Isolation of mesenchymal stem cells from equine umbilical cord blood.

Background: There are no published studies on stem cells from equine cord blood although commercial storage of equine cord blood for future autologous stem cell transplantations is available. Mesenchymal stem cells (MSC) have been isolated from fresh umbilical cord blood of humans collected non-invasively at the time of birth and from sheep cord blood collected invasively by a surgical intrauterine approach. Mesenchymal stem cells isolation percentage from frozen-thawed human cord blood is low and the future isolation percentage of MSCs from cryopreserved equine cord blood is therefore expectedly low. The hypothesis of this study was that equine MSCs could be isolated from fresh whole equine cord blood.

Results: Cord blood was collected from 7 foals immediately after foaling. The mononuclear cell fraction was isolated by Ficoll density centrifugation and cultured in a DMEM low glucose based media at 38.5 degrees C in humidified atmosphere containing 5% CO2. In 4 out of 7 samples colonies with MSC morphology were observed. Cellular morphology varied between monolayers of elongated spindle-shaped cells to layered cell clusters of cuboidal cells with shorter cytoplasmic extensions. Positive Alizarin Red and von Kossa staining as well as significant calcium deposition and alkaline phosphatase activity confirmed osteogenesis. Histology and positive Safranin O staining of matrix glycosaminoglycans illustrated chondrogenesis. Oil Red O staining of lipid droplets confirmed adipogenesis.

Conclusion: We here report, for the first time, the isolation of mesenchymal-like stem cells from fresh equine cord blood and their differentiation into osteocytes, chondrocytes and adipocytes. This novel isolation of equine cord blood MSCs and their preliminary in vitro differentiation positions the horse as the ideal pre-clinical animal model for proof-of-principle studies of cord blood derived MSCs.