Endometrial Cell Attachment Research Articles

HYALURONIC ACID PATHWAY EXPRESSION IN PAIRED EUTOPIC ENDOMETRIAL AND ENDOMETRIOMA CELLS

Cellular processes involved in the development of peritoneal endometriotic implants and endometriomas from refluxed endometrial cells (ECs) is poorly understood. Progesterone and estrogen influence the hyaluronic acid (HA) system which has been shown to be involved in the initial development of endometriotic lesions in vitro and in vivo (Knudtson, Dachaud). We previously showed that P4 inhibits attachment of ECs; however, the effect of P4 on the HA system within endometriomas has not yet been studied.

Human embryonic stem cell–derived blastocyst-like spheroids resemble human trophectoderm during early implantation process

To study the use of human embryonic stem cell-derived trophoblastic spheroids (BAP-EB) as human blastocyst surrogates for studying early implantation and trophoblast development. Laboratory study. University research laboratory. Infertile invitro fertilization patients donating endometrial aspirates and human embryonic stem cells (hESCs: VAL3 and H9/WA09). In BAP-EB derived from hESC, transcriptomes analyzed by next-generation RNA sequencing, effects of Hippo signaling pathway studied by a YAP inhibitor, comparison of attachment of BAP-EB onto primary endometrial epithelial cells (EEC) collected at prereceptive and receptive phases, and antibody blocking assay used to study the molecule(s) involved in BAP-EB attachment. Gene expression profiles and endometrial cell attachment rates. The BAP-EB differentiation protocol for VAL3 could be used to induce trophoblast differentiation in another hESC line, H9. Transcriptomic analysis showed that the epiblast signature gene expression was reduced while that of the trophoblast was induced during BAP-EB differentiation. Specifically, trophectoderm signature genes were induced in BAP-EB at 48 hours and 72 hours after induction of differentiation. The Hippo signaling pathway was one of the pathways induced during BAP-EB differentiation, and YAP1 inhibitor statistically significantly reduced attachment, outgrowth, and trophoblast gene expressions of BAP-EB. A statistically significantly higher number of BAP-EB derived from both VAL3 and H9 attached onto receptive EEC than prereceptive EEC. The antibody blocking assay demonstrated that endometrial E-cadherin might be critical in early implantation. The data suggest that BAP-EB possesses a trophectoderm-like signature, which supports the use of BAP-EB as a blastocyst surrogate for the study of trophoblast development and endometrial receptivity.

Inhibition of Hyaluronic Acid Synthesis Decreases Endometrial Cell Attachment, Migration, and Invasion.

To characterize the effects of 4-methylumbelliferone (4-MU) on expression of the hyaluronic acid (HA) system and on attachment, migration, and invasion of endometrial epithelial (EECs) and stroma cells (ESCs) to peritoneal mesothelial cells (PMCs), this in vitro study was performed in an Academic Center. De-identified endometrial tissue samples used were from reproductive-aged women. EECs and ESCs isolated from menstrual endometrial biopsies were treated with 4-MU or vehicle. Real-time polymerase chain reaction and western blot were used to assess expression of HA synthases (HAS), hyaluronidase, and standard CD44. Established in vitro assays were used to assess attachment, migration, and invasion with and without treatment with 4-MU. Chi square and Student's t-test were used to analyze the results as appropriate. The addition of 4-MU decreased mRNA and protein expression of HAS 2, HAS 3, and CD44 in EECs and ESCs compared to control. Treatment with 4-MU also decreased attachment, migration, and invasion of EECs and ESCs to PMCs compared to control. 4-MU decreases endometrial cell adhesion, migration, and invasion to PMCs. This effect appears to be mediated by a decrease in HAS 2, HAS 3, and CD44. 4-MU is a potential treatment for endometriosis. Future in vivo studies are needed to evaluate 4-MU as a therapeutic agent for endometriosis.

Impact of a Chinese Medicinal Formula, Xiao Liu Fang, on the “3A” Ability of Endometrial Stromal Cells in Patients with Endometriosis

The pathogenesis of endometriosis (EMS) is complicated, and treatment results are unsatisfactory. It has become the focus of gynecological research. Analysis targeting the pathogenesis of EMS is the key to providing more effective treatments. In recent years, the superiority of traditional Chinese medicine in treating EMS has been highlighted, so we investigated the impact of a Chinese medicinal formula (Xiao Liu Fang) on the “3A” ability, in situ, of ectopic endometrial stromal cells in patients with EMS. Primary endometrial stromal cells were isolated using a modified net filtration method, cultured, and identified in different groups. Endometrial cell attachment was measured using the methyl thiazolyl tetrazolium (MTT) colorimetric assay, cell aggression was detected by the transwell cell-invasion assay, and angiogenesis was defined by evaluating the mRNA concentrations of intercellular cell adhesion molecule 1 (ICAM-1), cyclooxygenase 2 (COX-2), matrix metallo peptidase 9 (MMP-9), and vascular endothelial growth factor (VEGF). Attachment, aggression, and angiogenesis (AAA) plays an important role in EMS, and a high dose of the Xiao Liu Fang extract can be used for the treatment of EMS owing to its inhibition of the AAA of endometrial stromal cells. Therefore, in-depth studies targeting the effective mechanisms and targets of traditional Chinese medicine (TCM) are of great significance for the prevention and treatment of EMS.

Endometrial stromal cell attachment and matrix homeostasis in abdominal wall endometriomas.

How does progesterone alter matrix remodeling in abdominal wall endometriomas compared with normal endometrium? Progesterone may prevent attachment of endometrial cells to the abdominal wall, but does not ameliorate abnormal stromal cell responses of abdominal wall endometriomas. Menstruation is a tightly orchestrated physiologic event in which steroid hormones and inflammatory cells cooperatively initiate shedding of the endometrium. Abdominal wall endometriomas represent a unique form of endometriosis in which endometrial cells inoculate fascia or dermis at the time of obstetrical or gynecologic surgery. Invasion of endometrium into ectopic sites requires matrix metalloproteinases (MMPs) for tissue remodeling but endometrium is not shed externally. Observational study in 14 cases and 19 controls. Tissues and stromal cells isolated from 14 abdominal wall endometriomas were compared with 19 normal cycling endometrium using immunohistochemistry, quantitative PCR, gelatin zymography and cell attachment assays. P values < 0.05 were considered significant and experiments were repeated in at least three different cell preps to provide scientific rigor to the conclusions. The results indicate that MMP2 and MMP9 are not increased by TGFβ1 in endometrioma stromal cells. Although progesterone prevents attachment of endometrioma cells to matrix components of the abdominal wall, it does not ameliorate these abnormal stromal cell responses to TGFβ1. N/A. Endometriomas were collected from women identified pre-operatively. Not all endometriomas were collected. Stromal cells from normal endometrium were from different patients, not women undergoing endometrioma resection. This work provides insight into the mechanisms by which progesterone may prevent abdominal wall endometriomas but, once established, are refractory to progesterone treatment. Tissue acquisition was supported by NIH P01HD087150. Authors have no competing interests.

Inhibition of hylauronic acid's synthesis decreases endometrial cell attachment

Inhibition of hylauronic acid's synthesis decreases endometrial cell attachment

Abnormal peritoneal regulation of chemokine activation-The role of IL-8 in pathogenesis of endometriosis.

Endometriosis is a chronic inflammatory disease associated with an impairment in immune response. Disorders in the peritoneal fluid and ectopic endometrium macrophage populations and their secretory products create a specific microenvironment inducing the development of the disease. The important factors involved in inflammation associated with endometriosis are chemokines, especially interleukin (IL)-8. For this reason, the current study briefly reviews the role of IL-8 in the pathogenesis of endometriosis. A systematic review was done on all published studies that compared IL-8 expression and concentration in patients with and without endometriosis to evaluate their potential as biomarkers for the disease. IL-8 induces chemotaxis of neutrophils and other immune cells; also, it is a potent angiogenic agent. Most researchers pointed to the increased peritoneal and serum IL-8 levels and showed correlation with the severity of the disease, size and number of the active lesions. IL-8 takes part in all processes during the development of the disease: adhesion, invasion, and implantation of ectopic tissue. Additionally, the chemokine plays a role in growth and maintenance of ectopic endometrial tissue directly affecting endometrial cell proliferation. IL-8 might also protect ectopic cells against death by apoptosis. It may act as an autocrine growth factor in the endometrium and promotes the vicious circle of endometrial cell attachment and, in consequence, may lead to a transformation from acute to chronic inflammation stage.

The signal transduction pathways via protease activated receptor-1 (PAR-1) in human decidual stromal cells

Background:Wepreviously demonstrated a remarkably higher association of pelvic endometriosis in women with ovarian endometrioma. However, information regarding occurrence of pelvic endometriosis in women with demoid cyst is unknown even thesewomenexperience similar retrogrademenstruation like womenwithovarianendometriosis.During theprocessof endometrial cell attachment, an event of immunedefect or tolerance occurs that finally decide the survival or clearance of autologous cells in pelvic environment. Here, we retrospectively evaluated recorded files of laparoscopy from 1982 to 2008 at our university and examined the incidence of pelvic endometriosis in women with benign ovarian cysts. Material and methods: We performed a retrospective study conducted in 2988 cases that had undergone laparoscopic surgery between September 1982 and April 2008 for the indication of ectopic pregnancy, tubal infertility and other benign gynecologic diseases. We analyzed occurrence of pelvic endometriosis in women with ovarian endometrioma and dermoid cyst during 25 years observation period.With informed consent, cystwall from20 womenwithdermoidcysts and20womenwithovarianendometrioma and corresponding eutopic endometria and peritoneal tissues were prospectively collected during laparoscopy. Tissue expression of FOXP3+ Treg cells was examined by immunohistochemistry and peritoneal fluid (PF) levels of TGF and IL-6 were measured by ELISA. Results: Among 2988 laparoscopy cases, 350 cases (11.7%)were found to have ovarian endometrioma, 414 (13.8%) cases had dermoid cyst and 398 (13.3%) cases were treated for fertility screening or uterine myoma with bilateral pathology free ovary. A predominance of both ovarian endometrioma and dermoid cysts was found inwomen in their 20th and30thyears of age.Womenwithdermoid cysts had a significantly decreased occurrence of pelvic endometriosis (74 cases, 18.6%) when compared with that of women with ovarian endometrioma (267 cases, 76.3%) and with women with bilateral normal ovary (188 cases, 47.2%). A significantly higher expressionof FOXP3, a transcriptional factorofTregcells,was found in cyst wall and peritoneum of women with dermoid cysts having peritoneal lesions comparing to similar tissues derived from dermoid cysts without any peritoneal lesions. A relationship between FOXP3 expression and TGF /interleukin-6 levels in peritoneal fluid (PF) will be discussed. Conclusions: Higher FOXP3+ Treg cells in the peritoneum may be associated with decreased occurrence of peritoneal lesions in women with benign ovarian cyst. A possible immunosurveillance secondary to different pelvic environmentmight be involved in this protective effect against endometriosis.

Role of FoxP3+Treg cells in decreased occurrence of endometriosis in women with benign ovarian cyst

Background:Wepreviously demonstrated a remarkably higher association of pelvic endometriosis in women with ovarian endometrioma. However, information regarding occurrence of pelvic endometriosis in women with demoid cyst is unknown even thesewomenexperience similar retrogrademenstruation like womenwithovarianendometriosis.During theprocessof endometrial cell attachment, an event of immunedefect or tolerance occurs that finally decide the survival or clearance of autologous cells in pelvic environment. Here, we retrospectively evaluated recorded files of laparoscopy from 1982 to 2008 at our university and examined the incidence of pelvic endometriosis in women with benign ovarian cysts. Material and methods: We performed a retrospective study conducted in 2988 cases that had undergone laparoscopic surgery between September 1982 and April 2008 for the indication of ectopic pregnancy, tubal infertility and other benign gynecologic diseases. We analyzed occurrence of pelvic endometriosis in women with ovarian endometrioma and dermoid cyst during 25 years observation period.With informed consent, cystwall from20 womenwithdermoidcysts and20womenwithovarianendometrioma and corresponding eutopic endometria and peritoneal tissues were prospectively collected during laparoscopy. Tissue expression of FOXP3+ Treg cells was examined by immunohistochemistry and peritoneal fluid (PF) levels of TGF and IL-6 were measured by ELISA. Results: Among 2988 laparoscopy cases, 350 cases (11.7%)were found to have ovarian endometrioma, 414 (13.8%) cases had dermoid cyst and 398 (13.3%) cases were treated for fertility screening or uterine myoma with bilateral pathology free ovary. A predominance of both ovarian endometrioma and dermoid cysts was found inwomen in their 20th and30thyears of age.Womenwithdermoid cysts had a significantly decreased occurrence of pelvic endometriosis (74 cases, 18.6%) when compared with that of women with ovarian endometrioma (267 cases, 76.3%) and with women with bilateral normal ovary (188 cases, 47.2%). A significantly higher expressionof FOXP3, a transcriptional factorofTregcells,was found in cyst wall and peritoneum of women with dermoid cysts having peritoneal lesions comparing to similar tissues derived from dermoid cysts without any peritoneal lesions. A relationship between FOXP3 expression and TGF /interleukin-6 levels in peritoneal fluid (PF) will be discussed. Conclusions: Higher FOXP3+ Treg cells in the peritoneum may be associated with decreased occurrence of peritoneal lesions in women with benign ovarian cyst. A possible immunosurveillance secondary to different pelvic environmentmight be involved in this protective effect against endometriosis.

Ovarian steroids affect endometrial cell attachment to normal ovarian surface epithelial cells

Ovarian steroids are primary regulators of the growth and maintenance of established endometriotic implants; however, little is known about their role in the development of the early endometriotic lesion, and specifically implants on the ovarian stroma and the development of endometriomas. Here, we assessed the effect of estradiol (E2) and progesterone (P4) on endometrial epithelial (EEC) and endometrial stromal cell (ESC) attachment and invasion to normal ovarian surface epithelium (NOSE) cells.

Ovarian steroid alter endometrial epithelial cell attachment to peritoneal mesothelial cells

Sampson's theory suggests that endometrial cells(ECs) transported retrograde through the fallopian tubes implant on peritoneal mesothelial cells (PMCs) to initiate the development of early endometriotic lesions (ELs). While ovarian steroids are primary regulators of established ELs, little is known about their role in the initial attachment of ECs to PMCs. Here, we assessed the effect of estradiol (E2) and progesterone (P4) on menstrual epithelial cell (EEC) attachment to PMC using an established model.

The role of the peritoneum in the pathogenesis of endometriosis

BACKGROUND Endometriosis affects 6-10% of women of reproductive age and is associated with chronic pelvic pain, dysmenorrhoea, dyspareunia and infertility. Endometriosis is defined by the presence of endometrial tissue outside the uterus, most commonly attached to the pelvic peritoneum. The endometrium in women with endometriosis is reported to be altered and there is increasing evidence that the phenotype of the pelvic peritoneum may also play a role in the establishment and maintenance of the disease. The aim of this review is to discuss the putative role of the pelvic peritoneum in the pathophysiology of peritoneal endometriosis. METHODS A review was undertaken of the published literature on (i) the anatomy and physiology of the peritoneum and (ii) the potential roles played by peritoneal cells in the establishment and maintenance of peritoneal endometriosis. The current understanding of the biology of peritoneal endometriosis is summarized and the potential interaction of the peritoneum with ectopic endometrial cells in endometriosis is highlighted. RESULTS Several studies indicate that differential expression of peritoneal mesothelial adhesion factors occurs in women with endometriosis, providing potential ectopic endometrial cell attachment sites for the establishment of endometriosis lesions. Changes in the peritoneal mesothelial cell phenotype, including loss of tight junctions, may allow ectopic cells to bind to, or early lesions to invade into, the extracellular matrix. Epithelial-to-mesenchymal transition of peritoneal mesothelial cells may also lead to an increase in lesion invasion and formation of fibrotic tissue in and around the lesion. There is evidence that the peritoneal mesothelium may also play a role in the invasion potential of ectopic cells by production of MMPs increasing local tissue remodelling. Peritoneal immune scavenging function may be lowered in women with endometriosis; for example there is a notable increase in macrophage-derived secretion products in women with endometriosis associated with increases in cell proliferation, cell adhesion and neovascularization. CONCLUSIONS The pelvic peritoneum appears to play a key role in the development and maintenance of endometriosis.

Raf-1, a Potential Therapeutic Target, Mediates Early Steps in Endometriosis Lesion Development by Endometrial Epithelial and Stromal Cells

Endometriosis is a hormone-sensitive gynecological disorder characterized by the benign growth of endometrial-like tissue in the pelvic cavity. Endometriotic lesions composed of endometrial stromal cells (ESC) and glandular epithelial cells (EEC) are thought to arise from menstrual endometrial tissue reaching the pelvic cavity via retrograde menstruation. The cause of endometriotic lesion formation is still not clear. Recent evidence suggest that cytokines may play a role in the early development of endometriosis lesions. Because cytokines and growth factors signal via the v-raf-1 murine leukemia viral oncogene homolog 1 (Raf-1) kinase pathway, we have examined the role of Raf-1 in early steps of endometriosis lesion formation, specifically attachment of endometrial cells to peritoneal mesothelial cells (PMC) and invasion of endometrial cells through PMC (trans-mesothelial invasion). Raf-1 antagonist GW5074 decreased attachment to PMC and trans-mesothelial invasion by primary EEC and ESC. Raf-1 also mediated TGFβ-induced trans-mesothelial invasion by the established, low-invasive EEC line EM42. TGFβ treatment of EEC resulted in Raf-1 phosphorylation at S338 and phosphorylation of ERK, suggesting that TGFβ activates Raf-1 signaling in these cells. GW5074 had little effect on ESC proliferation but inhibited EEC growth significantly under reduced serum conditions. Antagonizing Raf-1 activity and expression via GW5074 and specific Raf-1 small interfering RNA, respectively, did not alter EEC resistance to growth inhibition by TGFβ. Raf-1 inhibition blocked induction of EEC growth by epidermal growth factor. Our data suggest that Raf-1 may mediate pathologic steps involved in early endometriosis lesion formation and may be a mediator of TGFβ and epidermal growth factor actions in endometriosis.

Hormonal regulation of endometrial olfactomedin expression and its suppressive effect on spheroid attachment onto endometrial epithelial cells

Olfactomedin (Olfm) is a member of a diverse group of extracellular matrix proteins important for neuronal growth. Recent microarray studies identified Olfm as one of the down-regulated transcripts in receptive endometrium at the time of embryo attachment and implantation. However, the underlying molecular mechanisms that govern Olfm expression and its effect on embryo attachment and implantation remain unknown. The expression of Olfm in the human endometrium was investigated by real-time PCR, western blotting and immunohistochemistry on human endometrial biopsies from natural and ovarian stimulated cycles. To investigate the function of Olfm in trophoblast-endometrial cell attachment, an in vitro spheroid-endometrial cell co-culture study was performed. Human endometrial Olfactomedin-1 and -2(Olfm-1 and -2) transcripts decreased significantly from the proliferative to the secretory phases of the menstrual cycle. Olfm protein was strongly expressed in the luminal and glandular epithelium and moderately in the stromal cells of human endometria. Ovarian stimulation significantly decreased (P < 0.05) the expression of endometrial Olfm-1 and -2 transcripts in patients receiving IVF treatment when compared with those in the natural cycle. Importantly, recombinant Olfm-1 suppressed JAr spheroid attachment onto Ishikawa cells and this was not associated with changes of β-catenin and E-cadherin expression in trophoblast and endometrial cells. Decreased expression of Olfm during the receptive phase of the endometrium may allow successful trophoblast attachment for implantation.

Inhibition of CD44 N- and O-linked glycosylation decreases endometrial cell lines attachment to peritoneal mesothelial cells

The attachment of endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs) to peritoneal mesothelial cells (PMCs) with and without inhibition of N- and O-linked glycosylation, the viability of EECs and ESCs, and the expression of CD44 surface density were evaluated. Inhibition of CD44 N- and O-linked glycosylation by using tunicamycin and/or B-GalNAc statistically significantly inhibited endometrial cell attachment to peritoneal mesothelial cells, suggesting a role in establishment of early endometriotic lesions.

Evolving Spectrum:

Although the exact etiology of endometriosis is unknown, several hypotheses about its origin exist. Of these, Sampson's theory of retrograde menstruation is the most widely accepted. Multiple in-vitro and in vivo models have been developed to study endometriosis. Several key steps are required to establish an endometriotic implant: presence of ectopic endometrial glands and stroma, attachment of endometrial cells to the peritoneum, invasion into the mesothelium, and survival and growth of the ectopic tissue. Many of these steps are similar to those associated with neoplasia, and numerous biologic pathways are involved. It is likely that both intrinsic factors within the ectopic endometrium and permissive alterations within the host are important to the development of endometriosis.

Higher expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 (Flk-1) and metalloproteinase-9 (MMP-9) in a rat model of peritoneal endometriosis is similar to cancer diseases

BackgroundEndometriosis is a common disease characterized by the presence of a functional endometrium outside the uterine cavity, causing pelvic pain, dysmenorrheal, and infertility. This disease has been associated to development of different types of malignancies; therefore new blood vessels are essential for the survival of the endometrial implant. Our previous observations on humans showed that angiogenesis is predominantly found in rectosigmoid endometriosis, a deeply infiltrating disease. In this study, we have established the experimental model of rat peritoneal endometriosis to evaluate the process of angiogenesis and to compare with eutopic endometrium.MethodsWe have investigated the morphological characteristics of these lesions and the vascular density, VEGF and its receptor Flk-1 and MMP-9 expression, and activated macrophage distribution, using immunohistochemistry and RT-PCR.ResultsAs expected, the auto-transplantation of endometrium pieces into the peritoneal cavity is a well-established method for endometriosis induction in rats. The lesions were cystic and vascularized, and demonstrated histological hallmarks of human pathology, such as endometrial glands and stroma. The vascular density and the presence of VEGF and Flk-1 and MMP-9 were significantly higher in endometriotic lesions than in eutopic endometrium, and confirmed the angiogenic potential of these lesions. We also observed an increase in the number of activated macrophages (ED-1 positive cells) in the endometriotic lesions, showing a positive correlation with VEGF.ConclusionThe present endometriosis model would be useful for investigation of the mechanisms of angiogenesis process involved in the peritoneal attachment of endometrial cells, as well as of the effects of therapeutic drugs, particularly with antiangiogenic activity.

In Vitro Models to Study the Pathogenesis of Endometriosis

Several in vitro models that attempt to replicate the intraperitoneal environment have been developed to study the pathogenesis of endometriosis. The chicken chorioallantotic membrane has been used, but it has not been well characterized and may introduce some species specific variables. In vitro models using human tissues include amniotic membrane, human peritoneal explants, and cell culture monolayers. These models have been used to qualitatively, quantitatively, and temporally assess attachment of endometrial cells to peritoneal mesothelial and subsequent transmesothelial invasion. These models have also been used to assess the role of cytokines in the development of the early endometriotic lesion. Two- and three dimensional invasion chamber models have been utilized to assess endometrial cell interactions with peritoneal mesothelial cells and the extracellular matrix. Invasion models are also useful to evaluate novel therapeutic approaches. This review will focus on the above models to assist reproductive scientists interested in the pathogenesis of endometriosis.

Inhibition of O-linked glycosylation of CD-44 decreases endometrial cells attachment to peritoneal mesothelial cells

OBJECTIVE: CD44, the major glycoprotein ligand for hyaluronan (HA), has multiple N- and O-linked glycosylation sites. We previously demonstrated that abrogation of peritoneal mesothelial cell (PMC) -associated HA inhibits endometrial cell (EC) attachment to PMCs [1] and inhibition of N-linked CD44 glycosylation inhibited EC attachment to PMCs [2]. Here, we assessed the effect of O-linked glycosylation inhibition on EC attachment to PMCs.

Peroxisome-proliferator activator receptor-gamma activation decreases attachment of endometrial cells to peritoneal mesothelial cells in an in vitro model of the early endometriotic lesion.

The aim of this study was to investigate whether peroxisome proliferator-activated receptor (PPAR)-gamma activation has an effect on the attachment of endometrial cells to peritoneal mesothelial cells in a well-established in vitro model of the early endometriotic lesion. The endometrial epithelial cell line EM42 and mesothelial cell line LP9 were used for this study. EM42 cells, LP9 cells or both were treated with the PPAR-gamma agonist ciglitazone (CTZ) at varying concentrations (10, 20 and 40 microM) x 48 h with subsequent co-culture of EM42 and LP9 cells. The rate of EM42 attachment and invasion through LP9 cells was then assessed and compared with control (EM42 and LP9 cells co-cultured without prior treatment with CTZ). Next, attachment of CTZ-treated and untreated EM42 cells to hyaluronic acid (HA), a cell adhesion molecule (CAM) on peritoneal mesothelial cells, were assessed. Although there was no difference in EM42 attachment when LP9 cells alone were treated with CTZ, treatment of EM42 cells with 40 microM CTZ decreased EM42 attachment to LP9 cells by 27% (P < 0.01). Treatment of both EM42 and LP9 cells with 40 microM CTZ decreased EM42 attachment to LP9 by 37% (P < 0.01). Treatment of EM42 cells with 40 microM CTZ decreased attachment to HA by 66% (P = 0.056). CTZ did not decrease invasion of EM42 cells through the LP9 monolayer. CTZ may inhibit EM42 cell proliferation. In conclusion, CTZ significantly decreased EM42 attachment to LP9 cells and HA in an in vitro model of the early endometriotic lesion.