Effects of continuous passage on immunomodulatory properties of human adipose-derived stem cells

Human adipose-derived stem cells (hADSCs) have the ability to influence immune response, and hence are key cell sources for tissue repair and regeneration. In this study we explored the effect of continuous passage on the immunomodulatory properties of hADSCs to provide some advises for large-scale production of hADSCs for clinical applications. We found that after continuous passage, the specific surface markers expression levels as well as the adipogenic and osteogenic differentiation capacities of hADSCs had no obvious changes. However, the secretion levels of IL-10 and HGF reduced dramatically along with passage numbers. Furthermore, the INF-γ level was found higher in which medium peripheral blood mononuclear cells were co-cultured with hADSCs with higher passage numbers. Also, the in vivo experiments showed that the peritonitis model mice, which were injected with higher passage numbers of hADSCs, tended to have higher levels of inflammation. All these together indicated that continuous passage has only minor effect on the cell phenotypes but will impair the immunomodulatory properties of hADSCs. This suggests that hADSCs could be prepared by continuous passage, but only those cells of lower passage numbers would be ideal therapeutic tools.