Objective: Two main sources for isolation of equine mesenchymal stem cells (MSCs) are bone marrow (BM) and fat tissue (FT) which are proper candidates for cell therapy in equine regenerative medicine. MSC populations isolated from different sources exhibit significant differences in their characteristics such as growth rate. Aim of this study was to investigate growth rate of BM-MSCs versus FT-MSCs. Methods: MSCs were isolated from fat tissue and bone marrow of 3 mares, cultured and passaged until passage3 (P3). Cells of each horse at P3 were seeded in 12 wells-plates with density of 30000 cells per well. After 24h, the cells of 3 wells were daily trypsinized, counted and averaged from day 1 to 8. Then, growth curve was plotted and population doubling (PDT) time was calculated. Results: FT-MSCs and BM-MSCs became adaptive to the culture conditions during first 3 days and then started to enter the logarithmic phase (days 3-6). FT-MSCs after 7 days don’t reach to plateau phase and their growth was continued with decreased rate. However, Logarithmic growth of BM-MSCs was finished at day 6 and cell population start to decrease at day 7. Mean of PDT was 43.82 and 78.15 h for FT-MSCs and BM-MSCs, respectively. Conclusion: Our finding indicates that growth rate of FT-MSCs is significantly faster than BM-MSCs in vitro. It means that the proliferation of FT-MSCs to reach appropriate number for transplantation purposes needs less time in vitro.

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