A single-cell chromatin accessibility dataset of human primed and naïve pluripotent stem cell-derived teratoma.

Teratoma, due to its remarkable ability to differentiate into multiple cell lineages, is a valuable model for studying human embryonic development. The similarity of the gene expression and chromatin accessibility patterns in these cells to those observed in vivo further underscores its potential as a research tool. Notably, teratomas derived from human naïve (pre-implantation epiblast-like) pluripotent stem cells (PSCs) have larger embryonic cell diversity and contain extraembryonic lineages, making them more suitable to study developmental processes. However, the cell type-specific epigenetic profiles of naïve PSC teratomas have not been yet characterized. Using single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq), we analyzed 66,384 cell profiles from five teratomas derived from human naïve PSCs and their post-implantation epiblast-like (primed) counterparts. We observed 17 distinct cell types from both embryonic and extraembryonic lineages, resembling the corresponding cell types in human fetal tissues. Additionally, we identified key transcription factors specific to different cell types. Our dataset provides a resource for investigating gene regulatory programs in a relevant model of human embryonic development.

Swing Trend Prediction of Main Guide Bearing in Hydropower Units Based on MFS-DCGNN.

Hydropower units are the core equipment of hydropower stations, and research on the fault prediction and health management of these units can help improve their safety, stability, and the level of reliable operation and can effectively reduce costs. Therefore, it is necessary to predict the swing trend of these units. Firstly, this study considers the influence of various factors, such as electrical, mechanical, and hydraulic swing factors, on the swing signal of the main guide bearing y-axis. Before swing trend prediction, the multi-index feature selection algorithm is used to obtain suitable state variables, and the low-dimensional effective feature subset is obtained using the Pearson correlation coefficient and distance correlation coefficient algorithms. Secondly, the dilated convolution graph neural network (DCGNN) algorithm, with a dilated convolution graph, is used to predict the swing trend of the main guide bearing. Existing GNN methods rely heavily on predefined graph structures for prediction. The DCGNN algorithm can solve the problem of spatial dependence between variables without defining the graph structure and provides the adjacency matrix of the graph learning layer simulation, avoiding the over-smoothing problem often seen in graph convolutional networks; furthermore, it effectively improves the prediction accuracy. The experimental results showed that, compared with the RNN-GRU, LSTNet, and TAP-LSTM algorithms, the MAEs of the DCGNN algorithm decreased by 6.05%, 6.32%, and 3.04%; the RMSEs decreased by 9.21%, 9.01%, and 2.83%; and the CORR values increased by 0.63%, 1.05%, and 0.37%, respectively. Thus, the prediction accuracy was effectively improved.

A novel approach to alleviate acetaminophen-induced hepatotoxicity with hybrid balloon flower root-derived exosome-like nanoparticles (BDEs) with silymarin via inhibition of hepatocyte MAPK pathway and apoptosis.

INTRODUCTION: Balloon flower root-derived exosome-like nanoparticles (BDEs) have recently been proposed as physiologically active molecules with no cytotoxicity. However, the therapeutic effects of drug-induced hepatotoxicity of BDEs have not been elucidated. BDEs contain a large amount of platycodin D, which is widely known to be effective in regulating inflammation and ameliorating systemic toxicity. Thus, the main therapeutic activity of BDEs is attributed to inhibiting the inflammatory response and alleviating toxicity. In this study, we fabricated the hybrid BDEs fused with liposomes containing silymarin (SM) to enhance the synergistic effect on inhibition of acetaminophen-induced hepatotoxicity (APAP). OBJECTIVE: Considering the potential therapeutic effects of BDEs, and the potential to achieve synergistic effects to improve therapeutic outcomes, we constructed hybrid BDEs with a soy lecithin-based liposome loaded with SM. Since liposomes can provide higher thermal stability and have greater structural integrity, these might be more resistant to clearance and enzymatic degradation of drug molecules. METHODS: Hybrid BDEs with liposome-loaded SM (BDEs@lipo-SM) were fabricated by thin-film hydration and extrusion. BDEs@lipo-SM were characterized using dynamic light scattering and high-performance liquid chromatography. After confirmation of the physical properties of BDEs@lipo-SM, various therapeutic properties were evaluated. RESULTS: BDEs@lipo-SM were internalized by hepatocytes and immune cells and significantly decreased mRNA expression of apoptosis and inflammation-relevant cytokines by inhibiting the hepatocyte MAPK pathway. BDEs@lipo-SM significantly induced an increase in glutathione levels and inhibited APAP-induced hepatotoxicity. CONCLUSION: From this study, we know that BDEs are reliable and safe nanovesicles containing natural metabolites derived from balloon flower, and they can facilitate intercellular communication. BDEs are also easily modified to enhance drug loading capacity, targeting effects, and long-term accumulation in vivo. BDEs@lipo-SM have therapeutic benefits for acute liver injury and can alleviate cell death and toxicity. They can be efficiently delivered to the liver and effectively inhibit APAP-induced hepatotoxicity by inhibiting the MAPK signaling pathway and apoptosis, which accelerates liver recovery in the APAP-induced acute liver injury model. These findings highlight that BDEs represent an attractive delivery vehicle for drug delivery.

Predictive value of plasma ephrinB2 levels for amputation risk following endovascular revascularization in peripheral artery disease.

Background: The aim of this study is to investigate the expression levels of ephrinB2 in patients with lower extremity peripheral arterial disease (PAD) and explore its association with the severity of the disease and the risk of amputation after endovascular revascularization. Methods: During the period from March 2021 to March 2023, this study collected blood samples and clinical data from 133 patients diagnosed with lower extremity PAD and 51 healthy volunteer donors. The severity of lower extremity PAD patients was classified using the Rutherford categories. The expression of ephrin-B2 in plasma samples was detected using the Western Blotting. Results: Compared to the control group, the levels of serum ephrinB2 in patients were significantly elevated (p < 0.001). Moreover, the plasma EphrinB2 levels were positively correlated with white blood cell counts (r = 0.204, p = 0.018), neutrophil counts (r = 0.174, p = 0.045), and neutrophil-to-lymphocyte ratio (NLR) (r = 0.223, p = 0.009). Furthermore, the AUCs of plasma ephrinB2 level, NLR, and their combination as predictors for amputation events within 30 months after lower extremity PAD endovascular revascularization were 0.659, 0.730 and 0.811. In the high-ephrinB2 group, the incidence of amputation events within 30 months after endovascular revascularization was higher. Conclusions: Plasma EphrinB2 levels may be linked to lower extremity PAD development, inflammation, and postoperative amputation. Combining EphrinB2 and NLR can improve amputation prediction accuracy after endovascular revascularization in lower extremity PAD patients.

Down-regulation of long noncoding RNA HOXA11-AS nullifies the impact of microRNA-506-3p on chondrocytes proliferation and apoptosis in osteoarthritis.

OBJECTIVES: This study was directed towards exploring the impacts of lncRNA HOXA11-AS-mediated microRNA (miR)-506-3p on chondrocytes proliferation and apoptosis in osteoarthritis (OA). METHODS: The articular cartilages were provided by OA patients who received total knee arthroplasty, and Human Chondrocyte (HC)-OA (HCOA) was also attained. The miR-506-3p and HOXA11-AS expressions in articular cartilages from OA patients and HCOA cells were analyzed via qPCR. After gain- and loss-of-function assays in HCOA cells, MTT assay and flow cytometry (FC) were used for assessing cell viability and apoptosis, accordingly. The levels of PIK3CA, AKT, and mTOR as well as AKT and mTOR phosphorylation levels assessed using western blotting (WB). The targeting correlation of HOXA11-AS and miR-506-3p as well as miR-506-3p and PIK3CA was assessed through Dual-Luciferase Reporter gene Assay (DLRA). RESULT: The articular cartilages from OA patients and Human Chondrocyte (HC)-OA (HCOA) cells showed increased HOXA11-AS and decreased miR-506-3p. Mechanistically, HOXA11-AS was capable of binding to miR-506-3p to increase PIK3CA, the target gene of miR-506-3p. miR-506-3p suppression facilitated HCOA cell proliferation and reduced their apoptosis, which was nullified by further silencing HOXA11-AS or silencing PIK3CA. The down-regulation of HOXA11-AS disrupted the PI3K/AKT/mTOR pathway, which was counteracted by further miR-506-3p inhibition. CONCLUSION: The silencing of HOXA11-AS might block the PI3K/AKT/mTOR pathway through miR-506-3p up-regulation, thereby restricting HCOA cell proliferation and provoking apoptosis.

Inhalation of 2, 4-di-tert-butylphenol-Loaded micelles suppresses respiratory syncytial virus infection in mice.

Human respiratory syncytial virus (RSV) is a common cause of respiratory infections in infants, young children, and elderly people. However, there are no effective treatments or vaccines available in most countries. In this study, we explored the anti-RSV potential of 2, 4-Di-tert-butylphenol (2, 4-DTBP), a compound derived from Houttuynia cordata Thunb. To overcome the poor solubility of 2, 4-DTBP, we encapsulated it in polymeric micelles and delivered it by inhalation. We found that 2, 4-DTBP-loaded micelles inhibited RSV infection in vitro and improved survival, lung pathology, and viral clearance in RSV-infected mice. Our results suggested that 2, 4-DTBP-loaded micelle is a promising novel therapeutic agent for RSV infection.

A spatiotemporal atlas of cholestatic injury and repair in mice.

Cholestatic liver injuries, characterized by regional damage around the bile ductular region, lack curative therapies and cause considerable mortality. Here we generated a high-definition spatiotemporal atlas of gene expression during cholestatic injury and repair in mice by integrating spatial enhanced resolution omics sequencing and single-cell transcriptomics. Spatiotemporal analyses revealed a key role of cholangiocyte-driven signaling correlating with the periportal damage-repair response. Cholangiocytes express genes related to recruitment and differentiation of lipid-associated macrophages, which generate feedback signals enhancing ductular reaction. Moreover, cholangiocytes express high TGFß in association with the conversion of liver progenitor-like cells into cholangiocytes during injury and the dampened proliferation of periportal hepatocytes during recovery. Notably, Atoh8 restricts hepatocyte proliferation during 3,5-diethoxycarbonyl-1,4-dihydro-collidin damage and is quickly downregulated after injury withdrawal, allowing hepatocytes to respond to growth signals. Our findings lay a keystone for in-depth studies of cellular dynamics and molecular mechanisms of cholestatic injuries, which may further develop into therapies for cholangiopathies.

A spatiotemporal atlas of mouse liver homeostasis and regeneration.

The mechanism by which mammalian liver cell responses are coordinated during tissue homeostasis and perturbation is poorly understood, representing a major obstacle in our understanding of many diseases. This knowledge gap is caused by the difficulty involved with studying multiple cell types in different states and locations, particularly when these are transient. We have combined Stereo-seq (spatiotemporal enhanced resolution omics-sequencing) with single-cell transcriptomic profiling of 473,290 cells to generate a high-definition spatiotemporal atlas of mouse liver homeostasis and regeneration at the whole-lobe scale. Our integrative study dissects in detail the molecular gradients controlling liver cell function, systematically defining how gene networks are dynamically modulated through intercellular communication to promote regeneration. Among other important regulators, we identified the transcriptional cofactor TBL1XR1 as a rheostat linking inflammation to Wnt/ß-catenin signaling for facilitating hepatocyte proliferation. Our data and analytical pipelines lay the foundation for future high-definition tissue-scale atlases of organ physiology and malfunction.

Multimodal cell atlas of the ageing human skeletal muscle.

Muscle atrophy and functional decline (sarcopenia) are common manifestations of frailty and are critical contributors to morbidity and mortality in older people1. Deciphering the molecular mechanisms underlying sarcopenia has major implications for understanding human ageing2. Yet, progress has been slow, partly due to the difficulties of characterizing skeletal muscle niche heterogeneity (whereby myofibres are the most abundant) and obtaining well-characterized human samples3,4. Here we generate a single-cell/single-nucleus transcriptomic and chromatin accessibility map of human limb skeletal muscles encompassing over 387,000 cells/nuclei from individuals aged 15 to 99 years with distinct fitness and frailty levels. We describe how cell populations change during ageing, including the emergence of new populations in older people, and the cell-specific and multicellular network features (at the transcriptomic and epigenetic levels) associated with these changes. On the basis of cross-comparison with genetic data, we also identify key elements of chromatin architecture that mark susceptibility to sarcopenia. Our study provides a basis for identifying targets in the skeletal muscle that are amenable to medical, pharmacological and lifestyle interventions in late life.

Understanding vegetation phenology responses to easily ignored climate factors in china's mid-high latitudes.

Previous studies have primarily focused on the influence of temperature and precipitation on phenology. It is unclear if the easily ignored climate factors with drivers of vegetation growth can effect on vegetation phenology. In this research, we conducted an analysis of the start (SOS) and end (EOS) of the growing seasons in the northern region of China above 30°N from 1982 to 2014, focusing on two-season vegetation phenology. We examined the response of vegetation phenology of different vegetation types to preseason climatic factors, including relative humidity (RH), shortwave radiation (SR), maximum temperature (Tmax), and minimum temperature (Tmin). Our findings reveal that the optimal preseason influencing vegetation phenology length fell within the range of 0-60 days in most areas. Specifically, SOS exhibited a significant negative correlation with Tmax and Tmin in 44.15% and 42.25% of the areas, respectively, while EOS displayed a significant negative correlation with SR in 49.03% of the areas. Additionally, we identified that RH emerged as the dominant climatic factor influencing the phenology of savanna (SA), whereas temperature strongly controlled the SOS of deciduous needleleaf forest (DNF) and deciduous broadleaf forest (DBF). Meanwhile, the EOS of DNF was primarily influenced by Tmax. In conclusion, this study provides valuable insights into how various vegetation types adapt to climate change, offering a scientific basis for implementing effective vegetation adaptation measures.

Experimental study of a canine model for a newly designed adjustable prefenestration aortic stent graft.

PURPOSE: When performing thoracic aortic endovascular repair (TEVAR) on lesions of the aortic arch, physician- modified fenestration or in situ fenestration is often used to maintain patent branches. We designed a new adjustable prefenestration aortic stent graft that can both isolate pathologies in the aortic arch and obtain patent branches simultaneously. In this study, we use this new type of stent to perform fenestrated TEVAR in a canine's aorta. This study aims to evaluate the safety and feasibility of the new device, which may provide preliminary data for potential human application. METHODS: Eight Labrador Retriever canines underwent fenestrated TEVAR using the new stent device. Digital subtract angiography (DSA) was performed before and after fenestrated TEVAR to evaluate the safety and feasibility of the procedure. For the device deployment, at the "large curvature" side in the endograft, there is a rectangular prefenestration area (2 × 5 cm) without the polytetrafluoroethylene membrane, and at both longer side edges of the fenestration, there are two slide rails. A moveable membrane that covers the same area as the prefenestration area is initially set at the prefenestration position. A stay line is connected from the distal site of the moveable membrane that controls it to the distal position along the slide rail, which releases the fenestration. After the positioning of the prefenestration is determined, the outer sheath of the delivery system is released, and the stay line at the end of the delivery system is pulled outside the body. The animals were divided into a 1-month group (n = 4) and a 3-month group (n = 4) after the fenestrated TEVAR. Computed tomography (CT) was performed before euthanasia, and video of the DSA during the procedures and CT angiography (CTA) images were then studied. RESULTS: The procedure success rate was 100%, but the total survival rate was only 87.5%. There were no aortic-related deaths during follow-up, and during the operation, there were no stent-graft-related accidents. In addition, no stent-graft migrations were observed in the CTA, and all branch arteries were kept patent by the adjustable fenestration. Finally, histological examination and electron microscope results showed no obvious vascular injury or inflammation. CONCLUSION: Based on the results of this study, we judge the safety and feasibility of the use of the newly designed adjustable prefenestration aortic stent graft in a fenestrated-TEVAR canine model to be acceptable. Our preliminary data may provide a first reference for evaluating the new stent's potential use in humans.

An injectable signal-amplifying device elicits a specific immune response against malignant glioblastoma.

Despite exciting achievements with some malignancies, immunotherapy for hypoimmunogenic cancers, especially glioblastoma (GBM), remains a formidable clinical challenge. Poor immunogenicity and deficient immune infiltrates are two major limitations to an effective cancer-specific immune response. Herein, we propose that an injectable signal-amplifying nanocomposite/hydrogel system consisting of granulocyte-macrophage colony-stimulating factor and imiquimod-loaded antigen-capturing nanoparticles can simultaneously amplify the chemotactic signal of antigen-presenting cells and the "danger" signal of GBM. We demonstrated the feasibility of this strategy in two scenarios of GBM. In the first scenario, we showed that this simultaneous amplification system, in conjunction with local chemotherapy, enhanced both the immunogenicity and immune infiltrates in a recurrent GBM model; thus, ultimately making a cold GBM hot and suppressing postoperative relapse. Encouraged by excellent efficacy, we further exploited this signal-amplifying system to improve the efficiency of vaccine lysate in the treatment of refractory multiple GBM, a disease with limited clinical treatment options. In general, this biomaterial-based immune signal amplification system represents a unique approach to restore GBM-specific immunity and may provide a beneficial preliminary treatment for other clinically refractory malignancies.

Cell atlas of CCl 4-induced progressive liver fibrosis reveals stage-specific responses.

Chronic liver injury leads to progressive liver fibrosis and ultimately cirrhosis, a major cause of morbidity and mortality worldwide. However, there are currently no effective anti-fibrotic therapies available, especially for late-stage patients, which is partly attributed to the major knowledge gap regarding liver cell heterogeneity and cell-specific responses in different fibrosis stages. To reveal the multicellular networks regulating mammalian liver fibrosis from mild to severe phenotypes, we generated a single-nucleus transcriptomic atlas encompassing 49 919 nuclei corresponding to all main liver cell types at different stages of murine carbon tetrachloride (CCl 4)-induced progressive liver fibrosis. Integrative analysis distinguished the sequential responses to injury of hepatocytes, hepatic stellate cells and endothelial cells. Moreover, we reconstructed cell-cell interactions and gene regulatory networks implicated in these processes. These integrative analyses uncovered previously overlooked aspects of hepatocyte proliferation exhaustion and disrupted pericentral metabolic functions, dysfunction for clearance by apoptosis of activated hepatic stellate cells, accumulation of pro-fibrotic signals, and the switch from an anti-angiogenic to a pro-angiogenic program during CCl 4-induced progressive liver fibrosis. Our dataset thus constitutes a useful resource for understanding the molecular basis of progressive liver fibrosis using a relevant animal model.

Treatment strategies for endoleak after endovascular repair of the abdominal aortic aneurysm: A single center retrospective study.

BACKGROUND: Endovascular abdominal aortic aneurysm repair (EVAR) is the most frequently used treatment for aneurysm in abdominal aorta. The endoleak after EVAR causes the aneurysm sac to remain enlarged and risk for rupture. AIMS: The purpose of the study was to assess the efficacy of strategies and techniques for endoleak treatment. METHODS: This study was a single center retrospective study of 30 patients who had kinds of endoleak. The 30 patients were from a cohort of 597 patients who received EVAR from the Secondary Xiangya Hospital, Central South University between Jan 2014 to Dec 2021, what is follow-up well and diagnosed as endoleak. Data included basic clinical information, aspects of the endoleak treatment techniques, and follow-up findings. RESULTS: The 30 patients with endoleak were diagnosed by computed tomography angiography or digital subtraction angiography. Age is 69 ± 7.9 yrs. 26 patients are male with only 4 female patients. Immediate endoleak after EVAR is 46.7%and delayed endoleak is 53.3%. The classification of endoleak is type Ⅰ:76.6%; type Ⅱ 26.7%; type Ⅲ:6.7%; type Ⅳ:6.7%; type Ⅴ:13.3%. Different treatment of endoleak includes: screening, endovascular re-intervention and open surgery. There are 3 patients (10.0%) underwent emergency EVAR due to their rupture condition of aneurysm. All the endoleak patients' CTA image characteristics has been reviewed. The follow-up rate is 93.3%. There are 6 patients (21.4%) died during follow-up. No aneurysm sac rupture death has been recorded. CONCLUSIONS: Endoleak after EVAR is the most frequent complication that directly affects survival and re-intervention rates. Our findings suggested that different treatment strategies based on the individual patient's situation is important for their endoleak treating result.

Animal study on adjustable pre - fenestration aortic stent - graft. / å¯è°ƒèŠ‚é¢„å¼€çª—ä¸»åŠ¨è„‰è¦†è†œæ”¯æž¶çš„åŠ¨ç‰©å®žéªŒç ”ç©¶.

OBJECTIVES: To isolate aortic arch pathologies and keep the branches superior in arch patent, it always need physicians to do in-vivo fenestration or in-situ fenestration when performing the thoracic endovascular aortic repair (TEVAR). However, both of those fenestration techniques need structure modification of the stent-graft, which may affect their long-term stability. We designed an adjustable pre-fenestration aortic stent-graft to treat pathologies in this area and obtained a patent branch arteries. This study used this new designed stent-graft to perform fenestrated-TEVAR (f-TEVAR) in canine aorta. This study aims to identify its feasibility and safety through animal experiments, which might provide preliminary data for potential human implantation. METHODS: A total of 8 Labrador Retrievers were underwent f-TEVAR by using the new devices. Digital subtraction angiography was performed before and after f-TEVAR to evaluate the success of the procedures. All the canines were divided into a 4-week group (feeding for 4 weeks after operation) and a 12-week group (feeding for 12 weeks after operation). Computed tomography angiography (CTA) were performed before euthanasia. RESULTS: The success rate of operation was 100%. During the operation, there was no accident of major bleeding or failure to be released by fenestration. Adjustable fenestration worked well. No stent-graft migration was found in CTA at 4 weeks and 12 weeks after the operation. All branch arteries kept by the adjustable fenestration were patent. CONCLUSIONS: The result of feasibility and safety of the new designed adjustable pre-fenestration aortic stent-graft in f-TEVAR of canine is acceptable. This study provides a reference for further optimization of this stent and human f-TEVAR implantation involving aortic arch lesions.

Spatiotemporal transcriptomic atlas of mouse organogenesis using DNA nanoball-patterned arrays.

Spatially resolved transcriptomic technologies are promising tools to study complex biological processes such as mammalian embryogenesis. However, the imbalance between resolution, gene capture, and field of view of current methodologies precludes their systematic application to analyze relatively large and three-dimensional mid- and late-gestation embryos. Here, we combined DNA nanoball (DNB)-patterned arrays and in situ RNA capture to create spatial enhanced resolution omics-sequencing (Stereo-seq). We applied Stereo-seq to generate the mouse organogenesis spatiotemporal transcriptomic atlas (MOSTA), which maps with single-cell resolution and high sensitivity the kinetics and directionality of transcriptional variation during mouse organogenesis. We used this information to gain insight into the molecular basis of spatial cell heterogeneity and cell fate specification in developing tissues such as the dorsal midbrain. Our panoramic atlas will facilitate in-depth investigation of longstanding questions concerning normal and abnormal mammalian development.

Cell transcriptomic atlas of the non-human primate Macaca fascicularis.

Studying tissue composition and function in non-human primates (NHPs) is crucial to understand the nature of our own species. Here we present a large-scale cell transcriptomic atlas that encompasses over 1 million cells from 45 tissues of the adult NHP Macaca fascicularis. This dataset provides a vast annotated resource to study a species phylogenetically close to humans. To demonstrate the utility of the atlas, we have reconstructed the cell-cell interaction networks that drive Wnt signalling across the body, mapped the distribution of receptors and co-receptors for viruses causing human infectious diseases, and intersected our data with human genetic disease orthologues to establish potential clinical associations. Our M. fascicularis cell atlas constitutes an essential reference for future studies in humans and NHPs.

Rolling back human pluripotent stem cells to an eight-cell embryo-like stage.

After fertilization, the quiescent zygote experiences a burst of genome activation that initiates a short-lived totipotent state. Understanding the process of totipotency in human cells would have broad applications. However, in contrast to in mice1,2, demonstration of the time of zygotic genome activation or the eight-cell (8C) stage in in vitro cultured human cells has not yet been reported, and the study of embryos is limited by ethical and practical considerations. Here we describe a transgene-free, rapid and controllable method for producing 8C-like cells (8CLCs) from human pluripotent stem cells. Single-cell analysis identified key molecular events and gene networks associated with this conversion. Loss-of-function experiments identified fundamental roles for DPPA3, a master regulator of DNA methylation in oocytes3, and TPRX1, a eutherian totipotent cell homeobox (ETCHbox) family transcription factor that is absent in mice4. DPPA3 induces DNA demethylation throughout the 8CLC conversion process, whereas TPRX1 is a key executor of 8CLC gene networks. We further demonstrate that 8CLCs can produce embryonic and extraembryonic lineages in vitro or in vivo in the form of blastoids5 and complex teratomas. Our approach provides a resource to uncover the molecular process of early human embryogenesis.