Clinical effects of prebreeding intrauterine platelet-rich plasma in mare

Platelet-rich plasma (PRP) is being used with increasing frequency in both human and veterinary medicine. By concentrating platelets, growth factors are recruited to aid in tissue healing and repair. In women, intrauterine PRP treatment improved endometrial receptivity. In mares, a limited number of studies focused on treating subfertile mares with intrauterine autologous blood products. Our aim was to examine the safety and efficacy of intrauterine administration of autologous PRP prepared with a commercial platelet isolation device (Restigen PRP® , [platelet buffy coat concentration device], Owl Manor, Warsaw, IN). We hypothesized that the treatment would be both safe and effective in addressing intrauterine inflammation, based on the frequency of adverse events, intrauterine fluid grade and pregnancy rate following treatment. Notably, we elected to focus on clinical end points rather than histologic or cytologic evaluations, and used frozen-thawed semen as opposed to fresh or cooled transported semen. In this clinical-based crossover study, inclusion criteria were failure to achieve pregnancy after artificial insemination with frozen semen, absence of clinical evidence of infectious endometritis, and normal physical exam parameters. Eighteen mares of various breeds, ages and parities were used. Each mare served as her own control and was bred to the same stallion as the previous cycle. Breeding management was performed in a routine manner. Autologous PRP was prepared by an experienced operator using Restigen PRP kits and uterine body infusion was performed 12 - 48 hours prior to artificial insemination. Postinsemination, intrauterine fluid was graded via transrectal ultrasonography using a predetermined scale based on volume and echogenicity. Pregnancy status was determined via transrectal ultrasonography from 13 - 16 days postovulation or via embryo flush performed 7 - 8 days postovulation. No adverse events were recorded in association with intrauterine infusion of PRP. Data were analyzed using nonparametric tests. There was no difference (p > 0.05) in post-breeding intrauterine fluid score between treatment and control groups. Postbreeding intrauterine fluid score improved in 7/18 mares (39%) and was unchanged in 6/18 (33%). There was substantial effect of treatment on pregnancy rate, as 11/18 mares (61%) became pregnant in the treated cycle as opposed to 0/18 (0%) in control cycle. Results indicated that intrauterine infusion of autologous PRP prepared with a commercial platelet isolation device in the periovulatory period was a safe procedure, and associated with improved breeding outcomes in this population of mares. To better determine efficacy, further studies are in progress to differentiate these results from those of second cycle pregnancy rates without PRP use.

Keywords: Mare, platelet-rich plasma, frozen semen, artificial insemination, safety, inflammation

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.