Term Placenta Research Articles

Emerging models of human and non-human primate placental development - Centre for Trophoblast Research 17th annual meeting 2024.

The 17th annual meeting of the Centre for Trophoblast Research (CTR) took place at the University of Cambridge, UK, on 1-2 July 2024. This year's meeting provided an opportunity to reflect on the significant advancements made recently in modelling the human placenta in vitro. The meeting featured 12 invited speakers and attracted 260 participants from 25 countries. Many of the speakers were leading figures who have developed methods to derive human trophoblast stem cells or organoids from first trimester and term placentas, and from pluripotent stem cells. Accompanying the invited presentations were flash talks selected from the abstract submissions and poster presentations. The meeting concluded with a stimulating panel discussion to evaluate the current human trophoblast models. This Meeting Review aims to capture the spirit of the event and highlight the key themes and take-home messages that emerged.

Organoid generation from trophoblast stem cells highlights distinct roles for cytotrophoblasts and stem cells in organoid formation and expansion.

BackgroundOrganoids are stem-cell derived, self-organised, three-dimensional cultures that improve in vitro recapitulation of tissue structure. The generation of trophoblast organoids using primary placental villous digests (containing cytotrophoblasts and trophoblast stem cells (TSC)) improved high-throughput assessment of early trophoblast differentiation. However, the relative contributions of cytotrophoblasts and TSCs to trophoblast organoid growth and differentiation remain unclear, with implications for model interpretation. Here we sought to generate organoids from side-population trophoblasts (SpTSCs) to better understand the contribution of TSC to trophoblast organoid formation. MethodsMethods were adapted from Haider et al., 2018 to generate organoids from Okae TSCs (OkTSCs) or SpTSCs. Organoid growth was compared with primary villous trophoblast organoids and cellular composition interrogated by immunohistochemistry. ResultsOrganoids can be derived from first-trimester SpTSCs that exhibit similar architecture to those from primary villous trophoblast. However, organoids established from pure TSC populations (OkTSC or SpTSC) have different growth dynamics to primary placental villous digest-derived organoids – with OkTSCs developing faster and spontaneously generating migratory cells, whilst SpTSC organoids grow more slowly. Importantly, depletion of SpTSC from first-trimester villous digests ablates organoid formation. Finally, the capacity of the side-population technique to isolate late-gestation TSC enabled the generation of trophoblast organoids from term placentae, although these were significantly smaller than their first-trimester SpTSC counterparts. DiscussionTogether, this work highlights the requirement of TSC for organoid formation, and the functional distinction between TSC and cytotrophoblasts. Proof-of-principle data demonstrating organoid generation from late gestation TSC isolated directly from the placenta lays the groundwork for future disease models.

Discovery of a multipotent cell type from the term human placenta.

We report a population of multipotent cells isolated from term human placentas, for the first time, that differentiates into cardiomyocytes and vascular cells with clonal ability, migratory ability, and trancriptomic evidence of immune privilege. Caudal-type homeobox-2 (CDX2) is a conserved factor that regulates trophectoderm formation and placentation during early embryonic development but has not previously been implicated in developmentally conserved regenerative mechanisms. We earlier reported that murine Cdx2 cells restored cardiac function after intravenous delivery in male mice with experimental myocardial infarction (MI). Here we demonstrate that CDX2 cells found in human chorion are poised for cardiovascular differentiation. We isolated CDX2 cells from term placentas of 150 healthy patients and showed that they spontaneously differentiate into cardiomyocytes, functional vascular cells, and retain homing ability in vitro with a transcriptome that supports enhanced cardiogenesis, vasculogenesis, immune modulation, and chemotaxis gene signatures. They restore cardiac function when administered to NOD/SCID mice subjected to MI. CDX2 cells can be clonally propagated in culture with retention of cardiovascular differentiation. Our data compels further use of this ethically feasible cell source in the design of therapeutic strategies for cardiovascular disease.

The autophagy process and oxidized LDL independently modulate the invasion and differentiation of extravillous trophoblastic cells to an endothelial-like phenotype in normoxia

IntroductionThe mechanisms leading to proper placentation are not fully understood. Extravillous trophoblasts (EVTs) are crucial for placentation through invasion and vascular remodeling, which, when impaired, promote a poor placentation. How autophagy could regulate EVTs function and the study of regulators of these processes, such as oxidized low-density lipoproteins (ox-LDL), could contribute to better understand events associated with pregnancy complications related to abnormal placental development, such as preeclampsia (PE). AimTo investigate the role of autophagy and oxidized LDL (ox-LDL) in invasion and endothelial-like phenotype acquisition of a model of EVTs, as well as to determine the levels of autophagy flux markers in control and PE placentas. MethodsInvasion and endothelial-like phenotype acquisition assays were performed in a cell line model of first trimester EVTs: HTR-8/SVneo cultured in normoxia (oxygen concentration of 20 %), in the absence or the presence of the autophagy inhibitor bafilomycin or/and ox-LDL. Markers of autophagic flux were evaluated in human term placentas. ResultsAutophagy is essential for EVTs to acquire an endothelial-like phenotype but does not affect invasion. Conversely, ox-LDL decreases invasion and reticular structures formation, independent of autophagy. At pregnancy term, the levels of the autophagy markers LC3 and p62 are deregulated in the trophoblast cells of PE placentas. ConclusionAutophagy is necessary for proper endothelial-like phenotype acquisition in HTR-8/SVneo cultured in normoxia, and ox-LDL impairs this process as well as the invasion of EVTs by a mechanism independent of autophagy. Changes in autophagy and/or in the concentration of ox-LDL could affect placental vascular remodeling.

Sex-specific phenotypical, functional and metabolic profiles of human term placenta macrophages

BackgroundPlacental macrophages, Hofbauer cells (HBC) are the only fetal immune cell population within the stroma of healthy placenta along pregnancy. They are central players in maintaining immune tolerance during pregnancy. Immunometabolism emerged a few years ago as a new field that integrates cellular metabolism with immune responses, however, the immunometabolism of HBC has not been explored yet. Here we studied the sex-specific differences in the phenotypic, functional and immunometabolic profile of HBC.MethodsHBC were isolated from human term placentas (N = 31, 16 from male and 15 female neonates). Ex vivo assays were carried out to assess active metabolic and endoplasmic reticulum stress pathways by flow cytometry, confocal microscopy, gene expression and in silico approaches.ResultsHBC from female placentas displayed a stronger M2 phenotype accompanied by high rates of efferocytosis majorly sustained on lipid metabolism. On the other hand, male HBC expressed a weaker M2 phenotype with higher glycolytic metabolism. LPS stimulation reinforced the glycolytic metabolism in male but not in female HBC. Physiological endoplasmic reticulum stress activates IRE-1 differently, since its pharmacological inhibition increased lipid mobilization, accumulation and efferocytosis only in female HBC. Moreover, differential sex-associated pathways accompanying the phenotypic and functional profiles of HBC appeared related to the placental villi environment.ConclusionsThese results support sex-associated effects on the immunometabolism of the HBC and adds another layer of complexity to the intricate maternal-fetal immune interaction.Graphical abstract

Surveillance for Toxoplasma gondii, Brucella spp., and Chlamydia spp. in Australian Fur Seal (Arctocephalus pusillus doriferus) Abortions.

The intracellular pathogens Toxoplasma gondii, Brucella spp., and Chlamydia spp. are all known causative agents of abortion in wildlife. Both T. gondii and Brucella spp. have been identified in marine mammal abortions and a limited number of studies have detected their potential presence in Australian fur seals (Arctocephalus pusillus doriferus), but data are sparse for these pathogens in Australian fur seal breeding colonies. Australian fur seals have been shown to have a high degree of third-trimester pregnancy loss in one of their largest breeding colonies. Additionally, pup production has declined at the largest breeding colony for the species. This study surveyed the presence of T. gondii, Brucella spp., and Chlamydia spp. as potential infectious causes of this reproductive loss. Aborted fetuses were collected from two of the largest breeding colonies for the species, Seal Rocks (n=19) and Kanowna Island (n=34). These were examined grossly and through histopathological evaluation, in conjunction with molecular testing for all three pathogens. Placentas were collected from full-term births during the pupping season from Kanowna Island (n=118). These were used to compare the molecular prevalence of the three pathogens in presumed successful pregnancies. Chlamydia spp. was not detected in aborted fetuses in this study. Brucella spp. was detected with PCR in both aborted fetuses (9.4%) and placentas from full-term births (3.4%), and T. gondii was detected using routine histopathology (n=2/53), immunohistochemistry (n=3/4), and PCR (n=4/53) in tissues from aborted fetuses. Toxoplasma gondii was present in 7.5% of third-trimester abortions and absent from all full-term placentas. Brucella spp. was detected in both aborted fetuses and full-term placentas. This is the first description of vertical transmission of T. gondii in a marine mammal from the southern hemisphere.

Pathologic findings of the placenta and clinical implications - recommendations for placental examination.

The placenta is a unique and complex organ that combines the circulatory systems of two or more individuals within a single dynamic organ with a set, short lifespan. A diverse spectrum of disorders, including infections as well as metabolic, genetic, circulatory, and maturation defects, may affect its function. Pathology investigation of the placenta is key for identifying several pathogenic processes in both the mother and the foetus. Aberrant placentation, maternal and foetal vascular compromise, infection, inflammatory immunologic conditions, and disorders of maturation are elements of newly proposed classification schemes. The clinical impact of placental examination consists of diagnosing maternal and foetal disease, identifying the potential for recurrence, correlating clinical pathological findings with distinct morphologic features, and identifying the aetiology responsible for growth restriction or foetal death. Gestational trophoblastic disease occurs more frequently in the first trimester; however, in very rare cases, it can affect the term or third-trimester placenta. The application of reproducible nomenclature is expected to facilitate progress in the diagnosis and treatment of obstetric and foetal disorders with placental manifestation. Therefore, this review aims to facilitate communication between obstetricians, neonatologists, and pathologists involved in this diagnostic process.

Development of human amniotic epithelial cell-derived extracellular vesicles as cell-free therapy for dry eye disease

PurposeThis study aimed to investigate the therapeutic potential of extracellular vesicles (EVs) derived from human amniotic epithelial cells (hAEC-EVs) for Dry Eye Disease (DED) treatment. MethodsHighly purified EVs were isolated from the culture supernatants of hAECs, which obtained from term placenta and characterized. Proteomic contents were analyzed for assessing its biological function related to the therapeutic potentials for DED. Subsequently, we examined the therapeutic efficacy of hAEC-EVs on human corneal epithelial cells exposed to hyperosmotic stress and in an experimental DED mouse model induced by desiccation stress. ResultsProteomic analysis of hAEC-EVs revealed proteins linked to cell proliferation and anti-inflammatory responses. We demonstrated efficient uptake of hAEC-EVs by ocular surface cells. Under DED conditions, EV treatment increased corneal epithelial cell proliferation and migration, and concurrently reducing inflammatory cytokines. In the DED mouse model, hAEC-EVs showed significant improvements in corneal staining score, tear secretion, corneal irregularity, and conjunctival goblet cell density. Additionally, hAEC-EVs exhibited a mitigating effect on ocular surface inflammation induced by desiccation. ConclusionsThese findings suggest that hAEC-EVs hold potential as a cell-free therapy for corneal epithelial defects and ocular surface diseases, presenting a promising treatment option for DED.

Does placental VEGF-A protein expression predict early neurological outcome of neonates from FGR complicated pregnancies?

Fetal hypoxia due to placental dysfunction is thehallmark of fetal growth restriction (FGR). Preferential perfusion of the brain (brain-sparing effect), as a part of physiological placental cardiovascular compensatory mechanisms to hypoxia, in FGR was reported. Therefore, the correlation between vascular endothelial growth factor A (VEGF-A) protein expression in the FGR placentas and newborns' early neurological outcome was examined. This study included 50 women with FGR complicated pregnancies and 30 uneventful pregnancies. Fetal hemodynamic parameters, neonatal acid-base status after delivery, placental pathohistology and VEGF-A expression were followed. Early neonatal morphological brain evaluation by ultrasound and functional evaluation of neurological status by Amiel- Tison Neurological Assessment at Term (ATNAT) were performed. VEGF-A protein expression level was significantly higher in the FGR placentas than normal term placentas (Fisher-Freeman-Halton's test, p≤0.001). No statistically significant correlation between placental VEGF-A expression and different prenatal and postnatal parameters was noticed. Whereas the alteration of an early neurological status assessed by ATNAT was found in 58 % of FGR newborns, morphological brain changes evaluated by UZV was noticed in 48 % of cases. No association between the level of placental VEGF-A expression and the early neurological deficits was found. As far as we know this is the first study of a possible connection between VEGF-A protein expression in the FGR placentas and neonates' early neurological outcomes. The lack of correlation between the FGR placental VEGF-A expression and neonates' neurological outcome could indicate that optimal early neurodevelopment may take place due to compensatory mechanism not related to placental VEGF-A expression.

Pathological characteristics of full- term placenta in SARS-CoV-2 patients

Pathological characteristics of full- term placenta in SARS-CoV-2 patients

Arachidonic acid metabolism regulates the development of retinopathy of prematurity among preterm infants.

Extremely preterm infants are at risk of developing retinopathy of prematurity (ROP), characterized by neovascularization and neuroinflammation leading to blindness. Polyunsaturated fatty acid (PUFA) supplementation is recommended in preterm infants to lower the risk of ROP, however, with no significant improvement in visual acuity. Reasonably, this could be as a result of the non-consideration of PUFA metabolizing enzymes. We hypothesize that abnormal metabolism of the arachidonic acid (AA) pathway may contribute to severe stages of ROP. The present study investigated the AA-metabolizing enzymes in ROP pathogenesis by a targeted gene expression analysis of blood (severe ROP = 70, No/Mild = 56), placenta (preterm placenta = 6, full term placenta = 3), and human primary retinal cell cultures and further confirmed at the protein level by performing IHC in sections of ROP retina. The lipid metabolites were identified by LC-MS in the vitreous humor (VH; severe ROP = 15, control = 15). Prostaglandins D2 (p = 0.02), leukotrienes B5 (p = 0.0001), 11,12-epoxyeicosatrienoic acid (p = 0.01), and lipid-metabolizing enzymes of the AA pathway such as CYP1B1, CYP2C8, COX2, and ALOX15 were significantly upregulated while EPHX2 was significantly (0.04) downregulated in ROP cases. Genes involved in hypoxic stress, angiogenesis, and apoptosis showed increased expression in ROP. An increase in the metabolic intermediates generated from the AA metabolism pathway further confirmed the role of these enzymes in ROP, while metabolites for EPHX2 activity were low in abundance. Inflammatory lipid intermediates were higher compared to anti-inflammatory lipids in VH and showed an association with enzyme activity. Both the placenta of preterm infants who developed ROP and hypoxic retinal cultures showed a reduced expression of EPHX2. These findings suggested a strong involvement of EPHX2 in regulating retinal neovascularization and inflammation. The study results underscore the role of arachidonic acid metabolism in the development of ROP and as a potential target for preventing vision loss among preterm-born infants.

Statement of Retraction: Impact of maternal iron deficiency anaemia on the expression of the newly discovered multi-copper ferroxidase, Zyklopen, in term placentas

Statement of Retraction: Impact of maternal iron deficiency anaemia on the expression of the newly discovered multi-copper ferroxidase, Zyklopen, in term placentas

Relation between possible under-diagnosed/treated glucose dysmetabolism, delayed villous maturation, and lethal fetal pneumonia

BackgroundGestational diabetes mellitus (GDM) is a known risk factor for stillbirth (Rosenstein et al., 2012) [1]. Delayed villous maturation (DVM), predominantly seen in term placentas in pregnancies complicated with glucose dysmetabolism, may in part be a consequence of excessive maternal glucose leading to release of fetal insulin and other growth factors that promote excessive placental growth at the expense of villous maturation (Redline, 2012) [2]. CasesWe present three cases of under-diagnosed/treated glucose dysmetabolism in women in their first pregnancies cared for in other hospitals in the United Kingdom (UK) with the fatal fetal/neonatal outcomes and confirmed DVM in the placenta and congenital pneumonia on post-mortem examination in all three cases. ConclusionThis cluster supports a hypothesis that DVM and glucose dysmentabolism may make babies more susceptible to severe perinatal infection. All three cases received the antenatal care in their subsequent pregnancies in our unit and had confirmed glucose dysmetabolism which was treated and resulted in healthy babies.

The role of placental kisspeptin in trophoblast invasion and migration: an assessment in Kiss1r knockout mice, BeWo cell lines and human term placenta.

Context There is mounting evidence implicating kisspeptin signalling in placental development and function. Aims This study aimed to elucidate kisspeptin's role in trophoblast invasion and migration using three experimental models. Methods First, we examined the mouse fetus and placenta in a kisspeptin receptor (Kiss1r) knockout (KO) model. Fetal/placental weights and gene expression (quantitative polymerase chain reaction) were assessed. Second, we determined kisspeptin effects on a human trophoblast (BeWo) cell line in vitro . Third, we examined KISS1 and KISS1R gene expression in human placenta from term and pre-term pregnancies. Key results No difference was found in fetal or placental weight between Kiss1r KO and wildtype mice. However, expression of the trophoblast invasion marker, Mmp2 mRNA, was greater in the placental labyrinth zone of Kiss1r KO mice. BeWo cell models of villus cytotrophoblast and syncytiotrophoblast cells exhibited kisspeptin protein expression, with greater expression in syncytiotrophoblast, consistent with KISS1 mRNA. Kisspeptin treatment inhibited the migratory potential of cytotrophoblast-like cells. Finally, while no difference was seen in KISS1 and KISS1R mRNA between term and pre-term placentas, we saw a difference in the relative expression of each gene pre-term. We also observed a positive correlation between KISS1 expression and maternal body mass index. Conclusions Our results indicate that kisspeptin may inhibit trophoblast invasion. Implications Further investigation is required to clarify specific regulatory mechanisms.

Unique Ultrastructural Alterations in the Placenta Associated With Macrosomia Induced by Gestational Diabetes Mellitus

Abstract Objective To investigate the morphological and ultrastructural alterations in placentas from pregnancies with gestational diabetes mellitus (GDM)–induced macrosomia, term nondiabetic macrosomia, and normal pregnancies. Methods Sixty full-term placentas were collected, and clinical data along with informed consent were obtained from pregnant women who underwent regular visit checks and delivered their newborns in Northwest Women’s and Children’s Hospital between May and December 2022. Placentas were divided into three equal groups: normal pregnancy (control group), nondiabetic macrosomia group, and macrosomia complicated with GDM (diabetic macrosomia) group. Gross morphological data of placentas were recorded, and placental samples were processed for examination of ultrastructural and stereological changes using transmission electron microscopy. Analysis of variance and chi-squared test were used to examine the differences among the three groups for continuous and categorical variables, respectively. Results The baseline characteristics of mothers and neonates did not differ across the three groups, except for a significantly higher birth weight in the diabetic macrosomia group (4172.00 ± 151.20 vs. 3192.00 ± 328.70, P < 0.001) and nondiabetic macrosomia group (4138.00 ± 115.20 vs. 3192.00 ± 328.70, P < 0.001) compared with control group. Examination of the placentas revealed that placental weight was also highest in the diabetic macrosomia group compared with control group (810.00 ± 15.81 vs. 490.00 ± 51.48, P < 0.001) and nondiabetic macrosomia group (810.00 ± 15.81 vs. 684.00 ± 62.69, P < 0.001), but the ratio of neonatal birth weight to placental weight (BW/PW) was significantly lower in the diabetic macrosomia group compared with that in the control group (5.15 ± 0.19 vs. 6.54 ± 0.63, P < 0.001) and nondiabetic macrosomia group (5.15 ± 0.19 vs. 6.09 ± 0.52, P < 0.001) group. In contrast, the BW/PW ratio in nondiabetic macrosomia did not differ significantly from that in the control group. Distinct ultrastructural changes in terminal villi and stereological alterations in microvilli were observed in the diabetic macrosomia group, including changes in the appearance of cytoplasmic organelles and the fetal capillary endothelium and thickness of the vasculo-syncytial membrane and basal membrane. Conclusion Significant ultrastructural and stereological alterations were discovered in the placentas from pregnant women with macrosomia induced by GDM. These alterations may be the response of the placenta to the hyperglycemia condition encountered during pregnancies complicated with GDM.

Unlocking the secrets of Hofbauer cells in placental (patho-) physiology: Isolation and quality assessment in human term placenta

IntroductionHofbauer cells (HBCs) are macrophages of fetal origin that reside in the villous tissue. They are the only immune cells within healthy villi. While HBCs perform innate immune functions such as phagocytosis and antigen presentation, they are increasingly recognized for their diverse roles in placental physiology e.g. vascular functionality, tissue homeostasis, tolerance. Consequently, HBCs are of utmost interest in a variety of non-physiological placental conditions. IsolationVillous tissue is collected freshly after delivery and finely minced. The resulting tissue is digested in a two-step process, using Trypsin/DNase to separate cytotrophoblasts and collagenase/DNase to penetrate deeper into the villous stroma, containing HBCs, and obtain a single cell suspension. After a density gradient centrifugation, the corresponding cell layer is collected and subjected to negative immune selection of HBCs, yielding unaffected cells that have not been activated during the isolation process. Quality controlIn addition to a classical immunocytochemistry (ICC) approach including macrophage markers, and markers for potentially contaminating cell types (e.g. fibroblasts, muscle, mesenchymal cells), we have developed a multi-color flow cytometry (FC) panel. This panel assesses Hofbauer cell purity and polarization states more accurately and comprehensively than qualitative ICC, using percentage analysis of parent cells to estimate the expression levels of specific markers. DiscussionThe presented protocol allows us to isolate HBCs in significant numbers and high purity, even from placentae compromised by preeclampsia (PE) with limited placental volume. We have successfully developed and implemented this protocol to study healthy, diabetic and PE macrophages, aiding a better understanding of the underlying placental pathophysiology at the cellular level.

Maternal SARS-CoV-2 impacts fetal placental macrophage programs and placenta-derived microglial models of neurodevelopment

BackgroundThe SARS-CoV-2 virus activates maternal and placental immune responses. Such activation in the setting of other infections during pregnancy is known to impact fetal brain development. The effects of maternal immune activation on neurodevelopment are mediated at least in part by fetal brain microglia. However, microglia are inaccessible for direct analysis, and there are no validated non-invasive surrogate models to evaluate in utero microglial priming and function. We have previously demonstrated shared transcriptional programs between microglia and Hofbauer cells (HBCs, or fetal placental macrophages) in mouse models.Methods and resultsWe assessed the impact of maternal SARS-CoV-2 on HBCs isolated from 24 term placentas (N = 10 SARS-CoV-2 positive cases, 14 negative controls). Using single-cell RNA-sequencing, we demonstrated that HBC subpopulations exhibit distinct cellular programs, with specific subpopulations differentially impacted by SARS-CoV-2. Assessment of differentially expressed genes implied impaired phagocytosis, a key function of both HBCs and microglia, in some subclusters. Leveraging previously validated models of microglial synaptic pruning, we showed that HBCs isolated from placentas of SARS-CoV-2 positive pregnancies can be transdifferentiated into microglia-like cells (HBC-iMGs), with impaired synaptic pruning behavior compared to HBC models from negative controls.ConclusionThese findings suggest that HBCs isolated at birth can be used to create personalized cellular models of offspring microglial programming.

Confined placental mosaicism: Distribution of chromosomally abnormal cells over the term placenta

ObjectiveNon-invasive prenatal testing (NIPT) investigates placental DNA and may detect confined placental mosaicism (CPM). The aim of this study was to confirm CPM in the term placenta in cases with abnormal NIPT but normal follow-up cytogenetic studies of fetus and mother. Additionally we examined the distribution of abnormal cells over the placenta. MethodsFour chorionic villus (CV) biopsies from four placental quadrants were requested in cases where CPM was assumed. Both cell lineages of the CV, cytotrophoblast (CTB) and mesenchymal core (MC), were analyzed separately with SNP array. ResultsThe chromosome aberration was confirmed in 67 % of the placentas. Three quarters of the CTB and MC biopsies from these mosaic placentas were uniformly normal (57 %) or abnormal (20 %), and a minority showed mosaicism. Among 16 cases of CPM where first trimester CV were examined as well, 11 had chromosomally normal results during pregnancy. DiscussionCytogenetic investigations of term placental biopsies suspected to be affected with CPM did not reveal the chromosome aberration in one third of the placentas. This is caused by the patchy pattern in which chromosomally abnormal cells are distributed over the placenta with the majority of the biopsies being uniformly normal. Further CPM research, including its clinical impact, requires the analysis of more than four biopsies to get insight into the extent of the affected part. Moreover, a subset of CPM type 1 and 3 seems to be only detectable with NIPT and not with first trimester CVS.

Sex-biased regulatory changes in the placenta of native highlanders contribute to adaptive fetal development.

Compared with lowlander migrants, native Tibetans have a higher reproductive success at high altitude though the underlying mechanism remains unclear. Here, we compared the transcriptome and histology of full-term placentas between native Tibetans and Han migrants. We found that the placental trophoblast shows the largest expression divergence between Tibetans and Han, and Tibetans show decreased immune response and endoplasmic reticulum stress. Remarkably, we detected a sex-biased expression divergence, where the male-infant placentas show a greater between-population difference than the female-infant placentas. The umbilical cord plays a key role in the sex-biased expression divergence, which is associated with the higher birth weight of the male newborns of Tibetans. We also identified adaptive histological changes in the male-infant placentas of Tibetans, including larger umbilical artery wall and umbilical artery intima and media, and fewer syncytial knots. These findings provide valuable insights into the sex-biased adaptation of human populations, with significant implications for medical and genetic studies of human reproduction.

Distinct biological characteristics of mesenchymal stem cells separated from different components of human placenta

Mesenchymal stem cells (MSCs) have tremendous potential in cell therapy and regenerative medicine. The placenta-derived MSCs (PMSCs) are becoming favorable sources as they are ethically preferable and rich in MSCs. Although several subgroups of PMSCs have been identified from human term placenta, optimal sources for specific clinical applications remain to be elucidated. This study aimed to isolate MSCs from various components of the placenta, and compare their biological characteristics, including morphology, proliferation, immunophenotype, differentiation potential, growth factor and cytokine secretion, and immunomodulatory properties. Finally, four distinct groups of PMSCs were isolated from the placenta: amniotic membrane-derived MSCs (AM-MSCs), chorionic membrane-derived MSCs (CM-MSCs), chorionic plate-derived MSCs (CP-MSCs), and chorionic villi-derived MSCs (CV-MSCs). The results showed that CV-MSCs had good proliferation ability, and were easier to induce osteogenic and chondrogenic differentiation; CP-MSCs exhibited the strongest inhibitory effect on the proliferation of activated T cells, secreted high levels of EGF and IL-6, and could well differentiate into osteoblasts, adipocytes, and chondroblasts; AM-MSCs showed good growth dynamics in the early generations, were able to grow at high density, and tended to induce differentiation into osteogenic and neural lineages. These findings may provide novel evidence for the selection of seed cells in clinical application.