Endothelin type A receptor (ETA) expression is regulated by HOXA10 in human endometrial stromal cells

Endothelins and their receptors in embryo implantation

As a critical stage of pregnancy, the implantation of blastocysts into the endometrium is a progressive, excessively regulated local tissue remodeling step involving a complex sequence of genetic and cellular interplay executed within an optimal time frame. For better understanding the causes of infertility and, more importantly, for developing powerful strategies for successful implantations and combating infertility, an increasing number of recent studies have been focused on the identification and study of newly described substances in the reproductive tree. The endothelins (ET), a 21-aminoacidic family of genes, have been reported to be responsible for the contraction of vascular and nonvascular smooth muscles, including the smooth muscles of the uterus. Therefore, this review aims to comprehensively discuss the physiological role of endothelins and signaling through their receptors, as well as their probable involvement in the implantation process.

Endometriosis impairs bone marrow-derived stem cell recruitment to the uterus whereas bazedoxifene treatment leads to endometriosis regression and improved uterine stem cell engraftment

Endometriosis is a disease defined by the ectopic growth of uterine endometrium. Stem cells contribute to the generation of endometriosis as well as to repair and regeneration of normal endometrium. Here we demonstrate that the selective estrogen receptor modulator bazedoxifene (BZA), administered with conjugated estrogens (CEs), leads to regression of endometriosis lesions as well as reduction in stem cell recruitment to the lesions. Female mice underwent transplantation of male bone marrow. Endometrium was transplanted in the peritoneal cavity of half to create experimental endometriosis. Mice with or without experimental endometriosis were randomized to BZA/CE or vehicle treatment. Endometriosis lesions, bone marrow-derived mesenchymal stem cell engraftment of the lesions, and eutopic endometrium as well as ovarian stimulation were assessed. BZA treatment significantly reduced lesion size, gland number, and expression of proliferation marker proliferating cell nuclear antigen. Ovarian weight was not affected. Stem cells were recruited to the endometriosis lesions, and this recruitment was dramatically reduced by BZA/CE treatment. Stem cell engraftment was reduced in the uterus of animals with endometriosis; however the number of stem cells engrafting the uterus was completely restored by treatment with BZA/CE. Competition between endometriosis and the eutopic endometrium for a limited supply of stem cells and depletion of normal stem cells flux to the uterus is a novel mechanism by which endometriosis interferes with endometrial function and fertility. BZA/CE not only treats lesions of endometriosis, it also dramatically reduces stem cell recruitment to the lesions and restores stem cell engraftment of the uterine endometrium.

Treatment with bazedoxifene, a selective estrogen receptor modulator, causes regression of endometriosis in a mouse model

Endometriosis is a common estrogen-dependent disorder. Medical treatments currently consist of progestins or GnRH agonists; however, neither is fully effective and both entail significant side effects. Selective estrogen receptor (ER) modulators (SERM) have tissue-selective actions, acting as an ER agonist in some tissues and ER antagonist in others. The SERM bazedoxifene (BZA) effectively antagonizes estrogen-induced uterine endometrial stimulation without countering estrogenic effects in bone or central nervous system. These properties make it an attractive candidate for use in the treatment of endometriosis. Experimental endometriosis was created in reproductive-age CD-1 mice. After 8 wk, 10 animals received i.p. injections of BZA (3 mg/kg·d) for 8 wk, whereas 10 received vehicle control. Mice were killed, and implant size was assessed. The mean size of the implants after treatment was 60 mm(2) in the control group and 21 mm(2) in the BZA treatment group (P = 0.03). Quantitative PCR and immunohistochemical analysis were used to determine the effect on endometrial gene expression. PCNA, ERα, and LIF mRNA and protein expression were significantly decreased in endometrium of the treated group. Caspase 3 mRNA expression was increased. Expression of PR and Hoxa10 were not significantly altered by treatment. There was no evidence of ovarian enlargement or cyst formation. Decreased PCNA and ER expression demonstrated that the regression of endometriosis likely involved decreased estrogen-mediated cell proliferation. BZA may be an effective novel agent for the treatment of endometriosis due to greater endometrial-specific estrogen antagonism compared with other SERM.