Equine marrow-derived mesenchymal stem cells: isolation, differentiation and culture optimization

Most studies regarding the marrow-derived equine mesenchymal stem cells (MSCs) have mainly focused on the cell transplantation without considering the capacity of differentiation and in vitro requirements of the cells. These concerns were investigated in the present study. Equine MSCs were isolated from the sternal marrow aspirates and expanded through two successive subcultures. Passage-2 equine MSC cultures were then treated with appropriate supplements in order to examine the cell osteogenic, chondrogenic and adipogenic differentiation potential. Furthermore, the culture of the cells was investigated in terms of the optimal concentration of fetal bovine serum (FBS) and the initial cell-seeding density. Additionally, a growth curve was plotted for the cells to study their growth characteristics. According to our findings, equine MSCs were easily generated specialized bone, cartilage and adipose cell lineages as confirmed by specific staining and RT-PCR analysis. Moreover, the cells exhibited rapid expansion when being cultivated in the medium with 15% FBS at 100 cells/cm(2). Growth curves indicated that these cells rapidly entered the log phase after a brief lag (adaptation) period. In summary, marrow-derived equine MSCs possess tripotent differentiation capacity and rapid growth rate in the appropriate culture conditions.