A comprehensive review of Asherman's syndrome: causes, symptoms and treatment options

Efficacy of Applying Hyaluronic Acid Gels in the Primary Prevention of Intrauterine Adhesion after Hysteroscopic Myomectomy: A Meta-Analysis of Randomized Controlled Trials

Intrauterine adhesion (IUA), which mainly occurs after intrauterine surgery or an inflammatory process, is an important but often neglected condition in women of reproductive age. The presentation of IUA varies greatly, ranging from symptom-free to severe, with amenorrhea or infertility. With much advanced development of intrauterine instruments, more intrauterine diseases can be successfully cured by hysteroscopic surgery. Among these, submucosal myoma is one of the best examples. Submucosal myomas are often related to abnormal bleeding, anemia, and possible infertility or miscarriage. However, submucosal myoma after hysteroscopic myomectomy may be complicated by IUA in various grades of severity, and its incidence and prevalence might be nearly one-quarter to one-third of patients, suggesting an urgent need for efforts to decrease the risk of developing IUA after hysteroscopic myomectomy. Many strategies have been reported to be useful for this purpose, and intrauterine application of anti-adhesive gels, such as polyethylene oxide–sodium carboxymethylcellulose (PEO-NaCMC) or auto-crosslinked hyaluronic acid (ACHA), has become increasingly popular in routine clinical practice. This meta-analysis is aimed at investigating the effect of ACHA on the primary prevention of IUA formation after hysteroscopic myomectomy. A pooled analysis of three studies (hysteroscopic surgeries for fibroids, polyps, and septum) including 242 women showed that using PEO-NaCMC or ACHA gel decreased the IUA rate with an odds ratio (OR) of 0.364 (95% confidence interval (CI) 0.189–0.703, p = 0.03). Pooled analysis of two studies that limited the use of ACHA in 119 women showed that the application of ACHA gel for the primary prevention of IUA in patients after hysteroscopic myomectomy led to a statistically significant reduction of the development of IUA postoperatively (OR 0.285, 95% CI 0.116–0.701, p = 0.006). All of this suggests that the use of ACHA gel in patients after hysteroscopic myomectomy could significantly reduce de novo IUA, although more evidence is needed.

In Vivo Evaluation of the Efficacy and Safety of a Novel Degradable Polymeric Film for the Prevention of Intrauterine Adhesions

STUDY OBJECTIVE

To study the safety of a degradable polymeric film (DPF) and its efficacy on reducing the risk of intrauterine-adhesion (IUA) formation in a rat model.

DESIGN

A series of case-control studies relying on random allocation, where feasible.

SETTING

University and good practice animal laboratories.

ANIMALS

The animal models comprised female and male Oncins France Strain A and female Wistar rats.

INTERVENTION(S) AND MEASUREMENTS

The Oncins France Strain A rats were used for in vivo evaluation of the impact of the DPF on endometrial thickness and its effect on fertility. For in vivo evaluation of the biologic response, 40 Wistar rats were randomly allocated to intervention and control groups, with matched sampling time after surgery. Finally, for the in vivo evaluation of the DPF's efficacy on IUA prevention, a total of 24 Wistar rats were divided into 3 groups: 1 treated with the DPF, 1 treated with hyaluronic acid gel, and a sham group.

MAIN RESULTS

The DPF did not have a significant impact on endometrial thickness, and there were no significant differences in the number of conceived or prematurely terminated pregnancies, confirming its noninferiority to no treatment. The DPF did not induce irritation at 5 days and 28 days. Finally, the DPF significantly reduced the likelihood of complete IUA formation compared with hyaluronic acid gel- and sham-implanted animals, where only 27% of the animals had their uterine cavity obliterated compared with 80% and 100%, respectively.

CONCLUSION

The DPF is a safe film that is effective in preventing IUA formation after intrauterine curettage in rats.

Intrauterine transplantation of autologous menstrual blood stem cells increases endometrial thickness and pregnancy potential in patients with refractory intrauterine adhesion

AIM

This study was designed to evaluate the effects of intrauterine transplantation of menstrual blood stem cells (MenSCs) on endometrial thickness and pregnancy outcomes in patients with refractory intrauterine adhesion (IUA).

METHODS

This study included a group of infertile women (n = 12, age 22-40 years), with refractory IUA. Autologous MenSCs isolated from the women's menstrual blood were expanded in vitro and transplanted into their uteruses, followed by hormone replacement therapy. Transvaginal ultrasound examination was performed to assess the endometrial thickness. Transabdominal ultrasound was conducted to detect pregnancy outcome.

RESULTS

Autologous MenSCs were successfully isolated and expanded from menstrual blood and transplanted into the uterus of each patient. A significant improvement of the endometrial thickness was observed from 3.9 ± 0.9 to 7.5 ± 0.6 mm (P < 0.001). No adverse reaction was observed. The duration of menstruation was increased from 2.4 ± 0.7 to 5.3 ± 0.6 days (P < 0.001). Five out of 12 patients achieved clinical pregnancy and the pregnancy rate was 41.7%.

CONCLUSIONS

Intrauterine transplantation of autologous MenSCs results in regeneration of endometrium, a prolongation of menstrual duration and an increase rate of pregnancy in patients with refractory IUA.

Concomitant Adenomyosis among Patients with Asherman Syndrome

STUDY OBJECTIVE

To characterize obstetric outcomes for concomitant Asherman syndrome and adenomyosis.

DESIGN

A retrospective cohort study.

SETTING

A community teaching hospital affiliated with a large academic medical center.

PATIENTS

A total of 227 patients with Asherman syndrome with available hysteroscopy and pelvic ultrasound reports.

INTERVENTIONS

Telephone survey to assess and compare the obstetric outcomes of patients with Asherman syndrome with concomitant adenomyosis (Group A) vs patients with Asherman syndrome without concomitant adenomyosis (Group B).

MEASUREMENTS AND MAIN RESULTS

A telephone survey and confirmatory chart review were conducted to obtain information on patients' demographics, gynecologic and obstetric history, past medical and surgical history, and Asherman syndrome management. Adenomyosis was a common sonographic finding, detected in 39 patients with Asherman syndrome (17.2%). In this cohort, 77 patients attempted pregnancy and produced 87 pregnancies. Age (odds ratio [OR] 0.67; 95% confidence intervals [CI], 0.52-0.86) was negatively associated with a pregnancy outcome. Age (OR 0.83; 95% CI, 0.73-0.95) and severe Asherman disease (OR 0.06; 95% CI, <0.01-0.99) were negatively associated with a live birth outcome. Adenomyosis was not an independent predictor of pregnancy rate, miscarriage rate, or live birth rate among patients with Asherman syndrome.

CONCLUSION

Adenomyosis is relatively common in patients with Asherman syndrome. Adenomyosis does not seem to add any distinct detriment to fertility among patients with Asherman syndrome.

The role of ultrasound imaging in the management of partial placental retention after third trimester livebirth

Objectives: To evaluate the impact of different ultrasound signs in the management and the role of ultrasound guidance in the surgical evacuation of partial placental tissue retention.Methods: This is an observational cohort study and retrospective case assessment of 82 patients with clinical symptoms of partial placental retention following a third trimester singleton livebirth between January 2013 and May 2019. The ultrasound signs were recorded using a standardized protocol and the outcome of the management strategy and the use of ultrasound guidance during any surgical procedure was evaluated.Results: Out of the 64 patients who had a vaginal birth, 25 (39.1%) had a manual removal of the placenta at delivery. Fifteen patients were confirmed as not having retained placental tissue and did not require further treatment. Four patients were referred after failed surgical management and four after failed conservative management. All surgical procedures were vacuum aspiration and forceps removal under continuous ultrasound guidance. A significantly lower gestational age at delivery (p < .05), shorter interval between delivery and ultrasound diagnosis (p < .05) and lower number of patients presenting with heavy bleeding was found in the conservative compared to the surgical management subgroups (p < .05). The incidence of feeding vessels was significantly (p < .05) higher in the surgical than in the conservative management subgroups and associated with increased myometrial vascularity. Six patients developed intra-uterine adhesions. In four of these cases, ultrasound examination showed a hyperechoic mass surrounded by normal myometrial vascularity and no feeding vessel.Conclusions: Ultrasound imaging accurately differentiated between patient with and without partial placental retention after third trimester livebirth. Ultrasound-guided vacuum aspiration is safe and efficient in these cases.

Transforming growth factor-β1 in intrauterine adhesion

Intrauterine adhesion (IUA), led by trauma to the basal layer, can prevent the endometrium from growing, resulting in complications in females, such as infertility and amenorrhea. Transforming growth factor-β1 (TGF-β1) plays a crucial role in inducing and promoting the differentiation and proliferation of mesenchymal cells, in the secretion of extracellular matrix-associated components, and is a major cytokine in initiating and terminating tissue repair downstream of the TGF-β/Smad signaling pathway. Some evidence supports that TGF-β1 is closely associated with the occurrence and development of IUA, and is regarded as an early risk factor of disease recurrence. Furthermore, the role of TGF-β1 has been demonstrated to be potentially regulated by a variety of cytokines, hormones, enzymes, and microRNAs. This review provides an overview of the expression, function, and regulation of TGF-β1 in IUA, with a brief discussion and perspectives on its future clinical implications on the diagnosis and treatment of IUA.

Asherman syndrome: Audit of a single-operator cohort of 423 cases

Background

The diagnosis of Asherman syndrome, or ‘intra‐uterine adhesions’ is often overlooked when the symptoms of amenorrhea and hematometra are missing.

Aims

This audit reviews the clinical data of a large cohort of patients treated by a single operator.

Materials and Methods

From July 1998 till the end of December 2017, 423 patients with intra‐uterine adhesions were treated by a single operator. Clinical information was obtained by review of the medical files and phone interviews.

Results

Amenorrhea was recorded in 163/423 patients (38.5%), 225/423 (53.2%) patients did not have amenorrhea and for 35/423 (8.3%) patients the information was missing. A hematometra was documented in 19/423 (4.5%) patients. Pregnancy was achieved in 215/246 (87.4%). Patients with stage II disease did best with a pregnancy rate of 94.5% (P = 0.029).

Conclusion

Asherman syndrome should be considered in any woman with a history of miscarriage or postpartum curettage who then fails to conceive again.

In situ repair abilities of human umbilical cord-derived mesenchymal stem cells and autocrosslinked hyaluronic acid gel complex in rhesus monkeys with intrauterine adhesion

Increasing occurrence of moderate to severe intrauterine adhesion (IUA) is seriously affecting the quality of human life. The aim of the study was to establish IUA models in nonhuman primates and to explore the dual repair effects of human umbilical cord-derived mesenchymal stem cells (huMSCs) loaded on autocrosslinked hyaluronic acid gel (HA-GEL) on endometrial damage and adhesion. Here, we recorded the menstrual cycle data in detail with uterine cavities observed and endometrial tissues detected after intervention, and the thicker endometria, decreased amount of fibrotic formation, increased number of endometrium glands, etc., suggested that both HA-GEL and huMSC/HA-GEL complexes could partially repair IUA caused by mechanical injury, but huMSC/HA-GEL complex transplantation had notable dual repair effects: a reliable antiadhesion property and the promotion of endometrial regeneration.

Advances in the Application of Biomimetic Endometrium Interfaces for Uterine Bioengineering in Female Infertility

The Asherman’s syndrome, also known as intrauterine adhesion, often follows endometrium injuries resulting from dilation and curettage, hysteroscopic resection, and myomectomy as well as infection. It often leads to scarring formation and female infertility. Pathological changes mainly include gland atrophy, lack of vascular stromal tissues and hypoxia and anemia microenvironment in the adhesion areas. Surgical intervention, hormone therapy and intrauterine device implantation are the present clinical treatments for Asherman’s syndrome. However, they do not result in functional endometrium recovery or pregnancy rate improvement. Instead, an increasing number of researches have paid attention to the reconstruction of biomimetic endometrium interfaces with advanced tissue engineering technology in recent decades. From micro-scale cell sheet engineering and cell-seeded biological scaffolds to nano-scale extracellular vesicles and bioactive molecule delivery, biomimetic endometrium interfaces not only recreate physiological multi-layered structures but also restore an appropriate nutritional microenvironment by increasing vascularization and reducing immune responses. This review comprehensively discusses the advances in the application of novel biocompatible functionalized endometrium interface scaffolds for uterine tissue regeneration in female infertility.

Meta-analysis on the use of hyaluronic acid gel to prevent intrauterine adhesion after intrauterine operations

Intrauterine adhesion (IUA) is a severe complication that occurs following abortion, and hyaluronic acid gel has been used to prevent IUA following intrauterine operation. The present study aimed to systematically evaluate the efficacy of hyaluronic acid gel in preventing IUA following intrauterine operation. In the current study, a literature search was performed using PubMed, Cochrane Library and EMbase databases for randomized controlled clinical trials that used hyaluronic acid gel as an adjuvant therapy following intrauterine operation. The terms 'hyaluronic acid', 'intrauterine adhesions', 'Asherman's syndrome', 'IUA', 'dilatation and curettage', 'abortion' and 'hysteroscopic' were used to search for articles published online before July 31, 2018. RevMan 5.3 software was used to analyze the indicators of uterine cavity adhesion formation and pregnancy rates following intrauterine operation. A total of seven randomized controlled clinical studies were included, consisting of 952 patients who underwent intrauterine operation. The meta-analysis indicated that the use of hyaluronic acid gel reduced the incidence of IUA [relative risk (RR)=0.42; 95% confidence interval (CI)=0.30-0.57; P<0.001] and the score for IUA after an intrauterine operation (mean difference=-1.29; 95%=-1.73 to -0.84; P<0.001). A subgroup analysis revealed that the preventive effect of hyaluronic acid gel on IUA was not affected by the type of intrauterine operation, namely abortion (RR=0.40; 95% CI=0.26-0.62; P<0.001) and hysteroscopy (RR=0.44; 95% CI=0.28-0.68; P<0.001). The preventive effect of hyaluronic acid gel on IUA was also not affected by primary disorders/diseases including the following: Abortion (RR=0.48; 95% CI=0.29-0.78; P=0.003); IUA (RR=0.38; 95% CI=0.21-0.67; P<0.001) and submucosal myoma of the uterus, endometrial polyps or mediastinum uterus (RR=0.40; 95% CI=0.18-0.90; P=0.03). Hyaluronic acid gel improved pregnancy rates after intrauterine operations (RR=1.94; 95% CI=1.46-2.60; P<0.001). In conclusion, hyaluronic acid gel was indicated to significantly reduce the incidence of IUA following intrauterine operation, regardless of the type of intrauterine operation or the presence of primary diseases. Treatment with hyaluronic acid gel was also revealed to increase pregnancy rates following intrauterine operation.

Effects of uterus derived mesenchymal stem cells and their exosomes on asherman's syndrome

Asherman's syndrome has become a growing problem with the incidence of cesarean and endometrial surgical procedures. A surgical procedure that can damage to the basal layer of the endometrium is formed as intrauterine adhesion and can cause asherman's syndrome. Mesenchymal stem cells (MSCs) are characterized by some characteristics such as non-immunogenic, angiogenic, antifibrotic, antiapoptotic and antiinflammatory properties, also they support tissue repair by secretion of various factors and chemokines in cellular therapy. Exosomes are active paracrine components with a great potential for repairing damaged tissue. Exosomes include many paracrine factors responsible for regeneration and angiogenesis. In this study, 10 newborn Wistar rats were used to obtain MSCs. A total of 24 adult Wistar rats were also used. The rats were divided into 4 groups: untreated control group; asherman control group; asherman + uterine-derived MSCs group; asherman + uterine-derived MSCs-exosomes group. At the end of the experiment, uterine tissues were evaluated by histochemical and immunohistochemical. As a result of MSCs and exosomes treatments, proliferation and vascularization in uterine tissue was increased. It was also shown to reduce fibrosis with masson's trichrome staining. MMP-2 and MMP-9 expression was enhanced by MSC and exosomal therapy; in addition, TIMP-2 expression was decreased. In our study, it was shown that proliferation and vascularization increased and fibrosis decreased in uterus as a result of MSC and exosome treatments. Our results indicate that the exosomal treatment restored the damage of asherman's syndrome at tissue at a shorter time than the MSCs group.

Effect of Autologous Adipose-Derived Stromal Vascular Fraction Transplantation on Endometrial Regeneration in Patients of Asherman's Syndrome: a Pilot Study

This study aimed to investigate the efficacy of the transplantation of autologous adipose-derived stromal vascular fraction (AD-SVF) containing adipose stem cells (ASCs) in regenerating functional endometrium in patients with severe Asherman's syndrome (AS). This was a prospective clinical study involving six infertile women aged 20-44 years who were diagnosed with severe AS by hysteroscopy. Autologous AD-SVF were isolated from patient's adipose tissue obtained by liposuction and then transplanted into uterus by transcervical instillation using an embryo transfer catheter followed by estrogen hormone therapy. Endometrial growth and pregnancy outcomes were assessed after fresh or frozen embryo transfer. Of the five patients who remained in the study, two women who had amenorrhea resumed their menstruation with irregular scant bleeding. Three women with oligomenorrhea had increased menstrual amount. Before therapy, the maximum EMT measured ultrasonographically was 3.0 ± 1.0 mm (range: 1.7 to 4.4 mm), which significantly increased to 6.9 ± 2.9 mm (range: 5.2 to 12.0 mm, p = 0.043) after cell transplantation and hormone therapy. Five women had embryo transfer after therapy: one fresh and four frozen-thawed. One woman conceived but aborted spontaneously at 9-week gestation. AD-SVF is a safe and easily available cell product containing adipose-derived stem cells. Autologous transplantation of AD-SVF may regenerate damaged human endometrium and increase endometrial receptivity. Our study showed the feasibility of AD-SVF in restoring endometrial function and increasing endometrial thickness. This cell therapy may become a promising treatment for infertile women with endometrial dysfunction and needs further investigation.

Secondary Prevention of Intrauterine Adhesions Following Hysteroscopic Surgery in Women With Asherman Syndrome: Is Something Better Than Nothing?

Asherman syndrome is a reproductive disorder characterized by intrauterine adhesions and amenorrhea, infertility, abnormal placentation, or pregnancy loss. Treatment of Asherman syndrome involves hysteroscopic lysis of adhesions. Many surgeons utilize postoperative measures such as hormone therapy, solid mechanical devices, or barrier gels to prevent recurrent adhesions in this setting. However, there is limited high-quality evidence to support their use. Additional research is needed on the safety and efficacy of these commonly used methods to guide patient care.

Therapeutic options and drug delivery strategies for the prevention of intrauterine adhesions

Intrauterine adhesions (IUAs) are bands of fibrous tissue that form in the endometrial cavity and associated with the increased risk of abnormal menstruation, recurrent pregnancy loss, secondary infertility, and pregnancy complications. Physical barriers, including intrauterine device and hydrogel, were clinical available to prevent the post-operational IUAs. But physically separation of the injured endometrium relies on the own limited healing power and often ends with recurrence. In recent years, the mechanisms driving IUAs treatment has validated the application of hormones, and further stem cell therapy has also led to the development of novel therapeutic agents with promising efficacy in pre-clinical and initial clinical studies. Still, it is challenging to delivery the therpaeutic factors to the injured uterus. Herein, in this review, we discuss the traditional intervention methods for the prevention of IUAs, as well as novel therapeutics and delivery strategies that will most likely change the treatment paradigms for better clinical outcomes. The combination strategy that using physical barriers as the delivery carriers for therapeutics might provide new alternatives for the prevention of IUAs.

Human Umbilical Cord Blood Serum/Plasma: Cytokine Profile and Prospective Application in Regenerative Medicine

The concentrations of cytokines and growth factors in human umbilical cord blood serum and plasma samples were measured by multiplex analysis. It was found that in comparison with peripheral blood serum of adult donors, umbilical cord blood serum and plasma contain significantly higher concentrations of the most studied molecules including IL-4, 5, 6, 7, 10 and 15, MCP-1, SCF, and SDF, as well as growth factors directly involved in the processes of regeneration (G-CSF, HGF, PDGF-BB, and VEGF). Thus, umbilical cord blood plasma and especially serum are a rich source of cytokines and growth factors with anti-inflammatory, anti-apoptotic, and angiogenic effects and can be used in various fields of regenerative medicine.

Using 17β-estradiol heparin-poloxamer thermosensitive hydrogel to enhance the endometrial regeneration and functional recovery of intrauterine adhesions in a rat model

Mechanical damage or infection to the endometrium can lead to the formation of adhesions in the uterine cavity, which may result in reduced reproductive outcome and/or pregnancy complications. The prognosis of this disease is poor due to few effective treatments and the complex environment of endometrium. Heparin-Poloxamer Hydrogel (HP hydrogel) is a nontoxic and biodegradable biomaterial, which has been commonly used as a sustained-release delivery system. In this study, we applied a mini-endometrial curette to scrape the endometrium of rats to mimic the process of curettage in patients. After the establishment of IUA model in rats, we injected the thermo-sensitive hydrogel(E₂-HP hydrogel) into the injured uterine cavity and evaluated the therapeutic effect of E₂-HP hydrogel on the recovery of IUA. Our results showed that E₂-HP hydrogel can significantly facilitate the regeneration of injured endometrium along with inhibiting the cell apoptosis in IUA model. Furthermore, we revealed that E₂-HP hydrogel on the recovery of IUA was closely associated with the upregulation of kisspeptin through activating the ERK1/2 and MAPKs p38 pathways. In conclusion, E₂-HP hydrogel can effectively transfer E₂ into the injured endometrium and it can be considered as a promising therapeutic method for the women with intrauterine adhesions.

CSF1-associated decrease in endometrial macrophages may contribute to Asherman's syndrome

PROBLEM

Asherman's syndrome (AS) is characterized by endometrial fibrosis leading to intrauterine adhesions and symptoms like hypomenorrhea, infertility, and recurrent pregnancy loss. Macrophages are key regulators of inflammation, tissue repair, regeneration, and fibrosis. However, the role of macrophages in AS remains unclear.

METHOD OF STUDY

Endometrial biopsies of AS patients and controls were collected during the late proliferating phase of menstrual cycle. Fibrosis and proliferation markers were detected by Masson's trichrome staining and immunohistochemistry. Macrophages were examined by immunostaining and flow cytometry. The expression levels of CCL2, CSF1, CSF1R, and GM-CSF were detected by quantitative real-time polymerase chain reaction (q-PCR) and immunohistochemistry. A well-differentiated endometrial cell line Ishikawa (IK) was used for in vitro studies. Macrophages differentiating from THP-1 monocytic cells were polarized by IL-4/IL-13. Their culture supernatants (M(IL-4/13)-S) were applied to H₂ O₂ or bleomycin-damaged IK cells.

RESULTS

In AS patients, endometrial stroma was replaced by fibrous tissue and cell proliferation was reduced. Macrophages in endometrial tissue were mainly alternative activated macrophages and their number was significantly decreased in AS patients. The CSF1 expression level was reduced in AS patients. M(IL-4/13)-S promoted the growth and migration of IK cells and inhibited H₂ O₂ -induced apoptosis. M(IL-4/13)-S protected IK cells from bleomycin-induced fibrosis.

CONCLUSION

Macrophages are critical cells involved in the process of endometrial repair and fibrosis. The decreased amount of endometrial macrophages may be attributed to the reduced expression level of CSF1. Manipulation of macrophage activation/function may provide a novel therapeutic target for AS.

Optimal waiting period for fresh embryo transfer after hysteroscopic adhesiolysis: a retrospective cohort study

Supplemental Digital Content is available in the text

Background:

Very few studies have been conducted regarding the optimal time interval between hysteroscopic adhesiolysis and the embryo transfer (ET). Investigation of this optimal time may be helpful for assisted reproductive technology. Therefore, we investigated effects of the interval between hysteroscopic adhesiolysis and ET upon in vitro fertilization (IVF) cycle outcomes.

Methods:

Patients were recruited between January 2014 and September 2017 at the Reproductive Hospital Affiliated to Shandong University. Patients who were diagnosed with intra-uterine adhesion (IUA) and underwent hysteroscopic adhesiolysis before fresh IVF-ET or intra-cytoplasmic sperm injection cycles were classified into three groups according to the interval between hysteroscopic adhesiolysis and ET: less than 90 days (Group 1), 90 to 180 days (Group 2), and greater than 180 days (Group 3). Baseline characteristics, controlled ovarian stimulation (COS) response, and pregnancy outcomes after ET were compared. Analysis of variance or non-parametric tests were used to test numerical data. The Pearson's Chi-squared test was used to test categorical data.

Results:

A total of 312 patients were recruited as follows: 112 in Group 1, 137 in Group 2, and 63 in Group 3. There were no differences in baseline and COS characteristics among the three groups. The live-birth rate in Group 2 (40.1%) was significantly higher than that in Group 1 (17.9%; χ² = 14.545, P < 0.001). There were no significant differences in the rates of biochemical, ongoing, and clinical pregnancy, and biochemical and clinical pregnancy abortion, as well as stillbirth among the groups. In the mild IUA patients, the live-birth rate was significantly higher in Group 2 (42.6%) compared with Group 1 (22%; χ² = 8.413, P = 0.004). In the moderate IUA patients, Group 2 (35.7%) had a higher frequency of live births than Group 1 (6.7%; χ² = 8.187, P = 0.004).

Conclusions:

The optimal waiting period for fresh ET after hysteroscopic adhesiolysis was 90 to 180 days in the current study.

Uterine Glands: Developmental Biology and Functional Roles in Pregnancy

All mammalian uteri contain glands in the endometrium that develop only or primarily after birth. Gland development or adenogenesis in the postnatal uterus is intrinsically regulated by proliferation, cell-cell interactions, growth factors and their inhibitors, as well as transcription factors, including forkhead box A2 (FOXA2) and estrogen receptor α (ESR1). Extrinsic factors regulating adenogenesis originate from other organs, including the ovary, pituitary, and mammary gland. The infertility and recurrent pregnancy loss observed in uterine gland knockout sheep and mouse models support a primary role for secretions and products of the glands in pregnancy success. Recent studies in mice revealed that uterine glandular epithelia govern postimplantation pregnancy establishment through effects on stromal cell decidualization and placental development. In humans, uterine glands and, by inference, their secretions and products are hypothesized to be critical for blastocyst survival and implantation as well as embryo and placental development during the first trimester before the onset of fetal-maternal circulation. A variety of hormones and other factors from the ovary, placenta, and stromal cells impact secretory function of the uterine glands during pregnancy. This review summarizes new information related to the developmental biology of uterine glands and discusses novel perspectives on their functional roles in pregnancy establishment and success.

Human amniotic epithelial cells improve fertility in an intrauterine adhesion mouse model

BACKGROUND

Intrauterine adhesion (IUA) is an adhesion of the uterine cavity or cervical canal resulting from damage to the basal layer of the endometrium; this condition is usually accompanied by fibrosis of the endometrium. Previous studies have demonstrated that human amniotic epithelial cells (hAECs) have stem cell characteristics; however, it is unclear whether hAECs have the therapeutic potential to restore fertility after IUA.

METHODS

A murine IUA model was established by mechanical injury to the uterus. Then, 106 hAECs were transplanted by intraperitoneal injection. The endometrium thickness, number of glands, and fibrosis area were measured by hematoxylin and eosin (H&E) staining and Masson staining. Molecules (including vWF, VEGF, PCNA, ER, PR, LC3, and p62) related to endometrial angiogenesis, cell proliferation, and autophagy were assayed by IHC staining. Pregnancy outcomes were also evaluated. Finally, hAECs were cocultured with human endometrial mesenchymal stem cells (hEnSCs) damaged by H2O2 to verify the paracrine effect on endometrial stromal cells in vitro.

RESULTS

The IUA uterine cavity presented with adhesion and even atresia, accompanied by a thinner endometrium, fewer glands, increased fibrosis area, and fewer microvessels. However, hAECs significantly improved the uterine structure after IUA. After hAEC treatment, the endometrium was thicker, the number of endometrial glands was increased, fibrosis was reduced, and more microvessels were generated. The expression levels of VEGF, PCNA, and ER were increased in the hAEC-treated endometrium, indicating improvements in angiogenesis and stromal cell proliferation. hAECs also increased pregnancy outcomes in IUA mice, and the pregnancy rate and fetus number increased. Furthermore, we observed altered autophagy in the IUA uterine model, and hAEC transplantation upregulated autophagy. An in vitro study showed that hAECs activated autophagy in (hEnSCs) treated with H2O2 in a paracrine manner.

CONCLUSIONS

Our results demonstrated that hAECs have the potential to repair the uterus after injury, providing a new strategy for the prevention and treatment of Asherman syndrome.

Transplantation of human endometrial perivascular cells with elevated CYR61 expression induces angiogenesis and promotes repair of a full-thickness uterine injury in rat

BACKGROUND

Disruptions of angiogenesis can have a significant effect on the healing of uterine scars. Human endometrial perivascular cells (CD146+PDGFRβ+) function as stem cells in the endometrium. Cysteine-rich angiogenic inducer 61 (CYR61) plays an important role in vascular development. The purpose of this study was to observe the effects of the transplantation of human endometrial perivascular cells (En-PSCs) overexpressing CYR61 on structural and functional regeneration in rat models of partial full-thickness uterine excision.

METHODS

We first sorted human En-PSCs from endometrial single-cell suspensions by flow cytometry. Human En-PSCs expressing low or high levels of CYR61 were then generated via transfection with a CYR61-specific small interfering ribonucleic acid (si-CYR61) construct or overexpression plasmid. To establish a rat model of uterine injury, a subset of uterine wall was then resected from each uterine horn in experimental animals. Female rats were randomly assigned to five groups, including a sham-operated group and four repair groups that received either PBS loaded on a collagen scaffold (collagen/PBS), En-PSCs loaded on a collagen scaffold (collagen/En-PSCs), En-PSCs with low CYR61 expression loaded on a collagen scaffold (collagen/si-CYR61 En-PSCs), and En-PSCs overexpressing CYR61 loaded on a collagen scaffold (collagen/ov-CYR61 En-PSCs). These indicated constructs were sutured in the injured uterine area to replace the excised segment. On days 30 and 90 after transplantation, a subset of rats in each group was sacrificed, and uterine tissue was recovered and serially sectioned. Hematoxylin and eosin staining and immunohistochemical staining were then performed. Finally, the remaining rats of each group were mated with fertile male rats on day 90 for a 2-week period.

RESULTS

Sorted En-PSCs expressed all recognized markers of mesenchymal stem cells (MSCs), including CD10, CD13, CD44, CD73, CD90, and CD105, and exhibited differentiation potential toward adipocytes, osteoblasts, and neuron-like cells. Compared with En-PSCs and En-PSCs with low CYR61 expression, En-PSCs with elevated CYR61 expression enhanced angiogenesis by in vitro co-culture assays. At day 90 after transplantation, blood vessel density in the collagen/ov-CYR61 En-PSCs group (11.667 ± 1.287) was greater than that in the collagen/En-PSCs group (7.167 ± 0.672) (P < 0.05) and the collagen/si-CYR61 En-PSCs group (3.750 ± 0.906) (P < 0.0001). Pregnancy rates differed among groups, from 40% in the collagen/PBS group to 80% in the collagen/En-PSCs group, 12.5% in the collagen/si-CYR61 En-PSCs group, and 80% in the collagen/ov-CYR61 En-PSCs group. In addition, four embryos were evident in the injured uterine horns of the collagen/ov-CYR61 En-PSCs group, while no embryos were identified in the injured uterine horns of the collagen/PBS group.

CONCLUSIONS

The results showed that CYR61 plays an important role in angiogenesis. Collagen/ov-CYR61 En-PSCs promoted endometrial and myometrial regeneration and induced neovascular regeneration in injured rat uteri. The pregnancy rate of rats treated with transplantation of collagen/En-PSCs or collagen/ov-CYR61 En-PSCs was improved. Moreover, the number of embryos implantation on the injured area in uterus was increased after transplantation of collagen/ov-CYR61 En-PSCs.

Cell and biomaterial-based approaches to uterus regeneration

Asherman's syndrome (AS) is an endometrial disorder in which intrauterine adhesions crowd the uterine cavity and wall. The fibrotic adhesions are primarily the result of invasive uterine procedures that usually involve the insertion of surgical equipment into the uterus. This syndrome is accompanied by a number of clinical manifestations, including irregular or painful menstruation and infertility. The most prevalent treatment is hysteroscopy, which involves the physical removal of the fibrous strands. Within the last decade, however, the field has been exploring the use of cell-based therapeutics, in conjunction with biomaterials, to treat AS. This review is a recapitulation of the literature focused on cellular therapies for treating AS.

Exosomal transfer of bone marrow mesenchymal stem cell-derived miR-340 attenuates endometrial fibrosis

Bone marrow mesenchymal stem cells (BMSCs) have potential therapeutic benefits for the treatment of endometrial diseases and injury. BMSCs interact with uterus parenchymal cells by direct contact or indirect secretion of growth factors to promote functional recovery. In this study, we found that BMSC treatment in rats subjected to mechanical damage (MD) significantly increased microRNA-340 (miR-340) levels in the regenerated endometrium. Then we employed knockin and knockdown technologies to upregulate or downregulate the miR-340 level in BMSCs (miR-340⁺ BMSCs or miR-340⁻ BMSCs) and their corresponding exosomes, respectively, to test whether exosomes from BMSCs mediate miR-340 transfer. We found that the exosomes released from the primitive BMSCs or miR-340⁺ BMSCs but not miR-340⁻ BMSCs increased the miR-340 levels in primary cultured endometrial stromal cells (ESCs) compared with control. Further verification of this exosome-mediated intercellular communication was performed using exosomal inhibitor GW4869. Tagging exosomes with red fluorescent protein demonstrated that exosomes were released from BMSCs and transferred to adjacent ESCs. Compared with controls, rats receiving primitive BMSC treatment significantly improved functional recovery and downregulated collagen 1α1, α-SMA and transforming growth factor (TGF)-β1 at day 14 after MD. The outcomes were significantly enhanced by miR-340⁺ BMSC treatment, and were significantly weakened by miR-340⁻ BMSC treatment, compared with primitive BMSC treatment. In vitro studies reveal that miR-340 transferred from BMSCs suppresses the upregulated expression of fibrotic genes in ESCs induced by TGF-β1. These data suggest that the effective antifibrotic function of BMSCs is able to transfer miR-340 to ESCs by exosomes, and that enhancing the transfer of BMSC-derived miR-340 is an alternative modality in preventing intrauterine adhesion.

Summary: miR-340 in the exosomes released from BMSCs are transferred to endometrial cells, which regulate gene expression, repress endometrial fibrosis and promote functional recovery in rats subjected to mechanical damage.

The study on the safety and efficacy of amnion graft for preventing the recurrence of moderate to severe intrauterine adhesions

Transcervical resection of adhesion (TCRA) is the standard treatment for the intrauterine adhesions, but the recurrence of adhesions is a tough problem for the gynecologist. In addition, the therapeutic strategy after TCRA about prevention of recurrence remains controversial especially for the patients with moderate to severe intrauterine adhesions (IUAs). Hence, we designed this study to explore the safety and efficacy of fresh amnion grafts for preventing the recurrence after TCRA for patients with moderate to severe IUAs. One hundred patients with moderate to severe IUAs who presented with a history of hypomenorrhea, amenorrhea and infertility were included in the study from January 2015 to December 2017. Patients were divided into amnion group (52 patients) and chitosan group (48 patients). Fresh amnion grafts or intrauterine injections of chitosan were administered after TCRA. Transvaginal ultrasonography (TVUS) and hysteroscopy were performed at the first and third month after the operation. The surgical procedures for all patients were completed successfully without relevant complications. In amnion group, 8 patients exhibited relapse in the first month and 2 patients in three months after surgery; in chitosan group, 23 women exhibited relapse in the first month and 18 patients in three months after surgery. Statistical analysis revealed that the recurrence rate of adhesion in amnion group was significantly lower than those of chitosan group in the first and three months after surgery (P ₁  = 0.000, P ₂  = 0.000). After TCRA, fresh amnion graft plays a significant role in preventing further adhesions than injections of chitosan.

Stem Cells and Endometrial Regeneration: From Basic Research to Clinical Trial

Monthly changes in the endometrial cycle indicate the presence of endometrial stem cells. In recent years, various stem cells that exist in the endometrium have been identified and characterized. Additionally, many studies have shown that Bone Marrow Mesenchymal Stem Cells (BM-MSCs) provide an alternative source for regenerating the endometrium and repairing endometrial injury. This review discusses the origin of endometrial stem cells, the characteristics and main biomarkers among five types of putative endometrial stem cells, applications of endometrium-derived stem cells and menstrual blood-derived stem cells, the association between BM-MSCs and endometrial stem cells, and progress in repairing endometrial injury.

Meta-analysis of the use of amniotic membrane to prevent recurrence of intrauterine adhesion after hysteroscopic adhesiolysis

BACKGROUND

Various adjuvant therapies have failed to improve clinical symptoms and pregnancy rates among patients with moderate-to-severe intrauterine adhesion.

OBJECTIVES

To evaluate the ability of amniotic membrane to prevent the recurrence of intrauterine adhesion after hysteroscopic adhesiolysis.

SEARCH STRATEGY

The Cochrane Library, Embase, and PubMed databases were searched for articles published before December 31, 2017, using the terms: ("amnion") and ("intrauterine adhesions" or "Asherman syndrome" or "IUA" or "endometrial injury" or "uterine adhesion" or "hysteroscopic" or "hysteroscopic adhesiolysis").

SELECTION CRITERIA

Randomized controlled trials of amniotic membrane therapy after hysteroscopic adhesiolysis.

DATA COLLECTION AND ANALYSIS

Four studies were included in the meta-analysis (300 patients in total). Dichotomous outcomes were expressed as relative risk (RR) with 95% confidence intervals (CIs). Continuous variables were expressed as mean difference.

MAIN RESULTS

Amniotic membrane increased menstrual blood volume after hysteroscopic adhesiolysis (mean difference 6.15, 95% CI 4.20-8.11; P<0.001). By contrast, this treatment did not affect the rates of intrauterine adhesion recurrence (RR 0.84, 95% CI 0.61-1.16; P=0.290); pregnancy (RR 1.40, 95% CI 0.78-2.50; P=0.260); or spontaneous abortion (RR 0.88, 95% CI 0.38-1.99; P=0.750).

CONCLUSIONS

The use of amniotic membrane increased menstrual blood volume but failed to improve other measures assessed in the current meta-analysis.

Stem cell therapy in Asherman syndrome and thin endometrium: Stem cell- based therapy

The endometrium is one of the essential components of the uterus. The endometrium of human is a complex and dynamic tissue, which undergoes periods of growth and turn over during any menstrual cycle. Stem cells are initially undifferentiated cells that display a wide range of differentiation potential with no distinct morphological features. Stem cell therapy method recently has become a novel procedure for treatment of tissue injury and fibrosis in response to damage. Currently, there is massive interest in stem cells as a novel treatment method for regenerative medicine and more specifically for the regeneration of human endometrium disorder like Asherman syndrome (AS) and thin endometrium. AS also known as intrauterine adhesion (IUA) is a uterine disorder with the aberrant creation of adhesions within the uterus and/or cervix. Patients with IUA are significantly associated with menstrual abnormalities and suffer from pelvic pain. In addition, IUA might prevent implantation of the blastocyst, impair the blood supply to the uterus and early fetus, and finally result in the recurrent miscarriage or infertility in the AS patients. It has been evidenced that the transplantation of different stem cells with a diverse source in the endometrial zone had effects on endometrium such as declined the fibrotic area, an elevated number of glands, stimulated angiogenesis, the enhanced thickness of the endometrium, better formed tissue construction, protected gestation, and improved pregnancy rate. This study presents a summary of the investigations that indicate the key role of stem cell therapy in regeneration and renovation of defective parts.