Fetal Liver Research Articles

Long-chain perfluoroalkylether carboxylic acids PFO5DoA and PFO4DA alter glucose, bile acid, and thyroid hormone homeostasis in fetal rats from 5-day maternal oral exposure

Chemical monitoring studies in North Carolina, USA and Shandong, China have reported detections of perfluoroalkylether carboxylic acids of increasing chain length with ether bonds between each fluorinated carbon. Despite detection there is limited hazard data available to inform risk assessment. Here, we exposed pregnant Sprague-Dawley rats to two of these compounds, perfluoro-3,5,7,9-butaoxadecanoic acid (PFO4DA) and perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoA), from gestation days 18-22 across a series of doses (0.3-62.5mg/kg/d) via oral gavage. PFO5DoA was acutely toxic to rat dams and fetuses at the top two doses (30 and 62.5mg/kg), while PFO4DA did not cause acute toxicity at any doses tested. PFO5DoA significantly increased maternal liver weight (≥3mg/kg; 28% increase at 10mg/kg) while PFO4DA did not affect maternal liver weight up to 62.5mg/kg. PFO4DA and PFO5DoA both significantly reduced serum total thyroxine in maternal (≥10mg/kg for both) and fetal (≥1mg/kg) rats. Both compounds significantly reduced fetal liver glycogen concentrations, increased fetal serum total bile acids, and altered expression levels of multiple genes associated with glucose metabolism in the fetal liver. Serum concentrations of PFO5DoA were higher than PFO4DA in both rat dams and fetuses at equivalent maternal oral doses indicating greater accumulation. Dose response modelling of several fetal endpoints as a function of serum molar concentration indicates PFO5DoA was ∼3-4-fold more potent than PFO4DA. PFO5DoA and PFO4DA produced maternal and fetal toxicity from short-term oral maternal exposure indicating need for additional toxicity data to evaluate potential human health risks.

Carvacrol modulates antioxidant enzymes, DNA integrity, and apoptotic markers in zearalenone-exposed fetal rat liver

Maternal exposure to zearalenone (ZEA), a mycotoxin, can impact fetal liver development. This study investigated the protective effects of carvacrol (CRV) against ZEA-induced fetal liver damage. Thirty-two pregnant rats were allocated to four groups (eight rats/group); control, CRV (75 mg/kg), ZEA (5 mg/kg), and co-treated group (ZEA + CRV). The animals were given their doses during the gestation period. Maternal exposure to ZEA revealed a significant increase in the malondialdehyde (MDA) level in the fetal liver. In contrast, glutathione S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activities, besides glutathione (GSH) levels, were decreased in ZEA-intoxicated rats. Additionally, ZEA increased the expression of pro-apoptotic genes (P53, Bax, and caspase-9), elevated the immunoreactivity of caspase-3, decreased anti-apoptotic Bcl-2, and induced severe fatty degeneration, congestion, and necrosis in the fetal liver. The comet assays revealed significant DNA damage, as evidenced by reduced head DNA content and increased tail DNA content and tail moment in the ZEA-exposed rats. Surprisingly, co-treatment with CRV significantly mitigated fetal hepatic lipid peroxidation, antioxidant disturbance, apoptosis, and DNA damage after maternal exposure to ZEA. These findings highlight the potential of CRV as a promising approach to mitigate ZEA-associated developmental hepatotoxicity.

Epigenetic modification of IGF2/H19 imprinting control region regulates PGC-1α/PI3K/AKT2 pathway in a rat model of intrauterine growth restriction.

Intrauterine growth restriction (IUGR) is associated with adverse metabolic outcomes during adulthood. Histone modifications and changes in DNA methylation-affected genes are important for fetal development. This study aimed to confirm the epigenetic mechanisms in IUGR. IUGR models were established in Sprague-Dawley rats using a maternal nutritional restriction approach during pregnancy. The abundance of insulin-like growth factor 2 (IGF2), phosphoinositide 3-kinase (PI3K), AKT serine/threonine kinase 2 (AKT2), and PPAR gamma coactivator 1 alpha (PGC-1α) was examined by real-time polymerase chain reaction (RT-PCR) and Western blotting analysis. Chromatin immunoprecipitation RT-PCR was employed to analyze histone modification in CCCTC-binding factor (CTCF)1-4 binding sites of the IGF2/H19 imprinting control region (ICR). The methylation states of CTCF1-4 binding sites were studied by pyrosequencing. The IUGR models were constructed successfully. IGF2 mRNA abundance in the placenta, fetal liver, and newborn liver was decreased in the IUGR group (P <0.01). Meanwhile, as compared with the control group, the expression levels of AKT2, PI3K, and PGC-1α were lower in newborn and 8-week-old livers in the IUGR group (P <0.05). In addition, knocking down IGF2 reduced the protein expression levels of AKT2-P and PGC-1α (P <0.05). In CTCF binding sites 1-4 of the IGF2/H19 ICR, AcH3 enrichment was significantly lower in CTCF1-3 in newborn and 8-week-old IUGR rats. H3K4me3 enrichment was significantly lower in the CTCF1-4 of newborn and 8-week-old IUGR groups (P <0.01). H3K9me2 enrichment was significantly higher in the IUGR group (P <0.01). The CpG dinucleotide methylation levels of CTCF1 and CTCF3, but not those of CTCF2 and CTCF4 binding sites in IUGR rat fetal, 4-week old, and 8-week-old livers decreased significantly (P <0.05). The methylation status and histone modification in the IGF2/H19 ICR are related to growth and lipid metabolism via the PGC-1α/PI3K/AKT2 pathway in IUGR rats.

Sex-bias metabolism of fetal organs, and their relationship to the regulation of fetal brain-placental axis.

The placenta plays influential role in the fetal development of mammals. But how the metabolic need of the fetal organs is related to that of the placenta, and whether this relationship is influenced by the sex of the fetus remain poorly understood. This study used pigs to investigate metabolomic signatures of male and female fetal organs, and determine the relevance of gene expression of the placenta and brain to the metabolism of peripheral organs. Untargeted metabolomics analysis was performed with the day-45 placenta, kidney, heart, liver, lung and brain of male and female pig fetuses to model sex differences in themetabolism of the peripheral organs relative to that of the brain and placenta. Transcriptomic analysis was performed to investigate the expression of metabolic genes in the placenta and fetal brain of both sexes. The results of this study show that the fetoplacental metabolic regulation was not only influenced by the fetal sex but also dependent on the metabolic requirement of theindividual organs of the fetus. Neural network modeling of metabolomics data revealed differential relationship of the metabolic changes of the peripheral organs with the placenta and fetal brain between males and females. RNA sequencing further showed that genes associated with themetabolism of the peripheral organs were differentially expressed in the placenta and fetal brain. The findings of this study suggest a regulatory role of the fetal brain and placenta axis in the sex-bias metabolism of the peripheral organs.

Human GM-CSF/IL-3 enhance tumor immune infiltration in humanized HCC patient-derived xenografts

Background & AimsResponses to immunotherapies in hepatocellular carcinoma (HCC) are suboptimal with no biomarkers to guide patient selection. “Humanized” mice represent promising models to address this deficiency but are limited by variable chimerism and underdeveloped myeloid compartments. We hypothesized that expression of human GM-CSF and IL-3 increases tumor immune cell infiltration, especially myeloid-derived cells, in humanized HCC patient-derived xenografts (PDXs). Material and MethodsNOG (NOD/Shi-scid/IL-2Rγnull) and NOG-EXL (huGM-CSF/huIL-3 NOG) mice conditioned with Busulfan underwent i.v. injection of human CD34+ cells. HCC PDX tumors were then implanted subcutaneously (SQ) or orthotopically (OT). Following serial blood sampling, mice were euthanized at defined tumor sizes. Tumor, blood, liver, and spleen were analyzed by flow cytometry and immunohistochemistry. ResultsHumanized NOG-EXL mice demonstrated earlier and increased human chimerism compared to humanized NOG mice (82.1% vs 43.8%, p<0.0001) with increased proportion of human monocytes (3.2% vs 1.1%, p=0.001) and neutrophils (0.8% vs 0.3%, p=0.02) in circulation. HCC tumors in humanized NOG-EXL mice had increased human immune cell infiltration (57.6% vs 30.2%, p=0.04), noting increased regulatory T cells (14.6% vs 6.8%, p=0.04), CD4+ PD-1 expression (84.7% vs 32.0%, p<0.01), macrophages (1.2% vs 0.6%, p=0.02), and neutrophils (0.5% vs 0.1%, p<0.0001). No differences were observed in tumor engraftment or growth latency in SQ tumors, but OT tumors required implantation at two rather than four weeks post-humanization for successful engraftment. Finally, utilizing adult bone marrow instead of fetal livers enabled partial HLA-matching to HCC tumors but required more CD34+ cells. ConclusionsHuman GM-CSF and IL-3 expression in humanized mice resulted in features more closely approximating the immune microenvironment of human disease, providing a promising model for investigating critical questions in immunotherapy for HCC. Impact and ImplicationsThis study introduces a unique mouse model at a critical point in the evolution of treatment paradigms for patients with hepatocellular carcinoma (HCC). Immunotherapies have become first line treatment for advanced HCC; however, response rates remain low with no clear predictors of response to guide patient selection. In this context, animal models that recapitulate human disease are greatly needed. Leveraging xenograft tumors derived from patients with advanced HCCs and a commercially available immunodeficient mouse strain that expresses human GM-CSF and IL-3, we demonstrate a novel but accessible approach for modeling the HCC tumor microenvironment.

Maternal and Cord Blood Levels of Metals and Fetal Liver Function

Exposure to metals during pregnancy has been associated with adverse birth outcomes, but its impact on fetal liver function remains poorly understood. This study for the first time aimed to investigate the association between maternal and umbilical cord blood Metals levels and umbilical liver enzymes. A comprehensive analysis was conducted on 450 mother-newborn pairs in 2022, measuring 13 Metals in serum samples from pregnant women during the third trimester and umbilical cord blood samples. Regression analyses were utilized to examine the relationship between levels of maternal and umbilical cord blood Metals and the levels of gamma-glutamyl transferase (GGT), umbilical alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). G-comp analyses evaluated the combined effect of metals exposure on umbilical liver enzymes. Elevated levels of certain Metals in cord blood and maternal samples were positively linked with increased umbilical GGT, ALP, ALT, and AST levels. Notably, zinc (Zn) levels in cord blood exhibited an inverse correlation with umbilical liver enzyme levels. Furthermore, g-comp analyses revealed significant positive associations between exposure to metals mixtures and umbilical liver enzyme levels. An increase of one quartile in the mixture of maternal and umbilical Metals was linked with 99.45 U/L (95% CI:37.72, 161.19, p < 0.01), 2.79 (95% CI: 0.92, 4.65, p < 0.01), and 87.17 (95% CI: 53.96, 120.38, p < 0.01) increase in ALP, ALT and GGT levels. Further examination of the weight of Metals revealed As, Cd, Ni, Pb, Hg and Cr with the highest positive effects and Zn with the highest negative effect in the mixture effect on the umbilical liver enzyme. In summary, our results underscore the potential influence of prenatal heavy metal exposure on fetal liver function.

Isolated Fetal Liver Calcifications: Case Report and Literature Review

ABSTRACTFetal liver calcifications (FLCs) are isolated or multiple areas of increased echogenicity in the fetal liver, with an estimated prevalence of 5–10 per 10 000 births. However, their clinical importance remains still unclear. Although they are often linked to infections, chromosomal disorders, thrombotic events, or tumors, isolated FLCs generally have a favorable outcome. This article aims to present a case of a 29‐year‐old pregnant woman with a low‐risk cfDNA test, who presented for the first trimester screening scan at our hospital at 12 weeks of pregnancy. The morphology scan at 20 weeks and 5 days revealed a normal fetal size with areas of increased echogenicity in the liver. No other fetal issues were identified. The patient was monitored throughout her pregnancy at our center, receiving genetic counseling and tests for detecting cystic fibrosis, STORCH (syphilis, cytomegalovirus, herpes virus 1;2, rubella, and toxoplasma), fetal echocardiography, and MRI, all of which were normal. At 35 weeks and 6 days, the patient gave birth to a healthy male, and all subsequent postnatal examinations confirmed the baby's health. This article aims to offer comprehensive insights into the management and postnatal outcomes of isolated FLCs, based on a review of the literature.

IGF1R signaling in perinatal mesenchymal stem cells determines definitive hematopoiesis in bone marrow

During the transition from embryonic to adult life, the sites of hematopoiesis undergo dynamic shifts across various tissues. In adults, while bone marrow becomes the primary site for definitive hematopoiesis, the establishment of the bone marrow niche for accommodating hematopoietic stem cells (HSCs) remains incompletely understood. Here, we reveal that perinatal bone marrow mesenchymal stem cells (BMSCs) exhibit highly activated insulin-like growth factor 1 receptor (IGF1R) signaling compared to adult BMSCs. Deletion of Igf1r in perinatal BMSCs hinders the transition of HSCs from the fetal liver to the bone marrow in perinatal mice and disrupts hematopoiesis in adult individuals. Conversely, the deletion of Igf1r in adult BMSCs, adipocytes, osteoblasts, or endothelial cells does not affect HSCs in the bone marrow. Mechanistically, IGF1R signaling activates the transcription factor nuclear factor of activated T cells c1 (NFATc1) in perinatal BMSCs, which upregulates CXCL12 and other niche factors for HSC retention. Overall, IGF1R signaling in perinatal BMSCs regulates the development of the bone marrow niche for hematopoiesis.

Transduction of Human Fetal Liver Hematopoietic CD34+ Stem and Progenitor Cells into a Cell Line by Enhancing Telomerase Activity

Background: Human fetal liver hematopoietic stem cells have proven potential as therapeutics but lack extensive research due to their limited supply. Even in vitro expanded fetal liver hematopoietic stem cells enter senescence or lose their self-renewal capacity after a few days in culture. The present study aimed to obtain a homogeneous and persistent supply of hematopoietic stem cells from the fetal liver by establishing a cell line through immortalization of cells by enhancing telomerase activity. Materials and Methods: Human fetal liver hematopoietic CD34+ stem and progenitor cells were transformed and immortalized using retroviruses carrying the human telomerase (hTERT) gene. Following transduction, telomerase activity was assessed using the TRAP assay and telomere length was examined by Southern blotting in transduced cells. Their characterization was conducted using flowcytometry to analyze the CD34+ population of hematopoietic stem cells and their colony forming potential using colony forming unit (CFU) assay. Results: After transduction with hTERT, the life span of human fetal liver hematopoietic CD34+ stem and progenitor cells were extended to 80 population doublings, without any change in cell morphology or population doubling times. Constitutive hTERT expression enhanced the replicative capacity and prevented terminal differentiation of CD34+ fetal liver hematopoietic stem and progenitor cells (FLHSPCs). Moreover, hTERT-transduced stem cells maintained their telomere length and telomerase activity. Conclusion: By introducing telomerase activity into hematopoietic stem and progenitor cells, their lifespan can be extended while maintaining stemness. These modified cells hold promise for in vitro research focused on studying hematopoietic stem cells derived from fetal liver.

Maternal NO2 exposure and fetal growth restriction: Hypoxia transmission and lncRNAs-proinflammation-mediated abnormal hematopoiesis

Epidemiological studies show a strong correlation between air pollution and fetal growth restriction (FGR), but existing results are controversial due to inherent limitations, such as causality of specific pollutants, developmental origin, and maternal-fetal transmission. To address this controversy, we first conducted a retrospective analysis of 28,796 newborns and revealed that maternal nitrogen dioxide (NO2) exposure during the second trimester was positively associated with FGR, with an adjusted odds ratio of 1.075 (95% confidence interval: 1.020-1.133) per 10 μg/m3 NO2 increase for small for gestational age. Then, by establishing an animal model of prenatal NO2 exposure, we confirmed its adverse effects on embryonic growth and hematopoiesis in the yolk sac and fetal liver, primarily affecting the differentiation of hematopoietic stem and progenitor cells and erythroid maturation. By applying internal exposure analyses coupled with 15N isotope tracing, we found that maternal NO2 inhalation induced acquired methemoglobinemia through its byproducts and placental hypoxia in pregnant mice. Importantly, by combining transcriptional profiling, bioinformatics analysis, and RNA binding protein immunoprecipitation (RIP)/chromatin immunoprecipitation (CHIP), we clarified that placental-fetal hypoxia transmission activated hypoxia-inducible factors, disturbed hematopoiesis through the hypoxia-inducible factor 1β-long noncoding RNAs-CCAAT/enhancer binding protein alpha-proinflammatory signaling pathway, ultimately contributing to FGR progression. These findings provide insights for risk prevention and clinical intervention to promote child well-being in NO2-polluted areas.

Loss of Bicra/Gltscr1 leads to a defect in fetal liver macrophages responsible for erythrocyte maturation in mice.

GLTSCR1, a protein encoded by the Bicra gene, is a defining subunit of the SWI/SNF (also called mammalian BAF) chromatin remodeling subcomplex called GBAF/ncBAF. To determine the role of GLTSCR1 during mouse development, we generated a Bicra germline knockout mouse using CRISPR/Cas9. Mice with homozygous loss of Bicra were born at Mendelian ratios but were small, pale and died within 24 hours after birth. Histology indicated blood-related defects including defective erythroblastic islands and irregularly sized red blood cells. Gene expression profiling of fetal livers pinpointed a defect in liver resident macrophages involved in the last stage of erythrocyte maturation, resulting in accumulation of nucleated erythrocytes in Bicra-/- pups. Together, these results demonstrate that Bicra is critical for fetal liver macrophage function during development.

Lung volumes are increased in fetuses with transposition of the great arteries on intrauterine MRI.

Fetal brain size is decreased in some children with complex CHDs, and the distribution of blood and accompanying oxygen and nutrients is regionally skewed from early fetal life dependent on the CHD. In transposition of the great arteries, deoxygenated blood preferentially runs to the brain, whereas the more oxygenated blood is directed towards the lungs and the abdomen. Knowledge of whether this impactsintrauterine organ development is limited. We investigated lung, liver, and total intracranial volume in fetuses with transposition of the great arteries using MRI.Eight fetuses with dextro-transposition and without concomitant disease or chromosomal abnormalities and 42 fetuses without CHD or other known diseases were scanned once or twice at gestational age 30 through 39 weeks. The MRI scans were conducted on a 1.5T system, using a 2D balanced steady-state free precession sequence. Slices acquired covered the entire fetus, slice thickness was 10 mm, pixel size 1.5 × 1.5 mm, and scan duration was 30 sec.The mean lung z score was significantly larger in fetuses with transposition compared with those without a CHD; mean difference is 1.24, 95% CI:(0.59;1.89), p < 0.001. The lung size, corrected for estimated fetal weight, was larger than in the fetuses without transposition; mean difference is 8.1 cm3/kg, 95% CI:(2.5;13.7 cm3/kg), p = 0.004.In summary, fetuses with dextro-transposition of the great arteries had both absolute and relatively larger lung volumes than those without CHD. No differences were seen in liver and total intracranial volume. Despite the small number of cases, the results are interesting and warrant further investigation.

Anti-LAN Antibodies: Clinical Implications and Case Presentation

Abstract Introduction/Objective The LAN system, originating from the 901 Series of High Incidence antigens, transitioned to a recognized System in 2012. The LAN antigen, situated on ABCB6, a multipass membrane protein associated with porphyrin transport, plays a crucial role in heme synthesis. Functionally, LAN acts as an ATP-binding cassette transporter on the red blood cell membrane. Comprising a single antigen, LAN exhibits elevated expression in various tissues including the heart, skeletal muscles, fetal liver, mitochondrial membrane, eye, and Golgi apparatus. Notably, LAN shows no specific association with any particular geographic or ethnic group. Resistant to Ficin/Papain, Trypsin, α-Chymotrypsin, and 0.2M DTT, LAN antibodies primarily consist of IgG and necessitate IAT for detection. While Anti-LAN has been implicated in Hemolytic Transfusion Reactions (HTRs), its involvement in Hemolytic Disease of the Fetus and Newborn (HDFN) remains infrequent. LAN-negative blood is exceedingly rare, often requiring Monocyte Monolayer Assay Testing (MMA) for clinical assessment. Methods/Case Report Case Presentation: An 81-year-old female with a medical history including seizure disorder, hypertension (HTN), hyperlipidemia (HLD), gastroesophageal reflux disease (GERD), small bowel obstruction, and high-grade de-differentiated metastatic retroperitoneal liposarcoma presented for preoperative evaluation. A type and screen ordered as part of outpatient preoperative assessments revealed a positive antibody screen. Further investigation traced the origin of the anti-LAN antibody to an external facility since 2017. Antibody identification indicated the reactivity of the patient’s plasma with all cells (1+ AHG in PEG), excluding the auto control. Utilizing rare frozen antisera anti-LAN, the patient was phenotyped for LAN, yielding a LAN-negative status. Subsequent testing with three rare frozen LAN-negative group O cells aimed to exclude clinically significant antibodies. Differential adsorption, employing a comprehensive baseline RBC phenotype record obtained from the external facility, ruled out anti-E, anti-K, and anti-Fyb, thereby confirming Anti-LAN specificity. Results (if a Case Study enter NA) NA Conclusion The exceptional rarity of LAN-negative blood underscores the high prevalence of reactivity to Anti-LAN antibodies, exceeding 99% in most populations. In select cases, autologous transfusion may emerge as a viable management strategy. Consequently, the patient’s surgical procedure has been deferred, with no immediate requirement for blood products.

Fetal Liver-like Organoids Recapitulate Blood-Liver Niche Development and Multipotent Hematopoiesis from Human Pluripotent Stem Cells.

The fetal liver is a hematopoietic organ, hosting a diverse and evolving progenitor population. While human liver organoids derived from pluripotent stem cells (PSCs) mimic aspects of embryonic and fetal development, they typically lack the complex hematopoietic niche and the interaction between hepatic and hematopoietic development. We describe the generation of human Fetal Liver-like Organoids (FLOs), that model human hepato-hematopoietic interactions previously characterized in mouse models. Developing FLOs first integrate a yolk sac-like hemogenic endothelium into hepatic endoderm and mesoderm specification. As the hepatic and hematopoietic lineages differentiate, the FLO culture model establishes an autonomous niche capable of driving subsequent progenitor differentiation without exogenous factors. Consistent with yolk sac-derived waves, hematopoietic progenitor cells (HPCs) within FLOs exhibit multipotency with a preference for myeloid lineage commitment, while retaining fetal B and T cell differentiation potential. We reconstruct in FLOs the embryonic monocyte-to-macrophage and granulocyte immune trajectories within the FLO microenvironment and assess their functional responses in the liver niche. In vivo, FLOs demonstrate a liver engraftment bias of hematopoietic cells, recapitulating a key phenomenon of human hematopoietic ontogeny. Our findings highlight the intrinsic capacity of liver organoids to support hematopoietic development, establishing FLOs as a platform for modeling and manipulating human blood-liver niche interactions during critical stages of development and disease.

Silencing of maternally expressed RNAs in Dlk1-Dio3 domain causes fatal vascular injury in the fetal liver

The mammalian imprinted Dlk1-Dio3 domain contains multiple lncRNAs, mRNAs, the largest miRNA cluster in the genome and four differentially methylated regions (DMRs), and deletion of maternally expressed RNA within this locus results in embryonic lethality, but the mechanism by which this occurs is not clear. Here, we optimized the model of maternally expressed RNAs transcription termination in the domain and found that the cause of embryonic death was apoptosis in the embryo, particularly in the liver. We generated a mouse model of maternally expressed RNAs silencing in the Dlk1-Dio3 domain by inserting a 3 × polyA termination sequence into the Gtl2 locus. By analyzing RNA-seq data of mouse embryos combined with histological analysis, we found that silencing of maternally expressed RNAs in the domain activated apoptosis, causing vascular rupture of the fetal liver, resulting in hemorrhage and injury. Mechanistically, termination of Gtl2 transcription results in the silencing of maternally expressed RNAs and activation of paternally expressed genes in the interval, and it is the gene itself rather than the IG-DMR and Gtl2-DMR that causes the aforementioned phenotypes. In conclusion, these findings illuminate a novel mechanism by which the silencing of maternally expressed RNAs within Dlk1-Dio3 domain leads to hepatic hemorrhage and embryonic death through the activation of apoptosis.

The evolving hematopoietic niche during development.

Mammalian hematopoietic stem cells (HSCs) emerge from the hemogenic endothelium in the major embryonic arteries. HSCs undergo a complex journey first migrating to the fetal liver (FL) and from there to the fetal bone marrow (FBM), where they mostly remain during adult life. In this process, a pool of adult HSCs is produced, which sustains lifelong hematopoiesis. Multiple cellular components support HSC maturation and expansion and modulate their response to environmental and developmental cues. While the adult HSC niche has been extensively studied over the last two decades, the niches present in the major embryonic arteries, FL, FBM and perinatal bone marrow (BM) are poorly described. Recent investigations highlight important differences among FL, FBM and adult BM niches and emphasize the important role that inflammation, microbiota and hormonal factors play regulating HSCs and their niches. We provide a review on our current understanding of these important cellular microenvironments across ontogeny. We mainly focused on mice, as the most widely used research model, and, when possible, include relevant insights from other vertebrates including birds, zebrafish, and human. Developing a comprehensive picture on these processes is critical to understand the earliest origins of childhood leukemia and to achieve multiple goals in regenerative medicine, such as mimicking HSC development in vitro to produce HSCs for broad transplantation purposes in leukemia, following chemotherapy, bone marrow failure, and in HSC-based gene therapy.

Cadmium-induced fetal erythropoiesis disturbances in mice

Maternal anemia has been identified as a contributing factor to adverse reproductive outcomes associated with cadmium (Cd) exposure, a common heavy metal. Our recent findings suggest that inhibited erythroid differentiation and enucleation also play significant roles in the direct embryonic toxicity resulting from maternal Cd exposure. However, the effects of Cd exposure on lipid metabolism remodeling, which is essential for physiological erythropoiesis, remain poorly understood. In the present study, pregnant mice were administered low doses of CdCl2 via oral exposure from early to late gestation to mitigate Cd-induced maternal anemia. Compared to vehicle-treated controls, embryos from Cd-treated mice exhibited a slight decrease in weight, though without signs of atrophy. Consistent with our previous observations, fetal livers from Cd-exposed embryos demonstrated a dose-dependent inhibition of erythroid differentiation, as confirmed by ex vivo analysis. Notably, an intrinsic decrease in lipid peroxidation during erythroid differentiation was observed in the bone marrow and fetal livers of vehicle-treated mice, attributed to diminished lipid content. In contrast, this decrease in lipid peroxidation was absent in fetal liver erythroblasts from Cd-treated mice, where an increase in lipid peroxidation was instead noted. These findings elucidate a potential mechanism, lipid peroxidation, underlying Cd-induced embryonic toxicity.

Single-cell multi-omics map of human fetal blood in Down syndrome

Down syndrome predisposes individuals to haematological abnormalities, such as increased number of erythrocytes and leukaemia in a process that is initiated before birth and is not entirely understood1–3. Here, to understand dysregulated haematopoiesis in Down syndrome, we integrated single-cell transcriptomics of over 1.1 million cells with chromatin accessibility and spatial transcriptomics datasets using human fetal liver and bone marrow samples from 3 fetuses with disomy and 15 fetuses with trisomy. We found that differences in gene expression in Down syndrome were dependent on both cell type and environment. Furthermore, we found multiple lines of evidence that haematopoietic stem cells (HSCs) in Down syndrome are ‘primed’ to differentiate. We subsequently established a Down syndrome-specific map linking non-coding elements to genes in disomic and trisomic HSCs using 10X multiome data. By integrating this map with genetic variants associated with blood cell counts, we discovered that trisomy restructured regulatory interactions to dysregulate enhancer activity and gene expression critical to erythroid lineage differentiation. Furthermore, as mutations in Down syndrome display a signature of oxidative stress4,5, we validated both increased mitochondrial mass and oxidative stress in Down syndrome, and observed that these mutations preferentially fell into regulatory regions of expressed genes in HSCs. Together, our single-cell, multi-omic resource provides a high-resolution molecular map of fetal haematopoiesis in Down syndrome and indicates significant regulatory restructuring giving rise to co-occurring haematological conditions.

Dendritic cell-specific deletion of PKCδ in offspring of allergic mothers prevents the predisposition for development of allergic lung inflammation in offspring.

In humans and in mice, maternal allergy predisposes offspring to development of allergy. In murine models, increased levels of maternal β-glucosylceramides are both necessary and sufficient for the development of allergic predisposition in offspring. Furthermore, increased numbers of CD11b+ dendritic cell subsets in the offspring of allergic mothers are associated with allergic predisposition. In vitro, β-glucosylceramides increase CD11b+ dendritic cell subset numbers through increased PKCδ signaling but it is not known if enhanced PKCδ signaling in dendritic cells is required in vivo. We demonstrate that dendritic cell-specific deletion of PKCδ prevents the β-glucosylceramide-induced increase in CD11b+ dendritic cell subset numbers both in vitro as well as in vivo in the fetal liver of offspring of mothers injected with β-glucosylceramides. Furthermore, dendritic cell-specific deletion of PKCδ in offspring prevents the maternal allergy-induced increase in CD11b+ dendritic cell subsets and decreases allergen-induced IL-5 and eosinophilia in lungs of offspring. However, loss of PKCδ in dendritic cells did not prevent development of allergen-specific IgE. Our study provides mechanistic insight into the function of PKCδ in the origins of allergic disease beginning in utero as well as the development of postnatal allergic lung inflammation.

Fetal hemochromatosis: rare case of hepatic and extrahepatic siderosis involving thyroid on fetal MRI

BackgroundNeonatal hemochromatosis (NH) is a rare condition that is characterized by severe neonatal liver disease in association with hepatic and extrahepatic excess iron deposition (siderosis), while sparing the reticuloendothelial system. The most common cause of fetal liver injury leading to the NH phenotype (accounting for over 95% of cases) is gestational alloimmune liver disease. This condition is caused by the transfer of maternal IgG antibodies through the placenta, targeting a fetal hepatocyte antigen. Prenatal diagnosis, particularly the identification of iron overload involving both liver and thyroid, is of significant importance and can have a profound impact on patient care. To our knowledge, no case has been reported on prenatal diagnosis of iron overload involving both liver and thyroid.Case presentationWe present an exceptionally rare case of fetal hemochromatosis in a primigravida, a case that significantly contributes to our understanding of this condition. The diagnosis was made with the presence of hepatic and extrahepatic siderosis involving the thyroid using Ultrasonography (USG) and fetal Magnetic Resonance Imaging (MRI) findings. A 23-year-old primigravida was referred to our center in view of oligohydramnios, Intrauterine Growth Restriction (IUGR) and echogenic bowel at 29 weeks of gestation. USG and fetal MRI showed features of coarse liver echotexture and iron overload involving the liver and thyroid; this is the first case describing iron accumulation in the fetal thyroid gland diagnosed in utero.ConclusionThis case underscores the critical importance of performing MRI in suspected cases of fetal hemochromatosis for early diagnosis and intervention, emphasizing the potential to significantly improve patient outcomes.