Post-Insemination Infusion of Wharton’s Jelly Mesenchymal Stromal/Stem Cells-Derived Conditioned Medium: A Novel Approach for Improving Pregnancy Outcomes in Problem Mare

Treating endometritis is one of the major challenges faced by veterinarians. The effect of post-insemination intrauterine infusion Wharton’s jelly mesenchymal stromal/stem cell-derived conditioned medium (WJ-MSC-CM) on the uterine response and pregnancy outcomes in problem mares was evaluated in this study. The cycles of 11 problem mares were randomly treated seven/eight hours after insemination with intrauterine infusion of 20 ml of WJ-MSC-CM (TRT) or non-conditioned Ringer’s lactate solution (CTR). Before (PRE) and 12 hours after (POST) treatment, an ultrasonographic examination and a low-volume flush (LVF) for efflux clarity evaluation and bacteriological and cytological analysis were made. Pregnancy diagnosis was performed at 14 days and confirmed at 60 days after ovulation. A decrease (P<0.05) in polymorphonuclear neutrophils infiltration and a trend toward significance in LVF efflux clarity (P<0.1) were observed in TRT cycles. Only a trend toward significance was observed comparing pregnancy frequencies between the two groups (CTR 14% vs. TRT 54%), the pregnancy rate of TRT cycles was comparable to that of normal mares (P>0.05) and higher (P<0.05) than that reported for problem mares in the literature. Post-insemination uterine infusion of WJ-MSC-CM in mares restores pregnancy rates to normal levels, by its anti-inflammatory effect.