Cell Proliferation

Characterizing cell identity in complex tissues such as the human retina is essential for studying its development and disease. While retinal organoids derived from pluripotent stem cells have been widely used to model development and disease of the human retina, there is a lack of studies that have systematically evaluated molecular and cellular fidelity of the organoids derived from various culture protocols in recapitulating their in vivo counterpart. To this end, we performed an extensive meta-atlas characterisation of cellular identities of the human eye, covering a wide range of developmental stages. The resulting map uncovered previously unknown biomarkers of major retinal cell types and those associated with cell-type specific maturation. Using our retinal cell identity map from the fetal and adult tissues, we systematically assessed the fidelity of the retinal organoids to mimic the human eye, enabling us to comprehensively benchmark the current protocols for retinal organoid generation.

Recent generation of stem cell-derived blastoids that recapitulate the architecture and cellular constitution of the human blastocyst offers an experimental model for the elucidation of the biology of early human development. To evaluate the fidelity of the blastoids for modelling human blastocysts, we first established a reference map of cell identity and lineage differentiation of the human blastocysts through the integration and curation of single-cell transcriptome data of ex vivo blastocysts profiled at a range of developmental timepoints in culture. We next use this reference map to assess the coverage and the authenticity of cell lineages and the progression of lineage differentiation of various blastoid models generated with different cellular sources and protocols. This reference map generated from this study enables the benchmarking of blastoids that may guide the optimization of the protocol for the generation of high-fidelity blastoid models that faithfully recapitulate the natural human blastocyst.

Cardiovascular diseases remain the leading cause of death worldwide; hence there is an increasing focus on developing physiologically relevant in vitro cardiovascular tissue models suitable for studying personalized medicine and pre-clinical tests. Despite recent advances, models that reproduce both tissue complexity and maturation are still limited. We have established a scaffold-free protocol to generate multicellular, beating and self-organized human cardiac organoids (hCO) in vitro from hiPSCs that can be cultured for long term. This is achieved by differentiation of hiPSC in 2D monolayer culture towards cardiovascular lineage, followed by further aggregation on low-attachment culture dishes in 3D. The generated human cardiac organoids (hCOs) containing multiple cell types that physiologically compose the heart, gradually self-organize and beat without external stimuli for more than 50 days. We have shown that 3D hCOs display improved cardiac specification, survival and maturation as compared to standard monolayer cardiac differentiation. We also confirmed the functionality of hCOs by their response to cardioactive drugs in long term culture. Furthermore, we demonstrated that hCOs can be used to study chemotherapy-induced cardiotoxicity. This study could help to develop more physiologically-relevant cardiac tissue models, and represent a powerful platform for future translational research in cardiovascular biology.

Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPS-CMs) have great potential in regenerative medicine. However, iPS-CMs are immature and resemble fetal cardiomyocytes, restricting their application. Although fetal cardiomyocytes in the human heart lose their proliferative potential during maturation and become tetraploid, iPS-CMs cannot replicate this tetraploidization and remain immature. To overcome this problem, we fused diploid iPSCs to establish tetraploid iPSCs and differentiated them into cardiomyocytes (4N-iPS-CMs). We found that 4N-iPS-CMs had more similar gene expression profiles, mitochondrial amounts, contractile impedance, and resistance to a potassium blocker in post-mitotic cardiomyocytes than conventional iPS-CMs. In addition, we successfully generated 4N-iPS-CMs from two individuals to mix two different genetic backgrounds. Thus, we demonstrated a novel strategy for generating human post-mitotic cardiomyocyte-like cells by generating tetraploid iPSCs.

Maternal drug exposure during pregnancy increases the risks of developmental cardiotoxicity, leading to congenital heart defects (CHDs). In this study, we used human stem cells as an in-vitro system to interrogate the mechanisms underlying drug-induced toxicity during cardiomyocyte differentiation, including anticancer tyrosine kinase inhibitor (TKI) drugs (imatinib, sunitinib, and vandetanib). H1-ESCs were treated with these drugs at sublethal levels during cardiomyocyte differentiation. We found that early exposure to TKIs during differentiation induced obvious toxic effects in differentiated cardiomyocytes, including disarranged sarcomere structure, interrupted Ca2+-handling, and impaired mitochondrial function. As sunitinib exposure showed the most significant developmental cardiotoxicity of all TKIs, we further examine its effect with in-vivo experiments. Maternal sunitinib exposure caused fetal death, bioaccumulation, and histopathologic changes in the neonatal mice. Integrative analysis of both transcriptomic and chromatin accessibility landscapes revealed that TKI-exposure altered GATA4-mediated regulatory network, which included key mitochondrial genes. Overexpression of GATA4 with CRISPR-activation restored morphologies, contraction, and mitochondria function in cardiomyocytes upon TKI exposure early during differentiation. Altogether, our study identified a novel crosstalk mechanism between GATA4 activity and mitochondrial function during cardiomyocyte differentiation, and revealed potential therapeutic approaches for reducing TKI-induced developmental cardiotoxicity for human health. HighlightsO_LIEarly-stage exposure to TKIs induced cardiotoxicity and mitochondrial dysfunction C_LIO_LIGATA4 transcriptional activity is inhibited by TKIs C_LIO_LINetwork analysis reveals interactions between GATA4 and mitochondrial genes C_LIO_LIGATA4-overexpression rescues cardiomyocytes and mitochondria from TKI exposure C_LI

The primary culture of donor-derived human corneal endothelial cells (CECs) is a promising cell therapy. It confers the potential to treat multiple patients from a single donor, alleviating the global donor shortage. Nevertheless, this approach has limitations preventing its adoption, particularly culture protocols allow limited expansion of CECs and there is a lack of clear parameters to identify therapy-grade CECs. To address this limitation, a better understanding of the molecular changes arising from the primary culture of CECs is required. Using single- cell RNA sequencing on primary cultured CECs, we identify their variable transcriptomic fingerprint at the single cell level, provide a pseudo temporal reconstruction of the changes arising from primary culture, and suggest markers to assess the quality of primary CEC cultures. This research depicts a deep transcriptomic understanding of the cellular heterogeneity arising from the primary expansion of CECs and sets the basis for further improvement of culture protocols and therapies.

Homologous recombination deficiency (HRD) testing has been approved by FDA for selecting epithelial ovarian cancer (EOC) patients who may benefit from the first-line poly (ADP-ribose) polymerase inhibitor (PARPi) maintenance therapy. However, the effects of HRD on the clinical outcomes of first-line chemotherapy and first-line PARPi maintenance therapy have not been rigorously evaluated in Chinese EOC patients. Here, we developed an HRD assay and applied it to two large Chinese EOC patient cohorts. In the first-line adjuvant chemotherapy cohort (FACT, N = 380), HRD status significantly improved PFS (median, 15.6 months vs. 9.4 months; HR, 0.688; 95% CI, 0.526 to 0.899; P = 0.003) and OS (median, 89.5 months vs. 60.9 months; HR, 0.636; 95% CI, 0.423 to 0.955; P = 0.008). In the first-line PARPi maintenance therapy cohort (FPMT, N = 83), HRD status significantly improved PFS (median, NA vs 12 months; HR, 0.438; 95% CI, 0.201 to 0.957; P = 0.033) and OS (median, NA vs NA months; HR, 0.12; 95% CI, 0.029 to 0.505; P = 0.001). Our results demonstrate that HRD status is a significant predictor for PFS and OS in both first-line chemotherapy and first-line PARPi maintenance therapy, providing strong real-world evidence for conducting genetic testing and improving clinical recommendations for Chinese EOC patients.

Acquiring a specific transcriptomic signature of the human and mouse cardiomyocyte (CM) will greatly increase our understanding of their biology and associated diseases that remain the most deadly across the world. In this study, using comprehensive transcriptomic mining of 91 cell types over 877 samples from bulk RNA-sequencing, single cell RNA-sequencing, and microarray techniques, we describe a unique 118-gene signature of human and mouse primary CMs. Once we had access to this CM-specific gene signature, we investigated the spatial heterogeneity of CMs throughout the heart tissue. Moreover, we compared the CM-specific gene signature to that of CMs derived from 10 differentiation protocols, and we identified the protocols that generate cells most similar to primary CMs. Finally, we looked at the specific differences between primary and differentiated CMs and found that differentiated cells underexpress genes related to CM development and maturity. The differentiated cells conversely overexpressed cell cycle-related genes, resulting in the progenitor features that remain in differentiated CMs compared to primary adult CMs. The presence of histone post translational modification H3K27ac from ChIP sequencing data sets were used to confirm transcriptomic findings. To the best of our knowledge, this is the most comprehensive study to date that unravels the unique transcriptomic signature of primary and differentiated CMs. This study provides important insights into our understanding of CM biology and the molecular mechanisms that make them such a unique cell type. Moreover, the specific transcriptomic signature of CMs could be used in developmental studies, stem cell therapy, regenerative medicine, and drug screening assays.

DNA methylation modification has been proved to play an important role in heart diseases. In this study, the role of Ten-Eleven Translocation-2 (TET2), which is a key demethylation enzyme, is investigated in cardiac remodeling. TET2 is abundant in endothelial cells but decreased in hypertrophic hearts. TET2 knockdown in endothelial cells triggers endothelial-to-mesenchymal transition (EndMT), while overexpression of TET2 inhibits the EndMT. In vivo, Cdh5-CreERT2/TET2flox/flox; Rosa26-mTmG+/- mice are developed and undergo transverse aortic constriction (TAC) subsequently to induce pathological cardiac hypertrophy model. Hearts of Cdh5-CreERT2/TET2flox/flox mice show more severe hypertrophy and fibrosis than controls in the TAC model. Furthermore, EGLN3 is identified to participate in EndMT as the downstream target of TET2 by using RNA sequencing and whole-genome bisulfite sequencing (WGBS). Finally, vitamin C, which can mimic TET2 restoration, is found to partially improve cardiac function and inhibit myocardial fibrosis. These insights into how TET2 alleviates cardiac fibrosis may open new avenues for treating cardiac remodeling in the future.

Reprogramming fibroblasts into induced cardiomyocytes (iCMs) holds great potential for cardiac regeneration. However, low conversion rate both in vitro and in vivo remains a significant challenge. To address this challenge, we focused on potential epigenetic barriers and screened 33 small-molecule inhibitors/degraders targeting histone acetyl post-translational modifications and related epigenetic factors. BET degraders were found to enhance cardiac reprogramming efficiency by degrading BRD4 and repressing genes involved in immune response, particularly those in the JAK/STAT pathway. We further identified that macrophage/oncostatin M activated the JAK/STAT pathway to repress cardiac reprogramming. BRD4 degrader treatment improved iCMs formation by inhibiting macrophage/oncostatin M-induced activation of the JAK/STAT pathway. Moreover, BRD4 degrader treatment enhanced MGT-mediated cardiac regeneration in vivo and improved myocardial performance post-myocardial infarction. These findings provide new insights into BRD4, macrophage/oncostatin M and JAK/STAT pathway in fibroblast to cardiomyocyte-like cell conversion and offer promising targets and small molecules to improve iCM reprogramming for clinical applications. HighlightsO_LIScreen of histone acetylation modifiers identified BRD4, a histone acetylation reader, as an important regulator in cardiac reprogramming. C_LIO_LIBRD4 degradation promoted cardiac reprogramming by repressing inflammation and the JAK-STAT pathway. C_LIO_LIBRD4 degradation inhibited macrophage/oncostatin M-induced activation of the JAK/STAT pathway. C_LIO_LIBRD4 degradation enhanced MGT-mediated cardiac regeneration in vivo and improved myocardial performance post-myocardial infarction. C_LI

In this study, we generated self-assembly cardiac organoids (COs) from human pluripotent stem cells by dual-phase modulation of Wnt/{beta}-catenin pathway, utilizing CHIR99021 and IWR-1-endo. The resulting COs exhibited a diverse array of cardiac-specific cell lineages, cardiac cavity-like structures and demonstrated the capacity of spontaneous beating and vascularization in vitro. We further employed these complex and functional COs to replicate conditions akin to human myocardial infarction and SARS-CoV-2 induced fibrosis. These models accurately captured the pathological characteristics of these diseases, in both in vitro and in vivo settings. In addition, we transplanted the COs into NOD SCID mice and observed that they survived and exhibited ongoing expansion in vivo. Impressively, over a span of 75-day transplantation, these COs not only established blood vessel-like structures but also integrated with the host mices vascular system. It is noteworthy that these COs developed to a size of approximately 8 mm in diameter, slightly surpassing the dimensions of the mouse heart. This innovative research highlighted the potential of our COs as a promising avenue for cardiovascular research and therapeutic exploration.

BackgroundAngiogenesis plays a crucial role in organ development. However, aberrant blood vessel growth is involved in various diseases, including tumors and neovascular eye diseases. Angiotensin-converting enzyme 2 (ACE2) is a critical enzyme regulating the health of cardiovascular system, and its post-translational modifications (PTMs) are crucial to determine ACE2 expression level and activity. Here, we studied how the PTM of ACE2 in vascular endothelial cells (ECs) affect pathological retinal neovascularization and tumor angiogenesis. MethodsThe angiogenic capabilities of ECs were assessed by tube formation, sprouting assays, and 5-ethynyl-2-deoxyuridine (EdU) and filopodia staining. EC angiogenesis was examined by poteome profiler array and aortic ring assays in vitro and by the oxygen-induced retinopathy (OIR) and tumor angiogenesis models in vivo. High-throughput screening involving data from RNA-seq, ATAC-seq, and ChIP-seq were used to explore the epigenetic and transcriptional regulations of pro-angiogenic genes regualtged by ACE2 PTMs. ResultsACE2 Ser-680 dephosphorylation in connection with Lys-788 ubiquitination increased EC angiogenic phenotype, which were manifested by aberrant vascularization in mouse OIR and tumor models. ACE2 Ser-680 dephosphorylation led to the activation of activator protein-1 (AP-1), which transactivated multiple genes involved in angiogenesis. AP- 1 inhibition mitigated such angiogenesis in vivo. ConclusionOur findings show a novel PTM mechanism of ACE2 involved in pathological angiogeneis. Specifically, ACE2 Ser-680 dephosphorylation facilitated AP-1 transactivation of the downstream pro-angiogenic genes in ECs.

Organoids can be broadly classified based on their source: either from primary cells or from in vitro stem cell differentiation. Organoids derived from primary cells have been developed for various organs such as the liver, intestine, and colon, demonstrating significant value in disease modeling and drug screening. However, primary cell-derived heart organoids have not yet been reported. In this study, we developed heart organoid-like spheroids using murine atrial and ventricular cells. We demonstrated that these spheroids largely preserved the cell lineages present in vivo. We further evaluated their responses to treatment with growth factors. Subsequently, we fused atrial and ventricular spheroids to observe the migration patterns of different cell types. Then, we generated mixed spheroids composed of cells from different heart regions or organs and found that region- or organ-specific cells tended to cluster together. Notably, liver- and intestine-derived cells promoted cardiomyocyte maturation within these mixed organoids. Finally, we performed a fibroblast ablation assay in heart spheroids derived from transgenic mice and observed the effects on other cell lineages. Overall, we successfully generated heart spheroids from murine primary cells and demonstrated their in vivo-like characteristics. Compared to stem cell-derived organoid systems, this primary cell-derived approach holds great promise for translational research due to its potential to better preserve native cellular features.

A thorough understanding of the cell behaviors of the human neural grafts is fundamental to exploit them to achieve cell therapy for recovering brain functions. Here by using immunohistological staining, we trace the cell fate of the intrastriatal human neural progenitor cell (NPC) grafts up to 9 months in adult rats, with multiple examining time points to provide a unified working time frame for future transplantation study. Lots of Nestin+/Sox2+ human cells continuously migrate along the white matter tracts into distal brain parenchyma even long time after transplantation, providing a potential for curing diffuse brain damage. Further analysis reveals a significant heterogeneity of the long-term sustained neural stem cells (NSC)/NPCs that progressing throughout different stages, mimicking the neural development of human forebrain. More importantly, the initial GFAP expression in human grafts marks the NSC progression instead of terminal astrocyte differentiation. The distally migrating human cells continuously show the capability to produce new neurons, albeit at a low efficiency in the intact brain. Further investigations in neural disease models are needed. Such study would benefit neural cell therapy with regarding to the optimization of the transplantation strategy and choosing of acting mode by neural grafts (e.g. via cell replacement or ex vivo gene therapy).

Cardiac manifestations are commonly observed in COVID-19 patients and prominently contributed to overall mortality. Human myocardium could be infected by SARS-CoV-2, and human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are susceptible to SARS-CoV-2 infection. However, molecular mechanisms of SARS-CoV-2 gene-induced injury and dysfunction of human CMs remain elusive. Here, we find overexpression of three SARS-CoV-2 coding genes, Nsp6, Nsp8 and M, could globally compromise transcriptome of hPSC-CMs. Integrated transcriptomic analyses of hPSC-CMs infected by SARS-CoV-2 with hPSC-CMs of Nsp6, Nsp8 or M overexpression identified concordantly activated genes enriched into apoptosis and immune/inflammation responses, whereas reduced genes related to heart contraction and functions. Further, Nsp6, Nsp8 or M overexpression induce prominent apoptosis and electrical dysfunctions of hPSC-CMs. Global interactome analysis find Nsp6, Nsp8 and M all interact with ATPase subunits, leading to significantly reduced cellular ATP level of hPSC-CMs. Finally, we find two FDA-approved drugs, ivermectin and meclizine, could enhance the ATP level, and ameliorate cell death and dysfunctions of hPSC-CMs overexpressing Nsp6, Nsp8 or M. Overall, we uncover the global detrimental impacts of SARS-CoV-2 genes Nsp6, Nsp8 and M on the whole transcriptome and interactome of hPSC-CMs, define the crucial role of ATP level reduced by SARS-CoV-2 genes in CM death and functional abnormalities, and explore the potentially pharmaceutical approaches to ameliorate SARS-CoV-2 genes-induced CM injury and abnormalities.

Although human embryonic stem cells (hESCs) are equipped with highly effective machinery for the maintenance of genome integrity, the frequency of genetic aberrations during long-term in vitro hESC culture has been a serious issue that raises concerns over their safety in future clinical applications. By passaging hESCs over a broad range of timepoints, we found that mitotic aberrations, such as the delay of mitosis, multipolar centrosomes, and chromosome mis-segregation, were increased in the late-passaged hESCs (LP-hESCs) in parallel with polyploidy compared to early-passaged hESCs (EP-hESCs). Through high-resolution genome-wide approaches and by following transcriptome analysis, we found that LP-hESCs with a minimal amplicon in chromosome 20q11.21 highly expressed TPX2 (targeting protein for Xklp2), a key protein for governing spindle assembly and cancer malignancy. Consistent with these findings, the inducible expression of TPX2 in EP-hESCs reproduced aberrant mitotic events, such as the delay of mitotic progression, spindle stability, misaligned chromosomes, and polyploidy. This data suggests that the amplification and increased transcription of the TPX2 gene at 20q11.21 could contribute to an increase in aberrant mitosis due to altered spindle dynamics.

Heart transplantation is the only curative option available for patients with advanced heart failure. However, donor organ shortage and graft rejection remain critical challenges in heart transplantation. Blastocyst complementation using pluripotent stem cells (PSCs) can be used to generate organs such as the pancreas and kidneys in animal models with abnormalities in essential developmental genes. Nonetheless, whether functional adult hearts can be generated with blastocyst complementation remains unclear, and it is unknown if parenchyma, blood vessels, and stroma can be generated concomitantly from PSCs using blastocyst complementation to avoid graft rejection. Here, we show the generation of functional adult hearts in acardiac Mesp1 and Mesp2 double-knockout (Mesp1/2-DKO) mice via blastocyst complementation using mouse PSCs. Our result shows that the generated hearts were structurally and functionally normal and restored embryonic lethality in Mesp1/2-DKO mice. All four cardiovascular lineages, including cardiomyocytes, vascular endothelial cells, smooth muscle cells, and cardiac fibroblasts, were virtually entirely derived from exogenous PSCs in the myocardium. Exogenous rat PSCs also generated rat-derived xenogeneic hearts in Mesp1/2-DKO mice via interspecies blastocyst complementation. Thus, blastocyst complementation is a viable technique for generating hearts derived from PSCs and may represent significant progress toward generating rejection-free hearts.

Heart failure (HF) is a common cardiovascular syndrome that poses significant morbidity and mortality risks. While genome-wide association studies reporting on HF abound, its genetic etiology remains poorly elucidated, primarily due to its inherent polygenic nature. Furthermore, these genetic insights have not been fully leveraged for the development of effective primary treatment strategies for HF. In this study, we conducted a large-scale integrated multi-trait analysis using European-ancestry GWAS summary statistics of coronary artery disease and HF, involving near 2 million samples to identify novel risk loci associated with HF. 72 loci were newly identified with HF, of which 44 were validated in the replication phase. Transcriptome association analysis revealed 215 HF risk genes, including EDNRA and FURIN. Pathway enrichment analysis of risk genes revealed their enrichment in pathways closely related to HF, such as response to endogenous stimulus (adjusted P = 8.83x10-3), phosphate-containing compound metabolic process (adjusted P = 1.91x10-2). Single-cell analysis indicated significant enrichments of these genes in smooth muscle cells, fibroblast of cardiac tissue, and cardiac endothelial cells. Additionally, our analysis of HF risk genes identified 74 potential drugs for further pharmacological evaluation. These findings provide novel insights into the genetic determinants of HF, highlighting new genetic loci as potential interventional targets to HF treatment, with significant implications for public health and clinical practice.

Zebrafish and urodele amphibians are capable of extraordinary myocardial regeneration thanks to the ability of their cardiomyocytes to undergo transient dedifferentiation and proliferation. Somatic cells can be temporarily reprogrammed to a proliferative, dedifferentiated state through transient expression of Oct3/4, Sox2, Klf4 and c-Myc (OSKM) transcription factors. Here, we utilized an OSKM-encoding non-integrating vector to induce transient reprogramming of mammalian cardiomyocytes in vitro. Reprogramming factor expression in neonatal rat cardiomyocytes triggered rapid cell dedifferentiation characterized by downregulation of cardiomyocyte specific gene and protein expression, sarcomere dis-assembly and loss of autorhythmic contractile activity. Concomitantly, a significant increase in cell cycle related gene expression and Ki67 positive cells was observed, indicating that dedifferentiated cardiomyocytes possess an enhanced proliferative capacity. A small proportion of cardiomyocytes progressed through mesenchymal to epithelial transition, further indicating the initiation of cell reprogramming. However, complete reprogramming to a pluripotent-like state was not achieved for the duration of the study (20 days), both in standard and embryonic stem cell culture media conditions. The transient nature of this partial reprogramming response was confirmed as cardiomyocyte-specific cell morphology, gene expression and contractile activity were recovered by day 15 after viral transduction. Further investigations into the complete downstream biological effects of ectopic OSKM expression in cardiomyocytes and the fate of these reprogrammed cells are warranted. Our results to date suggest that transient reprogramming could be a feasible strategy to recapitulate regenerative mechanisms of lower vertebrates and inform direct gene therapy approaches to cardiac regenerative medicine.

Understanding the mechanisms of blastocyst formation and implantation is crucial for advancing farm animal reproduction. However, research in this area is often hindered by the limited availability of embryos. In this study, we developed an efficient method to generate blastocyst-like structures (termed blastoids) from porcine expanded pluripotent stem cells (pEPSCs) through chemical induction with an efficiency up to 80%. These porcine blastoids closely resemble natural blastocysts in terms of morphology, cell composition, and single-cell transcriptomes. The tissue structures of the blastoids developed over time in culture, resembling the tissue morphology of gastrulation-stage embryos. This innovative approach not only provides a robust in vitro model for studying early embryogenesis in pigs but also holds the potential for improving reproductive efficiency and understanding the developmental processes of large farm animal species. The development of porcine blastoids represents a significant advancement in regenerative medicine and developmental biology.