Amniotic fluid embolism: a reappraisal

OBJECTIVES

Using cases from our own experience and from the published literature on amniotic fluid embolism (AFE), we seek to improve on existing criteria for diagnosis and discern associated risk factors. Additionally, we propose a novel theory of pathophysiology.

METHODS

This retrospective case review includes eight cases of AFE from two hospital systems and 21 from the published literature. All cases were evaluated using the modified criteria for research reporting of AFE by Clark et al. in Am J Obstet Gynecol, 2016;215:408-12 as well as our proposed criteria for diagnosis. Additional clinical and demographic characteristics potentially correlated with a risk of AFE were included and analyzed using descriptive analysis.

RESULTS

The incidence of AFE was 2.9 per 100,000 births, with five maternal deaths in 29 cases (17.2 %) in our series. None of the cases met Clark's criteria while all met our criteria. 62.1 % of patients were over the age of 32 years and two out of 29 women (6.9 %) conceived through in-vitro fertilization. 6.5 % of cases were complicated by fetal death. Placenta previa occurred in 13.8 %. 86.2 % of women had cesarean sections of which 52.0 % had no acute maternal indication.

CONCLUSIONS

Our criteria identify more patients with AFE than others with a low likelihood of false positives. Clinical and demographic associations in our review are consistent with those previously reported. A possible relationship between cesarean birth and risk of AFE was identified using our criteria. Additionally, we propose a new hypothesis of pathophysiology.

Stratification of Amniotic Fluid Cells and Amniotic Fluid by Sex Opens Up New Perspectives on Fetal Health

Amniotic fluid is essential for fetus wellbeing and is used to monitor pregnancy and predict fetal outcomes. Sex affects health and medicine from the beginning of life, but knowledge of its influence on cell-depleted amniotic fluid (AF) and amniotic fluid cells (AFCs) is still neglected. We evaluated sex-related differences in AF and in AFCs to extend personalized medicine to prenatal life. AFCs and AF were obtained from healthy Caucasian pregnant women who underwent amniocentesis at the 16th-18th week of gestation for advanced maternal age. In the AF, inflammation biomarkers (TNFα, IL6, IL8, and IL4), malondialdehyde, nitrites, amino acids, and acylcarnitines were measured. Estrogen receptors and cell fate (autophagy, apoptosis, senescence) were measured in AFCs. TNFα, IL8, and IL4 were higher in female AF, whereas IL6, nitrites, and MDA were similar. Valine was higher in male AF, whereas several acylcarnitines were sexually different, suggesting a mitochondrial involvement in establishing sex differences. Female AFCs displayed higher expression of ERα protein and a higher ERα/ERβ ratio. The ratio of LC3II/I, an index of autophagy, was higher in female AFCs, while LC3 gene was similar in both sexes. No significant sex differences were found in the expression of the lysosomal protein LAMP1, while p62 was higher in male AFCs. LAMP1 gene was upregulated in male AFCs, while p62 gene was upregulated in female ones. Finally, caspase 9 activity and senescence linked to telomeres were higher in female AFCs, while caspase 3 and β-galactosidase activities were similar. This study supports the idea that sex differences start very early in prenatal life and influence specific parameters, suggesting that it may be relevant to appreciate sex differences to cover knowledge gaps. This might lead to improving the diagnosis of risk prediction for pregnancy complications and achieving a more satisfactory monitoring of fetus health, even preventing future diseases in adulthood.

Evaluating the Clinical Application of Automatic Chromosome Harvesting for Prenatal Karyotype Analysis

Objective: The clinical value of an automatic chromosome harvester was evaluated, which included a comparison between the manual and automatic harvesting for the isolation of amniotic fluid cell chromosomes. Methods: Amniotic fluid samples from 96 high-risk gravida cases identified at 17-25 weeks treated at the Prenatal Diagnostic and Reproductive Center from June to July 2022 were collected. These samples underwent both manual and automatic chromosome collection, and their harvest time and number of amniotic cells were compared. These chromosomes were then used to produce karyotypic data for each sample using an automatic chromosomal karyotype analysis system, scan karyotype. Results: The average automatic harvesting time per sample, 3.92 min, was significantly lower than that of the manual harvesting, 7.89 min (p < 0.001). In addition, the average number of cells from the automatic harvesting (4.16 × 106 pieces) was significantly increased when compared with those of the manual group (2.10 × 106 pieces; p < 0.001). Further karyotyping revealed that both sets of chromosomes produced clear bands and good dispersion data, producing no significant differences in these evaluations (p > 0.05). However, the number of analyzable karyotypes obtained using the automatic harvester was significantly higher than those of the manual harvesting (p < 0.001). Conclusions: The automatic chromosome harvester can effectively save time, manual labor and consumables, harvest more analyzable karyotypes, and improve the efficiency of clinical diagnosis. The automatic chromosome harvester is highly stable and repeatable, which has the potential to help achieve large-scale standardized chromosome harvesting and is worthy of widespread clinical promotion.

scRNA-Seq of Cultured Human Amniotic Fluid from Fetuses with Spina Bifida Reveals the Origin and Heterogeneity of the Cellular Content

Amniotic fluid has been proposed as an easily available source of cells for numerous applications in regenerative medicine and tissue engineering. The use of amniotic fluid cells in biomedical applications necessitates their unequivocal characterization; however, the exact cellular composition of amniotic fluid and the precise tissue origins of these cells remain largely unclear. Using cells cultured from the human amniotic fluid of fetuses with spina bifida aperta and of a healthy fetus, we performed single-cell RNA sequencing to characterize the tissue origin and marker expression of cultured amniotic fluid cells at the single-cell level. Our analysis revealed nine different cell types of stromal, epithelial and immune cell phenotypes, and from various fetal tissue origins, demonstrating the heterogeneity of the cultured amniotic fluid cell population at a single-cell resolution. It also identified cell types of neural origin in amniotic fluid from fetuses with spina bifida aperta. Our data provide a comprehensive list of markers for the characterization of the various progenitor and terminally differentiated cell types in cultured amniotic fluid. This study highlights the relevance of single-cell analysis approaches for the characterization of amniotic fluid cells in order to harness their full potential in biomedical research and clinical applications.

Amniotic Fluid Cells, Stem Cells, and p53: Can We Stereotype p53 Functions?

In recent years, great interest has been devoted to finding alternative sources for human stem cells which can be easily isolated, ideally without raising ethical objections. These stem cells should furthermore have a high proliferation rate and the ability to differentiate into all three germ layers. Amniotic fluid, ordinarily discarded as medical waste, is potentially such a novel source of stem cells, and these amniotic fluid derived stem cells are currently gaining a lot of attention. However, further information will be required about the properties of these cells before they can be used for therapeutic purposes. For example, the risk of tumor formation after cell transplantation needs to be explored. The tumor suppressor protein p53, well known for its activity in controlling Cell Prolif.eration and cell death in differentiated cells, has more recently been found to be also active in amniotic fluid stem cells. In this review, we summarize the major findings about human amniotic fluid stem cells since their discovery, followed by a brief overview of the important role played by p53 in embryonic and adult stem cells. In addition, we explore what is known about p53 in amniotic fluid stem cells to date, and emphasize the need to investigate its role, particularly in the context of cell tumorigenicity.

p53 Is Active in Human Amniotic Fluid Stem Cells

Despite increasing interest in human amniotic fluid cells, very little is known about the regulation and function of p53 in this cell type. In this study, we show that undifferentiated human amniotic fluid cells express p53, yet at lower levels than in cancer cells. The p53 protein in amniotic fluid cells is mainly localized in the nuclei, however, its antiproliferative activity is compromised in these cells. Igf2, a maternal imprinted gene, and c-jun, a proto-oncogene, are regulated by p53 in these cells. DNA damage leads to an increase in p53 abundance in human amniotic fluid cells and to transcriptional activation of its target genes. Interestingly, cell differentiation toward the neural lineage leads to p53 induction as differentiation progresses.

Adenovirus E1A/E1B Transformed Amniotic Fluid Cells Support Human Cytomegalovirus Replication

The human cytomegalovirus (HCMV) replicates to high titers in primary human fibroblast cell cultures. A variety of primary human cells and some tumor-derived cell lines do also support permissive HCMV replication, yet at low levels. Cell lines established by transfection of the transforming functions of adenoviruses have been notoriously resistant to HCMV replication and progeny production. Here, we provide first-time evidence that a permanent cell line immortalized by adenovirus type 5 E1A and E1B (CAP) is supporting the full HCMV replication cycle and is releasing infectious progeny. The CAP cell line had previously been established from amniotic fluid cells which were likely derived from membranes of the developing fetus. These cells can be grown under serum-free conditions. HCMV efficiently penetrated CAP cells, expressed its immediate-early proteins and dispersed restrictive PML-bodies. Viral DNA replication was initiated and viral progeny became detectable by electron microscopy in CAP cells. Furthermore, infectious virus was released from CAP cells, yet to lower levels compared to fibroblasts. Subviral dense bodies were also secreted from CAP cells. The results show that E1A/E1B expression in transformed cells is not generally repressive to HCMV replication and that CAP cells may be a good substrate for dense body based vaccine production.

The effects of prenatal genetic analysis on fetuses born to carrier mothers with primary immunodeficiency diseases

OBJECTIVE

Prenatal genetic analysis in primary immunodeficiency diseases (PIDs) can decrease morbidity and mortality.

METHODS

We compared the postnatal prognoses of index cases and their subsequent sibling-fetuses using prenatal genetic analysis.

RESULTS

From 2007 to 2014, 14 sibling-fetuses receiving a prenatal diagnosis born to four mothers with WAS, three with X-CGD, and one each with IPEX, XLA and severe combined immunodeficiency [RAG2-SCID] were recruited. There were six affected, two carriers, and six wild types. Among the six affected, four [3X-CGD and 1RAG2-SCID] were terminated and two [1WAS and 1X-CGD] with early prophylactics underwent successful hematopoietic stem cell transplantation (HSCT) without infection. In the 12 index cases with a postnatal diagnosis, eight died (five due to infections and one each due to refractory bleeding, severe diarrhea, and post-transplant pneumothorax), two X-CGD underwent reconstituted HSCT after recurrent life-threatening infections, one WAS developed malignancy, and another WAS developed autoimmune disorders despite the administration of prophylactics and regular immunoglobulin infusion.

CONCLUSION

Instead of recurrent life-threatening infections leading to mortality in the postnatal diagnosis group, the severe PIDs who received early prophylactics were cured by HSCT, and all of mortality were terminations in the prenatal diagnosis group. Further large-scale studies are needed to validate this beneficial effect. Key message Prenatal genetic analysis in fetuses born to PIDs carrier mothers allows for the affected fetuses to receive optimal management including prophylactics against infections and HSCT if indicated. Patients with PIDs diagnosed postnatally who are prone to severe infections have higher rates of morbidity and mortality than their subsequent siblings who have a prenatal genetic diagnosis.

Levels of CD105+ cells increase and cell proliferation decreases during S-phase arrest of amniotic fluid cells in long-term culture

The present study aimed to improve the characterization of amniotic fluid cells (AFCs) in order to optimize their use in chromosomal prenatal diagnosis and as seed or stem cells for tissue engineering. The AFCs used in the current study were obtained from three females in their second trimester of pregnancy. The cells were cultured independently and characterized by cell morphology, cell markers, cell cycle distribution and chromosome Giemsa banding in an early- and late-passage. The AFCs remained homogeneous in culture and expressed mesenchymal markers, but not endothelial markers along the culture process. In addition, compared with the early-passage cells, the late-passage cells exhibit an increase in CD105 expression, a decrease in cell division and a delay in the cell cycle, and a number of cells underwent cell cycle arrest. However, the cells retained a normal karyotype. Therefore, the current study characterized AFCs in a clinical culture and confirmed that AFCs are mesenchymal precursors. The results obtained may be useful for the application of AFCs in prenatal diagnosis.

Titanium dioxide nanoparticles induce cytotoxicity and reduce mitotic index in human amniotic fluid-derived cells

Titanium dioxide (TiO2) nanoparticles (NPs) are commonly used materials present in many consumables for which most people are exposed to. The biological hazards of the NPs on human health have been demonstrated previously. In this study, we aimed to assess the cytotoxicity potency of TiO2 NPs on the primary human amniotic fluid cells. The cells derived from amniotic fluid were treated with different dosages of TiO2 NPs for some periods. Cell adhesion status was assessed using a light microscopic observation. Cell proliferation and cell death rates were determined using trypan blue staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Also, mitotic index was determined using fluorescence in situ hybridization with chromosome 8 centromer-specific DNA probe. Disrupted cell adhesion, decreased proliferation, and increased mortality rates were detected in the cells that were treated with TiO2 NPs depending on the dosage (p < 0.001). Also, reduced mitotic index was determined in the cells depending on the time and TiO2 dosage when compared with the controls (p < 0.0001). These results showed that TiO2 NPs have high cytotoxicity for amniotic fluid-derived cells. Therefore, different products containing TiO2 NPs should be used with care, especially for pregnant women.