Hypoxia leads to diminished ovarian reserve in an age dependent manner.

OBJECTIVES: Perinatal hypoxia causes premature activation and initiation of growth in dormant follicles, leading to diminished ovarian reserve. An indirect mechanism such as the release of stress-related hormones, may influence ovarian follicle recruitment under hypoxic conditions. We wanted to determine whether hypoxic ovarian damage results from increased follicle growth and "burnout" or from increased apoptosis, and whether this damage is age-dependent. DESIGN: Animal study Participants/Materials, Setting, Methods: Using adult 6-week-old (n=8) and one-day-old newborn (n=20) ICR (CD-1) female mice, ovarian follicular counts were conducted on H&E-stained sections. METHODS: Immunohistochemistry was performed on sections stained with Ki-67, anti-Caspase 3 and anti-FOXO3A. RESULTS: Exposure to hypoxia resulted in significantly reduced proportion of primordial follicles vs normoxia in both adult dams and newborn pups (3.17±2.75% vs. 17.89±4.4%; p=0.004; 40.59±14.88% vs. 81.92±31.56%, p=0.001, respectively), concomitant with increased growing- primary and secondary follicles, and more pronounced in adult dams vs newborn pups (6-fold vs. 2-fold, respectively). Ki67 staining revealed higher scores of cell proliferation in follicular granulosa cells after exposure to hypoxia than normoxia. However, Caspase 3 and Foxo3A staining did not show any differences in these markers of apoptosis in oocytes, granulosa cells, theca cells, or stromal cells when exposed to hypoxia versus normoxia. LIMITATIONS: The current study has several limitations; first, the sample size for each group is relatively small, which could limit the generalizability of the findings. Second, the study uses an ex vivo culture system, which may not fully capture the complex interactions that occur in the whole animal. Third, the exposure to hypoxia only lasted for 3 hours, which may not be long enough to observe all the potential effects. In addition, the study only analyzed specific markers of apoptosis in a few cell types, and other cell types or apoptotic pathways might be involved. Lastly, the study provides evidence for accelerated follicular activation and decreased ovarian reserve, but the underlying mechanisms are not fully explored. Conclusions Direct tissue hypoxia led to premature activation and initiation of growth in dormant follicles leading to diminished ovarian reserve. Hypoxic damage is age-dependent, with adult ovaries more susceptible than newborn ovaries. These findings support the possibility of follicular "burn out" as a potential mechanism responsible for hypoxia-induced loss of ovarian reserve.

Long-term pituitary down-regulation pretreatment for endometriosis - chronicles of guidelines and recommendations.

It was suggested in the 1980s that long-term pituitary down-regulation by a gonadotrophin-releasing hormone agonist, termed the ultra-long protocol, inducing a hypo-oestrogenic state, might improve reproductive outcomes in women with endometriosis. Subsequently, international guidelines strongly supported the long-term pituitary down-regulation protocol in women with endometriosis based on a Cochrane review from 2006. The recently published European Society for Human Reproduction and Embryology guideline, based on the updated Cochrane review from 2019 and newer evidence, has reversed this recommendation. This paper explores the past and current evidence that led to these recommendations and calls for a consideration of refinement of the international guidelines to include additional factors and evaluate whether a paradigm shift is needed in the approach to endometriosis-related infertility. We believe that this can optimize evidence-based patient-centred care and benefit women worldwide and improve the design of future studies.

Perinatal hypoxia leads to primordial follicle activation and premature depletion of ovarian reserve.

BACKGROUND: The human ovary contains 6-million follicles during the 20th week of embryonic development and 1 million at birth. Girls born at small for gestational age weight demonstrate higher FSH levels during infancy, an earlier onset of puberty, and menarche. In light of these observations, we hypothesized that exposure to hypoxia at the early neonatal period might impact the primordial follicular pool and lead to premature depletion of ovarian reserve. METHODS: Ovarian development in the rat model at days 1-5 postpartum reflects its human counterpart in the late perinatal period. We exposed newborn rat pups (n = 5) to controlled hypoxia, (5% oxygen/95% nitrogen) for 10 min three times daily for days 1-5 postpartum. On day 5, ovaries were harvested, H&E, Ki-67, and TUNEL staining were performed. RESULTS: The percentage of primordial follicles out of total follicles in ovaries of pups exposed to hypoxia was lower compared to control (76 ± 8.2% and 90.33 ± 6.3% respectively, p < .05). Correspondingly the percentage of primary and secondary follicles was higher than in control. The mean stromal Ki67 staining score was significantly lower in the study group (1.67 ± 0.58 and 2.5 ± 0.55 respectively, p < .05). TUNEL staining demonstrated no difference in stromal apoptosis rates between both groups. CONCLUSIONS: We provide evidence for the first time that perinatal hypoxia causes premature activation and growth initiation of dormant follicles. These changes were associated with decreased stromal cell proliferation, suggesting hypoxia-induced impairment of the support cell pool as a possible mechanism for accelerated follicular activation.

In Vitro Fertilization Entails a High Prevalence of Erectile and Male Sexual Dysfunction: A Prospective Case-Control Study.

PURPOSE: We evaluated the effect of in vitro fertilization (IVF) on sexual function in men, particularly for erectile dysfunction. MATERIALS AND METHODS: A prospective case-control study at a tertiary medical center. The study group comprised men of infertile couples that required IVF to conceive. The control group comprised men of couples who conceived spontaneously. The effects of IVF on sexual and erectile function were assessed based on the International Index of Erectile Function (IIEF-15) and the Self-Esteem and Relationship (SEAR) questionnaires. Participants were followed up to 1 year postpartum. RESULTS: Compared to the control group (378), for the IVF group (356), mean IIEF-15 scores were significantly lower: prior to pregnancy (31.7±4.5 vs 64.4±7.2, p <0.0001), at mid-pregnancy (37.3±5.1 vs 66.4±5.5, p <0.0001) and up to one year postpartum (42.3±4.9 vs 68.6±4.3, p <0.0001). Compared to the control group, in the IVF group, mean SEAR scores were significantly lower at these 3 respective time points (29.9±6.3 vs 66.5±8.3; 34.1±5.8 vs 66.9±7.2; and 40.9±6.7 vs 67.3±5.6; p <0.0001). At the 3 time points, for the IVF compared to the control group, the median monthly sexual intercourse rate was lower; and both the use of phosphodiesterase-5 inhibitor and psychologist/sexologist care were higher. CONCLUSIONS: The prevalence of erectile dysfunction among men participating in IVF in order to conceive is significantly higher compared to couples that conceived spontaneously, thus leading to an extremely high rate of phosphodiesterase-5 inhibitor use.

Progesterone Attenuates Brain Inflammatory Response and Inflammation-Induced Increase in Immature Myeloid Cells in a Mouse Model.

Progesterone has been shown to regulate immunity during pregnancy, and progesterone administration may reduce inflammation-induced preterm labor. We sought to determine the maternal brain immune response to LPS-induced inflammation in pregnant and non-pregnant mice and whether additional progesterone supplementation attenuates this response. Pregnant (P: n = 9) and non-pregnant mice (NP: n = 9) were randomized to pretreatment with vaginal progesterone/carrier (Replens), daily from days 13 to 16. On days 15 and 16, LPS/saline was administered by intraperitoneal injection (Replens + saline n = 3; Replens + LPS n = 3; progesterone + LPS n = 3). Mice were sacrificed on day 16 and maternal serum analyzed for IL-6 levels and brains analyzed for nNOS, NF-kB, IL-6 protein levels and for immature myeloid cells (IMCs) and microglial activity. LPS significantly increased brain nNOS, NF-kB, and IL-6 in both NP and P mice, with significantly greater responses in P mice. In both NP and P groups, progesterone significantly attenuated LPS-induced increase of nNOS and NF-kB, however with no effect on serum IL-6. In the NP brains, LPS significantly increased IMC population and progesterone reduced the IMC phenotype to levels similar to controls. In P mice, neither LPS nor LPS + progesterone altered the brain IMC population. LPS significantly increased the microglial activity in both NP and P groups, which was attenuated by progesterone. Progesterone attenuates brain inflammatory response to LPS in both NP and P mice although it has no effect on systemic inflammation. In NP mice, progesterone attenuated the increase in brain IMC following LPS administration. Our results suggest that endogenous progesterone during pregnancy may protect the brain from LPS-induced inflammation.

Maternal Progesterone Treatment Reduces Maternal Inflammation-Induced Fetal Brain Injury in a Mouse Model of Preterm Birth.

Maternal natural vaginal progesterone (nVP) administration has been shown to reduce the risk of preterm birth (PTB). The largest randomized trial of nVP for PTB (OPPTIMUM) noted a sonographic reduction in neonatal brain injury following nVP treatment. We investigated the neuroinflammatory protective effect of maternal nVP in a mouse model for maternal inflammation. Pregnant mice (n = 24) were randomized to nVP (1 mg/day) or vehicle from days 13-16 of gestation. At days 15 and 16, lipopolysaccharide (30 µg) or saline were administered. Mice were sacrificed 4 h following the last injection. Fetal brains and placentas were collected. Levels of NF-κB, nNOS, IL-6, and TNFα were determined by Western blot. Maternal lipopolysaccharide significantly increased fetal brain levels of IL-6 (0.33 ± 0.02 vs. 0.11 ± 0.01 u), TNFα (0.3 ± 0.02 vs. 0.10 ± 0.01 u), NF-κB (0.32 ± 0.01 vs. 0.17 ± 0.01 u), and nNOS (0.24 ± 0.04 vs. 0.08 ± 0.01 u), and reduced the total glutathione levels (0.014 ± 0.001 vs. 0.026 ± 0.001 pmol/µl; p < 0.01) compared with control. Maternal nVP significantly reduced fetal brain levels of IL-6 (0.14 ± 0.01 vs. 0.33 ± 0.02 u), TNFα (0.2 ± 0.06 vs. 0.3 ± 0.02 u), NF-κB (0.16 ± 0.01 vs 0.32 ± 0.01 u), and nNOS (0.14 ± 0.01 vs 0.24 ± 0.04 u), and prevented the reduction of fetal brain total glutathione levels (0.022 ± 0.001 vs. 0.014 ± 0.001 pmol/µl; p < 0.01) to levels similar to controls. A similar pattern was demonstrated in the placenta. Maternal nVP for PTB may protect the fetal brain from inflammation-induced brain injury by inhibiting specific inflammatory and oxidative pathways in both brain and placenta.

Maternal N-acetyl-cysteine prevents neonatal brain injury associated with necrotizing enterocolitis in a rat model.

INTRODUCTION: Preterm infants with necrotizing enterocolitis (NEC) are at increased risk of cerebral injury and neurodevelopmental dysfunction. N-acetyl-cysteine (NAC) is a known anti-inflammatory and antioxidant agent. Currently, there is no prophylactic treatment in clinical use to prevent NEC and its neurodevelopmental sequelae. We sought to determine whether brain inflammation/apoptosis accompanies NEC systemic inflammation, and whether it can be attenuated by maternal NAC treatment during pregnancy and/or in the neonatal period in a rat model. MATERIAL AND METHODS: An established NEC newborn model (hypoxia 5% O2 for 10 min and formula feeding thrice daily, beginning on day 1 for 4 days) was used in Sprague-Dawley rat pups (n = 32). An additional group of pups (n = 33) received NAC (300 mg/kg intraperitoneal thrice daily) in addition to NEC conditions (NEC-NAC). Control pups (n = 33) were nursed and remained with the dam in room air. Two additional groups included pups of dams treated once daily with NAC (300 mg/kg intravenous) in the last 3 days of pregnancy. After birth, pups were randomized into NAC-NEC (n = 33) with NEC conditions and NAC-NEC-NAC (n = 36) with additional postnatal NAC treatment. Pups were sacrificed on the fifth day of life. Pup serum interleukin (IL)-6 protein levels, and brain nuclear factor kappa B (NF-κB) p65, neuronal nitric oxide synthase (nNOS), Caspase 3, tumor necrosis factor alpha (TNF-α), IL-6 and IL-1ß protein levels were determined by ELISA, western blot and TUNEL staining, and the groups were compared using analysis of variance (ANOVA). RESULTS: NEC pups had significantly increased serum IL-6 levels compared with the control group as well as increased neuronal apoptosis and brain protein levels of NF-κB, nNOS, Caspase 3, TNF-α, IL-6 and IL-1ß compared with control. In all NAC treatment groups, levels of serum IL-6, neuronal apoptosis and brain NF-κB, nNOS, Caspase 3, TNF-α, IL-6 and IL-1ß protein levels were significantly reduced compared with the NEC group. The most pronounced decrease was demonstrated within the NAC-NEC-NAC group. CONCLUSIONS: NAC treatment can attenuate newborn inflammatory response syndrome and decrease offspring brain neuroapoptosis and inflammation in a rat model of NEC by inhibition of NF-κB, nNOS and Caspase 3 pathways.

Prophylactic antenatal N-Acetyl Cysteine administration combined with postnatal administration can decrease mortality and injury markers associated with necrotizing enterocolitis in a rat model.

BACKGROUND: Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease of neonates, especially premature neonates. To date, there is no prophylactic treatment against NEC, except breast milk and slow increase in enteral feeding, and there is no antenatal prophylaxis. AIMS: To assess possible protective effects of antenatal N-Acetyl Cysteine (NAC) against the intestinal pathophysiological changes associated with NEC in a rat model of NEC and against its associated mortality. METHODS: Newborn Sprague-Dawley rats were divided into 5 groups: control (n = 33); NEC (n = 32)-subjected to hypoxia and formula feeding for 4 days to induce NEC; NEC-NAC (n = 34)-with induced NEC and concomitant postnatal NAC administration; NAC-NEC (n = 33)-born to dams treated with NAC for the last 3 days of pregnancy starting at gestational age of 18 days, and then subjected to induced NEC after birth; NAC-NEC-NAC (n = 36)-subjected to induced NEC with both prenatal and postnatal NAC treatment. At day of life 5, weight and survival of pups in the different groups were examined, and pups were euthanized. Ileal TNF-α, IL-6, IL-1ß, IL-10, NFkB p65, iNOS and cleaved caspase 3 protein levels (western blot) and mRNA expression (RT-PCR) were compared between groups. RESULTS: Pup mortality was significantly reduced in the NAC-NEC-NAC group compared to NEC (11% vs. 34%, P<0.05). Ileal protein levels and mRNA expression of all injury markers tested except IL-10 were significantly increased in NEC compared to control. These markers were significantly reduced in all NAC treatment groups (NEC-NAC, NAC-NEC, and NAC-NEC-NAC) compared to NEC. The most pronounced decrease was observed in the NAC-NEC NAC group. CONCLUSIONS: Antenatal NAC decreases injury markers and mortality associated with NEC in a rat model. Antenatal administration of NAC may present a novel approach for NEC prophylaxis in pregnancies with risk for preterm birth.

The transcriptional profile of circulating myeloid derived suppressor cells correlates with tumor development and progression in mouse.

Myeloid derived suppressor cells (MDSCs) play key roles in cancer development. Accumulation of peripheral-blood MDSCs (PB-MDSCs) corresponds to the progression of various cancers, but provides only a crude indicator. We aimed toward identifying changes in the transcriptional profile of PB-MDSCs in response to tumor growth. CT26 colon cancer cells and B16 melanoma cells (106) were inoculated into peritoneal cavities of BALB/c mice and subcutaneously to C57-black mice, respectively. The circulating levels and global transcriptional patterns of PB CD11b+Ly6g+ MDSCs were assessed in control mice, and 4, 8, and 11 days following tumor cell inoculation. Although a significant accumulation of PB-MDSCs was demonstrated only 11 days following tumor induction, a pronounced transcriptional response was identified already on day 4 while the tumor was ~1 mm in size. Further transcriptional changes correlated with different stages of tumor growth. Key MDSC genes and canonical signaling pathways were activated along tumor progression. This phenomenon was demonstrated in both cancer models, and a consensus set of 817 genes, involved in myeloid cell recruitment and angiogenesis, was identified. The data suggest that the transcriptional signatures of PB-MDSC may serve as markers for tumor progression, as well as providing potential targets for future therapies.

CD11b+Ly6G+ myeloid-derived suppressor cells promote liver regeneration in a murine model of major hepatectomy.

Liver regeneration depends on sequential activation of pathways and cells involving the remaining organ in recovery of mass. Proliferation of parenchyma is dependent on angiogenesis. Understanding liver regeneration-associated neovascularization may be useful for development of clinical interventions. Myeloid-derived suppressor cells (MDSCs) promote tumor angiogenesis and play a role in developmental processes that necessitate rapid vascularization. We therefore hypothesized that the MDSCs could play a role in liver regeneration. Following partial hepatectomy, MDSCs were enriched within regenerating livers, and their depletion led to increased liver injury and postoperative mortality, reduced liver weights, decreased hepatic vascularization, reduced hepatocyte hypertrophy and proliferation, and aberrant liver function. Gene expression profiling of regenerating liver-derived MDSCs demonstrated a large-scale transcriptional response involving key pathways related to angiogenesis. Functionally, enhanced reactive oxygen species production and angiogenic capacities of regenerating liver-derived MDSCs were confirmed. A comparative analysis revealed that the transcriptional response of MDSCs during liver regeneration resembled that of peripheral blood MDSCs during progression of abdominal tumors, suggesting a common MDSC gene expression profile promoting angiogenesis. In summary, our study shows that MDSCs contribute to early stages of liver regeneration possibly by exerting proangiogenic functions using a unique transcriptional program.-Nachmany, I., Bogoch, Y., Sivan, A., Amar, O., Bondar, E., Zohar, N., Yakubovsky, O., Fainaru, O., Klausner, J. M., Pencovich, N. CD11b+Ly6G+ myeloid-derived suppressor cells promote liver regeneration in a murine model of major hepatectomy.

Progesterone treatment enhances the expansion of placental immature myeloid cells in a mouse model of premature labor.

INTRODUCTION: immature-myeloid cells (IMCs) are proangiogenic bone marrow (BM)-derived cells that normally differentiate into inflammatory cells such as neutrophils, monocytes and dendritic cells (DCs). We characterized placental IMCs comparing their gene expression and subpopulations to tumor IMCs, and tested our hypothesis that progesterone that inhibits preterm labor, may affect their abundance and differentiation. METHODS: differences between IMC-subpopulations in subcutaneous tumors versus placentas in C57BL/6 or ICR (CD-1) mice were analyzed by flow cytometry and gene expression was detected by microarrays. BM- and placental cells were incubated with or without progesterone and IMC subpopulations were analyzed. For preterm labor induction pregnant mice pretreated or not with progesterone were or were not treated with Lipopolysaccharide (LPS). RESULTS: we detected enrichment of granulocytic-IMCs in placentas compared to tumors, paralleled by a decrease in monocytic-IMCs. mRNA expression of placenta- versus tumor IMCs revealed profound transcriptional alterations. Progesterone treated BM-CD11b+ cells ex-vivo induced enrichment of granulocytic-IMCs and a decrease in monocytic-IMCs and DCs. LPS treatment in-vivo led to an increase in BM-IMCs in both progesterone pretreated or non-pretreated mice. In the placenta LPS decreased the IMC population while progesterone led to complete abrogation of this effect. DISCUSSION: placental IMCs differ from tumor-IMCs in both subpopulations and gene expression. Progesterone enhances the proliferation of placenta-specific granulocytic IMCs ex-vivo and LPS induced labor is accompanied by a decrease in placental IMCs only in progesterone non-pretreated mice. We thus speculate that the protective effect of progesterone in preventing preterm labor may be explained at least in part by this specific anti-inflammatory effect.

Anovulatory Patients Demonstrate a Sharp Decline in LH Levels upon GnRH Antagonist Administration during IVF Cycles.

To evaluate the decrease in luteinizing hormone (LH) levels following gonadotropin-releasing hormone (GnRH) antagonist administration in in vitro fertilization (IVF) cycles, data were retrospectively collected from 305 consecutive IVF or intracytoplasmic sperm injection (ICSI) cycles of patients who underwent ovarian stimulation with gonadotropins and were treated with GnRH antagonist for the prevention of premature luteinization. We compared the percent change in LH concentration from stimulation start to that observed before ovulation triggering in patients with or without anovulation. Anovulatory patients were younger, with higher body mass index (BMI), and demonstrated higher ovarian reserve parameters as compared to ovulatory patients. The decline in LH concentration was almost two-fold greater in anovulatory versus ovulatory patients. Numbers of oocytes, fertilizations, cleavage stage embryos, and transferred embryos were similar; however, implantation rates were higher in anovulatory versus ovulatory patients. Older patients (age ≥39) showed a smaller decline in LH levels as compared to younger ones (age <39) and exhibited poor IVF outcomes. There is a wide range of pituitary responses to GnRH antagonists. Anovulatory patients are more susceptible to GnRH antagonists and therefore demonstrate over-suppression of the pituitary. Older patients demonstrate a reduced pituitary response to GnRH antagonists than younger ones. Cycle scheduling with estradiol pretreatment did not influence LH decline, nor IVF treatment outcomes.

GnRH Agonist Triggering of Ovulation Replacing hCG: A 30-Year-Old Revolution in IVF Practice Led by Rambam Health Care Campus.

Final oocyte maturation is a crucial step in in vitro fertilization, traditionally achieved with a single bolus of human chorionic gonadotropin (hCG) given 36 hours before oocyte retrieval. This bolus exposes the patient to the risks of ovarian hyperstimulation syndrome (OHSS), particularly in the face of ovarian hyper-response to gonadotropins. Although multiple measures were developed to prevent OHSS, gonadotropin-releasing hormone (GnRH) agonist triggering is now globally recognized as the best approach to achieve this goal. The first report on the use of GnRH agonist as ovulation trigger in the context of OHSS prevention came from Rambam Health Care Campus, Haifa, Israel and appeared in 1988. This review details the events that culminated in worldwide acceptance of this measure and describes its benefit in the field of assisted reproductive technology.

'Model' versus 'everyday' patients: can randomized controlled trial data really be applied to the clinic?

New drug approval requires a new drug to undergo rigorous clinical trials to determine its efficacy and safety. A drug is approved only for the population on which it was tested, i.e. those who meet the inclusion criteria of the trial. The aim of this study was to determine what percentage of 'real life' patients in our clinic meet the inclusion and exclusion criteria used in large-scale clinical trials required for drug registration in the field of assisted reproduction. All 265 consecutive patients with pertinent data treated in a tertiary centre IVF Unit during 2015 were surveyed. Their demographic and clinical parameters were compared with inclusion and exclusion criteria used in nine major clinical trials. Only 97 out of 265 (37%) patients met the consensus inclusion criteria as defined by the nine clinical trials. The number of oocytes retrieved was 9.10 ± 5.34 in the patients that met the inclusion criteria (n = 97) versus 6.90 ± 5.23 (P = 0.00122) in those that did not (n = 168). Most 'real life' patients who come for treatment at a tertiary IVF centre do not meet the consensus of inclusion and exclusion criteria used for major clinical trials.

The development of endometriosis in a murine model is dependent on the presence of dendritic cells.

Endometriosis is a common condition associated with pelvic pain and infertility. This study group has previously shown that supplementation of dendritic cells led to enhancement of endometriosis lesion growth and angiogenesis. This study determined whether endometriosis is dependent on the presence of endogenous dendritic cells. Surgical induction of endometriosis was performed in CD11c⁺ DTR/GFP transgenic (Tg) female mice in which dendritic cells were ablated upon injection of diphtheria toxin (DT). Mice were allocated into four groups (n=5 each): group I, wild-type mice treated with vehicle; group II, wild-type mice treated with DT; group III, Tg mice treated with DT; and group IV, Tg mice treated with vehicle. After 10 days, mice were killed and endometriosis lesions were analysed by flow cytometry. DT treatment led to ablation of dendritic cells in spleens and endometriosis lesions in Tg mice while no ablation was observed in controls. Corresponding to dendritic cell ablation, endometriosis lesions in group III were ∼5-fold smaller than in the control groups (ANOVA P<0.0001). This study suggests that endometriosis development is dependent on the presence of endogenous dendritic cells. Therapies designed to inhibit dendritic cell infiltration as possible treatments for endometriosis warrant further study.

Tumor dormancy and the angiogenic switch: possible implications of bone marrow- derived cells.

Although escape from tumor dormancy has long been recognized as an important problem in the treatment of cancer, the molecular and cellular regulators underlying this transition remain poorly understood. The inability of the cancer cells to induce a complete and successful process of angiogenesis can result in tumor dormancy. In this case, the acquisition of sufficient angiogenic potential will result in the escape from indolence and in the initiation of tumor mass expansion. This stage in disease progression is known as the angiogenic switch. It is now becoming clear that the induction of the angiogenic switch is controlled by dynamic and complex biological processes involving the cancer cells, the associated stromal microenvironment and distant normal host cells, mostly from the bone marrow. Indeed, intricate tumor-host interactions are increasingly recognized as critical features of cancer. In particular, infiltrating cells of the immune system are crucial constituents of tumors and an important source of the growth stimulatory signals to the tumor cells. Tumor cells are surrounded by stromal cells, such as fibroblasts, lymphocytes, neutrophils, macrophages and mast cells, which communicate via a complex network of intercellular signaling pathways, mediated by surface adhesion molecules, cytokines and their receptors. However, the possible roles of these cells and molecules in the maintenance of micro-tumors in an occult state and in the induction of exit from the dormant state are not fully elucidated. In this review, we summarize recent findings and the current understanding of the role of bone marrow-derived cells, their recruitment into tumors and their interactive crosstalk with tumor cells, in leading to either the maintenance of, or exit from, tumor dormancy. Understanding the mechanisms of tumor growth and metastatic recurrence after periods of indolence is crucial for improving early detection, as well as increasing the cure rate for cancer patients.

Myeloid cell alterations in the mouse placenta precede the onset of labor and delivery.

OBJECTIVE: Immature myeloid cells (IMCs) are bone marrow-derived cells that normally differentiate into granulocytes, macrophages, and dendritic cells (DCs) but expand in pathological conditions such as malignancy. DCs are antigen-presenting cells that regulate the immune response. Both IMCs and DCs were shown to take part in angiogenesis; however, little is known of their function in the placenta. We sought to determine whether alterations in DC and IMC populations in the placenta precede the onset of delivery. STUDY DESIGN: Experiments were performed on 6-8 week old C57Bl/6 female mice. Placentas from pregnant mice that were killed on designated days, immunostained using fluorescently labeled anti-CD11b, Gr-1, CD11c, major histocompatibility II (MHCII), and CD45, and analyzed by flow cytometry and immunofluorescent microscopy. RESULTS: Throughout the latter part of pregnancy toward labor and delivery, the CD45(+)CD11b(+)Gr1(+)-IMC population decreased 29 ± 9.1% (day 12) and 30 ± 9.9% (day 15), vs 21 ± 8.1% (day18, n = 21, 15, and 27; P = .006 and P = .004, respectively), whereas the CD45(+)CD11c(+)MHCII(+)-DC population increased 0.87 ± 0.3% (day 12) and 0.70 ± 0.3% (day 15) vs 1.81 ± 1.3% (day 18, n = 21, 15, and 27, P = .002 and P = .001, respectively). Both myeloid cell populations were localized adjacent to CD31(+) endothelial cells in sites of placental angiogenesis. CONCLUSION: Labor and delivery are preceded by proangiogenic-myeloid cell alterations, reflected by a decrease in IMCs and an increase in DCs populating the mouse placenta. The intriguing possibility that delivery is preceded by the maturation of IMCs in part into DCs warrants further studies.

Immature myeloid cells derived from mouse placentas and malignant tumors demonstrate similar proangiogenic transcriptional signatures.

OBJECTIVE: To determine whether CD11b(+)Gr1(+) immature myeloid cells (IMCs), initially identified to infiltrate tumors and support angiogenesis and recently identified also in mouse and human placentas, are similar in that they share common gene expression. DESIGN: Animal experiment. SETTING: Reproductive immunology laboratory. ANIMAL(S): All 6- to 8-week-old C57Bl/6 female mice. MAIN OUTCOME MEASURE(S): We analyzed gene expression of IMCs isolated from placentas of pregnant mice (n = 3) and Lewis lung carcinoma tumors (n = 3), using flow cytometry. Expression patterns were compared to primary muscle cells (n = 4), using Affymetrix microarrays. Quantitative polymerase chain reaction (PCR) was used to validate microarray data. Similarity of gene expression was evaluated with the mass-distance algorithm. RESULT(S): The IMCs that infiltrate mouse placentas share ∼500 expressed genes with tumor IMCs (set a). This gene set is enriched with proangiogenic and inflammatory genes. Unique gene expression sets for tumor IMCs (set b) and placenta IMCs (set c) were also detected. CONCLUSION(S): The IMCs derived from placentas and tumors express common molecular signatures, suggesting similar origins and functions. This observation lends further support to the notion that the placenta uses a similar angiogenic machinery as tumors for survival and growth. Unique gene-sets, differentially expressed in tumor versus placenta-derived IMCs, may be required for specific IMC-hosting tissue interactions.