Bone marrow mesenchymal stem cell-derived exosomes shuttle microRNAs to endometrial stromal fibroblasts that promote tissue proliferation /regeneration/ and inhibit differentiation.

BACKGROUND: Human bone marrow-derived stem cells (hBMDSCs) are well characterized mediators of tissue repair and regeneration. An increasing body of evidence indicates that these cells exert their therapeutic effects largely through their paracrine actions rather than clonal expansion and differentiation. Here we studied the role of microRNAs (miRNAs) present in extracellular vesicles (EVs) from hBMDSCs in tissue regeneration and cell differentiation targeting endometrial stromal fibroblasts (eSF). METHODS: Extracellular vesicles (EVs) are isolated from hBMDSCs, characterized by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) techniques. Extracted total RNA from EVs was subjected to RNA seq analysis. Transfection and decidualization studies were carried out in endometrial stromal fibroblasts (eSF). Gene expression was analyzed by qRTPCR. Unpaired t-test with Welch's correction was used for data analysis between two groups. RESULTS: We identified several microRNAs (miRNAs) that were highly expressed, including miR-21-5p, miR-100-5p, miR-143-3p and let7. MiR-21 is associated with several signaling pathways involved in tissue regeneration, quiescence, cellular senescence, and fibrosis. Both miR-100-5p and miR-143-3p promoted cell proliferation. MiR-100-5p specifically promoted regenerative processes by upregulating TGF-ß3, VEGFA, MMP7, and HGF. MiR-100-5p blocked differentiation or decidualization as evidenced by morphologic changes and downregulation of decidualization mediators including HOXA10, IGFBP1, PRL, PR-B, and PR. CONCLUSION: EVs delivered to tissues by hBMDSCs contain specific miRNAs that prevent terminal differentiation and drive repair and regeneration. Delivery of microRNAs is a novel treatment paradigm with the potential to replace BMDSCs in cell-free regenerative therapies.

Micrometastasis of endometriosis to distant organs in a murine model.

Endometriosis is an inflammatory gynecological disorder among reproductive-aged women caused by the engraftment and proliferation of endometrial cells outside the uterus, most commonly in the pelvis. It is thought that the disease arises primarily from retrograde menstruation where cells from the endometrium travel through the fallopian tubes to the peritoneal cavity. However, migration of endometriosis-derived cells to distant organs outside of the peritoneal cavity have not been explored. In the present study, we developed and validated a mouse model of disseminated endometriosis using syngeneic DsRed endometrial tissue introduced into the peritoneum of immunocompetent mice. Flow cytometry and immunofluorescence analysis, demonstrated the presence of endometriosis-derived cells in multiple organs (including lung, spleen, liver and brain) in the murine endometriosis model. Immunostaining revealed the presence of DsRed+/CD45- cells in brain, liver and lung. Engraftment occurred in all experimental animals examined. Cells from endometriotic lesions are capable of migration to and engraftment of multiple organs outside of the peritoneal cavity. Micrometastasis of endometriosis is a novel and frequent phenomenon. These data suggest that widespread dissemination of endometriosis may be common, clinically unrecognized and contribute to the diffuse clinical manifestations of this disease.

The CXL12/CXCR4/CXCR7 axis in female reproductive tract disease: Review.

Initial studies on the chemokine stromal derived factor 1 (now referred to as CXCL12) were proposed to be enhanced in several diseases including those which affect the female reproductive tract. These include endometriosis, Asherman's syndrome, endometrial cancers, and ovarian cancers. Additionally, recent studies from our laboratory suggest that CXCL12 signaling is involved in leiomyomas (fibroids). These diseases present an inflammatory/hypoxic environment which further promotes pathology. At first, studies focused on signaling by CXCL12 via its well-known receptor, CXCR4. However, the discovery of CXCR7 as another receptor for CXCL12 with rather high binding affinity and recent reports about its involvement in endometrial disease and cancer progression has questioned the potential of "selective blockade"' of CXCR4 to treat these ailments. This review will focus on the signaling and effects of the potent chemokine CXCL12, and its long-known G protein-coupled receptor CXCR4, as well as the alternate receptor CXCR7 on the female reproductive tract and related diseases such as endometriosis, Asherman's syndrome, leiomyomas, endometrial cancer, and ovarian cancer. Although several other mechanisms are inherent to these diseases such as gene mutations, differential expression of miRNAs and epigenetics, for this review, we will focus on the CXCL12/CXCR4/CXCR7 axis as a novel target.

Icon immunoconjugate treatment results in regression of red lesions in a non-human primate (Papio anubis) model of endometriosis.

Endometriosis is a common condition in reproductive-aged women characterized by ectopic endometrial lesions of varied appearance, including red, white, blue, black or powder burn coloration, which contribute to chronic pain and infertility. The immunoconjugate molecule (Icon) targets Tissue Factor, a transmembrane receptor for Factor VII/VIIa that is aberrantly expressed in the endothelium supporting ectopic endometrial tissue. Icon has been shown to cause regression of endometriosis in a murine model of disease but prior to this study had not been tested in non-human primates. This study evaluated Icon as a novel treatment for endometriosis in non-human primates (Papio anubis) using an adenoviral vector (AdIcon) delivery system. Female baboons (n = 15) underwent surgical induction of endometriosis. After laparoscopic confirmation of endometriosis lesions 6-weeks post-surgery, the treatment group (n = 7) received weekly intraperitoneal injections of viral particles carrying the sequence for Icon, resulting in expression of the protein, while the control group (n = 8) received no treatment. Icon preferentially reduced the number and volume of red vascularized lesions. Icon may present a novel treatment for endometriosis by degrading red vascularized lesions, likely by targeting tissue factor aberrantly expressed in the lesion vasculature.

Hematogenous Dissemination of Mesenchymal Stem Cells from Endometriosis.

Endometriosis is ectopic growth of endometrial tissue traditionally thought to arise through retrograde menstruation. We aimed to determine if cells derived from endometriosis could enter vascular circulation and lead to hematogenous dissemination. Experimental endometriosis was established by transplanting endometrial tissue from DsRed+ mice into the peritoneal cavity of DsRed- mice. Using flow cytometry, we identified DsRed+ cells in blood of animals with endometriosis. The circulating donor cells expressed CXCR4 and mesenchymal stem cell (MSC) biomarkers, but not hematopoietic stem cell markers. Nearly all the circulating endometrial stem cells originated from endometriosis rather than from the uterus. Cells expressing DsRed, CXCR4, and MSCs markers were identified in the peritoneal wall and surrounding vessels of recipient mice, contributing to both endometriosis and angiogenesis. Cells originating in endometriosis lesions migrated and implanted in lung tissue and displayed makers of differentiation, indicating retained multipotency. In vitro these cells demonstrated multipotency and were able to differentiate into adipogenic, osteogenic, and chondrogenic lineages. Endometriosis lesions also expressed high levels of CXCL12, the CXCR4 receptor ligand. Serum CXCL12 levels were greater than in sham control mice. In humans with endometriosis, serum CXCL12 levels were significantly higher than controls, suggesting that the CXCL12/CXCR4 axis is operational in women with spontaneous endometriosis as well. Stem cells, rather than differentiated cells from endometriosis, enter the circulation in response to CXCL12. We identify an endometriosis-derived stem cell population, a potential mechanism of dissemination of this disease and a potential target for treatment of endometriosis. Stem Cells 2018;36:881-890.

Thrombin Augments LPS-Induced Human Endometrial Endothelial Cell Inflammation via PAR1 Activation.

PROBLEM: Risk factors for preterm birth include placental abruption, giving rise to excessive decidual thrombin, and intrauterine bacterial infection. Human endometrial endothelial cells (HEECs) express Toll-like receptors (TLRs), and infection-derived agonists trigger HEECs to generate specific inflammatory responses. As thrombin, in addition to inducing coagulation, can contribute to inflammation, its effect on HEEC inflammatory responses to the TLR4 agonist, bacterial lipopolysaccharide (LPS), was investigated. METHOD OF STUDY: HEECs were pre-treated with or without thrombin or specific protease-activated receptor (PAR) agonists, followed by treatment with or without LPS. Supernatants were measured for cytokines and chemokines by ELISA and multiplex analysis. RESULTS: Thrombin significantly and synergistically augmented LPS-induced HEEC secretion of interleukin (IL)-6, IL-8, granulocyte colony-stimulating factor (G-CSF), and growth-regulated oncogene-alpha (GRO-α), and significantly augmented monocyte chemotactic protein (MCP)-1, tumor necrosis factor-alpha (TNF-α), and vascular endothelial growth factor (VEGF) secretion additively. Similar to thrombin, a PAR1 agonist synergistically augmented the LPS-induced HEEC secretion of inflammatory IL-6, IL-8, G-CSF, and GRO-α. CONCLUSION: Thrombin, via PAR1 activation, synergistically augments LPS-induced HEEC production of chemokines involved in immune cell recruitment and survival, suggesting a mechanism by which intrauterine abruption and bacterial infection may together be associated with an aggravated uterine inflammatory response.

Endometriosis Located Proximal to or Remote From the Uterus Differentially Affects Uterine Gene Expression.

The mechanisms that lead to the altered uterine gene expression in women with endometriosis are poorly understood. Are these changes in gene expression mediated by proximity to endometriotic lesions or is endometriosis a systemic disease where the effect is independent of proximity to the uterus? To answer this question, we created endometriosis in a murine model either in the peritoneal cavity (proximal) or at a subcutaneous remote site (distal). The expression of several genes that are involved in endometrial receptivity (homeobox A10 [Hoxa10], homeobox A11 [Hoxa11], insulin-like growth factor binding protein 1 [Igfbp1], Kruppel-like factor 9 [Klf9], and progesterone receptor [Pgr]) was measured in the eutopic endometrium of mice transplanted with either proximal or distal endometriosis lesions. Decreased expression of Hoxa10, Igfbp1, Klf9, and total Pgr genes was observed in the eutopic endometrium of mice with peritoneal endometriosis. In the mice with distal lesions, overall expression of these genes was not as severely affected, however, Igfbp1 expression was similarly decreased and the effect on Pgr was more pronounced. Endometriosis does have a systemic effect that varies with distance to the end organ. However, even remote disease selectively and profoundly alters the expression of genes such as Pgr. This is the first controlled experiment demonstrating that endometriosis is not simply a local peritoneal disease. Selective alteration of genes critical for endometrial receptivity and endometriosis propagation may be systemic. Similarly, systemic effects of endometriosis on other organs may also be responsible for the widespread manifestations of the disease.

The Role of Stem Cells in the Etiology and Pathophysiology of Endometriosis.

Human endometrium is a dynamic organ that normally undergoes repetitive cyclic regeneration. To enable this rapid regeneration, it is not surprising that the endometrium contains a reservoir of progenitor stem cells. However, this pool of cells that allows the growth of the endometrium also allows for unrestrained growth that can reach beyond the endometrium. In this review, we will address the role of stem cells in endometriosis. Recent characterization of stem cell populations within human endometrium has opened the possibility of understanding their physiologic as well as their pathologic roles. While stem cells are critical to the cyclic regeneration of a healthy endometrium, we have shown that both endometrium-derived and bone marrow-derived stem cells can migrate to ectopic sites and contribute to the development of endometriosis. Furthermore, endometriosis interferes with the normal stem cell trafficking to the uterus that is necessary for endometrial growth and repair. Altered stem cell mobility and engraftment characterize this disease.

Genetic polymorphisms in Pakistani women with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is the major cause of anovulatory infertility. Although the genetic basis of PCOS is not well understood, it is a common metabolic and endocrine disorder. This study investigates the possible genomic variants associated with PCOS in Pakistani women from the Punjab region. DNA samples from 96 patients with genetically unrelated PCOS and 96 controls were analyzed by direct sequencing to determine the polymorphisms of different loci on follicle-stimulating hormone receptor (fshr), follicle-stimulating hormone ß (fshrß), luteinizing hormone chorionic gonadotropin (lhcgr), luteinizing hormone ß (lhß), estrogen receptor α (esr1), and estrogen receptor ß (esr2) genes. Significant associations were observed within the genotype frequencies, allele frequencies, and multi-single-nucleotide polymorphism (SNP) haplotype analysis of most polymorphisms studied. This study identified new SNPs at positions 605+52 Del/T in lhcgr genes occurring in this particular subpopulation. The strong r (2) value suggests that polymorphisms in the fshr and esr1 genes were in linkage disequilibrium. Our study provides evidence of statistically significant associations between susceptibility to PCOS in Pakistani women and the gene polymorphisms mentioned earlier. This suggests that the susceptible loci for PCOS lie within or very close to the chromosomal regions spanning these genes.

Toll-like receptor-mediated responses by placental Hofbauer cells (HBCs): a potential pro-inflammatory role for fetal M2 macrophages.

PROBLEM: Microbial-driven responses in placenta are linked with adverse pregnancy outcomes. The role of Toll-like receptor (TLR) function in Hofbauer cells (HBCs) and fetal macrophages of the placental villous core remains understudied. METHOD OF STUDY: Flow cytometry and immunohistochemistry (IHC) were used to establish the phenotype of HBCs. Regulation of cytokine secretion in response to treatment with TLR agonists and expression levels of TLRs and co-activators were compared in HBCs, placental fibroblasts (FIBs), and human umbilical vein endothelial cells (HUVECs) using ELISA and qPCR. RESULTS: Although flow cytometry and IHC revealed HBCs to be M2 (anti-inflammatory) macrophages, LPS and polyinosinic: polycytidylic acid [poly (I:C)] treatments markedly enhanced IL-6 secretion by HBCs, and expression of TLR-2, TLR-3, TLR-4, CD14, and MD-2 was the highest in HBCs. CONCLUSION: These results indicate that although HBCs are M2 macrophages, inflammatory responses are induced through TLR-3 and TLR-4 in this cell type, suggesting a role in microbial-driven placental/fetal inflammation.

Altered genome-wide methylation in endometriosis.

Endometriosis has been associated with aberrant methylation in the eutopic endometrium. Using a genome-wide methylation array, we identified differentially methylated genes in the endometrium from women with or without endometriosis. One hundred and twenty genes were significantly altered by >1.5-fold. In all, 59 genes were significantly hypermethylated and 61 genes were significantly hypomethylated. Changes in gene expression associated with the altered methylation status were validated using quantitative real-time polymerase chain reaction. A limited number of candidate genes are selectively methylated in the endometrium of women with endometriosis. Several genes not previously associated with endometriosis are aberrantly methylated and expressed. These include O-6-methylguanine-DNA methyltransferase, dual specificity phosphatase 22, cell division cycle associated 2, inhibitor of DNA binding 2, retinoblastoma binding protein 7, bone morphogenetic protein receptor, type 1B, tumor necrosis factor receptor 1B, zinc finger protein receptor 681, immunoglobulin superfamily, member 21, and tumor protein 73. Aberrant DNA methylation and gene expression of these genes may contribute to abnormal regulation of endometrial cell proliferation and function in women.

Treatment with bazedoxifene and conjugated estrogens results in regression of endometriosis in a murine model.

Bazedoxifene (BZA), a selective estrogen receptor modulator (SERM), inhibits the action of estrogens on endometrial proliferation. Here, we evaluate the effect of a tissue-selective estrogen complex (TSEC) containing BZA and conjugated estrogens (CE) on ectopic endometrial lesions in a mouse model of endometriosis. Experimental endometriosis was created in 60 female CD-1 mice. The mice were randomly divided into 10 groups that received varying doses of either BZA (1, 2, 3, or 5 mg/kg/day), BZA (1, 2, 3, or 5 mg/kg/day) in combination with CE (3 mg/kg/day), CE treatment alone (3 mg/kg/day), or vehicle control for 8 wk. Treatment with BZA alone or the TSEC containing BZA/CE led to a decrease in endometriotic lesion size compared to controls. The mean surface area of the untreated lesions was 19.6 mm(2). Treatment with BZA or BZA/CE resulted in reduced lesion size (to 8.8 and 7.8 mm(2), respectively). No significant difference was found in lesion size between the BZA and BZA/CE treatment groups or between different doses of either treatment. Ovarian cyst formation was not evident in the treated groups. Treatment with the TSEC containing higher BZA dosages (3 and 5 mg/kg/day) led to significantly lower levels of estrogen receptor (Esr1) mRNA expression compared to the control treatment. No differences were observed in expression of progesterone receptor (Pgr). Immunohistochemical analysis also demonstrated a decrease in ESR protein. The combination of CE and BZA may prove to be a novel treatment option for endometriosis.

Apolipoprotein E Induction in Syrian Hamster Testis Following Tributyltin Exposure: A Potential Mechanism of Male Infertility.

Tributyltin (TBT) is a common environmental contaminant used as the active ingredient in many products such as a biocides, wood preservatives, disinfecting agents, and antifouling paints. The TBT is a known endocrine disruptor. The aim of the current investigation was to determine the toxicity of TBT in the reproductive tract of adult male Syrian hamsters and to ascertain whether this compound results in untoward effects on apolipoprotein E (ApoE), a lipoprotein central to sex hormone synthesis. The TBT was administered orally to male Syrian hamsters at doses of 50, 100, and 150 ppm/kg for 65 days of treatment. We determined body weight, testis weight, sperm count, sperm morphology, testis histology, ApoE expression, serum lipid profile, testosterone level, follicle-stimulating hormone receptor (FSHR), and steroid hormone receptor expression compared to vehicle-treated controls. High doses of TBT significantly affected each of these parameters in Syrian hamsters. Weight and morphology of the testis were altered as well as sperm production. Real-time reverse-transcriptase polymerase chain reaction analysis revealed that expression of ApoE messenger RNA was upregulated in testes from TBT-treated groups compared with controls while the expression of androgen receptor, FSHR, estrogen receptor α (ESR1), and estrogen receptor ß (ESR2) was decreased. We posit that exposure to TBT hinders intracellular cholesterol transport resulting in abnormal sex steroid biosynthesis and subsequent spermatogenic defects. Importantly, these effects may account for the decreased level of normal sperm observed in hamsters exposed to TBT.

Human endometrial endothelial cells generate distinct inflammatory and antiviral responses to the TLR3 agonist, Poly(I:C) and the TLR8 agonist, viral ssRNA.

PROBLEM: Human endometrial endothelial cell (HEEC) innate immunity remains poorly characterized. Based on their direct contact with the circulation, HEECs are uniquely positioned to be exposed to viral infections. This study evaluated the innate immune response generated by HEECs after exposure to the TLR3 agonist, Poly(I:C) and the TLR8 agonist, viral ssRNA. METHOD OF STUDY: HEECs were treated with or without Poly(I:C) or ssRNA. Culture supernatants were measured for cytokines by multiplex analysis. RNA was analyzed by qRT-PCR for type I interferons and antiviral factors. RESULTS: Treatment of HEECs with Poly(I:C) rapidly upregulated the secretion of IL-2, IL-6, IL-8, IFN-γ, G-CSF, GM-CSF, MCP-1, MIP-1ß, RANTES, and GRO-α after 12 hr, while ssRNA treatment induced the slower secretion of IL-6, IL-8, IFN-γ, G-CSF, VEGF, and GRO-α after 24 hr. Both viral components induced HEEC IFN-α and IFN-ß expression. While treatment with Poly(I:C) induced APOBEC3G and OAS expression, treatment with ssRNA upregulated APOBEC3G and M×A mRNA. CONCLUSION: Our findings demonstrate that HEECs can differentially sense and respond to viral components by generating distinct inflammatory and antiviral immune responses, indicating that these cells likely play an active role in the immune protection of the uterus toward viral infections.

Lipopolysaccharide appears to activate human endometrial endothelial cells through TLR-4-dependent and TLR-4-independent mechanisms.

PROBLEM: Uterine innate immunity remains poorly characterized, and while endometrial endothelial cells are known to express Toll-like receptors (TLRs), little is known about their function in these cells. The present study evaluated the effect of Gram-negative bacterial lipopolysaccharide (LPS) on human endometrial endothelial cell (HEECs) cytokine secretion and tissue factor expression, and the role of TLR-4 in these responses. METHODS: Human endometrial endothelial cells were treated with or without LPS ± LPS-RS, a TLR-4 antagonist, via the binding of MD-2. After 24 hr, cell-free supernatants were evaluated for cytokines by multiplex analysis and cell lysates were analyzed for tissue factor expression by Western blot. RESULTS: Treatment of HEECs with LPS significantly upregulated the secretion of IL-6, IL-8, and G-CSF, and this was prevented by LPS-RS. LPS also induced tissue factor expression by the HEECs; however, this was unaffected by LPS-RS. CONCLUSION: These findings suggest that TLR-4 is functional in HEECs and its activation by bacterial LPS induces a specific cytokine/chemokine response. However, bacterial LPS also induced tissue factor expression in what seemed to be a TLR-4-independent fashion, suggesting that this bacterial component can act on the HEECs through TLR-4-dependent and TLR-4-independent pathways. These findings indicate that endometrial endothelial cells may play an active role in uterine innate immunity.

Global gene expression profiling of proliferative phase endometrium reveals distinct functional subdivisions.

The human endometrium follows a predictable pattern of development during the proliferative phase. Endometrial thickness increases after day 3 and then plateaus at days 9 to 10 of the menstrual cycle despite continued high serum levels of estrogen. We hypothesized that proliferative phase endometrium undergoes more than simple estrogen responsive growth, rather it is characterized by complex time-dependent functional activities reflected in differential gene expression. Nine endometrial RNA samples from healthy participants were subjected to microarray analysis and 15 samples were used for quantitative real-time polymerase chain reaction. The samples were divided into early, mid, or late proliferative phase. The early proliferative phase showed higher expression of genes including transforming growth factor ß2, chemokine (C-C motif) ligand 18 (CCL18), and metallothionein 2A. The mid-proliferative phase was characterized by higher expression of heat shock proteins and implantation-associated genes including Indian hedgehog, secreted frizzled protein 4, and progesterone receptor. In the late proliferative phase, we identified increased angiotensin II receptor, type 2 and large decrease in expression of genes related to natural killer (NK) cell function. We demonstrate a unique gene expression signature at distinct time points within the proliferative phase. The early proliferative phase is characterized by tissue remodeling, angiogenesis, and modulation of inflammation; the mid-proliferative phase is characterized not only by proliferation in response to estrogens but also marks the onset of expression of genes required for endometrial receptivity and a dampening of estrogen responsiveness. In the late proliferative phase, changes in immune function and NK cells predominate. The proliferative phase is not simply a uniform period of estrogen responsive endometrial growth that can be considered as a single experimental time point when evaluating endometrial development; rather the proliferative phase is complex with differing functions and patterns of gene expression.

Toll-like receptor 4 expression in decidual cells and interstitial trophoblasts across human pregnancy.

PROBLEM: Toll-like receptor-4 (TLR-4) protects against Gram-negative bacteria expressed lipopolysaccharide and 'danger signals' from injured or dying cells. Although decidual cells (DCs) and interstitial trophoblasts (ITs) are in close contact, TLR-4 has been studied extensively only in ITs. METHOD OF STUDY: Formalin-fixed, paraffin-embedded serial sections of endometrium in follicular and luteal phases and deciduas from first and second trimester elective terminations and third trimester normal deliveries were immunostained for TLR-4, trophoblast-specific cytokeratin, and DC-specific vimentin. HSCORE assessed TLR-4 immunostaining in DCs versus ITs. RESULTS: TLR-4 HSCORES were significantly higher in: (i) first trimester DCs than luteal phase pre-decidual stromal cells; (ii) first and third versus second trimester DCs, but similar between third trimester deciduas parietalis and basalis; (iii) first versus second trimester ITs; (iv) DCs versus ITs across gestation. CONCLUSION: Higher TLR-4 in DCs than ITs suggests DCs as primary targets for Gram-negative bacteria and/or inflammation-related danger signals.

Effects of etonogestrel treatment in the reproductive organs and uterine arteries of nonoophorectomized guinea pigs.

The endometria of women treated with long-term progestin-only contraceptives (LTPOCs) display abnormally enlarged, fragile blood vessels, decreased endometrial blood flow, oxidative stress, and unpredictable focal abnormal endometrial bleeding. Because human studies on the effects of LTPOC treatment are constrained for ethical and practical reasons, we assessed the suitability of nonoophorectomized guinea pigs (GPs) to best mimic the hormonal milieu of women. The present study demonstrates that treatment of GPs parallels the morphological changes following LTPOC treatment of the human endometrium and ovaries. Specifically, treatment resulted in larger hyperemic, uteri compared with controls. Histopathologic and immunohistochemical analysis demonstrated fewer endometrial glands, decreased luminal mucus, increased numbers of blood vessels, and focal hemorrhage. While increased staining for the cell mitosis marker, Ki67, was present in the zona functionalis, no such increase occurred in the basalis. Lastly, effects on vasomotor features of uterine arteries suggest changes that favor increased resistance and reduced blood flow promoting decreased ability to withstand elevations in transmural pressure.

Preeclampsia, hypoxia, thrombosis, and inflammation.

Reductions in uteroplacental flow initiate a cascade of molecular effects leading to hypoxia, thrombosis, inflammation, and endothelial cell dysfunction resulting in untoward pregnancy outcomes. In this review, we detail these effects and their relationship to preeclampsia (PE) and intrauterine growth restriction (IUGR).