Conceptus implantation and placentation: molecules related to epithelial–mesenchymal transition, lymphocyte homing, endogenous retroviruses, and exosomes

Abstract

Processes of conceptus implantation and placentation, unique to mammalian reproduction, have been extensively studied. It was once thought that processes of these events varied greatly, notably between invasive and noninvasive modes of implantation and/or placentation. Regardless of the mode of implantation, however, physiological and biochemical processes in conceptus implantation to the maternal endometrium including the kinds of gene expression and their products are now considered not to differ so much. Recent progress has identified that in addition to the hormones, cytokines, proteases and cell adhesion molecules classically characterized, epithelial-mesenchymal transition, molecules related to lymphocyte homing, the expression of endogenous retroviruses and possibly exosomes are all required for the progression of conceptus implantation to placentation. In this review, therefore, new findings related to these events are integrated into the context of conceptus implantation to the maternal endometrium.

TNF-α Regulated Endometrial Stroma Secretome Promotes Trophoblast Invasion

“…Indeed, it is well established that the trophectoderm at the time of implantation express mesenchymal markers (19,64,65). During the adhesion of the embryo to the endometrium, the embryonic trophectoderm upregulates the expression of genes characteristic of an epithelial to mesenchymal transition (EMT) in order to be able to migrate and invade the uterine cavity (64,(66)(67)(68). Thus, BLS were transferred into individual wells of a 96-well plate containing CM from HEC-1A, hESC, or DMEM/F-12 growth medium supplemented with low serum (1% FBS) as a control (Conditioned Media for all the cells was prepared using 1% FBS).…”

Promoting Roles of Embryonic Signals in Embryo Implantation and Placentation in Cooperation with Endocrine and Immune Systems

“…However, they also reduce attachment to the basement membrane, causing detachment of the epithelial cell layer that maintains embryo attachment. In contrast to the immune system, epithelial-mesenchymal transition (EMT) was reported to be involved in opening of the epithelial layer [84][85][86][87]. However, EMT simultaneously reduces the connection of epithelial cells to the basement membrane, undermining the anchoring foundation of the implanting embryo.…”

Outcomes of IVF programs with intrauterine administration of autologous mononuclear cells in women with repeated implantation failure

“…Сравнительный анализ оценки эффективности данного метода иммунотерапии в зависимости от активации МНК и вида программы ВРТ показал, что активация МНК ХГч повышает эффективность криоциклов в 1,2 раза, но не влияет на исходы стимулированных циклов, что, вероятно, связано с эффектами ХГч, используемого в качества триггера овуляции в стимулированных циклах, что согласуется с данными литературы о снижении частоты клинической беременности в стимулированных циклах по сравнению с криоциклами [3].…”