Equine umbilical cord blood contains a population of stem cells that express Oct4 and differentiate into mesodermal and endodermal cell types

Mesenchymal stem cells (MSCs) offer promise as therapeutic aids in the repair of tendon, ligament, and bone damage suffered by sport horses. The objective of the study was to identify and characterize stem‐like cells from newborn foal umbilical cord blood (UCB). UCB was collected and MSC isolated using human reagents. The cells exhibit a fibroblast‐like morphology and express the stem cell markers Oct4, SSEA‐1, Tra1‐60 and Tra1‐81. Culture of the cells in tissue‐specific differentiation media leads to the formation of cell types characteristic of mesodermal and endodermal origins. Chondrogenic differentiation reveals proteoglycan and glycosaminoglycan synthesis as measured histochemically and Sox9 and collagen 2A1 gene transcription. Osteocytes capable of mineral deposition, osteonectin and Runx2 transcription were evident. Hepatogenic cells formed from UCBs express albumin and cytokeratin 18. Multinucleated myofibers that express desmin were observed indicating partial differentiation into mature muscle cells. Interestingly, conventional human protocols for UCB differentiation into adipocytes were unsuccessful in foal UCB and adult horse adipose‐derived MSC. These results demonstrate that equine UCB can be induced to form multiple cell types that underlie their value for regenerative medicine in injured horses. In addition, this work suggests that subtle differences exist between equine and human UCB stem cells. J. Cell. Physiol. 215: 329–336, 2008. © 2007 Wiley‐Liss, Inc.