Expanded Adipose-Derived Stem Cells Suppress Mixed Lymphocyte Reaction by Secretion of Prostaglandin E2

Multipotent mesenchymal stem cells (MSCs) in adult tissue are known to be less immunogenic and immunosuppressive. Previous study showed that primary cultures of human adipose-derived stem cells (ADSCs) shared their immunomodulatory properties with other MSCs. However, whether passaged human ADSCs can retain their immunomodulatory effect after in vitro expansion remains unknown. In addition, the mechanism of ADSC-mediated immunomodulatory effect remains to be elucidated. This study aimed to investigate these issues by using passaged human ADSCs as an in vitro study model. Flow cytometry showed that passaged ADSCs expressed human leukocyte antigen (HLA) class I but not class II molecules, which could be induced to express to a high level with interferon-γ (IFN-γ) treatment. The study found that passaged ADSCs could not elicit lymphocyte proliferation after co-culturing with them, even after IFN-γ treatment. In addition, either IFN-γ–treated or non-treated ADSCs could inhibit phytohemagglutinin (PHA)-stimula...