Reproductive disorders, including intrauterine adhesion (IUA), premature ovarian insufficiency (POI), and polycystic ovary syndrome (PCOS), are great threats to female reproduction. Recently, mesenchymal stem cells derived–extracellular vesicles (MSC-EVs) have presented their potentials to cure these diseases, not only for the propensity ability they stemmed from the parent cells, but also for the higher biology stability and lower immunogenicity, compared to MSCs. EVs are lipid bilayer complexes, functional as mediators by transferring multiple molecules to recipient cells, such as proteins, microRNAs, lipids, and cytokines. EVs appeared to have a therapeutic effect on the female reproductive disorder, such as repairing injured endometrium, suppressing fibrosis of endometrium, regulating immunity and anti-inflammatory, and repressing apoptosis of granulosa cells (GCs) in ovaries. Although the underlying mechanisms of MSC-EVs have reached a consensus, several theories have been proposed, including promoting angiogenesis, regulating immunity, and reducing oxidate stress levels. In the current study, we summarized the current knowledge of functions of MSC-EVs on IUA, POI, and PCOS. Given the great potentials of MSC-EVs on reproductive health, the critical issues discussed will guide new insights in this rapidly expanding field.

Are other HOX genes, in addition to HOXA10, involved in endometrial receptivity? The highly expressed HOXA9, HOXA11 and HOXD10 genes also appear to be involved in endometrial receptivity. Within the HOX family of homeobox transcription factor genes are the leading candidates for the regulation of embryonic implantation. A crucial role of HOXA10 in endometrial receptivity has been well established. To identify HOX candidate genes, we performed data mining on all 39 human HOX genes in the ‘Human body index’ gene expression database of normal human tissue. The temporal and spatial expression pattern of four highly expressed HOX genes in the human endometrium was determined. To further investigate the function of these Hox genes, we used a robust in vivo mouse model in which we blocked maternal Hox gene expression. Analysis of a gene expression profile set in the public domain consisting of 504 samples representing 95 different normal human tissues, showed that in addition to HOXA10, also HOXA9, HOXA11, HOXB6 and HOXD10 mRNA showed increased expression in the human endometrium (16 samples). The temporal and spatial expression pattern of these four HOX genes throughout the menstrual cycle was determined in the endometrium from 27 female patients eligible for IVF-embryo transfer with a normal cycle by quantitative real-time PCR (qRT-PCR), western blot and immunohistochemistry. The role of maternal Hoxa9, Hoxa11 and Hoxd10 was assessed in a mouse implantation model by expression knockdown using RNA interference. Forty mice were transfected with Hoxa9-, Hoxa11- or Hoxd10-specific small hairpin RNA (shRNA) constructs or a vector control by injection into the uterine horn at Day 2 after vaginal plug detection (Day 1) (160 mice in total). The effects were examined by qRT-PCR and western blot at Day 4 and litter sizes counted at Day 9 of pregnancy. HOXA10, HOXA9, HOXA11 and HOXD10 all showed increased expression during the mid-secretory phase of the menstrual cycle (P < 0.01). Knockdown of Hoxa9, Hoxa11 and Hoxd10 in the murine uterus resulted in significantly reduced average implantation rates (P < 0.01) and, with regard to four Hox target genes, also correlated with a significantly increased empty spiracles homolog 2 (Emx2) and insulin-like growth factor binding protein-1 (Igfbp1), and decreased integrin β3 (Itgb3) and leukemia inhibitory factor (Lif), expression (P < 0.01). Menstrual cycle stage was not confirmed by serum hormone analysis. We verified the absence of significant differences in stage-specific expression of the reference genes used in our study (ACTB/Actb and GAPDH/Gapdh) and therefore possible limitations of this approach were minimized. In addition, the translatability of our data from a mouse model to patients needs to be investigated further. We provide evidence that three other HOX genes in addition to HOXA10 are involved in endometrial receptivity, and that part of their function is asserted through several known HOX target genes, suggesting the presence of a central HOX signal transduction pathway. This project was funded by the National Natural Science Foundation of China. The authors declare no conflict of interest.

Background: Thin endometrium on ovulation triggering day is associated with impaired pregnancy outcomes in women after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), but the role of thick endometrium on pregnancy outcomes remains controversial. Moreover, there has been insufficient evidence currently to analyze the influence of endometrial thickness (EMT) on obstetric complications and perinatal outcomes. Thus, we performed this meta-analysis to evaluate the effect of EMT on pregnancy, maternal, and perinatal outcomes in an enlarged sample size.Methods: The databases Pubmed, Embase, Cochrane Libraries, and Web of Science were searched for English articles evaluating the correlation between EMT and pregnancy, maternal, or perinatal outcomes in women who underwent IVF/ICSI. We included studies that depicted a clear definition of outcomes and EMT grouping on ovulation triggering day. The EMT effect was analyzed in fresh cycle. Qualities of studies were assessed by the Newcastle-Ottawa Scale (NOS). Odds ratios (ORs) and weighted mean difference (WMD) with 95% confidence intervals (CIs) were calculated for analyzing dichotomous and continuous outcomes respectively, under a fixed or random effect model.Results: A total of 22 pieces of literature were included for the final meta-analysis. A decreased trend towards pregnancy outcomes was observed, such as live birth rate (LBR), clinical pregnancy rate (CPR), and implantation rate (IR) in the thin endometrium groups (EMT 14 mm) had no effect on pregnancy outcomes compared to medium EMT groups (EMT 7–14 mm). Moreover, thin endometrium (EMT <7.5 mm) enhanced the incidence of hypertensive disorders of pregnancy (HDP) and small-for-gestational-age (SGA) infants, and decreased the birthweight (BW) of babies.Conclusions: Our studies indicated that thin endometrium not only had detrimental effect on pregnancy outcomes, but also increased the risk of HDP in women and SGA of babies, or decreased BW of babies. The thick endometrium does not have an adverse effect on IVF outcomes. Therefore, patients need to be informed on possible obstetric complications and perinatal outcomes caused by thin endometrium and are encouraged to actively cooperate with perinatal care.Systematic Review Registration: (https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=242637), identifier CRD42021242637.

The nature of the association between the number of oocytes retrieved and in vitro fertilization (IVF) outcomes after fresh embryo transfer remains unclear because of conflicting results reported in the studies on this subject. In addition, the influence of the quality of the embryos transferred is usually neglected. The objective of this study is to assess the relationships of the number of oocytes retrieved, the number and quality of embryos transferred, and the prospects of pregnancy after fresh embryo transfer. The data on 3131 infertile women undergoing their first IVF treatment cycle between January 2009 and December 2010 were collected retrospectively. Restricted cubic splines and stratified analyses were used to explore the relationships between the number of oocytes retrieved, the number and quality of embryos transferred, and the IVF outcomes. When stratified by the number and quality of transferred embryos, no significant differences in the chances for clinical pregnancy and live birth were found in three groups of oocytes yielded (≤6, 7–14, or ≥15). The relationship between the number of oocytes retrieved and pregnancy is nearly a reflection of the pattern of the relationship between the number of oocytes retrieved and the probability of having two good-quality embryos transferred. The patients with the “optimal” number of oocytes were not only younger but also had the highest probability of having two good-quality embryos replaced. Similarly aged patients have similar pregnancy prospects after fresh embryo transfer when the same number and quality of embryos are replaced, irrespective of their number of oocytes. Selecting the desired number of good-quality embryos for transfer is the key to IVF success. Thus, aiming at retrieving an optimal number of oocytes to maximize IVF outcomes in a fresh cycle could place undue stress on the patients and may not be the best medical decision.

Purpose: The aim of this meta-analysis was to evaluate the effect of growth hormone (GH) supplementation in poor responders undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Methods: PubMed, MEDLINE and Cochrane Library databases were searched for the identification of relevant randomized controlled trials. Outcome measures were live birth rate, clinical pregnancy rate, miscarriage rate, cycle cancelation rate, number of retrieved oocytes and total dose of gonadotropin. Results: Fifteen randomized controlled trails (RCTs) involving 1448 patients were eligible for the analysis. GH supplementation improved live birth rate (RR, 1.74; 95% CI, 1.19–2.54), clinical pregnancy rate (RR, 1.65; 95% CI, 1.31–2.08) and retrieved oocytes number (SMD, 0.72; 95% CI, 0.28–1.16), while reducing cancelled cycles rate (RR, 0.62; 95% CI, 0.44–0.85) and dose of Gonadotropin (SMD,-1.05 95% CI, − 1.62 - -0.49) for poor ovarian response patients. Besides, there was no significant difference in the miscarriage rate between GH group and control group. Conclusions: Based on the limited available evidence, growth hormone supplementation seems to improve IVF/ICSI outcomes for poor ovarian responders. Further randomized controlled trials with large sample sizes are required to clarify the effect of GH adjuvant therapy in the treatment of women with poor ovarian response.

Emerging evidence indicates that obesity impairs granulosa cell (GC) function, but the underlying mechanisms remain unclear. Gene expression profiles in GC of non-polycystic ovary syndrome (PCOS) obese (NPO), PCOS obese (PO), PCOS normal weight (PN) and non-PCOS normal weight (NPN) patients were analysed by microarray analysis. Compared with the NPN group, there were 16, 545 and 416 differently expressed genes in the NPO, PO and PN groups respectively. CD36 was the only intersecting gene, with greater than two fold changes in expression between the NPO versus NPN and PO versus NPN comparisons, and was not present in the PN versus NPN comparison. In addition, levels of CD36 protein were higher in GC from obese than normal weight patients. Furthermore, CD36 overexpression in a GC line inhibited cell proliferation, as determined by the cell counting kit-8 (CCK8) test, promoted cell apoptosis, as determined by flow cytometry, and inhibited the secretion of oestradiol by depositing triglyceride in cells and increasing cellular lipid peroxide levels. These adverse effects were reduced by sulfo-N-succinimidyloleate, a specific inhibitor of CD36. Together, the findings of this study suggest that obesity with and without PCOS should be regarded as separate entities, and that CD36 overexpression in GC of obese patients is one of the mechanisms by which obesity impairs GC function.