Human endometrium in cell culture: a new method for culturing human endometrium as separate epithelial and stromal components

Development and characterization of a polarized human endometrial cell epithelia in an air-liquid interface state

Human endometrial epithelia undergo injury repair and regeneration with the menstrual cycle; however, mechanisms underpinning the roles of endometrial epithelial cells in endometrial lesions and regeneration remain incompletely understood, mainly owing to the difficulty in the isolation and expansion of primary endometrial epithelial cells and the lack of reliable models for in vitro and in vivo studies. In this report, we sought to improve methods for the isolation and expansion of human endometrial epithelial cells with a Rho-associated protein kinase (ROCK) inhibitor–modified medium and subsequently characterize endometrial epithelium generated with primary cells cultured in an air–liquid interface (ALI) state. Immunocytochemistry staining revealed the expression of epithelial cellular adhesion molecule (EpCam) and stage-specific embryonic antigen-1 (SSEA-1) but a lack of CD13 in endometrial epithelial cells. Meanwhile, a large number of proliferative Ki67⁺ cells were observed in isolated epithelial cells. Importantly, the EpCam⁺/CD13⁻ cells were capable of forming spheroids, a characteristic of epithelial stem/progenitor cells. Interestingly, these cells also exhibited a capacity to reconstitute epithelial layers in an ALI state. Morphological analysis revealed mucosal secretion of differentiated epithelial cells with cilia and microvilli in ALI epithelial cells as determined by electronic microscopy. Immunoblotting assay further demonstrated the expression of endometrial epithelial cell markers keratin 17/19 and EpCam and stem cell marker OCT3/4 but not stromal cell marker Vimentin protein and CD13 in cell expansions. Furthermore, molecular analysis also showed that the exposure of cells to estrogen elevated the expression of estrogen receptor and progesterone receptors in ALI cultures. Our results shed light on the possibility of expanding sufficient numbers of endometrial epithelial cells for stem cell biology studies, and they provide a feasible and alternative model that can recapitulate the characteristics and physiology of endometrial epithelium in vivo.

Evidence for sulfatase and 17beta-hydroxysteroid dehydrogenase type 1 activities in equine epididymis and uterus

Our previous work showed that stallion testis produces high amounts of estrogens which are subsequently found in the ejaculate. These estrogens are mainly synthesized by testicular aromatase, and the major estrogen produced is estrone sulfate (E1S). The objective of this study was to investigate the potential role of E1S as a source of estrogens in the male and female horse reproductive tracts by determining whether both estrone sulfatase (Sulf) and 17beta-hydroxysteroid dehydrogenase type I (17beta-HSD1) activities were present in equine testes, epididymis and uterus. We assessed E1S bioconversion into estrone (E1) and estradiol (E2) in these tissues. Both Sulf and 17beta-HSD1 activities were well detected in the cauda epididymis and uterus. Additionally, Sulf activity was present in the distal corpus of the epididymis, and 17beta-HSDI in the proximal corpus. In contrast, aromatase gene expression, measured as an internal control of endogenous estrogen production, had high activity only in the testis. We found that seminal E1S of testicular origin can be metabolized to E2, especially in the cauda epididymis and uterus. Because E2 appears to play a major role in male and female reproduction, we propose that the bioconversion of seminal E1S could affect male and female fertility.

Histology of the human endometrium: from birth to senescence

Embryologically, the human endometrium is of mesodermal origin, and constitutes the mucosal lining of the fused Mullerian ducts of the uterus. In the adult, premenopausal woman, the endometrium follows a precisely programmed series of morphologic and physiologic events, characterized by growth, secretory differentiation, and in the absence of conception, degeneration and regeneration. Proliferation, secretion and degeneration are confined to the upper functionalis layer, whereas the lower basalis layer is the seat of regenerative endometrium. In the postmenopausal years, absence of biologically significant estrogenic stimulation leads to progressive endometrial involution, from proliferative to inactive in the mid-50s to atrophy in the late-60s. Cyclic endometrial alterations are controlled by the ovarian estrogens and progesterone via their respective endometrial intranuclear receptors, and possibly other peptides and enzymes. They provide appropriate environment for the implanting conceptus. The intimate inter-relationship between endometrial structure/function and steroid hormones during the premenopausal period serves as an indicator of the hypothalamo-pituitary-ovarian axis as related to ovulatory states.

Human endometrial cells grown on an extracellular matrix form simple columnar epithelia and glands

Normal human endometrial cells were grown on an extracellular matrix containing type IV collagen, laminin, heparan sulfate proteoglycan, and entactin (Matrigel). On the extracellular matrix, dispersed endometrial cells remained rounded, and aggregated to form mounds of cells, which continued to grow in this arrangement. At 10 d, light microscopy demonstrated that these mounds were comprised of an eosinophilic substance, containing individual fusiform stromal cells. About 50% of the mounds were covered with a single layer of polarized cuboidal to columnar cells with basal nuclei, whereas 60% contained columnar cells forming glandular structures with open lumina. These polarized cuboidal and columnar cells were epithelial, based on their positive staining for cytokeratins and the possession of microvilli, tonofilaments, abundant glycogen, ribosomes, and primitive junctional complexes. Kreyberg's stain showed the presence of mucin within the lumina of the glands, indicating that they were functional. Thus, human endometrial cells grown on an extracellular matrix form a simple cuboidal to columnar epithelium, a stromal component, and glandular structures, thereby mimicking the in vivo morphology of the endometrium.

Inhibition of Chlamydia trachomatis growth in endometrial cells by copper: possible relevance for the use of the copper IUD

There is agreement that the relative risk of developing pelvic inflammatory disease (PID) increases among women who use the intrauterine contraceptive device (IUD). The role of Chlamydia in causing PID among IUD users is not clear. The present study demonstrates that Chlamydia trachomatis growth can be inhibited in cultured human endometrial cells by copper ions at concentrations known to be released by the copper IUDs. More than 98% inhibition was produced with 10(-5) and 10(-6) M of copper. Both C. trachomatis serovar E and a lymphogranuloma venereum Chlamydia serovar L2 (LGV) were inhibited by the copper ions. Although the mechanism of the inhibition is not known, the continuous presence of the copper ions during and after adherence appeared to be necessary for maximal effect. If such inhibition occurs in vivo, it is possible that copper ions released from the copper-containing IUD may partially protect against chlamydial infection.

The effects of contraceptive hormones on the replication of Chlamydia trachomatis in human endometrial cells

Several recent reports have documented a lower incidence of pelvic inflammatory disease (PID) among oral contraceptive users. The interpretation of this observation is difficult because the action of the contraceptive hormones may be directly by action on a specific host cell-parasite relationship, or indirectly via their action on other systems. In the present study we investigated the susceptibility of cultured human epithelial cells of the endometrium to infection by chlamydia and the influence of contraceptive steroids (ethinyl estradiol, mestranol and medroxyprogesterone acetate) upon replication of chlamydia in these cells. Forty-eight hours post-infection, elementary and reticulate bodies were observed in vacuoles of the infected endometrial cells by electron microscopy. Treatment of chlamydial-infected cells with contraceptive steroids in three different concentrations (10(-5)M, 10(-6)M and 10(-7)M) resulted in no effect on chlamydial replication, as examined by one-step growth curve. These results indicate that contraceptive hormones do not prevent chlamydial infection by direct effect on the replication of the agent.