Impairment of the clinical tissue-implantation is due to the lack of a suitable organ donor and immunogenic rejection, which leads to the cause for the enormous loss of human life. The introduction of artificial regeneration of tissues by Langer and Vacanti in 1993, has revolutionized in the field of surgical organ transplantation, to alleviate the problem of tissue injury-related death. There is no doubt that the term “regenerative medicine” to open a new space of tissue reconstruction, but the complications that arise due to the proper machinery of the cell, supporting biomaterials and growth factors has yet to be resolved to expand its application in a versatile manner. The chapter would provide a significant overview of the artificial tissue regeneration while a triangular relationship between cells, matrixes, and growth factors should be established mentioning the necessity of biomedical tools as an alternative to organ transplantation.
- extracellular matrix
- therapeutic molecules
- regenerative medicine
Advances in biomaterials are implicated in the huge results as the artificial support matrices penetrate the barrier of all physicochemical properties in clinical tissue implantation, an artifact of regenerative tissue engineering applications. Unlike traditional tissue grafting, the artificial implanting process involves the replacement of any damaged tissues irrespective of age, diseases, and kinds of trauma. Based on the potential requirements, efforts in different fields that include material science, cell biology, medicine, theory and computational studies represent a versatile contribution in regenerative medicine to save thousands of lives. The preliminary idea of tissue engineering is to reconstruct the traditional surgical or mechanical device-related techniques; those though significantly prevented the untimely demises of lives. The time on demand of available organ donors and appropriate complimentary biological environments are implemented in the term ‘Tissue Engineering’ (TE) in 1933 by Langer and Vacanti . TE is the versatile gift of scientists who have greatly remodeled and mimicked the
The new generation of biomaterials has revolutionized the fields of regenerative medicine while, the development of 3D architecture could enable us to mimic the ideal
The challenge in tissue regeneration is the seeding of cells. The risk factors such as
This chapter will explore the sources of the 3D polymer construct and its validity in the biological niche, i.e. biocompatibility and cell motility through different growth factors.
2. Why is the 3D construct in tissue regeneration (TE)?
In tissue engineering, the assessment of cell compatibility is evaluated in a
Unlike 2D model, 3D constructs regulate the cell growth and proliferation in heterogeneity similar to
3. Choice of material in artificial supporting matrixes
The involvement of suitable materials, whether synthetic or naturally extracted in the fabrication of the artificial tissue environment, remains a challenge. The prerequisite in the development of 3D constructs includes biocompatibility, biodegradability, mechanical strength, interconnected and antimicrobial porous mechanical strength, antimicrobial and interconnected porous networks in which cellular activities could be performed analogously to their native tissue domicile. Taking into account the fact that biomaterials that actually contain the structural component or similar biochemical and physicochemical identity of native tissue have been granted for the processing of the platform in support of artificial cells. Meanwhile, the involvement of any unique material may or may not be able to create the imitation of equivalent tissues requires a broad understanding of the cell-matrix interaction. Therefore, the role of the combination of materials is considered as the essential means to overcome all the barriers that include bioactivity, biodegradability, microbial contamination and maximum mechanical flexibility which contribute as a key to tissue engineering.
3.1 Impact of naturally sourced biomaterials on cell-cell cross-talk
Mimicking of biological tissue environment using collagen is an attractive theme, which is due to the inherent features such as fibrous structure, biocompatibility and low antigenicity. However, the improvement of mechanical stability and biodegradability requires additional treatment that includes cross-linking or chemical modification in the presence of second party molecules. The approaches of modification of different natural biopolymer and its tuning into desired artificial tissue architecture that support the adhesion, proliferation, and migration of cells in biological niche are discussed here.
3.1.1 Collagen as base material and its derivatives
Collagen is a key component in extracellular matrixes and composed of RGD (arginine−glycine−aspartic acid) domains that plays a potential role in cell adhesion, growth and motility through its interaction with cells. But, the drawback due to poor mechanical stability and biodegradation is overcome by the modification with various natural polymers or synthetic polymers. In one approach, collagen molecules were chemically conjugated with oxidized guar gum to immobilize platelet-derived growth factor . The guar gum which is a water soluble and ionic polysaccharide was oxidized to poly(dialdehyade) guar gum in presence of sodium periodate. The resultant oxidized guar gum not only promoted the crosslinking of collagen molecules but also helped to immobilize the platelet-derived growth factor, enabling the formation of biologically active hybrid 3D scaffolds with excellent swelling, thermal and biodegradable properties. FTIR, SEM analysis was performed to confirm the synthesis of the hybrid structure. SEM morphology revealed the interconnected 3D porous honeycomb structure with an average pour size of 15 ± 7 μm. The hybrid scaffold was shown to promote the release of growth factors with the increase of NIH 3 T3 cell density and proliferation and was seen as a promising candidate for tissue engineering applications.
Recently, Diogo et al. developed a method of fabrication of ‘
3.1.2 Hyaluronic acid as base material and its derivatives
As like collagen, hyaluronic acid (HA) is also a part of extracellular matrix and shown to have a potential role in modulating inflammation, cell attachment, and migration as well as tissue morphogenesis, owing to the biodegradable, biocompatible, non-immunogenicity and anti-inflamatory properties. An attempt by Gao et al. was initiated to develop the self-crosslinked hyaluronic acid-grafted collagen-I hydrogel using EDAC/NHS reaction method. Further, chondrocytes was encapsulated into the hydrogel to verify the cell-matrix interaction and which had a significant effect on the secretion of cartilage-specific matrices to promote the migration, proliferation and gene expression of chondrocytes cells. The
In an approach, the injectable HA-SH/peptide hybrid hydrogels was developed based on the covalent/noncovalent supramolecular interaction between thiolated hyaluronic acid (HA-SH) and BPAA-AFF-OH short peptide to regulate the chondrogenic expression both
In order to improve the mechanical properties, methacrylated HA was modified with elastin-like polypeptide (ELP, consists of 70 repeats of the pentapeptide VPGVG) through free radical photopolymerization technique. The hydrogel made from the combination of MeHA/ELP revealed the tunable physicochemical and mechanical properties which is comparable to native tissue structure. Further, incorporation of zinc nanoparticles into the hydrogel had resulted an excellent antimicrobial platform for cell adhesion, growth, and proliferation phenomena (See Figure 3A). The ‘
Like various tissue regeneration processes, utilizing of HAbased cell supporting materials explicated the significant output in artificial salivary gland repairing and remodeling. In an experiment, Lee et al. demonstrated the synthesis of hyaluronic acid−catechol (HACA) conjugates based platform named as NiCHE (nature-inspired catechol conjugated hyaluronic acid environment) to mimic the mesenchyme of embryonic submandibular glands (eSMGs) as shown schematically in Figure 3B(i) . The NICHE was developed by the coating of HACA conjugates on the various polymeric scaffolds such as polycarbonate membrane, stiff agarose hydrogel, and polycaprolactone that led to cell adhesion and growth, vascular endothelial and proliferation of progeniotor of eSMGs cells isolated from ICR mice fetus [See Figure 3B(ii&iii)].
3.1.3 Gelatin as base material and its derivatives
Owing to the excellent biocompatibility, biodegradability and water solubility, gelatin has emerged tremendous interest for the formation of 3D hydrogel in tissue engineering application. Song et al. developed an injectable 3D printed gelatin hydrogel composed of continuous phase gelatin and gelatin microgels. The two-step cross-linked injectable gelatin was shown to exhibit the biocompatible lattice, cup-shaped, tube-shaped and rheological modified structure analogous to human anatomical features. The biocompatibility of the microgel led to the spread and expression of metabolic activities in mouse fibroblast cells, which can be attributed to the good cell-matrix interaction such as
Due to the limited clinical success in repairing defective cartilage, unlike conventional surgery, the biopolymer-based tissue engineering approach such as the production of gelatin-linked electrospun, gelatin-polycaprolactone (gelatin-PCL) nanofiber-filled decellularized extracellular matrix has been investigated to monitor biological functions. The decellularized composite has shown to exhibit the excellent mechanical property and promoted the cartilage regeneration with the secretion of collagen and glycosaminoglycan as shown in Figure 3C .
The development of gelatin methacrylate (GelMA) and poly (ethylene glycol) diacrylate (PEGDA) printed three layered scaffold, modified by lysine functionalized rosette nanotubes (RNTK) significantly improved the adhesion, growth and differentiation of adipose-derived mesenchymal stem cells (ADSCs). The RNTK not only acted as a potential biomimetic layer, its presence dramatically increased the secretion of collagen II, glycosaminoglycan, and total collagen as compared to native GelMA-PEGDA scaffolds, and have an potential impact on cartilage regeneration .
To improve wound repair caused by burns or accidental injuries, a versatile approach has been shown to fabricate the skin tissue analogue of a mechanically stable acellular elastomeric scaffold in the presence of biodegradable polyurethane and gelatin composite. The Gel-20%PU showed the best cell infiltration and biodegradation in a mouse
3.1.4 Sodium alginate as base material and its derivatives
The implementation of the osteogenic microenvironment loaded with therapeutic agents has emerged as the key pathway for bone tissue engineering in recent decades. Like various biopolymers, the utility of alginate, which is a polyionic-polysachharide comprising units of mannuronic acid and guluronic acid, has strengthened the field of next-generation polymer remodeling. The fabrication of calcium alginate bead based 3D implant made by the stacking of hexagonal closed pack (HCP) layers (Figure 3D(i)) in presence of glutaraldehyde crosslinker facilitated the spatiotemporal drug release in the artificial matrixes through the changes of the spatial coordinates of the drugs loaded layers. The supporting scaffold promoted the growth, progression and cytosketal reorganization of the osteoblast cells and triggered the expression of the alkaline phosphatase, runx2 and collagen type1 in human mesenchymal stem cells, attributed to the osteoconductive and osteogenic nature of the implant . The
3.1.5 Chitosan as base material and its derivatives
Chitosan, a polysaccharide with various functional groups has increased tremendous interest in biomedical applications such as tissue engineering. But, major problems due to poor solubility and biodegradability limit its monopoly use in the processing of cell supporting materials. This is avoided by the stacking or modifying with various synthetic or natural biomaterials. In a report, Li et al. developed the oxidized alginate hydrogel crosslinked with N, O-carboxymethyl chitosan with moderate swelling, degradation and porosity. The chitosan modified alginate scaffold revealed improved biocompatibility, as the number of free aldehyde groups in the oxidized alginate is reduced after crosslinking .
In another report , the methacrylated chitosan molecules were conjugated with lysozyme (an endo-carbohydrase) via riboflavin initiated photo-cross-linking to a constructed biodegradable and biocompatible hydrogel. The
3.1.6 Polyhydroxyalkanoates (PHA) as base material and its derivatives
Unlike different biomaterials,
3.1.7 Silk as base material and its derivatives
Silk is a naturally occurring fibrous protein with biodegradability, biocompatibility, and mechanical durability that has utility in tissue engineering applications. In one study, silk fibroin-grafted polycaprolactone nanofibers were able to deliver dual growth factors such as bone morphogenetic protein-2 (BMP-2), transforming growth factor-beta (TGF-β), in the regeneration of bone tissue . Li et al. also presented a similar type of biocompatibility while a PCL/silk 3D bioprinting scaffold was imposed to regenerate the meniscus tissue . The computer-assisted 3D printed silk matrices have attracted significant attention and found to be improved the cell–cell and cell-matrix interaction and enable their activity in patient specific tissue architecture . Similarly, the gelatin-silk composite was subjected to the fabrication of 3D bioprinting for cartilage tissue engineering in rabbit model .
The novel development of 4D printing hydrogel has gained significant attention in next generation biofabrication. The fabrication of 4D printing from 3D printing hydrogel was regulated by the modulation their interior or exterior properties with the proper controlled of expansion rate of the hydrogel in distilled water and salt water. The biocompatibility of assessment of the 4 D printing hydrogel was conducted in culture medium by shape change method as mentioned earlier. The results revealed the adhesion and growth of the PKH127 (green)-labeled human chondrocyte (hTBSCs) along with the deposition of cartilage extracellular matrix in the side of the construct. To verify the clinical applicability of the construct, the rabbit TBSC and chondrocytes-laden artificial 4D construct was implanted into the site of the rabbit trachea and the results of 8 weeks post-implantation revealed the regeneration of the respiratory epithelial layer and formation of neocartilage around the perichondrium. This findings proved the potential application of the cell laden 4D hydrogel in the recovery of respiratory organ, trachea regeneration . A very recently, the approach of development of electrical simulation modulated polypyrrole/silk fibroin (PPy/SF) based conductive composite scaffold has been opened up the new avenue in the neuronal tissue regeneration . The 3D printing electrospining method was used to fabricate for the alignment of silk fibrous, followed by the coating of polypyrrole (a mechanically stable conductive material) to get the desired silk fibroin (PPy/SF) composite scaffold as nerve guidance conduits (NGCs). Morphological tracking by SEM analysis exhibited the core-shell structure having interpenetrating PPy fibers on the smooth SF nanofibers with average diameter of 0.427 ± 0.083 μm. Resultant physicochemical properties such as mechanical stability (0.059 MPa) and conductivity (0.11446 ± 0.00145 mS/mm) of composite were comparable to ideal working in NGCs system, indicating the increase of mechanical property of the conduit by the coating of PPy. The ES controlled cell compatibility of the NGCs was evaluated with the seeding of Schwann cells (SCs) and it showed the significant growth, proliferation and migration of the cells with the expression of neurotrophic factors. Further, to investigate the effect of artificial NGCs on
3.1.8 Different synthetic materials and their combination
The synthetic materials based 3D hydrogel have also shown to mimic the native tissue stiffness while the optimum conditions for the 3D constructions are digitally controlled. The digital light processing (DLP) based printed poly(ethylene glycol)diacrylate (PEGDA) hydrogels exhibited nearly 60% of enhanced elastic modulus, suited for the support of 3 T3 cells adhesion and proliferation as shown in Figure 5A . In one study, degradable, polar hydrophobic and ionic porous polyurethane scaffolds were synthesized using a lysine-based crosslinker. The scaffolds demonstrated (see Figure 5B) the comprehensive mechanical, swelling and biocompatible properties that support the adhesion and growth of muscle cells in vascular tissue engineering . Apsite et al., reported the design and fabrication of polycaprolactone and poly(N-isopropylacrylamide) based multilayerd porous electrospun mats. The self-folding 4D bio-fabrication was found to act as good cells adhesion and viability, assigning as a new perspective in new generation tissue engineering . In a paper, Kutikov explained how the integration of hydrophilic polyethylene glycol into hydrophobic polyester block copolymers changes the physicochemical properties of 3D matrices. The incorporation also demonstrated the different types of cell adhesion, growth, and tissue regeneration both
4. Effect of growth factors on cell-matrix interaction
Enormous studies have been thoroughly investigated on the interaction between cellular and bio-mimetic 3D matrices
Mechanically, the function of growth factors is to drive progenitor cells to its damaged target tissues by extracellularly mediated signaling pathways. In fact, therapeutic molecules bind to the cell surface transmembrane receptor and then to the internalized receptor-protein complex through phosphorylation-mediated signal transduction that triggers down-regulation of cells, followed by reduction of overwhelming responses and stimulation at the cellular level to carry out biological functions. Furthermore, the non-diffusible method leads to the binding of growth factor to the cell surface without any major internalization or downregulation in the results of long-term biological activities, as shown in Figure 6A(i&ii) . Mimicking the
It has been a challenge to meet the need to develop a bio-mimetic tool for vascular tissue engineering. In contrast to various soft tissues, vascular tissue controls the supply of oxygen, essential cellular nutrients, the transport of waste products and stem cells as well as progenitor cells. Therefore, it is urgent to reconstruct the network of the neovascularization process with the initiation of adhesion, growth and differentiation of cells as a native tissue environment in artificial tissue engineering. Cao et al. demonstrated the therapeutic approaches of growth factors and their signal cascade that control neovascularization and the formation of neovessels using the spatiotemporally controlled 3D construct both
Understanding the mechanism and basic criteria in the process of tissue regeneration has unveiled the secret of the communication involved in cell–cell, cell-matrix interaction that enables healing in an artificial tissue environment such as native tissue repair processes. In fact, the biocompatibility of any fabricated 3D architecture plays an important role in adhesion, proliferation, migration, and differentiation of the cells of interest to biologically mimic the signaling cascade that triggers cellular activities. Several investigations have shown that 3D constructs comprising naturally extracted and synthetic materials having a porous and mechanically stable geometry promoted integrin ligand-mediated differentiation and tailored actin-cytoskeletal cell morphology in a better way. The studies also explained how the biological and biochemical performances of cells are influenced by the different growth factors mediated signaling pathways and the active function of the ECM components. Therefore, present review provided the core thinking behind the physicochemical features of supporting matrixes that significantly control the cell–cell and cell-matrix interaction towards the implementation of clinically approved artificial 3D biocomposite for the successful clinical tissue engineering applications.
Dr. Nilkamal Pramanik and Dr. Tanmay Rath acknowledge UGC, DST, SERB- DST (NPDF), Govt. of India, for their financial supports. Dr. Nilkamal Pramanik also gratefully acknowledges Dr. Tanmay Rath, Prof. Patit Paban Kundu (Department of Polymer Science and Technology) and Dr. Ranjan Kumar Basu (Department of Chemical Engineering), University of Calcutta for their kind guidance to carry the biomaterials based tissue engineering works.
Conflict of interest
No conflict of interest is a declaration.
Acronyms and abbreviations
Tissue Engineering Extracellular matrixes Epithelial growth factors Platelet derived growth factors Insulin like growth factors Hematopoietic cell growth factors Adipose tissue-derived mesenchymal stem cells Gelatin methacrylate Poly (ethylene glycol) diacrylate Hexagonal closed pack (2, 2, 6, 6-Tetramethylpiperidin-1-yl)oxyl or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl Simulated body fluid Human bone marrow derived mesenchymal stem cells Montmorillonite clay Hyaluronic acid Interpenetrating network based Bone morphogenetic protein-2 Poly(ethylene glycol)diacrylate Vascular epithelial growth factor
Epithelial growth factors
Platelet derived growth factors
Insulin like growth factors
Hematopoietic cell growth factors
Adipose tissue-derived mesenchymal stem cells
Poly (ethylene glycol) diacrylate
Hexagonal closed pack
(2, 2, 6, 6-Tetramethylpiperidin-1-yl)oxyl or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl
Simulated body fluid
Human bone marrow derived mesenchymal stem cells
Interpenetrating network based
Bone morphogenetic protein-2
Vascular epithelial growth factor