Background: Human multipotent stromal (skeletal, mesenchymal) stem cells (hMSC) are employed in an increasing number of clinical trials for tissue regeneration of age-related degenerative diseases. However, routine use of fetal bovine sera (FBS) for their in vitro expansion is not optimal and may pose a health risk for patients.
Methods: We carried out a side-by-side comparison of the effects of allogenic pooled human serum (HuS) versus FBS on hMSC proliferation and differentiation in vitro and in vivo. As a model for hMSC, we employed telomerase-immortalized hMSC; hMSC-TERT cell line.
Results: hMSC-TERT exhibited similar morphology and size when cultured in HuS vs. FBS as assessed by light microscopy and FACS analysis. We did not observe any significant differences in growth rates of hMSC-TERT during short-term (10 days) and long-term (100 days) culture in media supplemented with HuS vs. FBS. hMSC-TERT or primary bone marrow derived hMSC induced to osteoblastic or adipocytic differentiation in the presence of HuS or FBS showed comparable levels of gene expression and protein production of osteoblastic markers (CBFA1/Runx2, alkaline phosphastase, collagen type I and osteocalcin) or adipocytic markers (PPAR-gamma2, lipoprotein lipase (LPL), aP2), respectively. In order to test for the functional capacity of hMSC-TERT that have been maintained in long-term cultures in the presence of HuS vs. FBS, the cells were mixed with hydroxyapatite/tricalcium phosphate (HA/TCP) and implanted subcutaneously in immune deficient mice. hMSC maintained in HuS vs. FBS formed comparable heterotopic bone.
Discussion: Human serum can support proliferation and differentiation of hMSC in vitro and can maintain their bone forming capacity in vivo. The use of human serum in cell cultures of hMSC intended for cell-based therapy is preferable.