Platelet lysate induces chondrogenic differentiation of umbilical cord-derived mesenchymal stem cells

Purpose: Articular cartilage has a poor capacity for self-repair, and thus still presents a major challenge in orthopedics. Mesenchymal stem cells (MSCs) are multipotent stem cells with the potential to differentiate into chondrocytes in the presence of transforming growth factor beta (TGF-beta). Platelet lysate (PL) contains a relatively large number of growth factors, including TGF-beta, and has been shown to ameliorate cartilage repair. Here, we investigated the ability of PL to direct chondrogenic differentiation of MSCs along with other standard differentiation components in a pellet culture system. Methods: We isolated and expanded MSCs from human umbilical cords using a PL-supplemented medium and characterized the cells based on immunophenotype and potential for differentiation to adipocytes and osteocytes. We further cultured MSCs as pellets in a chondrogenic-differentiation medium supplemented with PL. After 21 days, the pellets were processed for histological analysis and stained with alician blue and acridine orange. The expression of SOX9 was investigated using RT-PCR. Results: MSCs maintained their stemness characteristics in the PL-supplemented medium. However, the distribution of cells in the pellets cultured in the PL-supplemented chondrogenic differentiation medium had a greater similarity to cartilage tissue-derived chondrocytes than to the negative control. The intense alician blue staining indicated an increased production of mucopolysaccharides in the differentiated pellets, which also showed elevated expression of SOX9. Conclusions: Our data suggest that MSCs could be differentiated to chondrocytes in the presence of PL and absence of exogenous TGF-beta. Further research needs to be conducted to understand the exact role and potential of PL in chondrogenic differentiation and chondrocyte regeneration.