LAUSR

Cytotoxic T‐lymphocyte‐associated protein 4 (CTLA4) can promote osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMMSCs), and CTLA4‐modified bone marrow mesenchymal stem cells possess immunoregulatory effects. In the present study, we aimed to construct a new tissue engineering bone using demineralized bone matrix and CTLA4 protein, designated as DBM‐CTLA4 (+). The effects of DBM‐CTLA4 (+) on the osteogenic differentiation of hBMMSCs and T lymphocyte activation were evaluated through in vitro experiments. The cumulative release of CTLA4 from DBM‐CTLA4 (+) was determined using enzyme‐linked immunosorbent assay. DBM‐CTLA4 (+) was co‐cultured in a Transwell chamber with either phytohemagglutinin‐treated hBMMSCs or human peripheral blood mononuclear cells (hPBMCs). Osteogenic differentiation of hBMMSCs was assessed by calcium deposition, ALP activity, and the protein levels of COL1A1, RUNX2, BMP2, and OPN. T lymphocyte activity was assessed by measuring the protein levels of IL‐2, L‐17, HLA‐DRA1, IFN‐γ, and RANKL. Our results showed that the cumulative release rates of CTLA4 at 7, 14, 21, and 28 days were 12.6% ± 1.4%, 30.2% ± 2.3%, 49.8% ± 3.8%, and 60.5% ± 2.7%, respectively. Compared to the negative control, DBM‐CTLA4 (+) promoted the proliferation of hBMMSCs, and enhanced calcium deposition, ALP activity, and protein levels of COL1A1, RUNX2, BMP2, and OPN. Moreover, DBM‐CTLA4 (+) decreased the levels of IL‐2, IL‐17, HLA‐DR, IFN‐γ, and RANKL in hPBMCs treated with phytohemagglutinin. In conclusion, DBM‐CTLA4 (+) promoted proliferation and osteogenic differentiation of hBMMSCs and suppressed T lymphocyte activation.