Effect of serum choice on replicative senescence in mesenchymal stromal cells

Background aims. Multipotent mesenchymal stromal cells (MSCs) are promising candidates for innovative cell therapeutic applications. Before their use, however, they usually need to be expanded in vitro with serum-supplemented media. MSCs can undergo replicative senescence during in vitro expansion, but it is not yet clear how serum supplements influence this process. Methods. In the present study, we compared how Media supplemented with fetal bovine serum (PBS) or calf serum (CS) affected morphology, proliferation, differentiation, senescence and other functional characteristics of human umbilical cord-derived MSCs (UC-MSCs). Results. UC-MSCs cultured in both FBS- and CS-containing media were able to differentiate along osteogenic and adipogenic lineages but ultimately reached proliferation arrest. However, senescence-associated characteristics, such as beta-galactosidase activity, reactive oxygen species levels, proliferation rate and gene expression, demonstrate that UC-MSCs grown with FBS have better proliferation potential and differentiation capacity. In contrast, UC-MSCs grown with CS have a higher proportion of apoptotic cells and senescent characteristics. Possible mechanisms for the observed phenotypes include changes in gene expression (Bax p16, p21 and p53) and cytokine production (interleukin-6 and interleukin-8). Conclusions. This study demonstrates that FBS-supplemented media provides a better microenvironment for the expansion of UC-MSCs in vitro than CS-supplemented media. This work provides insight into MSCs generation practices for use in basic research and clinical therapies.