In vitro assessment of immunogenicity in chondrocytes obtained from the B2M knockout induced pluripotent stem cells
Today, the cell-based technologies are one of the instruments used for the cartilage tissue repair. Creation of a universal hypoimmunogenic cartilage tissue graft from the differentiated derivatives of induced pluripotent stem cells (iPSCs) might solve the problem of the lack of the cartilage cell product. However, currently there is little data on immunogenicity of such tissue-engineered preparations. The study was aimed to create a cartilage implant from the differentiated derivatives of the B2M-deficient iPSCs and assess its immunogenicity. The previously developed protocol was used to ensure differentiation of both wild-type and B2M knockout iPSCs into chondrocyte-like cells. After quality control of the resulting cell lines by conducting polymerase chain reaction and immunocytochemical assessment, the resulting cell lines were co-cultured with the peripheral blood mononuclear cells of a healthy donor. When co-cultivation was over, activation and degranulation of CD8+ T cells was assessed by flow cytometry analysis based on the CD69 and CD107a expression on the cell surface, respectively. The iPSC-derived chondrocytes expressed the cartilage tissue markers. Flow cytometry analysis revealed no substantial differences in immunogenicity between the derivatives of wild-type and B2M knockout iPSCs, as well as from the cartilage tissue cells of a healthy donor. Immunogenicity of chondrocyte-like cells was higher than that of hypoimmunogenic non-edited iPSCs. The B2M knockout iPSCs demonstrated a trend towards greater activation of CD8+ T cells. Thus, the B2M knockout in the iPSC-derived chondrocytes had no significant effect on the tissue immunogenicity. It is necessary to further edit the genes encoding MHC II and CD47 to obtain a less immunogenic product.