Comparative in vitro characterization of adipose tissue and bone marrow mesenchymal stem cells (MSCs) from sheep and goats for potential applications in stem cell therapy and improved reproduction

Small ruminants, i.e., sheep and goats, are not only an important component of livestock production, but also a promising model for translational research in reproductive and regenerative medicine using mesenchymal stem cells (MSCs). MSCs, known for their pleiotropic effects and ability to secrete regulatory factors, are increasingly used in various fields of biomedicine and veterinary research. Here, a comparative study of the characteristics of MSCs from different tissues of sheep and goats, i.e., adipose tissue (AT) and bone marrow (BM), was performed, including the analysis of their in vitro isolation features, culturing characteristics, and interspecies differences. We found that MSC cultures obtained from AT and BM exhibit species-specific differences in proliferation rate and culturing time. We describe long-term culture of ovine (up to 40 passages) and caprine (up to 20 passages) MSCs for the first time. Growth curves were constructed, and morphological differences between the cultures and changes in them with increasing passage number were documented. Induction of adipogenic and osteogenic differentiation demonstrated that MSCs isolated from different sources (AT vs. BM) require different times for differentiation; however, interspecies differences in differentiation time were not apparent. The isolation, culture, and differentiation protocols reported here provide a stable method for generating MSC populations from AT and BM in sheep and goats. Sheep MSCs demonstrated a greater proliferative activity compared to goats, but goat MSCs had an earlier proliferation peak. Unlike ovine MSCs, goat AT- and BM-MSCs did not alter their morphology during long cultivation. Neither sheep nor goat MSCs had spontaneous mesenchymal differentiation, but both AT-MSCs displayed faster adipogenesis, with BM-MSCs predisposed to osteogenesis. The results of the study contribute to understanding the interspecies features of MSCs in vitro and lay the groundwork for the practical, cutting-edge applications of small ruminant MSCs across various biomedical and veterinary fields.