ABCA1 is associated with the development of acquired chemotherapy resistance and predicts poor ovarian cancer outcome

Aim: This study investigated the ATP binding cassette (ABC) transporter (ABCA1, ABCB1, ABCB3, ABCC2 and ABCG2) expression in high grade serous ovarian cancer (HGSOC) tissues, cell lines and primary cells to determine their potential relationship with acquired chemotherapy resistance and patient outcome. Methods: ABC transporter mRNA and protein expression (ABCA1, ABCB1, ABCB3, ABCC2 and ABCG2) was assessed in publicly available datasets and in a tissue microarray (TMA) cohort of HGSOC at diagnosis, respectively. ABC transporter mRNA expression was also assessed in chemosensitive ovarian cancer cell lines (OVCAR-5 and CaOV3) versus matching cell lines with acquired carboplatin resistance and in primary HGSOC cells from patients with chemosensitive disease at diagnosis (n = 10) as well as patients with acquired chemotherapy resistance at relapse (n = 6). The effects of the ABCA1 inhibitor apabetalone in carboplatin-sensitive and -resistant cell lines were also investigated. Results: High ABCA1 mRNA and protein expression was found to be significantly associated with poor patient outcome. ABCA1 mRNA and protein levels were significantly increased in ovarian cancer cell lines (OVCAR-5 CBPR and CaOV3 CBPR) with acquired carboplatin resistance. ABCA1 mRNA was significantly increased in primary HGSOC cells obtained from patients with acquired chemotherapy resistance. Apabetalone treatment reduced ABCA1 protein expression and increased the sensitivity of both parental and carboplatin-resistant ovarian cancer cells to carboplatin. Conclusion: These results suggest that inhibiting ABCA1 transporter may be useful in overcoming acquired chemotherapy resistance and improving outcome for patients with HGSOC.

Reduced Gonadotrophin Receptor Expression Is Associated with a More Aggressive Ovarian Cancer Phenotype

Follicle-stimulating hormone (FSH) and luteinising hormone (LH) play important roles in regulating cell growth and proliferation in the ovary. However, few studies have explored the expression of FSH and LH receptors (FSHR and LHCGR) in ovarian cancer, and their functional roles in cancer progression remain inconclusive. This study investigated the potential impact of both mRNA (FSHR, LHCGR) and protein (FSHR, LHCGR) expression on ovarian cancer progression using publicly available online databases, qRT-PCR (high grade serous ovarian cancers, HGSOC, n = 29 and benign ovarian tumors, n = 17) and immunohistochemistry (HGSOC, n = 144). In addition, we investigated the effect of FSHR and LHCGR siRNA knockdown on the pro-metastatic behavior of serous ovarian cancer cells in vitro. High FSHR or high LHCGR expression in patients with all subtypes of high-grade ovarian cancer was significantly associated with longer progression-free survival (PFS) and overall survival (OS). High FSHR protein expression was associated with increased PFS (p = 0.050) and OS (p = 0.025). HGSOC patients with both high FSHR and high LHCGR protein levels had the best survival outcome, whilst both low FSHR and low LHCGR expression was associated with poorest survival (p = 0.019). Knockdown of FSHR significantly increased the invasion of serous ovarian cancer cells (OVCAR3 and COV362) in vitro. LHCGR knockdown also promoted invasion of COV362 cells. This study highlights that lower FSHR and LHCGR expression is associated with a more aggressive epithelial ovarian cancer phenotype and promotes pro-metastatic behaviour.

Epithelial Ovarian Cancer and the Immune System: Biology, Interactions, Challenges and Potential Advances for Immunotherapy

Recent advances in the understanding of immune function and the interactions with tumour cells have led to the development of various cancer immunotherapies and strategies for specific cancer types. However, despite some stunning successes with some malignancies such as melanomas and lung cancer, most patients receive little or no benefit from immunotherapy, which has been attributed to the tumour microenvironment and immune evasion. Although the US Food and Drug Administration have approved immunotherapies for some cancers, to date, only the anti-angiogenic antibody bevacizumab is approved for the treatment of epithelial ovarian cancer. Immunotherapeutic strategies for ovarian cancer are still under development and being tested in numerous clinical trials. A detailed understanding of the interactions between cancer and the immune system is vital for optimisation of immunotherapies either alone or when combined with chemotherapy and other therapies. This article, in two main parts, provides an overview of: (1) components of the normal immune system and current knowledge regarding tumour immunology, biology and their interactions; (2) strategies, and targets, together with challenges and potential innovative approaches for cancer immunotherapy, with attention given to epithelial ovarian cancer.

Transcriptome analyses of ovarian stroma: tunica albuginea, interstitium and theca interna

The ovary has specialised stromal compartments, including the tunica albuginea, interstitial stroma and theca interna, which develops concurrently with the follicular antrum. To characterise the molecular determinants of these compartments, stroma adjacent to preantral follicles (pre-theca), interstitium and tunica albuginea were laser microdissected (n = 4 per group) and theca interna was dissected from bovine antral follicles (n = 6). RNA microarray analysis showed minimal differences between interstitial stroma and pre-theca, and these were combined for some analyses and referred to as stroma. Genes significantly upregulated in theca interna compared to stroma included INSL3, LHCGR, HSD3B1, CYP17A1, ALDH1A1, OGN, POSTN and ASPN. Quantitative RT-PCR showed significantly greater expression of OGN and LGALS1 in interstitial stroma and theca interna versus tunica and greater expression of ACD in tunica compared to theca interna. PLN was significantly higher in interstitial stroma compared to tunica and theca. Ingenuity pathway, network and upstream regulator analyses were undertaken. Cell survival was also upregulated in theca interna. The tunica albuginea was associated with GPCR and cAMP signalling, suggesting tunica contractility. It was also associated with TGF-β signalling and increased fibrous matrix. Western immunoblotting was positive for OGN, LGALS1, ALDH1A1, ACD and PLN with PLN and OGN highly expressed in tunica and interstitial stroma (each n = 6), but not in theca interna from antral follicles (n = 24). Immunohistochemistry localised LGALS1 and POSTN to extracellular matrix and PLN to smooth muscle cells. These results have identified novel differences between the ovarian stromal compartments.

4-Methylumbelliferone Inhibits Cancer Stem Cell Activation and Overcomes Chemoresistance in Ovarian Cancer

We have recently shown that the extracellular matrix molecule hyaluronan (HA) plays a role in the development of ovarian cancer chemoresistance. This present study determined if HA production is increased in chemotherapy-resistant ovarian cancers and if the HA inhibitor 4-methylubelliferone (4-MU) can overcome chemoresistance to the chemotherapeutic drug carboplatin (CBP) and inhibit spheroid formation and the expression of cancer stem cell (CSC) markers. We additionally assessed whether 4-MU could inhibit in vivo invasion of chemoresistant primary ovarian cancer cells in the chicken embryo chorioallantoic membrane (CAM) assay. The expression of the HA synthases HAS2 and HAS3 was significantly increased in chemoresistant compared to chemosensitive primary ovarian cancer cells isolated from patient ascites. 4-MU significantly inhibited HA production, cell survival, and spheroid formation of chemoresistant serous ovarian cancer cells. In combination with CBP, 4-MU treatment significantly decreased ovarian cancer cell survival and increased apoptosis of chemoresistant primary cells compared to CBP alone. 4-MU significantly reduced spheroid formation, expression of CSC markers ALDH1A1 and ABCG2 in primary cell spheroid cultures, and ALDH1 immunostaining in patient-derived tissue explant assays following treatment with CBP. Furthermore, 4-MU was very effective at inhibiting in vivo invasion of chemoresistant primary cells in CAM assays. Inhibition of HA is therefore a promising new strategy to overcome chemoresistance and to improve ovarian cancer survival.

Novel ex vivo ovarian cancer tissue explant assay for prediction of chemosensitivity and response to novel therapeutics

The majority of ovarian cancer patients present with advanced disease and despite aggressive treatment, prognosis remains poor. Response to first-line carboplatin-containing chemotherapy is usually good, however, recurrence rates and subsequent chemoresistance are very high and ultimately responsible for the fatal outcome of the disease. To improve treatment outcomes pre-clinical models that can predict individual patient response to 1st line chemotherapy and novel therapeutics are urgently required. In this study, we employed an ex vivo ovarian cancer tissue explant assay to assess response to carboplatin and an inhibitor of the extracellular matrix molecule, hyaluronan (4-methylubelliferone, 4-MU), shown to inhibit cancer metastasis. Cryopreserved ovarian cancer tissues were cultured on gelatine sponges for 48-120 h with increasing concentrations of carboplatin (0-400 μM) or 4-MU (1 mM) alone or the combination of both drugs. Effects on apoptosis and proliferation were assessed by immunohistochemistry using antibodies to cleaved caspase 3 or Ki67, respectively. The ex vivo tissue explant assay maintained viable tumor cells in an intact tumor microenvironment similar to the in vivo situation over the 120 h culture period. Carboplatin treatment promoted apoptosis in chemosensitive (P = 0.0047) but not chemoresistant cancer tissues. The combination of 4-MU (1 mM) and carboplatin (100 μM) significantly increased apoptosis (P = 0.0111) and reduced proliferation (P = 0.0064) in chemoresistant tissues. Overall, our results show that the ex vivo explant assay is a robust and cost effective model to assess chemosensitivity and the effect of novel therapeutics in ovarian cancer.

Keratin 5 overexpression is associated with serous ovarian cancer recurrence and chemotherapy resistance

This study investigated the clinical significance of keratin 5 and 6 expression in serous ovarian cancer progression and chemotherapy resistance. KRT5 and KRT6 (KRT6A, KRT6B & KRT6C) gene expression was assessed in publically available serous ovarian cancer data sets, ovarian cancer cell lines and primary serous ovarian cancer cells. Monoclonal antibodies which detect both K5/6 or only K5 were used to assess protein expression in ovarian cancer cell lines and a cohort of high grade serous ovarian carcinomas at surgery (n = 117) and after neoadjuvant chemotherapy (n = 21). Survival analyses showed that high KRT5 mRNA in stage III/IV serous ovarian cancers was significantly associated with reduced progression-free (HR 1.38, P < 0.0001) and overall survival (HR 1.28, P = 0.013) whilst high KRT6 mRNA was only associated with reduced progression-free survival (HR 1.2, P = 0.031). Both high K5/6 (≥ 10%, HR 1.78 95% CI; 1.03−2.65, P = 0.017) and high K5 (≥ 10%, HR 1.90, 95% CI; 1.12−3.19, P = 0.017) were associated with an increased risk of disease recurrence. KRT5 but not KRT6C mRNA expression was increased in chemotherapy resistant primary serous ovarian cancer cells compared to chemotherapy sensitive cells. The proportion of serous ovarian carcinomas with high K5/6 or high K5 immunostaining was significantly increased following neoadjuvant chemotherapy. K5 can be used to predict serous ovarian cancer prognosis and identify cancer cells that are resistant to chemotherapy. Developing strategies to target K5 may therefore improve serous ovarian cancer survival.

Oxygen-regulated gene expression in murine cumulus cells

Oxygen is an important component of the environment of the cumulus-oocyte complex (COC), both in vivo within the ovarian follicle and during in vitro oocyte maturation (IVM). Cumulus cells have a key role in supporting oocyte development, and cumulus cell function and gene expression are known to be altered when the environment of the COC is perturbed. Oxygen-regulated gene expression is mediated through the actions of the transcription factors, the hypoxia-inducible factors (HIFs). In the present study, the effect of oxygen on cumulus cell gene expression was examined following in vitro maturation of the murine COC at 2%, 5% or 20% oxygen. Increased expression of HIF-responsive genes, including glucose transporter-1, lactate dehydrogenase A and BCL2/adenovirus E1B interacting protein 3, was observed in cumulus cells matured at 2% or 5%, compared with 20% oxygen. Stabilisation of HIF1α protein in cumulus cells exposed to low oxygen was confirmed by western blot and HIF-mediated transcriptional activity was demonstrated using a transgenic mouse expressing green fluorescent protein under the control of a promoter containing hypoxia response elements. These results indicate that oxygen concentration influences cumulus cell gene expression and support a role for HIF1α in mediating the cumulus cell response to varying oxygen.

Csf2 null mutation alters placental gene expression and trophoblast glycogen cell and giant cell abundance in mice

Genetic deficiency in granulocyte-macrophage colony-stimulating factor (CSF2, GM-CSF) results in altered placental structure in mice. To investigate the mechanism of action of CSF2 in placental morphogenesis, the placental gene expression and cell composition were examined in Csf2 null mutant and wild-type mice. Microarray and quantitative RT-PCR analyses on Embryonic Day (E) 13 placentae revealed that the Csf2 null mutation caused altered expression of 17 genes not previously known to be associated with placental development, including Mid1, Cd24a, Tnfrsf11b, and Wdfy1. Genes controlling trophoblast differentiation (Ascl2, Tcfeb, Itgav, and Socs3) were also differentially expressed. The CSF2 ligand and the CSF2 receptor alpha subunit were predominantly synthesized in the placental junctional zone. Altered placental structure in Csf2 null mice at E15 was characterized by an expanded junctional zone and by increased Cx31(+) glycogen cells and cyclin-dependent kinase inhibitor 1C (CDKN1C(+), P57(Kip2+)) giant cells, accompanied by elevated junctional zone transcription of genes controlling spongiotrophoblast and giant cell differentiation and secretory function (Ascl2, Hand1, Prl3d1, and Prl2c2). Granzyme genes implicated in tissue remodeling and potentially in trophoblast invasion (Gzmc, Gzme, and Gzmf) were downregulated in the junctional zone of Csf2 null mutant placentae. These data demonstrate aberrant placental gene expression in Csf2 null mutant mice that is associated with altered differentiation and/or functional maturation of junctional zone trophoblast lineages, glycogen cells, and giant cells. We conclude that CSF2 is a regulator of trophoblast differentiation and placental development, which potentially influences the functional capacity of the placenta to support optimal fetal growth in pregnancy.

Seminal plasma differentially regulates inflammatory cytokine gene expression in human cervical and vaginal epithelial cells

Exposure to semen elicits an inflammatory response in the female reproductive tract of rodents and other animals. The nature and regulation of any similar response in humans is poorly understood. This study investigated seminal plasma induction of inflammatory cytokine and chemokine gene regulation in human cervical and vaginal epithelial cells in vitro. Affymetrix microarray gene profiling revealed that inflammatory cytokine genes were prevalent among 317 known genes differentially expressed in immortalized ectocervical epithelial (Ect1) cells after incubation with pooled human seminal plasma. A dose- and time-dependent induction by seminal plasma of IL8, IL6, CSF2 and CCL2 mRNA expression in Ect1 cells was verified by quantitative RT-PCR. This was accompanied by increases in Ect1 secretion of immunoactive gene products IL-8, IL-6, GM-CSF and MCP-1. Similar cytokine responses were elicited in primary ectocervical epithelial cells. Endocervical epithelial (End1) and vaginal epithelial (Vk2) cells were less responsive to seminal fluid, with induction of IL-8 and MCP-1, but not GM-CSF or IL-6. In a panel of 10 seminal plasma samples, considerable variation in inflammatory cytokine-inducing activity was evident. These experiments show that seminal plasma can elicit expression of a range of inflammatory cytokines and chemokines in reproductive tract epithelia, and implicate the ectocervix as the primary site of responsiveness, with gene-specific differences in the kinetics and site-restrictedness of the response. Seminal factor regulation of inflammatory cytokines in the cervical epithelium is implicated in controlling the immune response to seminal antigens, and defence against infectious agents introduced at intercourse.

Cytotoxicity and antibacterial activity of ethanol extract from leaves of a herbal drug, boneset (Eupatorium perfoliatum)

The cytotoxic and antibacterial activity of an ethanol extract of leaves of a herbal drug, boneset (Eupatorium perfoliatum), was investigated. The extract showed potent cytotoxicity with EC(50) values (12-14 microg/mL) comparable to a standard cytotoxic agent, chlorambucil. The extract showed a weak antibacterial activity against gram-positive test organisms (Staphylococcus aureus and Bacillus megaterium).

The effect of progestins on vascular endothelial growth factor, oestrogen receptor and progesterone receptor immunoreactivity and endothelial cell density in human endometrium

One common side-effect of contraceptive use is that it often leads to disrupted endometrial bleeding patterns. This may be due to changes in endothelial density and vessel integrity. To investigate whether the level of endometrial immunoreactive vascular endothelial growth factor (VEGF), oestrogen receptor or progesterone receptor (PR) have any role in this, women were treated with either Mircette, a monophasic oral contraceptive, or Implanon, a long-acting gestagen, and immunohistochemistry performed. In addition a small number of endometria were studied from women treated with levonorgestrel released from an intrauterine coil. During the untreated normal cycle, there was a significant increase in glandular VEGF immunoreactivity and a significant decrease in PR immunoreactivity in the midand late secretory phases compared to the proliferative phase. There was a significant positive correlation between stromal VEGF immunoreactivity and endothelial cell density. This correlation was also apparent during treatment with Implanon, but not with Mircette. Disrupted bleeding patterns were associated with Implanon and to a lesser extent with Mircette. Both contraceptives significantly reduced glandular VEGF immunoreactivity but the intrauterine treatment with levonorgestrel resulted in strong glandular epithelial staining and intense staining of decidualized stromal cells. Implanon significantly increased glandular PR staining, but Mircette significantly reduced stromal PR staining when compared to secretory phase before-treatment biopsies. There were no changes in endothelial cell density or glandular or stromal ER during the normal cycle, or with use of either contraceptive. There was no association of the parameters measured with bleeding patterns or histological category.

The effect of etonogestrel on VEGF, oestrogen and progesterone receptor immunoreactivity and endothelial cell number in human endometrium

Contraceptive use often leads to disrupted endometrial bleeding patterns in women. In this study, two different contraceptive regimes (Mircette, a monophasic oral contraceptive and Implanon, a long-acting gestagen) were used and their effects on the immunoreactivity of vascular endothelial growth factor (VEGF), oestrogen receptor (ER), progesterone receptor (PR) and endothelial cell number were determined. During the untreated normal cycle, there was a significant increase (P = 0.005) in glandular VEGF immunoreactivity and a significant decrease (P < 0.05) in PR immunoreactivity in the mid- and late secretory phases compared with the proliferative phase. There was a significant positive correlation (gamma = 0.38, P = 0.046) between stromal VEGF immunoreactivity and endothelial cell number. This correlation was also apparent during treatment with Implanon, but not with Mircette. Disrupted bleeding patterns were associated with Implanon and, to a lesser extent, with Mircette. Both contraceptives significantly reduced glandular VEGF immunoreactivity. Implanon significantly increased (P = 0.016) glandular PR staining, but Mircette significantly reduced (P = 0.027) stromal PR staining when compared with secretory before-treatment biopsies. There were no changes in endothelial cell number or glandular or stromal ER during the normal cycle, or with use of either contraceptive. There was no association between the parameters measured with bleeding patterns and histological category.

Protection against tetanus toxin in mice nasally immunized with recombinant Lactococcus lactis expressing tetanus toxin fragment C

Mice inoculated intranasally (i.n.) with a recombinant strain of live Lactococcus lactis expressing tetanus toxin fragment C (TTFC), produced both serum and secretory antibodies to TTFC. Killed bacteria which had accumulated TTFC intracellularly in vitro also elicited protective serum antibody responses. There was no requirement for either colonization or invasion of the mucosa. In addition secretory antibody responses in the lung and nasal tissues were elicited after i.n. inoculation in the presence of an adjuvant.

Factors affecting the immunogenicity of tetanus toxin fragment C expressed in Lactococcus lactis

The relative immunogenicity of tetanus toxin fragment C (TTFC) has been determined in three different strains of inbred mice when expressed in Lactococcus lactis as a membrane-anchored protein (strain UCP1054), as an intracellular protein (strain UCP1050), or as a secreted protein which is partly retained within the cell wall (strain UCP1052). Protection against toxin challenge (20 x LD50) could be obtained without the induction of anti-lactococcal antibodies. When compared in terms of the dose of expressed tetanus toxin fragment C required to elicit protection against lethal challenge the membrane-anchored form was significantly (10-20 fold) more immunogenic than the alternative forms of the protein.

An immunohistochemical study of the vascularization of the human Graafian follicle

The wall of the largest Graafian follicle or corpus luteum was biopsied in 22 patients at laparoscopy. Both granulosa and theca cells were contained in 18 samples. These samples were classified as pre-luteinizing hormone (LH) surge (n = 3), LH surge (n = 3), early luteal (n = 3), mid-luteal (n = 4), late luteal (n = 3) and menstrual (n = 2). A double-staining immunohistochemical protocol was used to demonstrate proliferating endothelial cells: mouse-anti-rat-proliferating cell nuclear antigen, for proliferating cells; mouse-anti-human-CD34 antibody for endothelial cells. The percentage of endothelial cells proliferating (proliferation index) and the area of tissue occupied by endothelial cells (areal fraction) were determined for granulosa and theca layers. Intra- and inter-slide coefficients of variation were < 15%. The granulosa layer was avascular until the LH surge subsided. Maximum vascularization was achieved by the mid-luteal phase. The theca endothelial cell proliferation index was constant from pre-LH surge to mid-luteal phases. The mean theca endothelial cell proliferation index for these phases was significantly greater than for the late luteal and menstrual phases. From first appearance in the granulosa layer, endothelial cells had the same proliferation index as the theca endothelial cells, the proliferation index decreasing significantly in both after the mid-luteal phase (P = 0.018). It is concluded that endothelial cell proliferation is unchanged throughout the follicular, early and mid-luteal phases, decreasing significantly in the late luteal phase. By contrast, endothelial cell invasion of the membrane granulosa, presumably in response to a chemotactic stimulus, occurs after the LH surge has subsided.

Human follicular fluid maturity and endothelial cell chemotaxis

Follicular fluid of varying maturity was collected from the largest Graafian follicle of 23 ovulatory patients during laparoscopy (five blood-stained samples were discarded) and from five patients undergoing oocyte collection for assisted reproduction. The endothelial cell (EC) chemotactic potentials of the samples were tested with bovine aortic ECs in modified Boyden Chambers and an EC density score was determined for each sample. Intra-assay coefficients of variation (CV) varied from 2.9-17%; inter-assay CV was 45%. Therefore, cell density scores were expressed in terms of positive and negative control values from their respective plates. Serum progesterone was positively correlated with EC chemotactic potential (R2 = 14.9%). There was no correlation with day of cycle, follicular diameter, serum luteinizing hormone (LH) or oestradiol, or follicular fluid total protein levels (all R2 < or = 6%). Five subjects were in early and four in mid-follicular phase, seven were in early and two in late LH surge, and there were also five in-vitro fertilization (IVF) specimens. There was a statistically significant difference between the EC chemotactic potential of the five groups by analysis of variance (F = 5.98; P = 0.006). There was no significant difference between the late LH surge and the IVF samples (two-sample t-test). The mean cell density was higher for these two groups than the other three (P < 0.01 in all cases; two-sample t-test). It is concluded that the EC chemotactic potential of human follicular fluid increases after the LH surge and before ovulation.

Human follicular fluid maturity and endothelial cell mitogenesis

Follicular fluid, of varying maturity, (day 5-16 of cycle) was collected from the largest Graafian follicle of each of 22 ovulatory patients during laparoscopic procedures. Three samples were blood-stained and discarded. The mitogenic potential of each sample was determined using bovine aortic endothelial cells in the CellTiter 96 Non-Radioactive Cell Proliferation/Cytotoxicity Assay system. Intra- and inter-plate coefficients of variation were < 9%. The follicular fluid samples induced cell doubling times which varied from approximately 12-24 h and final cell numbers which, in the individual wells, ranged from 7828-30,900 (starting number 2000/well). Follicular fluid total protein content was unrelated to the mitogenic potential, (R2 = 0%). Serum oestradiol was negatively correlated with the mitogenic potential (R2 = 26%). No correlation was found with day of the menstrual cycle (R2 = 4.3%), maximum follicular diameter (R2 = 1.8%), or serum concentration of progesterone (R2 = 0.7%), luteinizing hormone (LH) (R2 = 1.5%) or follicle stimulating hormone (R2 = 0.1%). Five subjects were in 'early' and six in 'mid'-follicular phase, six were in 'early' and two in 'late' LH surge. There was no difference in the mitogenic response between these four groups by one-way analysis of variance (F = 0.21; P = 0.89). It is concluded that the mitogenic potential of human follicular fluid is not related to Graafian follicle maturity or, more particularly, to the LH surge.

Reduction in endometrial neutrophils in proximity to implanting rat blastocysts

An antiserum to rat neutrophils was raised and used to follow the distribution of endometrial neutrophils during the peri-implantation period. Uteri from four pregnant and four pseudopregnant rats killed at 14:00, 17:00, 20:30 and 23:00 h on day 5 of pregnancy and 09:00 h on day 6 were sectioned. Four sections from each of four implantation sites and four intersites from each rat were immunostained. There was wide variability among rats in the number of endometrial neutrophils, but a nested analysis of variance showed significantly fewer neutrophils at implantation sites than at intersites from 20:30 h onwards. This difference was primarily due to the presence of more neutrophils in intersite regions of the endometrium. The results from this study do not support a role for neutrophils in the implantation-associated increase in microvascular permeability or decidualization in rats.

Immunolocalization of the vasoconstrictor endothelin in human endometrium during the menstrual cycle and in umbilical cord at birth

OBJECTIVE

Our objective was to determine the localization of immunoreactive endothelin in human cyclic endometrium and in umbilical cord during normal delivery and after cesarean section.

STUDY DESIGN

Fixed dated endometrial tissue (n = 41) and umbilical cord (n = 6) were subjected to immunohistochemistry with an antiserum cross reacting with endothelin-1, -2 and -3.

RESULTS

Low levels of stromal endometrial staining were seen throughout the cycle. The strongest staining was in luminal epithelium throughout the secretory phase and in glandular epithelium in the late-secretory phase. In umbilical cord the most intense immunoreactivity was present on the amnion cells on the outer cord, with some staining in intermittent cells in the Wharton's jelly and in umbilical vein cells. No differences were detected between cord from normal delivery or cesarean section.

CONCLUSION

A paracrine role is suggested for endothelin in regulation of endometrial function and a role in vasoconstriction in the umbilical cord at birth.

In-vivo microscopy of the rat endometrial subepithelial capillary plexus during the oestrous cycle and after ovariectomy

Blood flow through the endometrium was visualized by using incident-light fluorescence microscopy and a video image recorded for later detailed analysis. The subepithelial microvascular density was calculated for each day of the oestrous cycle and at 7 days after ovariectomy. The results showed that the microvasculature was significantly more dense at dioestrus I, pro-oestrus, and after ovariectomy than at oestrus, with dioestrus II being in between. Mean capillary path lengths running from arteriole to venule were longest at pro-oestrus, followed by oestrus, dioestrus II, dioestrus I, and shortest after ovariectomy. The results suggest that endometrial growth and regression precede microvascular growth and regression. The technique of in-vivo microscopy provides an important new avenue for investigating the role of local factors in the control of the endometrial microcirculation.

Vascular response in a non-uterine site to implantation-stage embryos following interspecies transfers between the rat, mouse, and guinea-pig

Pre-implantation-stage embryos from rats, mice, and guinea-pigs were transferred to a non-uterine site--the anterior chamber of the eye--of female recipients. All 9 combinations of transfers were performed: 3 allogeneic (intraspecies) transfers as controls, and 6 xenogeneic (interspecies) transfers. Implantation, as judged by extravasation from blood vessels of the iris or ciliary body occurred with success rates of 90.4% per transfer in the control rat group. 76.9% in the control mouse group, and 81.8% in the control guinea-pig group. Significantly reduced implantation rates occurred in the rat to guinea-pig (0%), mouse to rat (46.9%), mouse to guinea-pig (6.7%), and guinea-pig to rat (0%) groups compared to controls. Reductions, although not significant, also occurred in the other 2 groups: rat to mouse (77.8%), and guinea-pig to mouse (44.4%). These results together with some ultrastructural and light-microscopical observations suggest a degree of species specificity involved in the vascular response to the implanting embryo. We propose that the peri-implantation embryo produces a signal(s) which is to some extent species specific and which in the normal allogeneic situation is responsible for the early vascular effects seen at implantation in most eutherian mammals.

Vascular response in a non-uterine site to implantation-stage embryos in the rat and guinea-pig: in vivo and ultrastructural studies

Preimplantation-stage embryos were transferred to the anterior eye chamber of recipient rats and guinea-pigs. After implantation had occurred the influence of the embryo on the iris vasculature was examined ultrastructurally. In both species, the earliest effect of embryonic implantation was an increased stromal oedema. Under increasing embryonic influence the vascular endothelial cells showed an increased number of projections into the vascular lumen, while in the rat, endothelial projections were also found pushing back into the basement membrane. In the rat, the endothelium became very irregular in thickness prior to complete disintegration and loss during more advanced stages of implantation. Rat embryonic trophoblast was found invading iris vasculature, particularly in areas where the iridial endothelium was partially or completely missing. Other cells in the iris, including the stroma, appeared to be less affected. In the guinea-pig, however, trophoblast cells appeared to be capable of invading the vasculature by displacing endothelial cells that still appeared morphologically normal.