Intrauterine infusion of platelet-rich or platelet-poor plasma to modulate persistent breeding induced endometritis in embryo donor mares

Goal was to assess postbreeding endometrial inflammatory response and embryo recovery rates in mares susceptible to persistent breeding induced endometritis (PBIE) treated with platelet-rich plasma (PRP) and platelet-poor plasma (PPP). We hypothesized that administration of PRP and PPP mitigate endometrial inflammation in mares susceptible to PBIE and platelets have an additive ability to modulate this response. Mares (n = 12) that had 3 cycles were classified as susceptible to PBIE, based on a challenge with killed sperm and randomly assigned in a crossover design. Mares received intrauterine infusions of 40 ml of lactate Ringer’s solution (LRS, control), or autologous PRP or PPP at 48 and 24 hours before and 6 and 24 hours postbreeding. PRP and PPP were prepared from blood, using a standard double centrifugation method. Platelet count and viability were assessed with spectral flow cytometry (CD41/61 coupled with IgG-PE conjugated). Ovulation was induced (≥ 35 mm follicle) with a gonadotropin releasing hormone agonist (histrelin) and mares were bred on subsequent day with fresh semen collected from a single stallion. At 6 hour postbreeding, uterine lavage (2 liters LRS) was performed immediately before infusion with treatment. Mares had daily measurements (height and width) of intrauterine fluid accumulation (IUF) at uterine body for 96 hours. Endometrial cytology was performed until 72 hours postovulation, and number of polymorphonuclear cells (# PMNs) was counted. Embryo flushing was performed 8 days postovulation with LRS. Recovered uterine fluid was aerobically cultured. Plasma was collected on the day of ovulation induction, 72 hours and 8 days postovulation to assess P 4 concentrations. Statistical analyses were performed with ANOVA-RM and posthoc Tukey’s (IUF, # PMNs, P 4 concentrations), whereas fertility and number of positive bacterial cultures were assessed with multivariate regression. Mean platelet concentrations were 608.7 ± 62 and 47.5 ± 12 × 103 /µl in PRP and PPP, respectively. In addition, there were no differences in platelet-viability between groups (97 ± 0.7 versus 97.2 ± 0.6%). Both treatment groups significantly reduced the # PMNs on endometrial cytology from 24 - 72 hours postbreeding. Infusion of PRP and PPP resulted in a significant reduction in IUF postbreeding when compared to control. Estrous cycles assigned as control resulted in a higher percentage (p < 0.05) of positive cultures (42%), compared to PRP cycles (0%), whereas cycles treated with PPP were not different (p > 0.05; 17%) from other groups. P 4 concentrations substantially increased in both treatment groups on day 8 postovulation. Mares treated with PRP tended to have higher (p = 0.08) embryo recovery rates (83%) than mares in control group (42%), whereas PPP had intermediate embryo recovery (60%). In conclusion, plasma infusion can be used as an alternate method to modulate inflammatory response in mares susceptible to PBIE and PRP apparently had additional antimicrobial properties compared to plasma PPP.

Keywords: Embryo transfer, endometritis, reproduction, 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.