Nano-biomaterial Fibrinogen/P(LLA-CL) for prevention of intrauterine adhesion and restoration of fertility

Endometrial damage resulting from surgical procedures is a significant cause of intrauterine adhesion, thin endometrium, and subsequent miscarriage and infertility. Unfortunately, there is currently no effective clinical solution to promote endometrial regeneration after severe injury. In this study, we combined fibrinogen (Fg) and P(LLA-CL) by electrostatic spinning to form a stable nano-biomaterial Fg/P(LLA-CL), which can promote endometrial regeneration. After inducing physical injury to rat endometrium, we found that Fg/P(LLA-CL) membranes placed in the uterine cavities increased endometrial thickness and the number of glands after injury, while reducing the area of endometrial fibrosis. In addition, Fg/P(LLA-CL) increased neovascularization and decreased COL1A1 deposition. The expression of TGF-β1, a cytokine that promotes fibrosis, was down-regulated in the early stage of injury. Finally, fertility assays confirmed that Fg/P(LLA-CL) improved the pregnancy rate in rats with endometrial injury, and its safety was verified by blood tests and pathological examination of heart, liver, spleen, lung, and kidney. Therefore, Fg/P(LLA-CL) shows great potential as a safe and nontoxic biomaterial for endometrial regeneration, ultimately improving pregnancy outcomes in patients with intrauterine adhesion.

Endometrial organoids: a reservoir of functional mitochondria for uterine repair

Background: Asherman's syndrome (AS) is a dreadful gynecological disorder of the uterus characterized by intrauterine adhesion with severe fibrotic lesions, resulting in a damaged basalis layer with infertility. Despite extensive research on overcoming AS, evidence-based effective and reproducible treatments to improve the structural and functional morphology of the AS endometrium have not been established. Methods: Endometrial organoids generated from human or mouse endometrial tissues were transplanted into the uterine cavity of a murine model of AS to evaluate their transplantable feasibility to improve the AS uterine environment. The successful engraftment of organoid was confirmed by detection of human mitochondria and cytosol (for human endometrial organoid) or enhanced green fluorescent protein signals (for mouse endometrial organoid) in the recipient endometrium. The therapeutic effects mediated by organoid transplantation were examined by the measurements of fibrotic lesions, endometrial receptivity and angiogenesis, and fertility assessment by recording the number of implantation sites and weighing the fetuses and placenta. To explore the cellular and molecular mechanisms underlying the recovery of AS endometrium, we evaluated the status of mitochondrial movement and biogenetics in organoid transplanted endometrium. Results: Successfully engrafted endometrial organoids with similar morphological and molecular features to the parental tissues dramatically repaired the AS-induced damaged endometrium, significantly reducing fibrotic lesions and increasing fertility outcomes in mice. Moreover, dysfunctional mitochondria in damaged tissues, which we propose might be a key cellular feature of the AS endometrium, was fully recovered by functional mitochondria transferred from engrafted endometrial organoids. Endometrial organoid-originating mitochondria restored excessive collagen accumulation in fibrotic lesions and shifted uterine metabolic environment to levels observed in the normal endometrium. Conclusions: Our findings suggest that endometrial organoid-originating mitochondria might be key players to mediate uterine repair resulting in fertility enhancement by recovering abrogated metabolic circumstance of the endometrium with AS. Further studies addressing the clinical applicability of endometrial organoids may aid in identifying new therapeutic strategies for infertility in patients with AS.

Restoring Fertility of Patients with Severe Asherman's Syndrome in the Office Setting: A Step-by-Step Recipe for Success

OBJECTIVE

To describe an effective in-office hysteroscopic strategy to restore fertility of patients with severe Asherman's syndrome.

DESIGN

A step-by-step video demonstration of the technique with an emphasis on the key portions of the procedure. A detailed narrated description of the steps is provided.

SETTING

Tertiary care University Hospital.

INTERVENTIONS

Three patients were managed by hysteroscopy performed in the office setting without anesthesia. Case 1 is a 34-year-old woman with obstetrical history of first-trimester incomplete abortion treated with Dilation and Curettage (D&C), followed by a tubal ectopic pregnancy treated with laparoscopic partial salpingectomy and a subsequent pregnancy on the tubal stump treated with uterine artery embolization. Case 2 is a 40-year-old woman with history of tubal ectopic pregnancy treated with salpingectomy, a surgical first-trimester voluntary termination of pregnancy with D&C and a full term vaginal delivery complicated with retained products of conception that were removed with D&C. Case 3 is a 35-year-old woman with two previous first-trimester spontaneous miscarriages both treated with D&C. Case 1 and 3 were treated using miniaturized mechanical instruments only; in case 2, miniaturized mechanical instruments and the 15 Fr bipolar mini-resectoscope were used. Preoperative 2D and 3D ultrasound were used to predict the complexity of the cases and to guide the surgeon during the procedure. Intrauterine lysis of adhesions was concluded when both tubal ostia were visualized, and the uterine cavity was determined to have adequate shape and volume. At the end of the procedures, hyaluronic acid-based gel was applied to prevent new intrauterine adhesion formation. Two weeks after the initial procedure, a second look diagnostic hysteroscopy was performed. Only one patient (#1) needed additional lysis of adhesions; in this case, at the end of the procedure, a Word catheter was inserted as a barrier method for the prevention of adhesion formation. Eight weeks later, the word catheter was removed, and additional lysis of adhesions was performed. All the surgical procedures were performed without complication, and a healthy endometrium was observed at the second look hysteroscopy, in all the three patients. All 3 patients conceived after the procedure. Pregnancy was achieved after one IVF cycle with the transfer of one frozen embryo in case 1 and spontaneously in cases 2 and 3. Patient 1 was delivered by elective caesarean section due to placenta previa, while the other two patients had normal vaginal deliveries. Patient 1 had Retained Products of Conception requiring hysteroscopic removal using a 27 Fr Resectoscope.

CONCLUSION

When using innovative miniaturized instruments and adequate surgical technique, hysteroscopic lysis of adhesions is a feasible and effective in-office strategy to restore fertility in patients with severe Asherman's syndrome. The use of 2D and 3D ultrasound played an important role in the preoperative workup of the patient with Asherman's syndrome.

Human Endometrium-Derived Adventitial Cell Spheroid-Loaded Antimicrobial Microneedles for Uterine Regeneration

Asherman's syndrome (AS) occurs as a consequence of severe damage to the endometrial basalis, usually leading to menstrual abnormalities, infertility, and recurrent miscarriage in women. Currently, human endometrium-derived adventitial cells (En-ADVs) are considered ideal seed cells with high pluripotency for regenerative medicine. However, critical issues such as noninvasive repair of tissues, targeting of native stem cells, and continuous action in the injured sites are not well resolved. Herein, En-ADV spheroid-loaded hierarchical microneedles (MN/En-ADV) for in situ intrauterine repair are developed. The flexible microneedles are fabricated with gelatin methacryloyl and lactoferrin, imparting the characteristics of rapid degradation and antimicrobial activity. Benefiting from an array of microwells on microneedles, En-ADVs can rapidly form 3D cell spheroids, which display higher potential for cell proliferation, differentiation, and migration than dissociated cells. With the application of MN/En-ADV, the repaired uteri show well-defined myometrial regeneration, angiogenesis, and an increase of endometrial receptivity in a rat AS model. Notably, embryos are able to implant in the reconstructed sites and remain viable, indicating that this system promotes the restoration of both normal morphology and reproductive function in the injured uterus. It is anticipated that multifunctional MN/En-ADV can be an ideal candidate for versatile in situ tissue regeneration.

Platelet-rich plasma for the management of intrauterine adhesions: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To conduct a systematic review and meta-analysis to assess the efficacy of platelet-rich plasma (PRP) infusion after adhesiolysis in patients with intrauterine adhesions (IUAs) by establishing the evidence from published randomized controlled trials (RCTs).

METHODS

PubMed, Scopus, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar databases were screened from inception till June 2021. Risk of bias of included studies was evaluated according to the Cochrane's Collaboration tool. The efficacy endpoints were summarized as risk ratio (RR) or mean difference (MD) with 95% confidence interval (CI) under the fixed-effects model.

RESULTS

Three RCTs met the inclusion criteria, comprising a total of 260 patients (132 and 128 patients were allocated to PRP and control groups, respectively). The RCTs revealed an overall low risk of bias. Compared with the control group, the PRP group had a statistically significant higher rate of patients with IUAs grade I-II after intervention (n = 3 RCTs, RR=1.23, 95% CI [1.11 to 1.36], p<0.001), higher duration of menstrual menses after intervention (n = 3 RCTs, MD=1.13 days, 95% CI [0.86 to 1.41], p<0.001), and higher amount of menstrual menses after intervention (n = 3 RCTs, MD=2.96 pads, 95% CI [0.31 to 3.61], p<0.001). All pooled analyses were homogeneous.

CONCLUSION

PRP treatment after hysteroscopic adhesiolysis is effective in decreasing the IUA grade and improving the duration and amount of menstrual menses. Nonetheless, additional RCTs are warranted to validate these conclusions.

Injectable Mesenchymal Stem Cell-Laden Matrigel Microspheres for Endometrium Repair and Regeneration

Endometrial injury and intrauterine adhesions are increasingly reported in recent years; however, treatment options remain limited. Intravenous injection of mesenchymal stem cells (MSCs) for endometrium regeneration has limited effectiveness as the retention rate of transplanted cells is low. Hydrogel-based tissue-engineered solutions, such as MSC-seeded bioscaffolds, are reported to increase retention rates; however, a less invasive alternative is still desirable. 560-µm homogeneous Matrigel microspheres are fabricated, loading them with about 1500 MSCs and injecting them into the injured endometria of rats' uteri. This minimally invasive procedure is proved to significantly increase endometrium thickness by over onefold after 21 d (p < 0.0001) and fertility rates from 25% to 75% in impaired and repaired uteri (p < 0.001), respectively. This study provides a minimally invasive alternative to endometrium repair with the promise to establish a broad-spectrum technique for MSC transplantation.

Role of hyaluronic acid intrauterine injection in the prevention of Asherman's syndrome in women undergoing uterine septum resection: An RCT

Background

Adhesion due to intrauterine surgery such as septal resection associated with damaged endometrium can increase the risk of Asherman's syndrome. The main goal of treatment in this syndrome is to repair the damaged endometrium for creating a physiological pregnancy.

Objective

To investigate the effect of intrauterine injection of hyaluronic acid on the prevention of Asherman's syndrome in women undergoing uterine septum resection.

Materials and Methods

In this double-blind randomized clinical trial, 65 women undergoing the uterine septum resection were divided into two groups; the case group (n = 34) and the control group (n = 31). Immediately after the septal resection with a resectoscope, 1cc of hyaluronic acid gel in the case group and 1cc normal saline solution as a placebo in the control group was injected into the uterine cavity. After two months, existence of intrauterine adhesions in the both groups was examined by the hysteroscope and assessment of menstrual patterns, according to the American Society for Reproductive Medicine criteria.

Results

Our results showed that after intervention, the incidence of Asherman's syndrome in the control group was higher than the case group (p = 0.012). In the case group, only four women had poor adhesion (Asherman's syndrome) at the end of the study, while the rest of them were free of any adhesions in the uterine cavity. In the control group, however, only 19 were free of intrauterine adhesions and 12 had mild symptoms.

Conclusion

The results of the study exhibited the hyaluronic acid capacity to reduce the risk of Asherman's syndrome in women with endometrial damage following a septal resection surgery.

The incidence of placenta related disease after the hysteroscopic adhesiolysis in patients with intrauterine adhesions

OBJECTIVE

To analyze the correlation between placenta related disease of pregnant women with antecedent hysteroscopic adhesiolysis due to intrauterine adhesions (IUA).

MATERIALS AND METHODS

This is a single center, non-randomized, open-label, retrospective cohort Study. 74 patients who had adhesiolysis and hormone therapy for IUA and progressed into the third trimester were group A and 296 without IUA were group B. The main outcome measure is the incidence of placenta related disease including placenta accreta spectrum, placenta previa, placental abruption, intrauterine growth restriction (IUGR), and pregnancy-induced hypertension (PIH). The second outcome is the perinatal, and intrapartum complications.

RESULTS

Patients in group A had a higher frequency of prior pregnancy times (2.51 ± 1.56 vs.1.84 ± 1.06, p = 0.001) and lower frequency of prior delivery times (0.20 ± 0.41 vs. 1.30 ± 0.51, p < 0.05) than group B at baseline. At delivery, there is no difference between the incidence of PIH and IUGR between two groups. However, a significantly higher frequency of placenta accreta (17.6% vs. 1.4%, OR = 15.56, 95% CI 4.91-49.34), placenta increta (5.4% vs. 0.7%, OR = 8.4, 95% CI 1.51-46.78), placenta previa (8.1% vs. 2.0%, OR = 4.265, 95%CI1.33-13.63) and postpartum hemorrhage (21.6% vs. 3.4%, OR = 7.890, 95% CI 3.41-18.26) were observed in group A than in group B.

CONCLUSIONS

Compared to general population, the rates of placenta accreta, placenta increta, placenta previa, postpartum hemorrhage are higher among the IUA patients after hysteroscopic adhesiolysis, and special attention is needed at the termination of the pregnancy.

Endometrial membrane organoids from human embryonic stem cell combined with the 3D Matrigel for endometrium regeneration in asherman syndrome

Asherman's syndrome (AS), a leading cause of uterine infertility worldwide, is characterized by scarring of the uterine surfaces lacking endometrial epithelial cells, which prevents endometrial regeneration. Current research on cell therapy for AS focuses on mesenchymal and adult stem cells from the endometrium. However, insufficient number, lack of purity, and rapid senescence of endometrial epithelial progenitor cells (EEPCs) during experimental processes restrict their use in cell therapies. In this study, we induced human embryonic stem cells-9 (H9-ESC) into EEPCs by optimizing the induction factors from the definitive endoderm. EEPCs, which act as endometrial epithelial cells, accompanied by human endometrial stromal cells provide a niche environment for the development of endometrial membrane organoids (EMOs) in an in vitro 3D culture model. To investigate the function of EMOs, we transplanted tissue-engineered constructs with EMOs into an in vivo rat AS model. The implantation of EMOs into the damaged endometrium facilitates endometrial regeneration and angiogenesis. Implanting EMOs developed from human embryonic stem cells into the endometrium might prove useful for "endometrial re-engineering" in the treatment of Asherman's syndrome.

Perivascular Stem Cell-Derived Cyclophilin A Improves Uterine Environment with Asherman's Syndrome via HIF1α-Dependent Angiogenesis

Asherman's syndrome (AS) is characterized by intrauterine adhesions or fibrosis resulting from scarring inside the endometrium. AS is associated with infertility, recurrent miscarriage, and placental abnormalities. Although mesenchymal stem cells show therapeutic promise for the treatment of AS, the molecular mechanisms underlying its pathophysiology remain unclear. We ascertained that mice with AS, like human patients with AS, suffer from extensive fibrosis, oligo/amenorrhea, and infertility. Human perivascular stem cells (hPVSCs) from umbilical cords repaired uterine damage in mice with AS, regardless of their delivery routes. In mice with AS, embryo implantation is aberrantly deferred, which leads to intrauterine growth restriction followed by no delivery at term. hPVSC administration significantly improved implantation defects and subsequent poor pregnancy outcomes via hypoxia inducible factor 1α (HIF1α)-dependent angiogenesis in a dose-dependent manner. Pharmacologic inhibition of HIF1α activity hindered hPVSC actions on pregnancy outcomes, whereas stabilization of HIF1α activity facilitated such actions. Furthermore, therapeutic effects of hPVSCs were not observed in uterine-specific HIF1α-knockout mice with AS. Secretome analyses of hPVSCs identified cyclophilin-A as the major paracrine factor for hPVSC therapy via HIF1α-dependent angiogenesis. Collectively, we demonstrate that hPVSCs-derived cyclophilin-A facilitates HIF1α-dependent angiogenesis to ameliorate compromised uterine environments in mice with AS, representing the major pathophysiologic features of humans with AS.

Autologous Bone Marrow-Derived Stem Cell Therapy for Asherman's Syndrome and Endometrial Atrophy: A 5-Year Follow-up Study

Background:

Based on the role of bone marrow (BM) stem cells in regeneration of endometrium, refractory cases of Asherman's syndrome (AS) and endometrial atrophy (EA) may benefit with BM-derived intrauterine stem cell instillation. Aims and Objectives: To evaluate the role of BM-derived autologous stem cell therapy in endometrial regeneration and restoration of menstruation and fertility in refractory cases of AS and EA.

Setting:

This study was conducted at a tertiary care center.

Design:

This was a prospective, single-arm longitudinal study.

Materials and Methods:

Twenty-five cases with refractory AS or EA were included. BM-derived mononuclear stem cells were instilled into the subendometrial zone followed by oral estrogen therapy for 3 months. Menstrual flow and endometrial thickness (ET) were assessed at 3, 6, and 9 months and 5 years.

Results:

Statistical analysis was carried out using statistical software STATA version 12.0. Mean prestem cell transfer ET (mm) was 3.3 ± 1.0. At the end of 3 months, there was a significant increase in ET (mm) to 5.1 ± 1.9 (P = 0.001), but there was no significant change at 6 months (5.6 ± 1.5; P = 0.164), at 9 months (6.1 ± 1.7; P = 0.135), or at the end of 5 years. Six of the seven amenorrheic patients resumed menses. Three patients had a successful pregnancy outcome.

Conclusion:

Intrauterine stem cell treatment is a promising novel approach for refractory cases of AS and EA.

Platelet-rich plasma in the management of Asherman's syndrome: An RCT

Background

Asherman's syndrome (AS) is a rare reproductive abnormality, resulting in endometrial collapse due to aggressive or recurrent endometritis and/or curettage.

Objective

We aimed to assess the effectiveness of using platelet-rich plasma (PRP) to lower the recurrence rate of intrauterine adhesions (IUAs) following hysteroscopy.

Materials and Methods

In this non-randomized clinical trial, women aged 20-45 years with AS diagnosed by sonohysterography, 3D sonography, hysteroscopy, or uterosalpingography between May 2018 and September 2018 were included. Participants (n = 30) were divided into case and control groups. Following hysteroscopic adhesiolysis, a Foley catheter was placed into the uterine cavity in all women. After two days, the catheter was removed, and 1-mL PRP was injected into the uterine cavity of women in the PRP (case) group, while the control received no PRP. All controls and subjects underwent diagnostic hysteroscopy 8-10 weeks following the intervention to assess the IUAs according to the American Society for Reproductive Medicine scoring system.

Results

Our results did not reveal any significant difference in the menstrual pattern of either the control or test groups before or after treatment (p = 0.2). Moreover, the IUA stage in both studied groups before and after treatment was similar (p = 0.2). The duration of menstrual bleeding in both studied groups before and after treatment was also similar.

Conclusion

PRP cannot change the menstrual pattern or development of postsurgical AS, as evaluated by follow-up hysteroscopy.

Endometrial Regeneration in Asherman's Syndrome: Clinical and Translational evidence of Stem Cell Therapies

Asherman's Syndrome or Intrauterine adhesions is an acquired uterine condition where fibrous scarring forms within the uterine cavity, resulting in reduced menstrual flow, pelvic pain and infertility. Until recently, the molecular mechanisms leading to the formation of fibrosis were poorly understood, and the treatment of Asherman's syndrome has largely focused on hysteroscopic resection of adhesions, hormonal therapy, and physical barriers. Numerous studies have begun exploring the molecular mechanisms behind the fibrotic process underlying Asherman's Syndrome as well as the role of stem cells in the regeneration of the endometrium as a treatment modality. The present review offers a summary of available stem cell-based regeneration studies, as well as highlighting current gaps in research.

Stem cell paracrine actions in tissue regeneration and potential therapeutic effect in human endometrium: a retrospective study

OBJECTIVE

Determining genetic and paracrine mechanisms behind endometrial regeneration in Asherman's syndrome and endometrial atrophy (AS/EA) patients after autologous CD133⁺ bone marrow-derived stem cell (CD133⁺ BMDSC) transplantation.

DESIGN

Retrospective study using human endometrial biopsies and mouse models.

SETTING

Fundación-IVI, IIS-La Fe, Valencia, Spain.

SAMPLES

Endometrial biopsies collected before and after CD133⁺ BMDSC therapy, from eight women with AS/EA (NCT02144987) from the uterus of five mice with only left horns receiving CD133⁺ BMDSC therapy.

METHODS

In human samples, haematoxylin and eosin (H&E) staining, RNA arrays, PCR validation, and neutrophil elastase (NE) immunohistochemistry (IHQ). In mouse samples, PCR validation and protein immunoarrays.

MAIN OUTCOME MEASURES

H&E microscopic evaluation, RNA expression levels, PCR, and growth/angiogenic factors quantification, NE IHQ signal.

RESULTS

Treatment improved endometrial morphology and thickness for all patients. In human samples, Jun, Serpine1, and Il4 were up-regulated whereas Ccnd1 and Cxcl8 were down-regulated after treatment. The significant decrease of NE signal corroborated Cxcl8 expression. Animal model analysis confirmed human results and revealed a higher expression of pro-angiogenic cytokines (IL18, HGF, MCP-1, MIP2) in treated uterine horns.

CONCLUSIONS

CD133⁺ BMDSC seems to activate several factors through a paracrine mechanism to help tissue regeneration, modifying endometrial behaviour through an immunomodulatory milieu that precedes proliferation and angiogenic processes. Insight into these processes could bring us one step closer to a non-invasive treatment for AS/EA patients.

TWEETABLE ABSTRACT

CD133⁺ BMDSC therapy regenerates endometrium, modifying the immunological milieu that precedes proliferation and angiogenesis.

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.

Hyaluronic Acid Hydrogel Integrated with Mesenchymal Stem Cell-Secretome to Treat Endometrial Injury in a Rat Model of Asherman's Syndrome

Stem cell therapies have made strides toward the efficacious treatment of injured endometrium and the prevention of intrauterine adhesions, or Asherman's syndrome (AS). Despite this progress, they are limited by their risk of tumor formation, low engraftment rates, as well as storage and transportation logistics. While attempts have been made to curb these issues, there remains a need for simple and effective solutions. A growing body of evidence supports the theory that delivering media, conditioned with mesenchymal stem cells, might be a promising alternative to live cell therapy. Mesenchymal stem cell-secretome (MSC-Sec) has a superior safety profile and can be stored without losing its regenerative properties. It is versatile enough to be added to a number of delivery vehicles that improve engraftment and control the release of the therapeutic. Thus, it holds great potential for the treatment of AS. Here, a new strategy for loading crosslinked hyaluronic acid gel (HA gel) with MSC-Sec is reported. The HA gel/MSC-Sec treatment paradigm creates a sustained release system that repairs endometrial injury in rats and promotes viable pregnancy.

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.

Cellular therapies for the endometrium: An update

An update on the current state of endometrial cell therapies in terms of cell types, mechanisms of action, delivery, safety, regulatory frameworks and future perspectives. This review focuses on clinical trials using angiogenesis-promoting therapies and stromal therapies piloted in the last 10 years for alleviating Asherman's syndrome and long-term infertility. All studies present promising preliminary results, indicating increased endometrial thickness and resumed menstruation. Further characterization of individual cell products, their mode of action and larger clinical trials will be essential to establishing cell therapy as a viable option for the treatment of infertility and fertility preservation.

Systemic administration of bone marrow-derived cells leads to better uterine engraftment than use of uterine-derived cells or local injection

Stem cells are recruited to the uterus where they differentiate into endometrial cells and have been suggested as potential therapy for uterine injury such as Asherman's syndrome. However, it is unknown whether local intrauterine injection may result in better stem cell engraftment of the uterus compared with systemic administration, and whether uterine‐derived cells (UDCs) may confer an advantage over BM‐derived cells (BMDCs). Mice underwent local injury to a single uterine horn. Green fluorescent protein (GFP)‐expressing BMDCs, UDCs or saline (control) were injected either intravenously or locally (uterine lumen) into wild‐type recipients. Two or 3 weeks post‐transplant, uterine tissues were collected for fluorescence‐activated cell sorting (FACS) and immunohistochemistry/immunofluorescence studies. Mice injected intravenously with BMDCs or UDCs had increased GFP⁺ cells recruitment to the non‐injured or injured uterus compared to those injected locally. No significant differences were noted in GFP⁺ cell recruitment to the injured versus non‐injured horn. In addition, systemic injection of BMDCs led to greater recruitment of GFP⁺ cells at 2 weeks and 3 weeks compared with UDCs. Immunohistochemical staining demonstrated that GFP⁺ cells were found in stroma but not in epithelium or blood vessels. Immunofluorescence analysis revealed that GFP⁺ cells were mostly CD45‐negative, and negative for CD31 and cytokeratin, confirming their stromal identity. In conclusion, the systemic route of administration results in better recruitment of BMDCs or UDCs to the injured uterus than local injection. In addition, BMDCs recruitment to the uterus is greater than UDCs. These findings inform the development of stem cell‐based therapies targeting the uterus.

Oxidized, Regenerated Cellulose Adhesion Barrier Plus Intrauterine Device Prevents Recurrence After Adhesiolysis for Moderate to Severe Intrauterine Adhesions

STUDY OBJECTIVE

To compare the efficacy of an oxidized, regenerated cellulose adhesion barrier (Interceed; Ethicon, Somerville, NJ) combined with an intrauterine device (IUD) versus an IUD alone for preventing adhesion recurrence following hysteroscopic adhesiolysis for moderate to severe intrauterine adhesions (IUAs).

DESIGN

Retrospective case series (Canadian Task Force classification III).

SETTING

Tertiary care teaching hospital.

PATIENTS

Patients undergoing treatment for moderate to severe IUAs. The severity of IUA was determined based on the American Fertility Society scoring system (mild, moderate, or severe).

INTERVENTIONS

All cases of hysteroscopic adhesiolysis were reviewed.

MEASUREMENTS AND RESULTS

Seventy-six women with moderate to severe IUAs treated between March 2009 and August 2015 were included. After hysteroscopic adhesiolysis, 35 patients were treated with an IUD alone (group 1), and 41 patients were treated with Interceed plus an IUD (group 2). A second hysteroscopy was performed in all cases three months after the initial hysteroscopy and both groups achieved significant reduction in adhesion scores and grade, especially in group 2 (scores, p < .001; grade, p = .039). Compared with group 1, menstruation dysfunction, pregnancy rate, and live birth rate in group 2 improved with no statistical difference (menstruation improvement, p = .764; pregnancy rate, p = .310; live birth rate, p = .068). However, an adhesion-free uterine cavity was regained significantly owing to the fewer operations in group 2 compared with group 1 (median, 3 vs 4; p = .001). The interval from initial hysteroscopy to conception was significantly shorter in group 2 (median, 12 months vs 51 months; p < .001).

CONCLUSIONS

For moderate to severe IUAs, Interceed combined with an IUD may be an alternative approach for reducing adhesion recurrence after hysteroscopic adhesiolysis.

Autologous menstrual blood-derived stromal cells transplantation for severe Asherman's syndrome

STUDY QUESTION

Does autologous transplantation of menstrual blood-derived stromal cells (menSCs) regenerate endometrium to support pregnancy in patients with severe Asherman's syndrome (AS)?

SUMMARY ANSWER

Autologous menSCs transplantation significantly increases endometrial thickness (ET) for women with severe AS.

WHAT IS KNOWN ALREADY

AS is a major cause of secondary infertility in women. Cell transplantation has been tried in a few clinical cases with encouraging results.

STUDY DESIGN, SIZE, DURATION

In this experimental, non-controlled and prospective 3-year clinical study involving seven patients with AS, autologous menSCs were isolated and cultured from menstrual blood of each patient within ~2 weeks and then transplanted back into their uterus. Endometrial growth and pregnancy were assessed after cell therapy.

PARTICIPANTS/MATERIALS, SETTING, METHOD

Infertile women, aged 20-40 years, diagnosed with severe AS (Grade III-V) by hysteroscopy and with menstrual fluid were recruited at the Shengjing Hospital affiliated to China Medical University. Autologous menSCs transplantation was conducted followed by HRT. Endometrial thickness was monitored with frozen embryo transfer (FET) as needed.

MAIN RESULTS AND THE ROLE OF CHANCE

We successfully cultured menSCs from seven patients and transferred the autologous cells back to their uterus. Our results showed that the ET was significantly (P = 0.0002) increased to 7 mm in five women, which ensured embryo implantation. Four patients underwent FET and two of them conceived successfully. One patient had spontaneous pregnancy after second menSCs transplantation.

LIMITATIONS, REASONS FOR CAUTION

Limited sample size, lack of rigorous controls or knowledge of underlying mechanism.

WIDER IMPLICATIONS OF THE FINDINGS

Autologous menSCs transplantation is a potential option for treating women with severe AS.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by Liaoning Provincial Science and Technology Program. The sponsor and authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

Registered in the Chinese Clinical Trial Registry (ChiCTR-ONB-15007464).

Intrauterine Adhesions Following Miscarriage: Look and Learn

OBJECTIVE

To examine the incidence of intrauterine adhesions (IUA) following the management of miscarriage in women with previously documented normal uterine cavities.

METHODS

We conducted a retrospective cohort study from two fertility clinics with standard practice protocols for evaluating the uterine cavity prior to infertility treatment and following clinical pregnancy loss. A database query and manual chart review identified 144 women with normal uterine cavities who experienced a miscarriage between January 2010 and November 2012 and returned to the clinic for follow-up hysteroscopy. Following documentation of a non-viable clinical pregnancy using transvaginal ultrasound, patients chose expectant, medical, or surgical management according to standardized clinical protocols. The primary outcome was the detection of IUA. Secondary outcomes included the presence of retained products of conception and various risk factors associated with the development of IUA.

RESULTS

The incidence of IUA following early pregnancy loss was 6.3%. There were no significant differences in patient characteristics between those with and without IUA. There was a significant association between IUA and increasing uterine size, particularly in the presence of multiple gestation (P = 0.039). Mechanical suction dilatation and curettage (D&C) was a risk factor for IUA, but manual vacuum aspiration was not a risk factor (P = 0.003). Retained products of conception were found in 13.9% of study participants, and the incidence did not differ among management options.

CONCLUSIONS

This appears to be the first documentation of IUA that were entirely attributable to the index miscarriage or its management. There appears to be an increased risk of IUA following D&C with larger uteri and multiple pregnancies and following mechanical suction D&C.

A 10-year Review of the Clinical Presentation and Treatment Outcome of Asherman's Syndrome at a Center with Limited Resources

Background:

Many women suffer from some degree of intrauterine adhesions (IUAs) presenting with various clinical symptoms and signs. Hysteroscopy is the mainstay of diagnosis, classification, and treatment of the IUA.

Aim:

This study was undertaken to review the clinical features and treatment outcome in patients diagnosed with Asherman's syndrome at the University of Maiduguri Teaching Hospital (UMTH), Maiduguri, over a 10 years period, 1997–2006.

Subjects and Methods:

This is a retrospective study of cases of Asherman's syndrome managed at the UMTH over a 10-year period, from January 1, 1997 to December 31, 2006. Case records of the patients were retrieved from medical records' Department. Sociodemographic and clinical information relating to clinical presentations, treatment modalities, and outcomes were collated. The data were analyzed using SPSS 16.0 Statistical Computer Package (SPSS Inc., IL, USA 2006). Chi-square and binary logistic regression were used for inferential statistics.

Results:

Asherman's syndrome constituted 8.1% (81/996) of all gynecological operations in UMTH during the study period. The case records retrieval rate was 96.3% (78/81 folders). Most of the patients, 59% (46/78) were in their third decade and majority 85.9% (67/78) were married. The most common risk factor was pregnancy-associated, accounting for 61.5% (48/78). Infertility and hypomenorrhea were the most common mode of presentations in 55.1% (43/78) and 32.1% (25/78) of cases, respectively. Most of the patients 85.9% (67/78) were treated by blind dilatation and curettage (D/C), Foley's catheter insertion and estrogen-progesterone combination. Correction of menses was seen in 37.2% (29/78) of the patients while the pregnancy rate was 32.1% (25/78). On binary logistic regression age of the respondents, multigravidity, and previous pelvic surgeries for pregnancy (C/S and D/C for abortion) emerged as the only respondent's related risk factors associated with the development of Asherman's syndrome.

Conclusion:

Asherman's syndrome is relatively common due to complications of pregnancy and delivery, and blind D/C has a relatively poor outcome. Age of the respondents, multigravidity, and previous pelvic surgeries for pregnancy (C/S and D/C for abortion) were associated with the development of Asherman's syndrome. Therefore, other methods of adhesiolysis such as hysteroscopic adhesiolysis should be explored.

Autologous cell therapy with CD133+ bone marrow-derived stem cells for refractory Asherman's syndrome and endometrial atrophy: a pilot cohort study

STUDY QUESTION

Could cell therapy using autologous peripheral blood CD133+ bone marrow-derived stem cells (BMDSCs) offer a safe and efficient therapeutic approach for patients with refractory Asherman's syndrome (AS) and/or endometrial atrophy (EA) and a wish to conceive?

SUMMARY ANSWER

In the first 3 months, autologous cell therapy, using CD133+ BMDSCs in conjunction with hormonal replacement therapy, increased the volume and duration of menses as well as the thickness and angiogenesis processes of the endometrium while decreasing intrauterine adhesion scores.

WHAT IS KNOWN ALREADY

AS is characterized by the presence of intrauterine adhesions and EA prevents the endometrium from growing thicker than 5 mm, resulting in menstruation disorders and infertility. Many therapies have been attempted for these conditions, but none have proved effective.

STUDY DESIGN, SIZE, DURATION

This was a prospective, experimental, non-controlled study. There were 18 patients aged 30-45 years with refractory AS or EA were recruited, and 16 of these completed the study. Medical history, physical examination, endometrial thickness, intrauterine adhesion score and neoangiogenesis were assessed before and 3 and 6 months after cell therapy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After the initial hysteroscopic diagnosis, BMDSC mobilization was performed by granulocyte-CSF injection, then CD133+ cells were isolated through peripheral blood aphaeresis to obtain a mean of 124.39 million cells (range 42-236), which were immediately delivered into the spiral arterioles by catheterization. Subsequently, endometrial treatment after stem cell therapy was assessed in terms of restoration of menses, endometrial thickness (by vaginal ultrasound), adhesion score (by hysteroscopy), neoangiogenesis and ongoing pregnancy rate. The study was conducted at Hospital Clínico Universitario of Valencia and IVI Valencia (Spain).

MAIN RESULTS AND THE ROLE OF CHANCE

All 11 AS patients exhibited an improved uterine cavity 2 months after stem cell therapy. Endometrial thickness increased from an average of 4.3 mm (range 2.7-5) to 6.7 mm (range 3.1-12) ( ITALIC! P = 0.004). Similarly, four of the five EA patients experienced an improved endometrial cavity, and endometrial thickness increased from 4.2 mm (range 2.7-5) to 5.7 mm (range 5-12) ( ITALIC! P = 0.03). The beneficial effects of the cell therapy increased the mature vessel density and the duration and intensity of menses in the first 3 months, with a return to the initial levels 6 months after the treatment. Three patients became pregnant spontaneously, resulting in one baby boy born, one ongoing pregnancy and a miscarriage. Furthermore, seven pregnancies were obtained after fourteen embryo transfers, resulting in three biochemical pregnancies, one miscarriage, one ectopic pregnancy, one baby born and one ongoing pregnancy.

LIMITATIONS, REASONS FOR CAUTION

Limitations of this pilot study include the small sample size and the lack of control group.

WIDER IMPLICATIONS OF THE FINDINGS

This novel autologous cell therapy is a promising therapeutic option for patients with these incurable pathologies and a wish to conceive.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the Spanish Ministry of Science and Innovation (SAF 2012-31017, Principal Investigator C.S.), Spanish Ministry of Health (EC11-299, Principal Investigator C.S.) and Regional Valencian Ministry of Education (PROMETEOII/2013/018, Principal Investigator C.S.). Four authors (X.S., I.C., A.P. and C.S.) are co-inventors of the patent resulting from this work (Application number: 62/013,121). S.C., C.A., F.R., J.F., J.P. and J.R. have no conflict of interest in relation to this work.

TRIAL REGISTRATION NUMBER

This study was registered with ClinicalTrials.gov (NCT02144987).

Induction of Asherman's Syndrome in Rabbit

BACKGROUND

Uterine synechiae or Asherman's syndrome is a condition that can cause infertility. The present experimental study was designed to establish the rabbit as an animal model for human Asherman's syndrome using the endometrial curettage.

METHODS

In an experimental study, female adult rabbits (n=18) were randomly divided into intact and ovariectomized groups. One third of caudal part of both uteri was submitted to traumatic endometrial curettage. One group was simultaneously ovariectomized. The intact rabbits were artificially induced ovulation during 10 days after surgery. One third of cranial part of both uteri was selected as the control. Synechiae occurring, luminal area/total area (LA/TA), endometrial area/total area (EA/TA), myometrial and perimetrial area/total area (MPA/TA), endometrial area/uterine wall area (EA/UWA), and myometrial and perimetrial area/uterine wall area (MPA/UWA) ratios of both uteri in six subdivided groups (n=6) were analysed in curetted and intact control parts. On days 15, 30 and 45 following surgery by two-way ANOVA and LSD test (p<0.05).

RESULTS

Histopathologic findings showed significant epithelial damage together with significant inflammatory reaction in the intact curettage group. The LA/TA ratios of the intact curettage group on days 15 and 45 were more than the intact control group on day 15. The EA/TA ratio of the intact curettage group on day 30 was less than the intact control group on day 30.

CONCLUSION

Uterine fibrosis was observed in intact curettage group, and this modified animal model showed a pathogenesis condition similar to intrauterine adhesions observed in human.

Preventive effect of oral mucosal epithelial cell sheets on intrauterine adhesions

STUDY QUESTION

Can regenerative-medicine techniques using oral mucosal epithelial cell sheets (OMECS) provide a new treatment method for intrauterine adhesions (IUA) which cause female infertility?

SUMMARY ANSWER

Transplantation of OMECS was confirmed to be effective in preventing IUA after endometrial damage in rats.

WHAT IS KNOWN ALREADY

Uterine disorders such as IUA, commonly known as Asherman's syndrome, are one factor that can result in infertility. Clinical therapy for this kind of disease is targeted at the prevention of re-adhesion by surgical synechiotomy, administration of hormones after the operation, and the use of intrauterine devices. Recently, a new approach called 'cell-sheet engineering', which harvests confluent culture cells as a contiguous cell sheet having intact cell-cell junctions and an extracellular matrix, without having to use enzymatic treatment, has been developed for tissue regeneration.

STUDY DESIGN, SIZE, DURATION

OMECS were prepared from rat oral mucosal tissues. An IUA model was made in rat uteri, and OMECS were transplanted into the model. Uteri transplanted with OMECS were compared with the non-transplanted control uteri by histological analysis at 1, 2 and 8 days after surgery (n = 3).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Oral mucosal tissues were resected from neonatal rats, and oral mucosal epithelial cells were collected with enzymatic treatment. An isolated cell suspension was seeded on a temperature-responsive cell culture-insert and incubated. After being detached from the insert, a cell sheet was transplanted onto the endometrium defect. At 1, 2 and 8 days after surgery, uteri were resected and examined.

MAIN RESULTS AND THE ROLE OF CHANCE

Histological examination of the non-treated specimens at 1, 2 and 8 days after surgery did not show any uterine cavities typically caused by IUA. In contrast, the histology of uteri transplanted with OMECS immediately after endometrial damage showed the presence of uterine cavities, and furthermore, stratified squamous epithelial cells on the luminal surface (n = 3).

LIMITATIONS, REASONS FOR CAUTION

The results of this study are difficult to apply directly to humans, because the structure and function of rat uteri are different from those of human.

WIDER IMPLICATIONS OF THE FINDINGS

Transplantation of OMECS offers a reliable method not only to protect the woman's fertility from intrauterine re-adhesion after synechiotomy for IUA or uterine lumen adhesion but also to prevent adhesion after any intrauterine surgery in clinical cases.

Autologous stem cell transplantation in refractory Asherman's syndrome: A novel cell based therapy

BACKGROUND:

There is substantial evidence that adult stem cell populations exist in human endometrium, and hence it is suggested that either endogenous endometrial stem/progenitor cells can be activated or bone marrow derived stem cells can be transplanted in the uterine cavity for endometrial regeneration in Asherman's syndrome (AS).

AIMS AND OBJECTIVES:

The objective was to evaluate the role of sub-endometrial autologous stem cell implantation in women with refractory AS in attaining menstruation and fertility.

SETTING:

Tertiary care referral center.

DESIGN:

Prospective case series.

MATERIALS AND METHODS:

Six cases of refractory AS with failed standard treatment option of hysteroscopic adhesiolysis in the past were included. Mononuclear stem cells (MNCs) were implanted in sub-endometrial zone followed by exogenous oral estrogen therapy. Endometrial thickness (ET) was assessed at 3, 6, and 9 months.

RESULTS:

Descriptive statistics and statistical analysis of study variables was carried out using STATA version 9.0. The mean MNC count was 103.3 × 106 (±20.45) with mean CD34+ count being 203,642 (±269,274). Mean of ET (mm) at 3 months (4.05 ± 1.40), 6 months (5.46 ± 1.36) and 9 months (5.48 ± 1.14) were significantly (P < 0.05) increased from pretreatment level (1.38 ± 0.39). Five out of six patients resumed menstruation.

CONCLUSION:

The autologous stem cell implantation leads to endometrial regeneration reflected by restoration of menstruation in five out of six cases. Autologous stem cell implantation is a promising novel cell based therapy for refractory AS.

A matched cohort study comparing the outcome of intrauterine adhesiolysis for Asherman's syndrome after uterine artery embolization or surgical trauma

STUDY OBJECTIVE

To compare the outcome of hysteroscopic adhesiolysis in women who had Asherman's syndrome after uterine artery embolization (UAE) with those who had Asherman's syndrome caused by surgical trauma.

DESIGN

A retrospective cohort study matched for age and intrauterine adhesion score (Canadian Task Force classification II-2).

SETTING

A tertiary hysteroscopic center in a teaching hospital.

PATIENTS

Nineteen women with Asherman's syndrome after UAE and 57 women with Asherman's syndrome caused by surgical trauma.

INTERVENTIONS

Hysteroscopic adhesiolysis was followed by a second-look hysteroscopy 1 month later. The scoring system proposed by the American Fertility Society was used to evaluate intrauterine adhesion during hysteroscopy.

MEASUREMENTS AND MAIN RESULTS

In the UAE group, only 42.1% of women experienced improvement in menstruation defined as a subjective increase in menstrual flow after surgery, which was significantly lower than that of 86.0% observed in the non-UAE group. In the UAE group, the reduction of the American Fertility Society (AFS) score after intrauterine adhesiolysis was 30%, which was significantly lower than that of 80% in the non-UAE group. The pregnancy rate and live birth rate in the UAE group (5% and 0%, respectively) were significantly lower than the corresponding rates in the non-UAE group (33% and 25%, respectively).

CONCLUSION

The outcome of hysteroscopic adhesiolysis in women with Asherman's syndrome after UAE was worse than in women with Asherman's syndrome caused by surgical trauma.

Hysteroscopic adhesiolysis for patients with Asherman's syndrome: menstrual and fertility outcomes

Purpose

Most patients with Asherman's syndrome present with infertility and menstrual problems. In this retrospective clinical study, we analyzed patients with Asherman's syndrome who underwent hysteroscopic adhesiolysis to examine their associated symptoms, disease etiologies, and fertility outcomes.

Methods

Twenty-seven patients with Asherman's syndrome that were diagnosed using hysteroscopy were recruited. The chief complaints were infertility, hypomenorrhea, and amenorrhea. Each case of Asherman's syndrome was classified according to the American Fertility Society classification. Hysteroscopic adhesiolysis was performed in all cases and concomitant transabdominal ultrasonography was conducted in cases with extensive and dense adhesions.

Results

There were no complications associated with the hysteroscopic procedure. Normal menstrual cycles resumed in all cases. Of the 16 infertile patients, 9 conceived. Three patients achieved term deliveries and one patient is currently pregnant. None of the patients had obstetric complications. Two patients had spontaneous abortions, one had an ectopic pregnancy, one had an abortion at 16 weeks' gestation due to cervical incompetence, and one had a molar pregnancy and required uterine artery embolization for uncontrolled hemorrhaging during a dilatation and curettage procedure.

Conclusions

Hysteroscopic adhesiolysis with transabdominal ultrasonography is a suitable treatment method for Asherman's syndrome. Subfertile patients with Asherman's syndrome undergoing adhesiolysis should be appropriately informed about the risk of associated life-threatening complications and preterm delivery.

Endometrial regeneration using autologous adult stem cells followed by conception by in vitro fertilization in a patient of severe Asherman's syndrome

In a woman with severe Asherman's syndrome, curettage followed by placement of intrauterine contraceptive device (IUCD) (IUCD with cyclical hormonal therapy) was tried for 6 months, for development of the endometrium. When this failed, autologous stem cells were tried as an alternative therapy. From adult autologous stem cells isolated from patient's own bone marrow, endometrial angiogenic stem cells were separated using immunomagnetic isolation. These cells were placed in the endometrial cavity under ultrasound guidance after curettage. Patient was then given cyclical hormonal therapy. Endometrium was assessed intermittently on ultrasound. On development of endometrium with a thickness of 8 mm and good vascularity, in vitro fertilization and embryo transfer was done. This resulted in positive biochemical pregnancy followed by confirmation of gestational sac, yolk sac, and embryonic pole with cardiac activity on ultrasound. Endometrial angiogenic stem cells isolated from autologous adult stem cells could regenerate injured endometrium not responding to conventional treatment for Asherman's syndrome.

Generating receptive endometrium in Asherman's syndrome

Intrauterine administration of bone marrow stem/progenitor cells to a woman with thin endometrium refractory to estrogen stimulation regenerated her endometrium sufficiently to support a pregnancy. Or was it local endometrial damage induced by concurrent curettage that stimulated endogenous endometrial stem/progenitor cells into action? Or both?