Replicative aging and differentiation potential of human adipose tissue-derived mesenchymal stromal cells expanded in pooled human or fetal bovine serum

Background aims. Mesenchymal stromal cells (MSC) are promising candidates for innovative cell therapeutic applications. For clinical-scale manufacturing, different supplements have been evaluated as alternatives for the commonly used fetal bovine serum (FBS). We have reported previously that pooled human AB serum (HS) accelerates the proliferation of adipose tissue-derived MSC (ASC) while maintaining key functions of MSC biology such as differentiation, immune suppression and growth factor secretion. ASC expanded in FBS-supplemented culture media undergo replicative aging that is associated with a progressive loss of differentiation capacity but without indications of cellular transformation. The effects of HS media on ASC long-term culture, however, remain poorly characterized. Methods. Long-term cultures of ASC in FBS and HS media were analyzed with respect to proliferation, marker expression, differentiation and immune suppression. Results. Despite signs of an accelerated proliferation, extended life span and clonogenic capacity of ASC cultivated in HS-supplemented media, HS and FBS cultures revealed no significant differences with respect to differentiation potential and expression of senescence markers. Anchorage-independent growth, which is indicative of tumorigenic properties, was not observed in either culture conditions. Similarly, immune suppressive activities were maintained. Donor variation regarding differentiation potential and marker expression became apparent in this study independent of the culture supplement or culture duration. Conclusions. We have demonstrated that the use of pooled allogeneic HS maintains the characteristics of ASC even after long-term expansion, further demonstrating that the use of HS is an alternative to FBS.