Abstract
Human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) are of great interest in tissue engineering. We obtained hWJ-MSCs from four patients, and then we stimulated their chondrogenic phenotype formation in vitro by adding resveratrol (during cell expansion) and a canonical Wnt pathway activator, LiCl, as well as a Rho-associated protein kinase inhibitor, Y27632 (during differentiation). The effects of the added reagents on the formation of hWJ-MSC sheets destined to repair osteochondral injuries were investigated. Three-dimensional hWJ-MSC sheets grown on P(NIPAM-co-NtBA)-based matrices were characterized in vitro and in vivo. The combination of resveratrol and LiCl showed effects on hWJ-MSC sheets similar to those of the basal chondrogenic medium. Adding Y27632 decreased both the proportion of hypertrophied cells and the expression of the hyaline cartilage markers. In vitro, DMSO was observed to impede the effects of the chondrogenic factors. The mouse knee defect model experiment revealed that hWJ-MSC sheets grown with the addition of resveratrol and Y27632 were well integrated with the surrounding tissues; however, after 3 months, the restored tissue was identical to that of the naturally healed cartilage injury. Thus, the combination of chondrogenic supplements may not always have additive effects on the progress of cell culture and could be neutralized by the microenvironment after transplantation.