Pilot experimental study on amniotic epithelial mesenchymal cell transplantation in natural occurring tendinopathy in horses. Ultrasonographic and histological comparison.

were grafted, in sterile conditions and under ultrasound control, into the most damaged area. Ultrasound controls were performed at 30, 60, 90, 120, 150 and 180 days after cells implantation; after horse euthanasia (180 days) tendon samples were collected and submitted to histological examination (cellularity, extracellular matrix fiber organization, blood vessels). Results: at baseline, in the acute cases, the ultrasound exam showed a focal, dis-homogeneous, hypo-echoic area into the superficial digital flexor tendon, with loss of the normal fibrillar pattern, while in the chronic cases the damaged tendon area appeared thickened and completely hyperechoic. At the final follow-up tendon echotexture was more regular, the cross-sectional area similar to the contra-lateral limb, and the collagen fibers were oriented in parallel to the longitudinal axis of the tendon both in the acute and chronic cases, suggesting a positive healing response. These findings were supported by the histological analyses which showed an almost complete restoration of normal tendon architecture with an optimal alignment of tendon fibers. Conclusions: the present pilot study supports the hypothesis that amniotic epithelial cells are provided of an excellent healing potential and shows a very good correlation between the ultrasound findings and the histologic features.