Immunohistochemical examination of trophoblast populations in human first trimester and term placentae and of first trimester spiral arteries with the monoclonal antibody GZ 112

Endometrial BMP2 Deficiency Impairs ITGB3-Mediated Trophoblast Invasion in Women With Repeated Implantation Failure

BACKGROUND

Repeated implantation failure (RIF) leads to a waste of high-quality embryos and remains a challenge in assisted reproductive technology. During early human placentation, the invasion of trophoblast cells into the decidua is an essential step for the establishment of maternal-fetal interactions and subsequent successful pregnancy. Bone morphogenetic protein 2 (BMP2) has been reported to regulate endometrial receptivity and promote trophoblast invasion. However, whether there is dysregulation of endometrial BMP2 expression in patients with RIF remains unknown. Additionally, the molecular mechanisms underlying the effects of BMP2 on human trophoblast invasion and early placentation remain to be further elucidated.

METHODS

Midluteal phase endometrial samples were biopsied from patients with RIF and from routine control in vitro fertilization followed by quantitative polymerase chain reaction and immunoblotting analyses. Human trophoblast organoids, primary human trophoblast cells, and an immortalized trophoblast cell line (HTR8/SVneo) were used as study models.

RESULTS

We found that BMP2 was aberrantly low in midluteal phase endometrial tissues from patients with RIF. Recombinant human BMP2 treatment upregulated integrin β3 (ITGB3) in a SMAD2/3-SMAD4 signaling-dependent manner in both HTR8/SVneo cells and primary trophoblast cells. siRNA-mediated integrin β3 downregulation reduced both basal and BMP2-upregulated trophoblast invasion and vascular mimicry in HTR8/SVneo cells. Importantly, shRNA-mediated ITGB3 knockdown significantly decreased the formation ability of human trophoblast organoids.

CONCLUSION

Our results demonstrate endometrial BMP2 deficiency in patients with RIF. ITGB3 mediates both basal and BMP2-promoted human trophoblast invasion and is essential for early placentation. These findings broaden our knowledge regarding the regulation of early placentation and provide candidate diagnostic and therapeutic targets for RIF clinical management.

A placental chorionic villous mesenchymal core cellular origin for infantile haemangioma

Aims

To investigate the expression of the placental cell-specific associated proteins in infantile haemangioma (IH).

Methods

Immunohistochemical staining was used to investigate the expression of human chorionic gonadotrophin (hCG), human placental lactogen (hPL), human leucocyte antigen-G (HLA-G), cytokeratin 7 (CK7) and smooth muscle actin in paraffin-embedded sections of proliferating and involuted IHs.

Results

The proteins hCG and hPL were expressed by the endothelium but not the pericyte layer of proliferating IH, but these proteins were not detected in involuted lesions. There was no expression of CK7 and HLA-G in IH.

Conclusions

The expression of hCG and hPL, but not CK7 or HLA-G, by the endothelium of proliferating IH supports a placental chorionic villous mesenchymal core cellular origin for IH rather than a trophoblast origin.

Automatic retrieval of single microchimeric cells and verification of identity by on-chip multiplex PCR

The analysis of rare cells is not an easy task. This is especially true when cells representing a fetal microchimerism are to be utilized for the purpose of non-invasive prenatal diagnosis because it is both imperative and difficult to avoid contaminating the minority of fetal cells with maternal ones. Under these conditions, even highly specific biochemical markers are not perfectly reliable. We have developed a method to verify the genomic identity of rare cells that combines automatic screening for enriched target cells (based on immunofluorescence labelling) with isolation of single candidate microchimeric cells (by laser microdissection and subsequent laser catapulting) and low-volume on-chip multiplex PCR for DNA fingerprint analysis. The power of the method was tested using samples containing mixed cells of related and non-related individuals. Single-cell DNA fingerprinting was successful in 74% of the cells analysed (55/74), with a PCR efficiency of 59.2% (860/1452) for heterozygous loci. The identification of cells by means of DNA profiling was achieved in 100% (12/12) of non-related cells in artificial mixtures and in 86% (37/43) of cells sharing a haploid set of chromosomes and was performed on cells enriched from blood and cells isolated from tissue. We suggest DNA profiling as a standard for the identification of microchimerism on a single-cell basis.

First trimester human endovascular trophoblast cells express both HLA-C and HLA-G

PROBLEM

In human pregnancies, trophoblasts, in contrast to placental connective tissue and the fetus itself, come into direct contact with the maternal allorecognizing system at special sites. Villous syncytiotrophoblasts washed around by maternal blood lack HLA class I proteins, whereas extravillous trophoblasts, which deeply invade maternal uterine tissues, express high amounts of HLA-G and also HLA-C, the latter to a lesser degree, however. A subpopulation of extravillous trophoblasts, the endovascular trophoblast, enters maternal spiral artery lumen and, like syncytiotrophoblast, comes into direct contact with maternal blood. Less is known about HLA class I distribution on this endovascular trophoblast subpopulation.

METHOD OF STUDY

A comparative immununohistochemical analysis was done on decidual cryo-sections containing trophoblast-invaded spiral arteries using different anti-HLA class I monoclonal antibodies (mAbs) and a peroxidase-labeled streptavidinbiotin detection system.

RESULTS

MAbs W6/32 (anti-HLA-A, -B, -C, -G), HCA2 (anti-HLA-A, -G) G233 and 87G (both anti-HLA-G) resulted in strong positivity on endovascular trophoblasts. L31 (anti-HLA-C) and HC10 (anti-HLA-B, -C) revealed clear positivity, whereas TU149 (anti-HLA-B, -C, some -A) produced a heterogeneous staining pattern, faintly positive on some endovascular trophoblastic cells and negative on others. MAb LA45 (anti-HLA-A, -B) did not bind to any endovascular trophoblast, neither did BFL.1 (anti-HLA-G) nor 16G1 (anti-HLA-G, soluble).

CONCLUSION

This study shows that trophoblastic cells belonging to the endovascular subpopulation express considerable amounts of HLA-G and slightly less HLA-C.

Fas and Fas-ligand are expressed in the uteroplacental unit of first-trimester pregnancy

PROBLEM

Fas and Fas-ligand (FasL) are thought to provide a strategy for reducing graft rejection in immunologically 'privileged' tissues by controlling injurious lymphocyte reactions. As the uteroplacental unit is often defined as an immune-privileged site, we investigated the expression of Fas and FasL in this tissue in the first trimester of pregnancy.

METHOD OF STUDY

Western blotting, immunohistochemistry, and double immunofluorescence were used for this examination.

RESULTS

Western blotting with purified first-trimester trophoblast cells revealed one specific band for FasL. The presence of FasL on different trophoblast populations could be confirmed by immunohistochemistry and double immunofluorescence. In the villous part of the placenta, FasL is mostly located on cytotrophoblast cells with no access to maternal blood flow, whereas in trophoblast-invaded uterine tissue, interstitial trophoblast cells, which are in close contact with maternal leukocytes, revealed a strong signal for FasL, but no staining for Fas on these cells. However, Fas was found on CD45+ maternal leukocytes.

CONCLUSION

Based on our experimental findings, we speculate that the abundant presence of FasL on trophoblast cells within the maternal decidua may play an important role in the maintenance of immune privilege in the pregnant uterus by endowing fetal trophoblast cells with a defense mechanism against activated maternal leukocytes, whereas in the villous part of the placenta, the Fas FasL system seems to be involved in the regulation of placental growth.