Objective: To investigate the regulatory effects of rat mesenchymal stem cell (MSC) on T lymphocyte proliferation by examining the early activated markers such as CD25 and CD69.
Methods: MSC had been isolated and expanded in vitro. Then it was identified by cell morphology, membrane phenotype, and differentiation potential. Nylon wool column was applied to purify T-lymphocytes. MSCs and T-lymphocytes were cultured together and were stimulated by phytohaemagglutinin (PHA), and then the expressions of CD25 and CD69 were assessed. The levels of TGF-beta1 and IL-10 in the supernatants of MSC cultures were detected by using ELISA.
Results: (1) The expression of CD25 is suppressed in a dose-dependent manner when the T-lymphocytes are co-cultured with 10,000 MSCs or more, while 100 MSCs have no detectable effect; (2) The suppression of CD25 can be lasted more than 96 hrs; (3) The down regulation of CD25 is mediated by some soluble factors; (4) The reduced expression of CD25 caused by MSC inhibition is not mediated by TGF-beta1 and IL-10.
Conclusion: MSCs have significant immune regulatory effects on PHA-stimulated T-lymphocyte culture. It might provide a remarkable immune suppression in organ-transplantation to achieve better outcome in the near future.