Endothelial cell heterogeneity and microglia regulons revealed by a pig cell landscape at single-cell level

Cross-Species Insights into Trophoblast Invasion During Placentation Governed by Immune-Featured Trophoblast Cells

Proper development of the placenta, the transient support organ forms after embryo implantation, is essential for a successful pregnancy. However, the regulation of trophoblast invasion, which is most important during placentation, remains largely unknown. Here, rats, mice, and pigs are used as biomedical models, used scRNA-seq to comparatively elucidate the regulatory mechanism of placental trophoblast invasion, and verified it using a human preeclampsia disease model combined with scStereo-seq. A dual-featured type of immune-featured trophoblast (iTrophoblast) is unexpectedly discovered. Interestingly, iTrophoblast only exists in invasive placentas and regulates trophoblast invasion during placentation. In a normally developing placenta, iTrophoblast gradually transforms from an immature state into a functional mature state as it develops. Whereas in the developmentally abnormal preeclamptic placenta, disordered iTrophoblast transformation leads to the accumulation of immature iTrophoblasts, thereby disrupting trophoblast invasion and ultimately leading to the progression of preeclampsia.

Spatiotemporal omics for biology and medicine

The completion of the Human Genome Project has provided a foundational blueprint for understanding human life. Nonetheless, understanding the intricate mechanisms through which our genetic blueprint is involved in disease or orchestrates development across temporal and spatial dimensions remains a profound scientific challenge. Recent breakthroughs in cellular omics technologies have paved new pathways for understanding the regulation of genomic elements and the relationship between gene expression, cellular functions, and cell fate determination. The advent of spatial omics technologies, encompassing both imaging and sequencing-based methodologies, has enabled a comprehensive understanding of biological processes from a cellular ecosystem perspective. This review offers an updated overview of how spatial omics has advanced our understanding of the translation of genetic information into cellular heterogeneity and tissue structural organization and their dynamic changes over time. It emphasizes the discovery of various biological phenomena, related to organ functionality, embryogenesis, species evolution, and the pathogenesis of diseases.

Advances in single-cell transcriptomics in animal research

Understanding biological mechanisms is fundamental for improving animal production and health to meet the growing demand for high-quality protein. As an emerging biotechnology, single-cell transcriptomics has been gradually applied in diverse aspects of animal research, offering an effective method to study the gene expression of high-throughput single cells of different tissues/organs in animals. In an unprecedented manner, researchers have identified cell types/subtypes and their marker genes, inferred cellular fate trajectories, and revealed cell‒cell interactions in animals using single-cell transcriptomics. In this paper, we introduce the development of single-cell technology and review the processes, advancements, and applications of single-cell transcriptomics in animal research. We summarize recent efforts using single-cell transcriptomics to obtain a more profound understanding of animal nutrition and health, reproductive performance, genetics, and disease models in different livestock species. Moreover, the practical experience accumulated based on a large number of cases is highlighted to provide a reference for determining key factors (e.g., sample size, cell clustering, and cell type annotation) in single-cell transcriptomics analysis. We also discuss the limitations and outlook of single-cell transcriptomics in the current stage. This paper describes the comprehensive progress of single-cell transcriptomics in animal research, offering novel insights and sustainable advancements in agricultural productivity and animal health.

Sexually Dimorphic Response to Hepatic Injury in Newborn Suffering from Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR), when a fetus does not grow as expected, is associated with a reduction in hepatic functionality and a higher risk for chronic liver disease in adulthood. Utilizing early developmental plasticity to reverse the outcome of poor fetal programming remains an unexplored area. Focusing on the biochemical profiles of neonates and previous transcriptome findings, piglets from the same fetus are selected as models for studying IUGR. The cellular landscape of the liver is created by scRNA-seq to reveal sex-dependent patterns in IUGR-induced hepatic injury. One week after birth, IUGR piglets experience hypoxic stress. IUGR females exhibit fibroblast-driven T cell conversion into an immune-adapted phenotype, which effectively alleviates inflammation and fosters hepatic regeneration. In contrast, males experience even more severe hepatic injury. Prolonged inflammation due to disrupted lipid metabolism hinders intercellular communication among non-immune cells, which ultimately impairs liver regeneration even into adulthood. Additionally, Apolipoprotein A4 (APOA4) is explored as a novel biomarker by reducing hepatic triglyceride deposition as a protective response against hypoxia in IUGR males. PPARα activation can mitigate hepatic damage and meanwhile restore over-expressed APOA4 to normal in IUGR males. The pioneering study offers valuable insights into the sexually dimorphic responses to hepatic injury during IUGR.

Inhibition of endothelial to mesenchymal transition in a large animal preclinical arterio-venous fistula model leads to improved remodeling and reduced stenosis

AIMS

Vein grafts are used for many indications, including bypass graft surgery and arterio-venous fistula (AVF) formation. However, patency following vein grafting or AVF formation is suboptimal for various reasons, including thrombosis, neointimal hyperplasia and adverse remodeling. Recently, endothelial to mesenchymal transition (EndMT) was found to contribute to neointimal hyperplasia in mouse vein grafts. We aimed to evaluate the clinical potential of inhibiting EndMT, and developed the first dedicated preclinical model to study the efficacy of local EndMT inhibition immediately prior to AVF creation.

METHODS AND RESULTS

We first undertook pilot studies to optimize the creation of a femoral AVF in pigs and verify that EndMT contributes to neointimal formation. We then developed a method to achieve local in vivo SMAD3 knockdown by dwelling a lentiviral construct containing SMAD3 shRNA in the femoral vein prior to AVF creation. Next, in Phase 1, 6 pigs were randomized to SMAD3 knockdown or control lentivirus to evaluate the effectiveness of SMAD3 knockdown and EndMT inhibition 8 days after AVF creation. In Phase 2, 16 pigs were randomized to SMAD3 knockdown or control lentivirus and were evaluated to assess longer-term effects on AVF diameter, patency and related measures at 30 days after AVF creation.In Phase 1, compared to controls, SMAD3 knockdown achieved a 75% reduction in the proportion of CD31+ endothelial cells co-expressing SMAD3 (p<0.001), and also a significant reduction in the extent of EndMT (p<0.05). In Phase 2, compared to controls, SMAD3 knockdown was associated with an increase in the minimum diameter of the venous limb of the AVF (1.56±1.66 versus 4.26±1.71mm, p<0.01) and a reduced degree of stenosis (p<0.01). Consistent with this, neointimal thickness was reduced in the SMAD3 knockdown group (0.88±0.51 versus 0.45±0.19mm, p<0.05). Furthermore, endothelial integrity (the proportion of luminal cells expressing endothelial markers) was improved in the SMAD3 knockdown group (p<0.05).

CONCLUSIONS

EndMT inhibition in a preclinical AVF model by local SMAD3 knockdown using gene therapy led to reduced neointimal hyperplasia, increased endothelialization and a reduction in the degree of AVF stenosis. This provides important proof-of-concept to pursue this approach as a clinical strategy to improve the patency of AVFs and other vein grafts.

Metabolic Responses to Redox Stress in Vascular Cells

Significance: Redox stress underlies numerous vascular disease mechanisms. Metabolic adaptability is essential for vascular cells to preserve energy and redox homeostasis. Recent Advances: Single-cell technologies and multiomic studies demonstrate significant metabolic heterogeneity among vascular cells in health and disease. Increasing evidence shows that reductive or oxidative stress can induce metabolic reprogramming of vascular cells. A recent example is intracellular L-2-hydroxyglutarate accumulation in response to hypoxic reductive stress, which attenuates the glucose flux through glycolysis and mitochondrial respiration in pulmonary vascular cells and provides protection against further reductive stress. Critical Issues: Regulation of cellular redox homeostasis is highly compartmentalized and complex. Vascular cells rely on multiple metabolic pathways, but the precise connectivity among these pathways and their regulatory mechanisms is only partially defined. There is also a critical need to understand better the cross-regulatory mechanisms between the redox system and metabolic pathways as perturbations in either systems or their cross talk can be detrimental. Future Directions: Future studies are needed to define further how multiple metabolic pathways are wired in vascular cells individually and as a network of closely intertwined processes given that a perturbation in one metabolic compartment often affects others. There also needs to be a comprehensive understanding of how different types of redox perturbations are sensed by and regulate different cellular metabolic pathways with specific attention to subcellular compartmentalization. Lastly, integration of dynamic changes occurring in multiple metabolic pathways and their cross talk with the redox system is an important goal in this multiomics era.

Increased [18F]FDG uptake in the infarcted myocardial area displayed by combined PET/CMR correlates with snRNA-seq-detected inflammatory cell invasion

Combined [18F]FDG PET-cardiac MRI imaging (PET/CMR) is a useful tool to assess myocardial viability and cardiac function in patients with acute myocardial infarction (AMI). Here, we evaluated the prognostic value of PET/CMR in a porcine closed-chest reperfused AMI (rAMI) model. Late gadolinium enhancement by PET/CMR imaging displayed tracer uptake defect at the infarction site by 3 days after the rAMI in the majority of the animals (group Match, n = 28). Increased [18F]FDG uptake at the infarcted area (metabolism/contractility mismatch) with reduced tracer uptake in the remote viable myocardium (group Mismatch, n = 12) 3 days after rAMI was observed in the animals with larger infarct size and worse left ventricular ejection fraction (LVEF) (34 ± 8.7 vs 42.0 ± 5.2%), with lower LVEF also at the 1-month follow-up (35.8 ± 9.5 vs 43.0 ± 6.3%). Transcriptome analyses by bulk and single-nuclei RNA sequencing of the infarcted myocardium and border zones (n = 3 of each group, and 3 sham-operated controls) revealed a strong inflammatory response with infiltration of monocytes and macrophages in the infarcted and border areas in Mismatch animals. Our data indicate a high prognostic relevance of combined PET/MRI in the subacute phase of rAMI for subsequent impairment of heart function and underline the adverse effects of an excessive activation of the innate immune system in the initial phase after rAMI.

Transcriptomic Analyses Reveal the Effects of Walnut Kernel Cake on Adipose Deposition in Pigs

With the rising cost of animal feed protein, finding affordable and effective substitutes is crucial. Walnut kernel cake, a polyphenol-, fiber-, protein- and fat-rich byproduct of walnut oil extraction, has been underexplored as a potential protein replacement in pig feed. In this study, we found that feeding large Diqing Tibetan pigs walnut kernel cake promoted adipose deposition and improved pork quality during pig growth. Transcriptome analysis revealed the upregulation of genes ANGPTL8, CCNP, ETV4, and TRIB3, associated with adipose deposition. Pathway analysis highlighted enrichment in adipose deposition-related pathways, including PPAR, insulin, PI3K-Akt, Wnt, and MAPK signaling. Further analysis identified DEGs (differentially expressed genes) positively correlated with adipose-related traits, such as PER2 and PTGES. Single-cell transcriptome data pointed to the specific expression of CD248 and PTGES in adipocyte progenitor/stem cells (APSCs), pivotal for adipocyte differentiation and adipose deposition regulation. This study demonstrates walnut kernel cake's potential to substitute soybean cake in pig feed, providing high-quality protein and promoting adipose deposition. It offers insights into feed protein replacement, human functional food, fat metabolism, and related diseases, with marker genes and pathways supporting pig breeding and pork quality improvement.

Unveiling the Genetic Mechanism of Meat Color in Pigs through GWAS, Multi-Tissue, and Single-Cell Transcriptome Signatures Exploration

Meat color traits directly influence consumer acceptability and purchasing decisions. Nevertheless, there is a paucity of comprehensive investigation into the genetic mechanisms underlying meat color traits in pigs. Utilizing genome-wide association studies (GWAS) on five meat color traits and the detection of selection signatures in pig breeds exhibiting distinct meat color characteristics, we identified a promising candidate SNP, 6_69103754, exhibiting varying allele frequencies among pigs with different meat color characteristics. This SNP has the potential to affect the redness and chroma index values of pork. Moreover, transcriptome-wide association studies (TWAS) analysis revealed the expression of candidate genes associated with meat color traits in specific tissues. Notably, the largest number of candidate genes were observed from transcripts derived from adipose, liver, lung, spleen tissues, and macrophage cell type, indicating their crucial role in meat color development. Several shared genes associated with redness, yellowness, and chroma indices traits were identified, including RINL in adipose tissue, ENSSSCG00000034844 and ITIH1 in liver tissue, TPX2 and MFAP2 in lung tissue, and ZBTB17, FAM131C, KIFC3, NTPCR, and ENGSSSCG00000045605 in spleen tissue. Furthermore, single-cell enrichment analysis revealed a significant association between the immune system and meat color. This finding underscores the significance of the immune system associated with meat color. Overall, our study provides a comprehensive analysis of the genetic mechanisms underlying meat color traits, offering valuable insights for future breeding efforts aimed at improving meat quality.

Mapping Cell Atlases at the Single-Cell Level

Recent advancements in single-cell technologies have led to rapid developments in the construction of cell atlases. These atlases have the potential to provide detailed information about every cell type in different organisms, enabling the characterization of cellular diversity at the single-cell level. Global efforts in developing comprehensive cell atlases have profound implications for both basic research and clinical applications. This review provides a broad overview of the cellular diversity and dynamics across various biological systems. In addition, the incorporation of machine learning techniques into cell atlas analyses opens up exciting prospects for the field of integrative biology.

Single-Cell RNA Sequencing Reveals the Cellular Landscape of Longissimus Dorsi in a Newborn Suhuai Pig

The introduction of single-cell RNA sequencing (scRNA-seq) technology has spurred additional advancements in analyzing the cellular composition of tissues. The longissimus dorsi (LD) in pigs serves as the primary skeletal muscle for studying meat quality in the pig industry. However, the single-cell profile of porcine LD is still in its infancy stage. In this study, we profiled the transcriptomes of 16,018 cells in the LD of a newborn Suhuai pig at single-cell resolution. Subsequently, we constructed a cellular atlas of the LD, identifying 11 distinct cell populations, including endothelial cells (24.39%), myotubes (18.82%), fibro-adipogenic progenitors (FAPs, 18.11%), satellite cells (16.74%), myoblasts (3.99%), myocytes (5.74%), Schwann cells (3.81%), smooth muscle cells (3.22%), dendritic cells (2.99%), pericytes (1.86%), and neutrophils (0.33%). CellChat was employed to deduce the cell-cell interactions by evaluating the gene expression of receptor-ligand pairs across different cell types. The results show that FAPs and pericytes are the primary signal contributors in LD. In addition, we delineated the developmental trajectory of myogenic cells and examined alterations in the expression of various marker genes and molecular events throughout various stages of differentiation. Moreover, we found that FAPs can be divided into three subclusters (NR2F2-FAPs, LPL-FAPs, and TNMD-FAPs) according to their biological functions, suggesting that the FAPs could be associated with the differentiation of tendon cell. Taken together, we constructed the cellular atlas and cell communication network in LD of a newborn Suhuai pig, and analyzed the developmental trajectory of myogenic cells and the heterogeneity of FAPs subpopulation cells. This enhances our comprehension of the molecular features involved in skeletal muscle development and the meat quality control in pigs.

Regulation of oxygen-glucose deprivation/reperfusion-induced inflammatory responses and M1-M2 phenotype switch of BV2 microglia by lobetyolin

To elucidate the protective mechanism of lobetyolin on oxygen-glucose deprivation/reperfusion (OGD/R)-induced damage in BV2 microglial cells. The OGD/R model was established using a chemical modeling method to simulate in vivo brain ischemia in lobetyolin-pretreated BV2 cells. The optimum lobetyolin dosage, chemical concentration, and OGD/R modeling duration were screened. The changes in cell morphology were observed, and the levels of immune response-related factors, including tumor necrosis factor-α (TNF-α), interleukin-6, inducible nitric oxide synthase (iNOS), and cluster of differentiation (CD)206, were detected using the enzyme-linked immunosorbent assay. The expression of chemokine-like-factor-1 (CKLF1), hypoxia-inducible factor (HIF)-1α, TNF-α, and CD206, was detected using western blotting. The gene expression of M1 and M2 BV2 phenotype markers was assessed using quantitative polymerase chain reaction (qPCR). The localization of M1 and M2 BV2 markers was detected using immunofluorescence analysis. The results showed that lobetyolin could protect BV2 cells from OGD/R-induced damage. After OGD/R, CKLF1/C-C chemokine receptor type 4 (CCR4) levels increased in BV2 cells, whereas the CKLF1/CCR4 level was decreased due to lobetyolin pretreatment. Additionally, BV2 cells injured with OGD/R tended to be M1 type, but lobetyolin treatment shifted the phenotype of BV2 cells from M1 type to M2 type. Lobetyolin decreased the expression of TNF-α and HIF-1α but increased the expression of transforming growth factor-β (TGF-β) in BV2 cells, indicating a dose-effect relationship. The qPCR results showed that lobetyolin decreased the expression of CD16, CD32, and iNOS at the gene level and increased the expression of C-C-chemokine ligand-22 and TGF-β. The immunofluorescence analysis showed that lobetyolin decreased CD16/CD32 levels and increased CD206 levels. Lobetyolin can protect BV2 cells from OGD/R-induced damage by regulating the phenotypic polarization of BV2 and decreasing inflammatory responses. Additionally, CKLF1/CCR4 may participate in regulating lobetyolin-induced polarization of BV2 cells via the HIF-1α pathway.

Luminescence of carbon quantum dots and their application in biochemistry

Similar to fullerenes, carbon nanotubes and graphene, carbon dots (CDs) are causing a lot of research work in their own right. CDs are a type of surface-passivated quantum dot that contain carbon atoms. Their distinctive characteristics, such as luminescent emission that varies with size and wavelength, resistance to photobleaching, easy biological binding, lack of toxicity, and economical production without the need for intricate synthetic processes, have led to a noteworthy surge in attention within the research community. Different techniques can be utilized to create these CDs, spanning from basic candle burning to laser ablation. This review article delves into the principles of fluorescence technology, providing insights into how different synthesis methods of quantum dots impact their luminescent properties. Additionally, it highlights the latest applications of quantum dots in catalysis and biomedical fields, with special emphasis on the current status of luminescent properties in biology and chemistry. Towards the end, the article discusses the limitations of quantum dots in current practical applications, pointing out that CDs hold promising potential for future applications.

White Adipose Tissue Heterogeneity in the Single-Cell Era: From Mice and Humans to Cattle

Adipose tissue is a major modulator of metabolic function by regulating energy storage and by acting as an endocrine organ through the secretion of adipokines. With the advantage of next-generation sequencing-based single-cell technologies, adipose tissue has been studied at single-cell resolution, thus providing unbiased insight into its molecular composition. Recent single-cell RNA sequencing studies in human and mouse models have dissected the transcriptional cellular heterogeneity of subcutaneous (SAT), visceral (VAT), and intramuscular (IMAT) white adipose tissue depots and revealed unique populations of adipose tissue progenitor cells, mature adipocytes, immune cell, vascular cells, and mesothelial cells that play direct roles on adipose tissue function and the development of metabolic disorders. In livestock species, especially in bovine, significant gaps of knowledge remain in elucidating the roles of adipose tissue cell types and depots on driving the pathogenesis of metabolic disorders and the distinct fat deposition in VAT, SAT, and IMAT in meat animals. This review summarizes the current knowledge on the transcriptional and functional cellular diversity of white adipose tissue revealed by single-cell approaches and highlights the depot-specific function of adipose tissue in different mammalian species, with a particular focus on recent findings and future implications in cattle.

Single cell analysis reveals a subset of cytotoxic-like plasmacytoid dendritic cells in people with HIV-1

Human plasmacytoid dendritic cells (pDCs) play a central role in initiating and activating host immune responses during infection. To understand how the transcriptome of pDCs is impacted by HIV-1 infection and exogenous stimulation, we isolated pDCs from healthy controls, people with HIV-1 (PWH) before and during toll-like receptor 9 (TLR9) agonist treatment and performed single-cell (sc)-RNA sequencing. Our cluster analysis revealed four pDC clusters: pDC1, pDC2, cytotoxic-like pDC and an exhausted pDC cluster. The inducible cytotoxic-like pDC cluster is characterized by high expression of both antiviral and cytotoxic genes. Further analyses confirmed that cytotoxic-like pDCs are distinct from NK and T cells. Cell-cell communication analysis also demonstrated that cytotoxic-like pDCs exhibit similar incoming and outgoing cellular communicating signals as other pDCs. Thus, our study presents a detailed transcriptomic atlas of pDCs and provides new perspectives on the mechanisms of regulation and function of cytotoxic-like pDCs.

A single-cell atlas of West African lungfish respiratory system reveals evolutionary adaptations to terrestrialization

The six species of lungfish possess both lungs and gills and are the closest extant relatives of tetrapods. Here, we report a single-cell transcriptome atlas of the West African lungfish (Protopterus annectens). This species manifests the most extreme form of terrestrialization, a life history strategy to survive dry periods that can last for years, characterized by dormancy and reversible adaptive changes of the gills and lungs. Our atlas highlights the cell type diversity of the West African lungfish, including gene expression consistent with phenotype changes of terrestrialization. Comparison with terrestrial tetrapods and ray-finned fishes reveals broad homology between the swim bladder and lung cell types as well as shared and idiosyncratic changes of the external gills of the West African lungfish and the internal gills of Atlantic salmon. The single-cell atlas presented here provides a valuable resource for further exploration of the respiratory system evolution in vertebrates and the diversity of lungfish terrestrialization.

Endothelial-derived angiocrine factors as instructors of embryonic development

Blood vessels are well-known to play roles in organ development and repair, primarily owing to their fundamental function in delivering oxygen and nutrients to tissues to promote their growth and homeostasis. Endothelial cells however are not merely passive conduits for carrying blood. There is now evidence that endothelial cells of the vasculature actively regulate tissue-specific development, morphogenesis and organ function, as well as playing roles in disease and cancer. Angiocrine factors are growth factors, cytokines, signaling molecules or other regulators produced directly from endothelial cells to instruct a diverse range of signaling outcomes in the cellular microenvironment, and are critical mediators of the vascular control of organ function. The roles of angiocrine signaling are only beginning to be uncovered in diverse fields such as homeostasis, regeneration, organogenesis, stem-cell maintenance, cell differentiation and tumour growth. While in some cases the specific angiocrine factor involved in these processes has been identified, in many cases the molecular identity of the angiocrine factor(s) remain to be discovered, even though the importance of angiocrine signaling has been implicated. In this review, we will specifically focus on roles for endothelial-derived angiocrine signaling in instructing tissue morphogenesis and organogenesis during embryonic and perinatal development.

Understanding tumour endothelial cell heterogeneity and function from single-cell omics

Anti-angiogenic therapies (AATs) are used to treat different types of cancers. However, their success is limited owing to insufficient efficacy and resistance. Recently, single-cell omics studies of tumour endothelial cells (TECs) have provided new mechanistic insight. Here, we overview the heterogeneity of human TECs of all tumour types studied to date, at the single-cell level. Notably, most human tumour types contain varying numbers but only a small population of angiogenic TECs, the presumed targets of AATs, possibly contributing to the limited efficacy of and resistance to AATs. In general, TECs are heterogeneous within and across all tumour types, but comparing TEC phenotypes across tumours is currently challenging, owing to the lack of a uniform nomenclature for endothelial cells and consistent single-cell analysis protocols, urgently raising the need for a more consistent approach. Nonetheless, across most tumour types, universal TEC markers (ACKR1, PLVAP and IGFBP3) can be identified. Besides angiogenesis, biological processes such as immunomodulation and extracellular matrix organization are among the most commonly predicted enriched signatures of TECs across different tumour types. Although angiogenesis and extracellular matrix targets have been considered for AAT (without the hoped success), the immunomodulatory properties of TECs have not been fully considered as a novel anticancer therapeutic approach. Therefore, we also discuss progress, limitations, solutions and novel targets for AAT development.

A single-cell transcriptome atlas of pig skin characterizes anatomical positional heterogeneity

Different anatomical locations of the body skin show differences in their gene expression patterns depending on different origins, and the inherent heterogeneous information can be maintained in adults. However, highly resolvable cellular specialization is less well characterized in different anatomical regions of the skin. Pig is regarded as an excellent model animal for human skin research in view of its similar physiology to human. In this study, single-cell RNA sequencing was performed on pig skin tissues from six different anatomical regions of Chenghua (CH) pigs, with a superior skin thickness trait, and the back site of large white (LW) pigs. We obtained 233,715 cells, representing seven cell types, among which we primarily characterized the heterogeneity of the top three cell types, including smooth muscle cells (SMCs), endothelial cells (ECs), and fibroblasts (FBs). Then, we further identified several subtypes of SMCs, ECs, and FBs, and discovered the expression patterns of site-specific genes involved in some important pathways such as the immune response and extracellular matrix (ECM) synthesis in different anatomical regions. By comparing differentially expressed genes of skin FBs among different anatomical regions, we considered TNN, COL11A1, and INHBA as candidate genes for facilitating ECM accumulation. These findings of heterogeneity in the main skin cell types from different anatomical sites will contribute to a better understanding of inherent skin information and place the potential focus on skin generation, transmission, and transplantation, paving the foundation for human skin priming.

Purinergic receptor P2 × 7 contributes to abdominal aortic aneurysm development via modulating macrophage pyroptosis and inflammation

The purinergic receptor P2 × 7 has been established as an important mediator of inflammation and participates in a variety of cardiovascular diseases including atherosclerosis, however, its role in abdominal aortic aneurysms (AAA) remains unclear. In this study, we demonstrate that P2 × 7 plays essential roles in AAA development via modulating macrophage pyroptosis and inflammation. P2 × 7 is highly expressed in human AAA specimen, as well as in experimental murine AAA lesions (both CaCl₂-and Angiotensin Ⅱ-induced AAA models), and it mainly confines in macrophages. Furthermore, P2 × 7 deficiency or pharmacological inhibition with its antagonist could significantly attenuate aneurysm formation in experimental murine AAA models, while P2 × 7 agonist could promote AAA development. The caspase-I activity, matrix metalloproteinase (MMP) activity, reactive oxygen species (ROS) production and pro-inflammatory gene expression were significant reduced in experimental AAA lesions in mice with P2 × 7 deficiency or inhibition. Mechanistically, macrophage P2 × 7 can mediate the activation of NLRP3 inflammasome and activate its downstream caspase-1 to initiate the pyroptosis pathway. After caspase-1 activation, it further cleaves pro-interleukin (IL)-1β and gasdermin D (GSDMD). Consequently, the N-terminal fragment of GSDMD forms pores on the cell membrane, leading to macrophage pyroptosis and release of the pro-inflammatory factor IL-1β. The resulting vascular inflammation further leads to the upregulation of MMP and ROS, thereby promoting AAA development. In summary, these data identify P2 × 7-mediated macrophage pyroptosis signaling pathway as a novel contributory mechanism of AAA formation.

The Sertoli Cell Complement Signature: A Suspected Mechanism in Xenograft Survival

The complement system is an important component of transplant rejection. Sertoli cells, an immune regulatory testicular cell, survive long-term when transplanted across immunological barriers; thus, understanding the mechanisms behind this unique survival would be of great benefit to the transplantation field. This study focused on Sertoli cell inhibition of complement as relevant in xenotransplantation. Neonatal pig Sertoli cells (NPSCs) survived activated human complement in vitro while neonatal pig islet (NPI) aggregates and pig aortic endothelial cell (PAEC) survival were diminished to about 65% and 12%, respectively. PAECs cultured in NPSC-conditioned media and human complement demonstrated a 200% increase in survival suggesting that NPSCs secrete complement-inhibiting substances that confer protection. Bioinformatic and molecular analyses identified 21 complement inhibitors expressed by NPSCs with several significantly increased in NPSCs compared to NPIs or PAECs. Lastly, RNA sequencing revealed that NPSCs express 25 other complement factors including cascade components and receptors. Overall, this study identified the most comprehensive Sertoli cell complement signature to date and indicates that the expression of a variety of complement inhibitors ensures a proper regulation of complement through redundant inhibition points. Understanding the regulation of the complement system should be further investigated for extending xenograft viability.

Single-cell omics: A new direction for functional genetic research in human diseases and animal models

Over the past decade, with the development of high-throughput single-cell sequencing technology, single-cell omics has been emerged as a powerful tool to understand the molecular basis of cellular mechanisms and refine our knowledge of diverse cell states. They can reveal the heterogeneity at different genetic layers and elucidate their associations by multiple omics analysis, providing a more comprehensive genetic map of biological regulatory networks. In the post-GWAS era, the molecular biological mechanisms influencing human diseases will be further elucidated by single-cell omics. This review mainly summarizes the development and trend of single-cell omics. This involves single-cell omics technologies, single-cell multi-omics technologies, multiple omics data integration methods, applications in various human organs and diseases, classic laboratory cell lines, and animal disease models. The review will reveal some perspectives for elucidating human diseases and constructing animal models.

Droplets microfluidics platform-A tool for single cell research

Cells are the most basic structural and functional units of living organisms. Studies of cell growth, differentiation, apoptosis, and cell-cell interactions can help scientists understand the mysteries of living systems. However, there is considerable heterogeneity among cells. Great differences between individuals can be found even within the same cell cluster. Cell heterogeneity can only be clearly expressed and distinguished at the level of single cells. The development of droplet microfluidics technology opens up a new chapter for single-cell analysis. Microfluidic chips can produce many nanoscale monodisperse droplets, which can be used as small isolated micro-laboratories for various high-throughput, precise single-cell analyses. Moreover, gel droplets with good biocompatibility can be used in single-cell cultures and coupled with biomolecules for various downstream analyses of cellular metabolites. The droplets are also maneuverable; through physical and chemical forces, droplets can be divided, fused, and sorted to realize single-cell screening and other related studies. This review describes the channel design, droplet generation, and control technology of droplet microfluidics and gives a detailed overview of the application of droplet microfluidics in single-cell culture, single-cell screening, single-cell detection, and other aspects. Moreover, we provide a recent review of the application of droplet microfluidics in tumor single-cell immunoassays, describe in detail the advantages of microfluidics in tumor research, and predict the development of droplet microfluidics at the single-cell level.

HIF1A Knockout by Biallelic and Selection-Free CRISPR Gene Editing in Human Primary Endothelial Cells with Ribonucleoprotein Complexes

Primary endothelial cells (ECs), especially human umbilical vein endothelial cells (HUVECs), are broadly used in vascular biology. Gene editing of primary endothelial cells is known to be challenging, due to the low DNA transfection efficiency and the limited proliferation capacity of ECs. We report the establishment of a highly efficient and selection-free CRISPR gene editing approach for primary endothelial cells (HUVECs) with ribonucleoprotein (RNP) complex. We first optimized an efficient and cost-effective protocol for messenger RNA (mRNA) delivery into primary HUVECs by nucleofection. Nearly 100% transfection efficiency of HUVECs was achieved with EGFP mRNA. Using this optimized DNA-free approach, we tested RNP-mediated CRISPR gene editing of primary HUVECs with three different gRNAs targeting the HIF1A gene. We achieved highly efficient (98%) and biallelic HIF1A knockout in HUVECs without selection. The effects of HIF1A knockout on ECs' angiogenic characteristics and response to hypoxia were validated by functional assays. Our work provides a simple method for highly efficient gene editing of primary endothelial cells (HUVECs) in studies and manipulations of ECs functions.