Temporal HLA profiling and immunomodulatory effects of human adult bone marrow- and adipose-derived mesenchymal stem cells

Aim: To investigate the temporal HLA expression profile and immunomodulatory function of mesenchymal stem cells (MSCs) during in vitro expansion. Materials & methods: Adult bone marrow-derived MSCs (BMSCs) and adipose-derived MSCs (AMSCs) were cultured and HLA class I and II mRNA expression were investigated during serial expansion using semiquantitative reverse-transcription PCR. The immunomodulatory properties of MSCs were monitored using peripheral blood mononuclear cell (PBMC) proliferation and cytotoxicity assays. Results: Semiquantitative reverse-transcription PCR revealed that classical HLA class I molecules were highly expressed in MSCs and remained relatively stable during extended culture. Variable expression levels of HLA class II molecules were detected in both BMSCs and AMSCs across passages. AMSCs were more resistant to PBMC-mediated cytotoxicity and suppressed PBMC proliferation more than BMSCs, although the effect was diminished with increasing passage. Conclusion: These findings provide i...