotection on spinal cord trauma in rats. The International Journal of Neuroscience. 2011; 121 (3):142-148 - 61.
Chen ZR, Ma Y, Guo HH, Lu ZD, Jin QH. Therapeutic efficacy of cyclosporin a against spinal cord injury in rats with hyperglycemia. Molecular Medicine Reports. 2018; 17 (3):4369-4375 - 62.
Attur MG, Patel R, Thakker G, Vyas P, Levartovsky D, Patel P, et al. Differential anti-inflammatory effects of immunosuppressive drugs: Cyclosporin, rapamycin and FK-506 on inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2 and PGE2 production. Inflammation Research. 2000; 49 (1):20-26 - 63.
Ibarra A, Correa D, Willms K, Merchant MT, Guizar-Sahagun G, Grijalva I, et al. Effects of cyclosporin-a on immune response, tissue protection and motor function of rats subjected to spinal cord injury. Brain Research. 2003; 979 (1-2):165-178 - 64.
Gold BG, Udina E, Bourdette D, Navarro X. Neuroregenerative and neuroprotective actions of neuroimmunophilin compounds in traumatic and inflammatory neuropathies. Neurological Research. 2004; 26 (4):371-380 - 65.
Kaymaz M, Emmez H, Bukan N, Dursun A, Kurt G, Paşaoğlu H, et al. Effectiveness of FK506 on lipid peroxidation in the spinal cord following experimental traumatic injury. Spinal Cord. 2005; 43 (1):22-26 - 66.
Saganova K, Galik J, Blasko J, Korimova A, Racekova E, Vanicky I. Immunosuppressant FK506: Focusing on neuroprotective effects following brain and spinal cord injury. Life Sciences. 2012; 91 (3-4):77-82 - 67.
Nottingham S, Knapp P, Springer J. FK506 treatment inhibits caspase-3 activation and promotes oligodendroglial survival following traumatic spinal cord injury. Experimental Neurology. 2002; 177 (1):242-251 - 68.
Karin N, Mitchell DJ, Brocke S, Ling N, Steinman L. Reversal of experimental autoimmune encephalomyelitis by a soluble peptide variant of a myelin basic protein epitope: T cell receptor antagonism and reduction of interferon gamma and tumor necrosis factor alpha production. The Journal of Experimental Medicine. 1994; 180 (6):2227-2237 - 69.
Martinon S, Garcia E, Gutierrez-Ospina G, Mestre H, Ibarra A. Development of protective autoimmunity by immunization with a neural-derived peptide is ineffective in severe spinal cord injury. PLoS One. 2012; 7 (2):e32027 - 70.
Martiñón S, García E, Gutierrez-Ospina G, Mestre H, Ibarra A. Development of protective autoimmunity by immunization with a neural-derived peptide is ineffective in severe spinal cord injury. PloS one. 2012; 7 (2):e32027-e - 71.
Rodriguez-Barrera R, Fernandez-Presas AM, Garcia E, Flores-Romero A, Martinon S, Gonzalez-Puertos VY, et al. Immunization with a neural-derived peptide protects the spinal cord from apoptosis after traumatic injury. BioMed Research International. 2013; 2013 :827517 - 72.
del Rayo Garrido M, Silva-Garcia R, Garcia E, Martinon S, Morales M, Mestre H, et al. Therapeutic window for combination therapy of A91 peptide and glutathione allows delayed treatment after spinal cord injury. Basic and Clinical Pharmacology and Toxicology. 2013; 112 (5):314-318 - 73.
Afshari K, Dehdashtian A, Haddadi NS, Haj-Mirzaian A, Iranmehr A, Ebrahimi MA, et al. Anti-inflammatory effects of metformin improve the neuropathic pain and locomotor activity in spinal cord injured rats: Introduction of an alternative therapy. Spinal Cord. 2018; 56 (11):1032-1041 - 74.
Wang C, Liu C, Gao K, Zhao H, Zhou Z, Shen Z, et al. Metformin preconditioning provide neuroprotection through enhancement of autophagy and suppression of inflammation and apoptosis after spinal cord injury. Biochemical and Biophysical Research Communications. 2016; 477 (4):534-540 - 75.
Zhang D, Xuan J, Zheng BB, Zhou YL, Lin Y, Wu YS, et al. Metformin improves functional recovery after spinal cord injury via autophagy flux stimulation. Molecular Neurobiology. 2017; 54 (5):3327-3341 - 76.
Markowicz-Piasecka M, Sikora J, Szydłowska A, Skupień A, Mikiciuk-Olasik E, Huttunen KM. Metformin—A future therapy for neurodegenerative diseases. In: Brambilla D, editor. Drug Discovery, Development and Delivery in Alzheimer’s Disease. Pharmaceutical Research. 2017;34(12):2614-2627 - 77.
Sengelaub DR, Xu XM. Protective effects of gonadal hormones on spinal motoneurons following spinal cord injury. Neural Regeneration Research. 2018; 13 (6):971-976 - 78.
Sengelaub DR, Han Q , Liu NK, Maczuga MA, Szalavari V, Valencia SA, et al. Protective effects of estradiol and dihydrotestosterone following spinal cord injury. Journal of Neurotrauma. 2018; 35 (6):825-841 - 79.
Samantaray S, Das A, Matzelle DC, Yu SP, Wei L, Varma A, et al. Administration of low dose estrogen attenuates gliosis and protects neurons in acute spinal cord injury in rats. Journal of Neurochemistry. 2016; 136 (5):1064-1073 - 80.
Yune TY, Kim SJ, Lee SM, Lee YK, Oh YJ, Kim YC, et al. Systemic administration of 17beta-estradiol reduces apoptotic cell death and improves functional recovery following traumatic spinal cord injury in rats. Journal of Neurotrauma. 2004; 21 (3):293-306 - 81.
Byers JS, Huguenard AL, Kuruppu D, Liu NK, Xu XM, Sengelaub DR. Neuroprotective effects of testosterone on motoneuron and muscle morphology following spinal cord injury. The Journal of Comparative Neurology. 2012; 520 (12):2683-2696 - 82.
Brotfain E, Gruenbaum SE, Boyko M, Kutz R, Zlotnik A, Klein M. Neuroprotection by estrogen and progesterone in traumatic brain injury and spinal cord injury. Current Neuropharmacology. 2016; 14 (6):641-653 - 83.
Bains M, Hall ED. Antioxidant therapies in traumatic brain and spinal cord injury. Biochimica et Biophysica Acta. 2012; 1822 (5):675-684 - 84.
Gao W, Chen SR, Wu MY, Gao K, Li YL, Wang HY, et al. Methylprednisolone exerts neuroprotective effects by regulating autophagy and apoptosis. Neural Regeneration Research. 2016; 11 (5):823-828 - 85.
Evaniew N, Noonan VK, Fallah N, Kwon BK, Rivers CS, Ahn H, et al. Methylprednisolone for the treatment of patients with acute spinal cord injuries: A propensity score-matched cohort study from a Canadian multi-Center spinal cord injury registry. Journal of Neurotrauma. 2015; 32 (21):1674-1683 - 86.
Bracken MB, Shepard MJ, Collins WF, Holford TR, Baskin DS, Eisenberg HM, et al. Methylprednisolone or naloxone treatment after acute spinal cord injury: 1-year follow-up data. Results of the second National acute spinal cord injury study. Journal of Neurosurgery. 1992; 76 (1):23-31 - 87.
Coutinho AE, Chapman KE. The anti-inflammatory and immunosuppressive effects of glucocorticoids, recent developments and mechanistic insights. Molecular and Cellular Endocrinology. 2011; 335 (1):2-13 - 88.
Ulndreaj A, Badner A, Fehlings MG. Promising neuroprotective strategies for traumatic spinal cord injury with a focus on the differential effects among anatomical levels of injury. F1000Res. 2017; 6 :1907 - 89.
Bracken MB, Shepard MJ, Hellenbrand KG, Collins WF, Leo LS, Freeman DF, et al. Methylprednisolone and neurological function 1 year after spinal cord injury. Results of the National acute spinal cord injury study. Journal of Neurosurgery. 1985; 63 (5):704-713 - 90.
Bracken MB, Shepard MJ, Holford TR, Leo-Summers L, Aldrich EF, Fazl M, et al. Administration of methylprednisolone for 24 or 48 hours or tirilazad mesylate for 48 hours in the treatment of acute spinal cord injury. Results of the third National acute spinal cord injury randomized controlled trial. National acute spinal cord injury study. Journal of the American Medical Association. 1997; 277 (20):1597-1604 - 91.
Mu X, Azbill RD, Springer JE. Riluzole and methylprednisolone combined treatment improves functional recovery in traumatic spinal cord injury. Journal of Neurotrauma. 2000; 17 (9):773-780 - 92.
Qian T, Guo X, Levi AD, Vanni S, Shebert RT, Sipski ML. High-dose methylprednisolone may cause myopathy in acute spinal cord injury patients. Spinal Cord. 2005; 43 (4):199-203 - 93.
Hurlbert RJ, Hadley MN, Walters BC, Aarabi B, Dhall SS, Gelb DE, et al. Pharmacological therapy for acute spinal cord injury. Neurosurgery. 2013; 72 (Suppl 2):93-105 - 94.
Ibarra A, Hauben E, Butovsky O, Schwartz M. The therapeutic window after spinal cord injury can accommodate T cell-based vaccination and methylprednisolone in rats. The European Journal of Neuroscience. 2004; 19 (11):2984-2990 - 95.
Festoff BW, Ameenuddin S, Arnold PM, Wong A, Santacruz KS, Citron BA. Minocycline neuroprotects, reduces microgliosis, and inhibits caspase protease expression early after spinal cord injury. Journal of Neurochemistry. 2006; 97 (5):1314-1326 - 96.
Tator CH, Hashimoto R, Raich A, Norvell D, Fehlings MG, Harrop JS, et al. Translational potential of preclinical trials of neuroprotection through pharmacotherapy for spinal cord injury. Journal of Neurosurgery. Spine. 2012; 17 (1 Suppl):157-229 - 97.
Garrido-Mesa N, Zarzuelo A, Galvez J. Minocycline: Far beyond an antibiotic. British Journal of Pharmacology. 2013; 169 (2):337-352 - 98.
Lee SM, Yune TY, Kim SJ, Park DW, Lee YK, Kim YC, et al. Minocycline reduces cell death and improves functional recovery after traumatic spinal cord injury in the rat. Journal of Neurotrauma. 2003; 20 (10):1017-1027 - 99.
Stirling DP, Koochesfahani KM, Steeves JD, Tetzlaff W. Minocycline as a neuroprotective agent. The Neuroscientist. 2005; 11 (4):308-322 - 100.
Marchand F, Tsantoulas C, Singh D, Grist J, Clark AK, Bradbury EJ, et al. Effects of etanercept and minocycline in a rat model of spinal cord injury. European Journal of Pain. 2009; 13 (7):673-681 - 101.
Moini-Zanjani T, Ostad SN, Labibi F, Ameli H, Mosaffa N, Sabetkasaei M. Minocycline effects on IL-6 concentration in macrophage and microglial cells in a rat model of neuropathic pain. Iranian Biomedical Journal. 2016; 20 (5):273-279 - 102.
Tan AM, Zhao P, Waxman SG, Hains BC. Early microglial inhibition preemptively mitigates chronic pain development after experimental spinal cord injury. Journal of Rehabilitation Research and Development. 2009; 46 (1):123-133 - 103.
Casha S, Zygun D, McGowan MD, Bains I, Yong VW, Hurlbert RJ. Results of a phase II placebo-controlled randomized trial of minocycline in acute spinal cord injury. Brain. 2012; 135 (Pt 4):1224-1236 - 104.
Geisler FH, Dorsey FC, Coleman WP. Recovery of motor function after spinal-cord injury—A randomized, placebo-controlled trial with GM-1 ganglioside. The New England Journal of Medicine. 1991; 324 (26):1829-1838 - 105.
Palmano K, Rowan A, Guillermo R, Guan J, McJarrow P. The role of gangliosides in neurodevelopment. Nutrients. 2015; 7 (5):3891-3913 - 106.
Popovich PG, Lemeshow S, Gensel JC, Tovar CA. Independent evaluation of the effects of glibenclamide on reducing progressive hemorrhagic necrosis after cervical spinal cord injury. Experimental Neurology. 2012; 233 (2):615-622 - 107.
Simard JM, Tsymbalyuk O, Ivanov A, Ivanova S, Bhatta S, Geng Z, et al. Endothelial sulfonylurea receptor 1-regulated NC Ca-ATP channels mediate progressive hemorrhagic necrosis following spinal cord injury. The Journal of Clinical Investigation. 2007; 117 (8):2105-2113 - 108.
Cordero K, Coronel GG, Serrano-Illan M, Cruz-Bracero J, Figueroa JD, De Leon M. Effects of dietary vitamin E supplementation in bladder function and spasticity during spinal cord injury. Brain Sciences. 2018; 8 (3):38 - 109.
Taoka Y, Ikata T, Fukuzawa K. Influence of dietary vitamin E deficiency on compression injury of rat spinal cord. Journal of Nutritional Science and Vitaminology (Tokyo). 1990; 36 (3):217-226 - 110.
Iwasa K, Ikata T, Fukuzawa K. Protective effect of vitamin E on spinal cord injury by compression and concurrent lipid peroxidation. Free Radical Biology and Medicine. 1989; 6 (6):599-606 - 111.
Robert AA, Zamzami M, Sam AE, Al Jadid M, Al Mubarak S. The efficacy of antioxidants in functional recovery of spinal cord injured rats: An experimental study. Neurological Sciences. 2012; 33 (4):785-791 - 112.
Zadeh-Ardabili PM, Rad SK, Khazaai H, Sanusi J, Zadeh MH. Palm vitamin E reduces locomotor dysfunction and morphological changes induced by spinal cord injury and protects against oxidative damage. Scientific Reports. 2017; 7 (1):14365 - 113.
Yan M, Yang M, Shao W, Mao XG, Yuan B, Chen YF, et al. High-dose ascorbic acid administration improves functional recovery in rats with spinal cord contusion injury. Spinal Cord. 2014; 52 (11):803-808 - 114.
Wang WG, Xiu RJ, Xu ZW, Yin YX, Feng Y, Cao XC, et al. Protective effects of vitamin C against spinal cord injury-induced renal damage through suppression of NF-kappaB and proinflammatory cytokines. Neurological Sciences. 2015; 36 (4):521-526 - 115.
Lee JY, Choi HY, Yune TY. Fluoxetine and vitamin C synergistically inhibits blood-spinal cord barrier disruption and improves functional recovery after spinal cord injury. Neuropharmacology. 2016; 109 :78-87 - 116.
van Neerven S, Mey J, Joosten EA, Steinbusch HW, van Kleef M, Marcus MA, et al. Systemic but not local administration of retinoic acid reduces early transcript levels of pro-inflammatory cytokines after experimental spinal cord injury. Neuroscience Letters. 2010; 485 (1):21-25 - 117.
Zhou Y, Zheng B, Ye L, Zhang H, Zhu S, Zheng X, et al. Retinoic acid prevents disruption of blood-spinal cord barrier by inducing autophagic flux after spinal cord injury. Neurochemical Research. 2016; 41 (4):813-825 - 118.
Lin HY, Tang HY, Davis FB, Davis PJ. Resveratrol and apoptosis. Annals of the New York Academy of Sciences. 2011; 1215 :79-88 - 119.
Denu JM. Fortifying the link between SIRT1, resveratrol, and mitochondrial function. Cell Metabolism. 2012; 15 (5):566-567 - 120.
Gut P, Verdin E. Rejuvenating SIRT1 activators. Cell Metabolism. 2013; 17 (5):635-637 - 121.
Zhao H, Chen S, Gao K, Zhou Z, Wang C, Shen Z, et al. Resveratrol protects against spinal cord injury by activating autophagy and inhibiting apoptosis mediated by the SIRT1/AMPK signaling pathway. Neuroscience. 2017; 348 :241-251 - 122.
Kesherwani V, Atif F, Yousuf S, Agrawal SK. Resveratrol protects spinal cord dorsal column from hypoxic injury by activating Nrf-2. Neuroscience. 2013; 241 :80-88 - 123.
Liu C, Shi Z, Fan L, Zhang C, Wang K, Wang B. Resveratrol improves neuron protection and functional recovery in rat model of spinal cord injury. Brain Research. 2011; 1374 :100-109 - 124.
Hodgetts SI, Harvey AR. Neurotrophic factors used to treat spinal cord injury. Vitamins and Hormones. 2017; 104 :405-457 - 125.
Weishaupt N, Blesch A, Fouad K. BDNF: The career of a multifaceted neurotrophin in spinal cord injury. Experimental Neurology. 2012; 238 (2):254-264 - 126.
Hernandez-Torres V, Gransee HM, Mantilla CB, Wang Y, Zhan WZ, Sieck GC. BDNF effects on functional recovery across motor behaviors after cervical spinal cord injury. Journal of Neurophysiology. 2017; 117 (2):537-544 - 127.
Sharma HS. Neuroprotective effects of neurotrophins and melanocortins in spinal cord injury: An experimental study in the rat using pharmacological and morphological approaches. Annals of the New York Academy of Sciences. 2005; 1053 :407-421 - 128.
Uchida S, Hayakawa K, Ogata T, Tanaka S, Kataoka K, Itaka K. Treatment of spinal cord injury by an advanced cell transplantation technology using brain-derived neurotrophic factor-transfected mesenchymal stem cell spheroids. Biomaterials. 2016; 109 :1-11 - 129.
Sharma HS. Neurotrophic factors in combination: A possible new therapeutic strategy to influence pathophysiology of spinal cord injury and repair mechanisms. Current Pharmaceutical Design. 2007; 13 (18):1841-1874 - 130.
Ji XC, Dang YY, Gao HY, Wang ZT, Gao M, Yang Y, et al. Local injection of Lenti-BDNF at the lesion site promotes M2 macrophage polarization and inhibits inflammatory response after spinal cord injury in mice. Cellular and Molecular Neurobiology. 2015; 35 (6):881-890 - 131.
Dobolyi A, Vincze C, Pal G, Lovas G. The neuroprotective functions of transforming growth factor beta proteins. International Journal of Molecular Sciences. 2012; 13 (7):8219-8258 - 132.
Krieglstein K, Strelau J, Schober A, Sullivan A, Unsicker K. TGF-beta and the regulation of neuron survival and death. Journal of Physiology, Paris. 2002; 96 (1-2):25-30 - 133.
Prewitt CM, Niesman IR, Kane CJ, Houle JD. Activated macrophage/microglial cells can promote the regeneration of sensory axons into the injured spinal cord. Experimental Neurology. 1997; 148 (2):433-443 - 134.
Kohta M, Kohmura E, Yamashita T. Inhibition of TGF-beta1 promotes functional recovery after spinal cord injury. Neuroscience Research. 2009; 65 (4):393-401 - 135.
Laron Z. Insulin-like growth factor 1 (IGF-1): A growth hormone. Molecular Pathology. 2001; 54 (5):311-316 - 136.
Davila D, Torres-Aleman I. Neuronal death by oxidative stress involves activation of FOXO3 through a two-arm pathway that activates stress kinases and attenuates insulin-like growth factor I signaling. Molecular Biology of the Cell. 2008; 19 (5):2014-2025 - 137.
Duarte AI, Santos P, Oliveira CR, Santos MS, Rego AC. Insulin neuroprotection against oxidative stress is mediated by Akt and GSK-3beta signaling pathways and changes in protein expression. Biochimica et Biophysica Acta. 2008; 1783 (6):994-1002 - 138.
Hung KS, Tsai SH, Lee TC, Lin JW, Chang CK, Chiu WT. Gene transfer of insulin-like growth factor-I providing neuroprotection after spinal cord injury in rats. Journal of Neurosurgery. Spine. 2007; 6 (1):35-46 - 139.
Sharma HS, Nyberg F, Gordh T, Alm P, Westman J. Topical application of insulin like growth factor-1 reduces edema and upregulation of neuronal nitric oxide synthase following trauma to the rat spinal cord. Acta Neurochirurgica. Supplement. 1997; 70 :130-133 - 140.
Utada K, Ishida K, Tohyama S, Urushima Y, Mizukami Y, Yamashita A, et al. The combination of insulin-like growth factor 1 and erythropoietin protects against ischemic spinal cord injury in rabbits. Journal of Anesthesia. 2015; 29 (5):741-748 - 141.
Cheng I, Park DY, Mayle RE, Githens M, Smith RL, Park HY, et al. Does timing of transplantation of neural stem cells following spinal cord injury affect outcomes in an animal model? Journal of Spinal Surgery. 2017; 3 (4):567-571 - 142.
Salewski RP, Mitchell RA, Shen C, Fehlings MG. Transplantation of neural stem cells clonally derived from embryonic stem cells promotes recovery after murine spinal cord injury. Stem Cells and Development. 2015; 24 (1):36-50 - 143.
Rong Y, Liu W, Wang J, Fan J, Luo Y, Li L, et al. Neural stem cell-derived small extracellular vesicles attenuate apoptosis and neuroinflammation after traumatic spinal cord injury by activating autophagy. Cell Death and Disease. 2019; 10 (5):340 - 144.
He BL, Ba YC, Wang XY, Liu SJ, Liu GD, Ou S, et al. BDNF expression with functional improvement in transected spinal cord treated with neural stem cells in adult rats. Neuropeptides. 2013; 47 (1):1-7 - 145.
Ankeny DP, McTigue DM, Jakeman LB. Bone marrow transplants provide tissue protection and directional guidance for axons after contusive spinal cord injury in rats. Experimental Neurology. 2004; 190 (1):17-31 - 146.
Kim YC, Kim YH, Kim JW, Ha KY. Transplantation of mesenchymal stem cells for acute spinal cord injury in rats: Comparative study between Intralesional injection and scaffold based transplantation. Journal of Korean Medical Science. 2016; 31 (9):1373-1382 - 147.
Nakajima H, Uchida K, Guerrero AR, Watanabe S, Sugita D, Takeura N, et al. Transplantation of mesenchymal stem cells promotes an alternative pathway of macrophage activation and functional recovery after spinal cord injury. Journal of Neurotrauma. 2012; 29 (8):1614-1625 - 148.
Okuda A, Horii-Hayashi N, Sasagawa T, Shimizu T, Shigematsu H, Iwata E, et al. Bone marrow stromal cell sheets may promote axonal regeneration and functional recovery with suppression of glial scar formation after spinal cord transection injury in rats. Journal of Neurosurgery. Spine. 2017; 26 (3):388-395 - 149.
Ban DX, Ning GZ, Feng SQ , Wang Y, Zhou XH, Liu Y, et al. Combination of activated Schwann cells with bone mesenchymal stem cells: The best cell strategy for repair after spinal cord injury in rats. Regenerative Medicine. 2011; 6 (6):707-720 - 150.
Allahdadi KJ, de Santana TA, Santos GC, Azevedo CM, Mota RA, Nonaka CK, et al. IGF-1 overexpression improves mesenchymal stem cell survival and promotes neurological recovery after spinal cord injury. Stem Cell Research and Therapy. 2019; 10 (1):146 - 151.
Wu S, Cui G, Shao H, Du Z, Ng JC, Peng C. The cotransplantation of olfactory ensheathing cells with bone marrow mesenchymal stem cells exerts antiapoptotic effects in adult rats after spinal cord injury. Stem Cells International. 2015; 2015 :516215 - 152.
Lopez-Vales R, Garcia-Alias G, Fores J, Vela JM, Navarro X, Verdu E. Transplanted olfactory ensheathing cells modulate the inflammatory response in the injured spinal cord. Neuron Glia Biology. 2004; 1 (3):201-209 - 153.
Zhang J, Chen H, Duan Z, Chen K, Liu Z, Zhang L, et al. The effects of co-transplantation of olfactory ensheathing cells and Schwann cells on local inflammation environment in the contused spinal cord of rats. Molecular Neurobiology. 2017; 54 (2):943-953 - 154.
Pearse DD, Pereira FC, Marcillo AE, Bates ML, Berrocal YA, Filbin MT, et al. cAMP and Schwann cells promote axonal growth and functional recovery after spinal cord injury. Nature Medicine. 2004; 10 (6):610-616 - 155.
Pearse DD, Bastidas J, Izabel SS, Ghosh M. Schwann cell transplantation subdues the pro-inflammatory innate immune cell response after spinal cord injury. International Journal of Molecular Sciences. 2018; 19 (9):2550 - 156.
Wang JM, Zeng YS, Wu JL, Li Y, Teng YD. Cograft of neural stem cells and schwann cells overexpressing TrkC and neurotrophin-3 respectively after rat spinal cord transection. Biomaterials. 2011; 32 (30):7454-7468 - 157.
Shin JC, Kim KN, Yoo J, Kim IS, Yun S, Lee H, et al. Clinical trial of human fetal brain-derived neural stem/progenitor cell transplantation in patients with traumatic cervical spinal cord injury. Neural Plasticity. 2015; 2015 :630932 - 158.
Sykova E, Homola A, Mazanec R, Lachmann H, Konradova SL, Kobylka P, et al. Autologous bone marrow transplantation in patients with subacute and chronic spinal cord injury. Cell Transplantation. 2006; 15 (8-9):675-687 - 159.
Satti HS, Waheed A, Ahmed P, Ahmed K, Akram Z, Aziz T, et al. Autologous mesenchymal stromal cell transplantation for spinal cord injury: A phase I pilot study. Cytotherapy. 2016; 18 (4):518-522 - 160.
Karamouzian S, Nematollahi-Mahani SN, Nakhaee N, Eskandary H. Clinical safety and primary efficacy of bone marrow mesenchymal cell transplantation in subacute spinal cord injured patients. Clinical Neurology and Neurosurgery. 2012; 114 (7):935-939 - 161.
Feron F, Perry C, Cochrane J, Licina P, Nowitzke A, Urquhart S, et al. Autologous olfactory ensheathing cell transplantation in human spinal cord injury. Brain. 2005; 128 (Pt 12):2951-2960 - 162.
Anderson KD, Guest JD, Dietrich WD, Bartlett Bunge M, Curiel R, Dididze M, et al. Safety of autologous human Schwann cell transplantation in subacute thoracic spinal cord injury. Journal of Neurotrauma. 2017; 34 (21):2950-2963 - 163.
Scivoletto G, Morganti B, Molinari M. Early versus delayed inpatient spinal cord injury rehabilitation: An Italian study. Archives of Physical Medicine and Rehabilitation. 2005; 86 (3):512-516 - 164.
Sumida M, Fujimoto M, Tokuhiro A, Tominaga T, Magara A, Uchida R. Early rehabilitation effect for traumatic spinal cord injury. Archives of Physical Medicine and Rehabilitation. 2001; 82 (3):391-395 - 165.
Marques MR, Nicola FC, Sanches EF, Arcego DM, Duran-Carabali LE, Aristimunha D, et al. Locomotor training promotes time-dependent functional recovery after experimental spinal cord contusion. Neuroscience. 2018; 392 :258-269 - 166.
Dobkin B, Apple D, Barbeau H, Basso M, Behrman A, Deforge D, et al. Weight-supported treadmill vs over-ground training for walking after acute incomplete SCI. Neurology. 2006; 66 (4):484-493