Characterization of Human Fetal Cartilage Progenitor Cells During Long-Term Expansion in a Xeno-Free Medium

BACKGROUND: Stem cell therapy requires a serum-free and/or chemically-defined medium for commercialization, but it is difficult to find one that supports long-term expansion of cells without compromising their stemness, particularly for novel stem cells. METHODS: In this study, we tested the efficiency of StemPro (R) MSC SFM Xeno Free (SFM-XF), a serum-free medium, for the long-term expansion of human fetal cartilage-derived progenitor cells (hFCPCs) from three donors in comparison to that of the conventional alpha-Modified Eagle's Medium (alpha-MEM) supplemented with 10% fetal bovine serum (FBS). RESULTS: We found that SFM-XF supported the expansion of hFCPCs for up to 28-30 passages without significant changes in the doubling time, while alpha-MEM with 10% FBS showed a rapid increase in doubling time at 10-18 passages depending on the donor. Senescence of hFCPCs was not observed until passage 10 in both media but was induced in approximately 15 and 25% of cells at passage 20 in SFM-XF and alpha-MEM with 10% FBS, respectively. The colony forming ability of hFCPCs in SFX-XF was also comparable to that in alpha-MEM with 10% FBS. hFCPCs expressed pluripotency genes like Oct-4, Sox-2, Nanog, SCF, and SSEA4 at passage 20 and 31 in SFM-XF; however, this was not observed when cells were cultured in alpha-MEM with 10% FBS. The ability of hFCPCs to differentiate into three mesodermal lineages decreased gradually in both media but it was less significant in SFM-XF. Finally we found no chromosomal abnormality after long-term culture of hFCPCs until passage 17 by karyotype analysis. CONCLUSION: These results suggest that SFM-XF supports the long-term expansion of hFCPCs without significant phenotypic and chromosomal changes. This study have also shown that hFCPCs can be mass-produced in vitro, proving their commercial value as a novel source for developing cell therapies.