Ov ine amniotic epithelial stem-like cells: in vitro characterization and in vivo xenograft in horses with superficial digital flexor tendon (SDFT) spontaneous defects

The present study has been performedto evaluate the characteristicsof ovine amniotic epithelial stemlike cells (oAECs) and their regenerativeproperties for xenograft inspontaneous injuries of equineSDFT.The oAECs collected from six different fetuses havebeen previously amplified in vitro and analyzed for theexpression patterns of surface and stemness molecularmarkers, for cytogenetic stability and for their potentialto differentiate in vitro into mesodermal cell lines..oAECs with stable properties were then stored in vialsand cryopreserved until their use. Fifteen horses withacute SDFT monolateral core lesions were selected forinclusion in the clinical study. A total of 7 X 106 oAECsin 500l of saline was grafted into the lesion under USguidance with the horses standing and with local analgesia.Clinical and US controls were performed everymonth for 4 months Longest follow-up is 26 months.Samples of the SDFT from a horse died for unrelatedcauses were submitted to histological evaluation oAECs show a very high proliferation activity, a constantphenotype and a stable expression profile. Alsothe cells display the capacity to differentiate into mesenchimallineage cells (osteoblasts and tenocytes). Tenhorses were able to return to their pre-injury activitylevel with good or excellent level of performance, twohorses obtained poor results, two horses had reinjuryand one horse died. Ultrasonographic examinationsshowed a progressive increase of the echogenicity ofthe lesions and the ultrasonographic infilling of thedefects. The grafted oAECs were able to express ovinecollagen type I fibers in the SDFT of the died horse.[...]