Interaction of human mesenchymal stem cells with cells involved in alloantigen-specific immune response favors the differentiation of CD4+ T-cell subsets expressing a regulatory/suppressive phenotype.

Our results strongly suggest that MSC-mediated inhibition of alloantigen-induced DC1 differentiation and preferential activation of CD4+ CD25+ T-cell subsets with presumed regulatory activity represent important mechanisms contributing to the immunosuppressive activity of MSC. Collectively, these data provide immunological support for the use of MSC to prevent immune complications related to both HSC and solid organ transplantation and to the theory that MSC are universal suppressors of immune reactivity.