Differential proMMP-2 and proMMP-9 Secretion in Human Pre-implantation Embryos at Day 5 of Development.

Abstract Background: The most commonly used non-invasive criterion for evaluating the probable success of transferring in vitro human embryos for implantation is their morphological development. With this criterion, however, embryos in cellular arrests go unnoticed. Extracellular matrix metalloproteases type 2 (MMP-2) and MMP-9 are key markers of embryonic development and the implantation process, according to various animal studies. The current study investigated the proMMP-2 and proMMP-9 expression in the culture media developing human embryos that were transferred for implantation. Methods: Forty-two patients were accepted in the Department of Reproductive Biology of a Hospital in México City, based on the Institutional inclusion criteria for in vitro fertilization. On day 5 of development, embryos were transferred to women, and the culture medium was stored at -70 to await assessment of the activity of proMMP-2 and proMMP-9 in substrate gel zymography. Results: The patients showing embryo sac development were assigned to the pregnant group (n =17) or non-pregnant (n =25). In both groups, the activity of proMMP-2 and proMMP-9 was evaluated in substrate gel zymography. Our results indicate for all 17 women able to achieve a full-term pregnancy, the activity band of proMMP-2 was found in the corresponding culture medium. For 11 of them, the band of proMMP-9. Regarding the other 25 patients, the expression band for proMMP-2 detected in 3 and that proMMP-9 in 11 individuals. Conclusions: On day 5 of embryo development, the evaluation of proMMP-2 and proMMP-9 in the embryo culture medium is a reliable indicator of embryo quality and capacity to establish pregnancy.