Improved Expansion of MSC Without Loss of Differentiation Potential

ABSTRACT

Mesenchymal stem cells (MSC) hold significant promise for tissue engineering and regenerative medicine. Clinical and pre-clinical applications of MSC require that they be expanded in culture with maximum efficiency while maintaining the ability to differentiate into key lineages. Fetal bovine serum (FBS) is a key factor in the in vitro maintenance of hMSC, but lot-to-lot variability can significantly impact experimental results. In order to produce a growth medium that consistently allows optimal expansion of hMSC, we tested different concentrations of FBS from several sources. Our results indicate that efficiency of expansion varies greatly among FBS samples, with a 1.8 to ~ 4.2 fold increase after a single passage. The FBS lot supporting the largest fold-expansion of hMSC was used in development of StemXVivo™ Mesenchymal Stem Cell Expansion Media. When tested against another commercially available MSC expansion medium, StemXVivo™ Mesenchymal Stem Cell Expansion Media resulted in a 5.6 fold expansion after two passages compared to a 2.8 fold expansion of cells in competitor medium. We then sought to confirm that cells expanded in StemXVivo Mesenchymal Stem Cell Expansion Media maintained their full differentiation potential. We assessed the phenotype of the cells after expansion and found them to be CD105⁺, CD90⁺ and CD34^-. We tested their ability to differentiate into chondrocytes, osteocytes, and adipocytes. Staining with lineage-specific antibodies confirmed efficient differentiation of the cells into these lineages. Thus, we concluded that pre-screening of several lots of FBS allows production of expansion medium that provides maximum MSC expansion efficiency without compromising pluripotency.