Mesenchymal stem cells are characterized by in vitro high proliferation and multilineage potential maintenance. This study aimed to isolate and characterize equine YS mesenchymal stem cells and compare these with amniotic membranes. The yolk sac (YS) and amniotic membranes (AM) were obtained from 20 pregnant mares with gestational age around 30 days. Cells were cultured in α-MEM supplemented with 15 % FBS, 1 % antibiotic solution, 1 % L-glutamine and 1 % nonessential amino acids. To cell characterization we used cytogenetic analysis, fibroblast colony-forming unit assays, cell growth curves, immunophenotyping, flow cytometry, differentiation assays and teratoma formation. Results: Both cell sources presented fibroblastoid and epithelioid-like format. The YS cells have lower colony formation potential then AM ones, 3 versus 8 colonies per 103 plated cells. However, YS cells grew progressively while AM cells showed steady. Both, the YS and amnion cells immunolabeled for Oct-4, Nanog, SSEA-3, cytokeratin 18, PCNA, and vimentin. In addition, presented mesenchymal, hematopoietic, endothelial and pluripotency markers in flow cytometry. Discussion: Both cell sources presented high plasticity and differed into osteogenic, adipogenic, and chondrogenic lineages, and no tumor formation in nude mice was observed. The results suggest that horse YS may be useful for cell therapy such as amnion-derived cells.
KEY WORDS: Horse; Mesenchymal stem cells; Placental stem cells; Regenerative medicine; Extraembryonic membranes.
FRANCIOLLI, A. L. R.; BARRETO, R. S. N.; MATIAS, G. S. S.; CARVALHO, R. C.; RODRIGUES, M. N.; FRATINI, P.; PIGNATARI, G. C.; RECHSTEINER, S. M. E. F.; MESS, A. M. & MIGLINO, M. A. Equine Yolk sac: a stem cells source. Int. J. Morphol., 38(5):1412-1420, 2020.