**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 *Pleurostylia capensis*, *Pterocarpus angolensis* and *Eucomis autumnalis*, having resveratrol playing proliferation and differentiation roles in tissue engineering of articular cartilage. High regulation of collagen type II has been observed chondrocytes treated with resveratrol [19]. This makes resveratrol potentially enhancing chondrocyte viability which can be applied in 3D bioprinting of cartilage constructs [20]. Recent publications show that bark and root water extracts of *Pterocarpus angolensis* plants in the stifle joints from the 3-month-old pig affect the accumulation of collagen type II in porcine articular cartilage in the middle zone. Cell culture experiments were designed to investigate the role of the bark and root water extracts of *P. angolensis* to induce the expression of collagen type II protein in porcine articular chondrocytes. Monolayer cells were treated with 15, 30 and 50 μg/ml of *P. angolensis* extract and hydrogen peroxide (2 μg/ml) for 4 days, and the untreated chondrocytes were used as controls. The results showed no significant difference in the cell index between the controls and chondrocytes that had been treated with the plant extracts at 15 and 30 μg/ml. A significant increase in the expression of collagen type II protein by the chondrocytes was observed and found to be optimal at a concentration of 30 μg/ml. There was an increase in the production of proteoglycans. However, the plant extracts at a 50 μg/ml induced apoptosis in the middle zone chondrocytes. In conclusion the findings of this study are of great importance in understanding the mechanisms through which *P. angolensis*  enables the healing of breached tissue [21]. In our laboratory, an (unpublished) in vitro study has observed the enhancement of proliferation and osteogenic differentiation (by increasing alkaline phosphate activity) of C2C12 myoblast cells treated with *Pleurostylia capensis* crude extract. Furthermore, proliferation and lineage differentiation of *P. angolensis* and *E. autumnalis* in porcine adipose-derived mesenchymal stem cells (pADMSCs) have also been recorded in our work (Figure not shown). However, the potential use of medicinal plants with tissue engineering methods to treat the cartilage and bone is exciting, yet not fully realized, and is likely to be a future treatment strategy.
