Effects of acellular equine amniotic allografts on the healing of experimentally induced full-thickness distal limb wounds in horses.

Objective: To characterize the growth factors contained in equine amniotic membrane allograft (eAM; StemWrap scaffold and StemWrap+ injection) and to evaluate the effect of eAM on equine distal limb wound healing.

Study Design: Prospective experimental controlled study.

Sample Population: Eight adult horses.

Methods: Transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), epidermal growth factor, platelet-derived growth factor-BB, and prostaglandin E (PGE ) concentrations in StemWrap+ were assessed with enzyme-linked immunosorbent assay. Two full-thickness 6.25-cm skin wounds were created on each metacarpus. On one forelimb, one wound was treated with eAM, and the other was left untreated (eAM control). On the contralateral limb, one wound was treated with a silicone dressing, and the other served as negative control. Three-dimensional images were obtained to determine wound circumference and surface area analyses at each bandage change until healed. Excessive granulation tissue was debrided once weekly for 4 weeks. Biopsy samples were taken to evaluate quality of wound healing via histologic and immunohistochemistry assays.

Results: StemWrap+ contained moderate concentrations of TGF-β1 (494.10 pg/mL), VEGF (212.52 pg/mL), and PGE (1811.61 pg/mL). Treatment of wounds with eAM did not affect time to healing or histologic quality of the healing compared with other groups but was associated with increased granulation tissue production early in the study, particularly on day 7.

Conclusion: Application of eAM resulted in increased granulation tissue production while maintaining appropriate healing of experimental wounds.

Clinical Significance: Use of eAM is likely most beneficial for substantial wounds in which expedient production of large amounts of granulation tissue is desirable.