Purpose: High hopes have been pinned on regenerative medicine strategies to meet the challenge of preventing the progression to osteoarthritis, in particular autologous chondrocyte implantation (ACI). The loss of chondrocyte phenotype during in vitro monolayer expansion, a step needed to obtain sufficient cell numbers, may be a key limitation in ACI. In this study, we determined whether a shorter and quicker monolayer expansion approach could improve chondrogenic differentiation.
Methods: We compared the effects of two serum types, foetal bovine serum (FBS) and Stemulate™ (a commercial source of human platelet lysate), on the expansion and re-differentiation potential of human chondrocytes isolated from 5 individuals. Chondrocytes were expanded with 10 % FBS or 10 % Stemulate™. Pellets were formed and cultured for 4 weeks in chondrogenic differentiation medium and assessed for the presence of cartilage matrix molecules and genes associated with chondrogenicity.
Results: Stemulate™ significantly enhanced proliferation rates (average population doublings; FBS 22.19 d ±6.22 d vs Stemulate™ 12.93 d ±4.64 d). Sulphated glycosaminoglycan (sGAG), total collagen and qRT-PCR analyses of cartilage genes showed that FBS-expanded chondrocytes demonstrated significantly better chondrogenic capacity than Stemulate™-expanded chondrocytes. Histologically, FBS-expanded chondrocyte pellets appeared to be more stable, spherical and had a more intense staining for toluidine blue, indicating a greater chondrogenic capacity.
Conclusions: Overall we have shown that although Stemulate™ positively influences chondrocyte proliferation, it has a negative effect on chondrogenic differentiation potential. This suggests that Stemulate™ may not be the ideal supplement for the expansion of chondrocytes and to maintain chondrocyte phenotype/genotype, and hence for cell therapies in the treatment of cartilage defects, including ACI.
© 2018 Published by Elsevier Inc.