Any trauma to a joint such as sports injury can lead to osteoarthritis especially injuries that include torn cartilage, dislocated joints and ligaments. In sports injury specifically, most of the ointments in the market are only applied after physical activity. Repair of the bone and cartilage continues to be a challenge. Autologous and allografts are the gold standard for the treatment of the bone and cartilage. They have an invasive, open surgical procedure that requires the tissue to be harvested from an alternative site within the patient. South Africa is rich in native flora that is currently tapped as medicine by traditional healers. However, little is known about the natural products of our native flora and their potential to serve as a remedy for sports injuries, fracture healing and osteoarthritis. The grand purpose of the project is to explore medicinal plants of South Africa as a potential source for bone and tissue engineering of articular cartilage.
- tissue engineering
- sports injury
- medicinal plants
Generally, with the extensive screening of plants used in traditional medicine, evidence of their rational use in treating infections, diseases, inflammation and other disorders has been provided [1, 2, 3]. Herbal extracts have extensively health benefits, and indigenous medicinal plants have been used traditionally as a major source of drugs for the treatment of various illnesses, including osteoarthritis (OA), asthma, cancer, heart disease, tuberculosis, swollen ankles and hypertension [4, 5, 6]. Extracted compounds of medicinal plants are usually used as inputs in toxicology, phytochemicals, pharmaceuticals and other chemical industries [3, 4, 5, 7, 8, 9]. Stem cell therapies involving cartilage regeneration and several current 3D bioprinting processes involve the use of synthetic and natural biological molecules such as growth factors to improve their proliferation and differentiation [9, 10, 11]. There is an ongoing search in the science community for alternatives of these growth factors and the existing synthetic materials, due to reports on their numerous negative effects and complete failure in cartilage regeneration [3, 12, 13, 14]. Several medicinal plant extracts have been suggested to stimulate adult stem cell proliferation and thus regeneration of damaged or diseased tissues. Many Chinese herbs have been found to exert adipogenic, osteogenic and chondrogenic effects on human mesenchymal stem cells (hMSCs). Dried root of
1.1 Role of medicinal plants in chondrocytes
In South Africa, numerous plants used traditionally have been employed in tissue engineering of articular cartilage. Studies have observed medicinal plants such as
1.2 Medicinal plant extract in scaffolds
Signals, morphogens responding stem cells and scaffolds that are biomimetic of the extracellular matrix are the three paramount requirements in regenerative medicine [22, 23]. Currently, empirical formulations, medicinal plants and their bioactive compounds are being merged with polymers that can be used in tissue regeneration. Many studies have tried to incorporate medicinal plants in the fabrication of different scaffolds for wound healing, bone fracture and cartilage regeneration.
Herbal plants have the potential in tissue engineering and regenerative medicine due to their minimal host inflammatory response, high level of tenability and the ability to progressively degenerate into non-cytotoxic components, which are either reabsorbed or removed from the biological system . Recently, studies have shown that scaffolds treated with
Similarly, we have evaluated natural polymer (chitosan and alginate) scaffolds incorporated with
The chondrogenic differentiation capacity of the herbal scaffolds was also evaluated using toluidine blue staining after 21 days in culture (Figure 2). Herbal scaffolds were found to enhance formation of chondrocytes (Figure 2a and c) compared to non-herbal scaffolds (Figure 2e). Herbal scaffolds also showed significant chondrogenic enhancement compared to the controls (Figure 2b, d and f).
Additionally, our anti-inflammatory assay for days 7, 14 and 21 using an interleukin 6 (IL-6) Elisa kit according to the manufacturer’s instructions confirmed the anti-inflammatory nature of
The degradation of mineral deposition during the in vitro regeneration process in tissue engineering is very important. Hence, we tried to assess the in vitro degradation capacity of our scaffolds using scanning electron microscope (SEM). It was observed that our herbal scaffolds showed significantly higher and gradual releasing of materials into the culture environment than our non-herbal scaffolds. The in vitro mineral deposition was confirmed using Fourier transform infrared spectrometer (FT-IR) spectrum (Figure 3a and b) on day 14 of incubation with pADMSCs in culture. The FT-IR data for the herbal scaffolds (Figure 3a) has an open-chain bond ▬C〓N▬ at peaks 1600.8 and 1416.4 which were reduced. The 1072.4 and 1029.8 peaks were longer and more pronounced. The peak bands after 824.15 that are assumed to be vibrations of P▬O▬H from Ca3 (PO4)2 seems to be extended to peak 450. In the case of the non-herbal scaffolds (Figure 3b), peak bands at 1600.8 and 1416.4 were longer and seen at 1593.7 and 1420, respectively. At 1072.4 it is almost absent and the peak band at 1015.7 is reduced.
The FT-IR analysis showed certain peaks which are in the same functional groups as alkyl carbonate, organic sulphate and phosphate ions [27, 28]. Furthermore, the presence of calcium, phosphate and carbonate compounds highlights the important relationship between intracellular calcium phosphate in osteoblasts and their role in mineralizing the extracellular matrix . The long sharp peak at 1017.2 cm−1 also corresponds to silicate (Si) ions. Silicate and Cu ions are usually encountered in the presence of a hydrated surface layer of both bone crystal and synthetic apatite crystals, which contain varying concentrations of a wide variety of mineral ions that play important roles during bone and cartilage regeneration .
1.3 Medicinal plant extracts in wound healing
The skin is susceptible to injury and is the body tissue most exposed to damage. Wound healing is a normal biological process involving proliferation and redifferentiation of fibroblasts and keratinocytes [31, 32]. Significant advances have been made in the past years in wound healing so as to bring solutions for the treatment of chronic wounds and speeding up of acute healing. Several recent studies have found plants to be significant in controlling wound healing [33, 34].
Furthermore, a study has used
Similarly, our study also evaluated the wound healing capacity of
Numerous polymeric constructs have been used in combination with growth factors for engineering and regeneration of tissues. This combination of polymer and growth factors for tissue repair depends largely on using biodegradable materials that can stimulate specific cellular responses at a molecular level which should be suitable, simple and cost-effective. Our data in this section offers pharmacological evidence on the potential use of the mentioned plant extracts in bone fracture, cartilage regeneration and wound treatment. In fact, medicinal plants found to have anti-inflammatory properties may partake in host modulatory therapy for various inflammatory diseases as proposed in [3, 39].
We would like to state that the herbs and all the substances in this study are for cartilage defects of grades 1, 2 and 3 according to outerbridge scale. Therefore, if congenital or after trauma large cartilage case is presented, then operative treatment is advised.
This research study was supported by the South African National Research Foundation. We thank the Tshwane University of Technology for their institutional support and Vleis 1 abattoir for providing pig knees.