Animal models of the placenta accreta spectrum: current status and further perspectives

Effect of pelvic artery embolization for postpartum hemorrhage on subsequent pregnancies: a single-center retrospective cohort study

OBJECTIVE

Pelvic artery embolization (PAE) is a uterus-saving treatment for postpartum hemorrhage (PPH); however, subfertility or abnormal placentation for subsequent pregnancy has been a concern in several previous reports. This study aimed to investigate the impact of PAE on subsequent pregnancies in women with a history of PPH.

METHODS

A retrospective cohort study was conducted on women transferred to the tertiary center for PPH and delivered for the next pregnancy at the same center later. The study group was divided into two groups based on PAE application to treat previous PPH.

RESULTS

Of the 62 women included, 66% (41/62) had received PAE for the previous PPH, while 21 had not. Pregnancy outcomes for subsequent pregnancies were compared between the PAE and non-PAE groups. The PAE group had a higher estimated blood loss volume for the present delivery than the non-PAE group (600 vs. 300 mL, p = 0.008). The PAE group also demonstrated a higher incidence of placenta previa (4.8% vs. 24.4%, p = 0.080) and placenta accreta (0% vs. 14.6%, p = 0.082) than the non-PAE group, although the difference was not statistically significant.

CONCLUSION

These findings suggest that the use of PAE to treat PPH may increase the risk of bleeding, placenta previa, and placenta accreta spectrum in subsequent pregnancies.

Current understanding of the pathogenesis of placenta accreta spectrum disorder with focus on mitochondrial function

AIM

The refinement of assisted reproductive technology, including the development of cryopreservation techniques (vitrification) and ovarian stimulation protocols, makes frozen embryo transfer (FET) an alternative to fresh ET and has contributed to the success of assisted reproductive technology. Compared with fresh ET cycles, FET cycles were associated with better in vitro fertilization outcomes; however, the occurrence of pregnancy-induced hypertension, preeclampsia, and placenta accreta spectrum (PAS) was higher in FET cycles. PAS has been increasing steadily in incidence as a life-threatening condition along with cesarean rates worldwide. In this review, we summarize the current understanding of the pathogenesis of PAS and discuss future research directions.

METHODS

A literature search was performed in the PubMed and Google Scholar databases.

RESULTS

Risk factors associated with PAS incidence include a primary defect of the decidua basalis or scar dehiscence, aberrant vascular remodeling, and abnormally invasive trophoblasts, or a combination thereof. Freezing, thawing, and hormone replacement manipulations have been shown to affect multiple cellular pathways, including cell proliferation, invasion, epithelial-to-mesenchymal transition (EMT), and mitochondrial function. Molecules involved in abnormal migration and EMT of extravillous trophoblast cells are beginning to be identified in PAS placentas. Many of these molecules were also found to be involved in mitochondrial biogenesis and dynamics.

CONCLUSION

The etiology of PAS may be a multifactorial genesis with intrinsic predisposition (e.g., placental abnormalities) and certain environmental factors (e.g., defective decidua) as triggers for its development. A distinctive feature of this review is its focus on the potential factors linking mitochondrial function to PAS development.

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

Exploring maternal-fetal interface with in vitro placental and trophoblastic models

The placenta, being a temporary organ, plays a crucial role in facilitating the exchange of nutrients and gases between the mother and the fetus during pregnancy. Any abnormalities in the development of this vital organ not only lead to various pregnancy-related disorders that can result in fetal injury or death, but also have long-term effects on maternal health. In vitro models have been employed to study the physiological features and molecular regulatory mechanisms of placental development, aiming to gain a detailed understanding of the pathogenesis of pregnancy-related diseases. Among these models, trophoblast stem cell culture and organoids show great promise. In this review, we provide a comprehensive overview of the current mature trophoblast stem cell models and emerging organoid models, while also discussing other models in a systematic manner. We believe that this knowledge will be valuable in guiding further exploration of the complex maternal-fetal interface.

Adipocytes in the Uterine Wall during Experimental Healing and in Cesarean Scars during Pregnancy

We have suggested that adipocytes in uterine scars may affect the development of the placenta accrete spectrum (PAS). In the experimental part, we explored adipocytes in the uterine wall by the twelfth sexual cycle after surgery. In the clinical part, we investigated adipocyte clusters in the cesarean scar of pregnant women with and without PAS. The uterine wall was evaluated in gross and histological sections using morphometry, histochemistry (hematoxylin and eosin stain, Mallory stain), and immunohistochemistry for FABP4 (adipocyte markers), CD68, CD163, CD206 (macrophages), CD 34 (endothelium), cytokeratin 8 (epithelium), aSMA (smooth muscle cells). The design included an experimental study on Sprague-Dawley rats (n = 18) after a full-thickness surgical incision on the seventh (n = 6), 30th (n = 6), and 60th day (n = 6). The clinical groups include pregnant women without uterine scars (n = 10), pregnant women with a uterine scar after previous cesarean sections (n = 10), and women with PAS (n = 11). Statistical processing was carried out using nonparametric methods. Comparisons were conducted using the Mann-Whitney U-test and Kruskal-Wallis test. Statistical significance was considered at p < 0.05. On the seventh day, the rat uterine horn was enveloped by adipose tissue, which contained crown-like structures with FABP4+, CD68+, CD206+, and CD163+ cells. FABP4+ cells in the uterine wall were absent by the 30th day. The number of CD206+ and CD163+ cells in the adipose tissue decreased by the 30th day. On the 60th day, the attachment of fat tissue was revealed in the form of single strands. The serous layer around the damaged area totally recovered on the 60th day. FABP4+ cells were not detected in the uterine wall samples from pregnant women without a previous cesarean section. Adipocytes were found in the scar during non-complicated pregnancy and with PAS. Reducing the number of CD68+ cells in adipocyte clusters, there were in myometrium with PAS. Increased CD206+ and CD163+ cells were revealed in uterine adipocyte clusters of the group. According to the experimental finding, adipocytes should be absent in the uterine wall by the 12th sexual cycle after a full-thickness surgical incision. The presence of adipocyte clusters in cesarean scar indicated the disturbance of cell interaction. Differences in the numbers of CD206 and CD163 cells in adipocyte clusters between groups with and without PAS may be indirect evidence that uterine adipocytes affect the development of PAS.

Upregulated CXCL8 in placenta accreta spectruma regulates the migration and invasion of HTR-8/SVneo cells

BACKGROUND

Placenta accreta spectrum (PAS) is mainly characterized by excessive invasion of the uterine muscle layer accompanied by a large number of foreign blood vessels, leading to severe bleeding during and after delivery. However, the mechanism of excessive invasion of nutrient cells in placenta accreta is currently unclear.

METHODS

We performed RNA sequencing of 6 PAS patients and 4 control donors, coupled with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The mRNA and protein expression of C-X-C motif ligand 8 (CXCL8) in the placental tissue was measured by qRT‒PCR, immunohistochemical staining and Western blotting. HTR-8/SVneo human villous trophoblast Neo cells were used for in vitro investigation of cell migration and invasion as well as the expression level of CXCL8.

RESULTS

A total of 1120 differentially expressed mRNAs were identified in PAS patients. Moreover, GO and KEGG analyses indicated that the differentially expressed mRNAs were most closely associated with immune system processes, biological adhesion and Wnt signaling pathway. The CXCL8 mRNA and protein levels in PAS tissue were significantly higher than those in normal placental tissue. Forced overexpression of CXCL8 significantly increased the migration and invasion of HTR-8/SVneo cells, accompanied by the upregulation of matrix metalloproteinase-2 and matrix metalloproteinase-9 and the downregulation of E-cadherin, which was reversed by knockdown of CXCL8.

CONCLUSIONS

CXCL8 was highly expressed in PAS, and knockdown of CXCL8 suppressed the migration and invasion of HTR-8/SVneo cells, suggesting its potential as a diagnostic and therapeutic target for PAS.