Administration of peripheral blood mononuclear cells into the uterine horn to improve pregnancy rate following bovine embryo transfer

Embryo transfer (ET) has been used to improve reproductive efficiency and genetic make-up in bovine species. However, the success rate of ET has not been improved since its inception. Here we examined whether administration of autologous peripheral blood mononuclear cells (PBMCs) into the uterine horn can improve pregnancy rates following bovine ET. First we determined that the abundance of interleukin (IL)-1α, IL-1β and IL-8 transcripts in PBMCs was greatest after 24 h of culture. PBMCs that had been cultured for 24 h were gently administered non-surgically to the uterine horn ipsilateral to the corpus luteum on day 4 of the estrous cycle. On day 7, the ET was carried out and the pregnancy rate in the PBMC-treated group was compared with that in the non-treated group. The pregnancy rate on day 60 in the PBMC-treated group (76.7%, 56/73) was significantly higher than that in the non-treated group (59.7%, 43/72, p < 0.05). These results indicate that administration of autologous PBMCs into the uterine horn improves pregnancy rates following bovine ET.