LAMELLAR HISTOLOGICAL AND IMMUNOHISTOCHEMICAL EVALUATION OF THE HOOF WALL IN HORSES WITH CHRONIC LAMINITIS TREATED WITH MESENQUIMAL STEM CELLS DERIVED FROM ADIPOSE TISSUE BY REGIONAL PERFUSION

Abstract

<h3>Background</h3> The objective was to evaluate the histological and immunohistochemical effects of regional perfusion of characterized mesenchymal stem cells derived from adipose tissue (Ad-MSC) in biopsy hoof samples from horses with laminitis. <h3>Methods</h3> Six mares with stable chronic laminitis in standard treatment for distal phalangeal realignment were subjected to regional perfusion of the digital vein with Ad-MSC (20 million cells, 3 infusions every 15 days) in one forelimb compared to placebo infusion in the contralateral one. Evaluations occurred in two 30-day periods, before and after treatment (from the second infusion). Dorsal hoof lamellar biopsies were taken 30 days before and 15 days after the therapeutic protocols. Histological 5-μm cuts stained with H&E and PAS were classified based on a crescent 1-5 scale lesion score system. The sum of each lesion grade represented the global lesion score. Immunohistochemistry for p63 positive cells were also performed in formalin-fixed samples. <h3>Results</h3> In the placebo limbs, there were increases over time in following histological variables: global lesion (P=0.01), keratinized axis loss (P=0.0001), stratum medium hyperplasia (P=0.001), primary epidermal lamellae homogeneity loss (P=0.003), and hyperkeratosis (P=0.05). Only the stratum medium hyperplasia score was increased in the Ad-MSC-treated hooves. P63-positive cells could be detected in all formalin-fixed paraffin-embedded samples, but background unspecific stain made counts imprecise to be made. <h3>Conclusion</h3> In conclusion Ad-MSC regional vascular perfusion prevented histological lesion progression in the lamellar tissue of horses with chronic laminitis. Our results confirm the therapeutic potential of Ad-MSC in the treatment of horses with stable chronic laminitis.