Efficient endothelial and smooth muscle cell differentiation from human pluripotent stem cells through a simplified insulin-free culture system

A Comparative Study of Human Pluripotent Stem Cell-Derived Macrophages in Modeling Viral Infections

Macrophages play multiple roles in innate immunity including phagocytosing pathogens, modulating the inflammatory response, presenting antigens, and recruiting other immune cells. Tissue-resident macrophages (TRMs) adapt to the local microenvironment and can exhibit different immune responses upon encountering distinct pathogens. In this study, we generated induced macrophages (iMACs) derived from human pluripotent stem cells (hPSCs) to investigate the interactions between the macrophages and various human pathogens, including the hepatitis C virus (HCV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and Streptococcus pneumoniae. iMACs can engulf all three pathogens. A comparison of the RNA-seq data of the iMACs encountering these pathogens revealed that the pathogens activated distinct gene networks related to viral response and inflammation in iMACs. Interestingly, in the presence of both HCV and host cells, iMACs upregulated different sets of genes involved in immune cell migration and chemotaxis. Finally, we constructed an image-based high-content analysis system consisting of iMACs, recombinant GFP-HCV, and hepatic cells to evaluate the effect of a chemical inhibitor on HCV infection. In summary, we developed a human cell-based in vitro model to study the macrophage response to human viral and bacterial infections; the results of the transcriptome analysis indicated that the iMACs were a useful resource for modeling pathogen-macrophage-tissue microenvironment interactions.

Human Pluripotent Stem Cells Derived Endothelial Cells Repair Choroidal Ischemia

Choroidal atrophy is a common fundus pathological change closely related to the development of age-related macular degeneration (AMD), retinitis pigmentosa, and pathological myopia. Studies suggest that choroidal endothelial cells (CECs) that form the choriocapillaris vessels are the first cells lost in choroidal atrophy. It is found that endothelial cells derived from human pluripotent stem cells (hPSC-ECs) through the MESP1+ mesodermal progenitor stage express CECs-specific markers and can integrate into choriocapillaris. Single-cell RNA-seq (scRNA-seq) studies show that hPSC-ECs upregulate angiogenesis and immune-modulatory and neural protective genes after interacting with ex vivo ischemic choroid. In a rat model of choroidal ischemia (CI), transplantation of hPSC-ECs into the suprachoroidal space increases choroid thickness and vasculature density. Close-up examination shows that engrafted hPSC-ECs integrate with all layers of rat choroidal vessels and last 90 days. Remarkably, EC transplantation improves the visual function of CI rats. The work demonstrates that hPSC-ECs can be used to repair choroidal ischemia in the animal model, which may lead to a new therapy to alleviate choroidal atrophy implicated in dry AMD, pathological myopia, and other ocular diseases.

Advances and Applications of Lung Organoids in the Research on Acute Respiratory Distress Syndrome (ARDS)

Acute Respiratory Distress Syndrome (ARDS) is a sudden onset of lung injury characterized by bilateral pulmonary edema, diffuse inflammation, hypoxemia, and a low P/F ratio. Epithelial injury and endothelial injury are notable in the development of ARDS, which is more severe under mechanical stress. This review explains the role of alveolar epithelial cells and endothelial cells under physiological and pathological conditions during the progression of ARDS. Mechanical injury not only causes ARDS but is also a side effect of ventilator-supporting treatment, which is difficult to model both in vitro and in vivo. The development of lung organoids has seen rapid progress in recent years, with numerous promising achievements made. Multiple types of cells and construction strategies are emerging in the lung organoid culture system. Additionally, the lung-on-a-chip system presents a new idea for simulating lung diseases. This review summarizes the basic features and critical problems in the research on ARDS, as well as the progress in lung organoids, particularly in the rapidly developing microfluidic system-based organoids. Overall, this review provides valuable insights into the three major factors that promote the progression of ARDS and how advances in lung organoid technology can be used to further understand ARDS.

BACH1 regulates the differentiation of vascular smooth muscle cells from human embryonic stem cells via CARM1-mediated methylation of H3R17

The role of BACH1 in the process of vascular smooth muscle cell (VSMC) differentiation from human embryonic stem cells (hESCs) remains unknown. Here, we find that the loss of BACH1 in hESCs attenuates the expression of VSMC marker genes, whereas overexpression of BACH1 after mesoderm induction increases the expression of VSMC markers during in vitro hESC-VSMC differentiation. Mechanistically, BACH1 binds directly to coactivator-associated arginine methyltransferase 1 (CARM1) during in vitro hESC-VSMC differentiation, and this interaction is mediated by the BACH1 bZIP domain. BACH1 recruits CARM1 to VSMC marker gene promoters and promotes VSMC marker expression by increasing H3R17me2 modification, thus facilitating in vitro VSMC differentiation from hESCs after the mesoderm induction. The increased expression of VSMC marker genes by BACH1 overexpression is partially abolished by inhibition of CARM1 or the H3R17me2 inhibitor TBBD in hESC-derived cells. These findings highlight the critical role of BACH1 in hESC differentiation into VSMCs by CARM1-mediated methylation of H3R17.

Small diameter expanded polytetrafluoroethylene vascular graft with differentiated inner and outer biomacromolecules for collaborative endothelialization, anti-thrombogenicity and anti-inflammation

Without differentiated inner and outer biological function, expanded polytetrafluoroethylene (ePTFE) small-diameter (<6 mm) artificial blood vessels would fail in vivo due to foreign body rejection, thrombosis, and hyperplasia. In order to synergistically promote endothelialization, anti-thrombogenicity, and anti-inflammatory function, we modified the inner and outer surface of ePTFE, respectively, by grafting functional biomolecules, such as heparin and epigallocatechin gallate (EGCG), into the inner surface and polyethyleneimine and rapamycin into the outer surface via layer-by-layer self-assembly. Fourier-transform infrared spectroscopy showed the successful incorporation of EGCG, heparin, and rapamycin. The collaborative release profile of heparin and rapamycin lasted for 42 days, respectively. The inner surface promoted human umbilical vein endothelial cells (HUVECs) adhesion and growth and that the outer surface inhibited smooth muscle cells growth and proliferation. The modified ePTFE effectively regulated the differentiation behavior of RAW264.7, inhibited the expression of proinflammatory mediator TNF-α, and up-regulated the expression of anti-inflammatory genes Arg1 and Tgfb-1. The ex vivo circulation results indicated that the occlusions and total thrombus weight of modified ePTFE was much lower than that of the thrombus formed on the ePTFE, presenting good anti-thrombogenic properties. Hence, the straightforward yet efficient synergistic surface functionalization approach presented a potential resolution for the prospective clinical application of small-diameter ePTFE blood vessel grafts.

Designed peptide-grafted hydrogels for human pluripotent stem cell culture and differentiation

Human pluripotent stem cells (hPSCs) have the ability to differentiate into cells derived from three germ layers and are an attractive cell source for cell therapy in regenerative medicine. However, hPSCs cannot be cultured on conventional tissue culture flasks but can be cultured on biomaterials with specific hPSC integrin interaction sites. We designed hydrogels conjugated with several designed peptides that had laminin-β4 active sites, optimal elasticities and different zeta potentials. A higher expansion fold of hPSCs cultured on the hydrogels was found with the increasing zeta potential of the hydrogels conjugated with designed peptides, where positive amino acid (lysine) insertion into the peptides promoted higher zeta potentials of the hydrogels and higher expansion folds of hPSCs when cultured on the hydrogels using xeno-free protocols. The hPSCs cultured on hydrogels conjugated with the optimal peptides showed a higher expansion fold than those on recombinant vitronectin-coated plates, which are the gold standard of hPSC cultivation dishes. The hPSCs could differentiate into specific cell lineages, such as mesenchymal stem cells (MSCs) and MSC-derived osteoblasts, even after being cultivated on hydrogels conjugated with optimal peptides for long periods of time, such as 10 passages.

Differentiation and Engineering of Human Stem Cells for Smooth Muscle Generation

Cardiovascular diseases are responsible for 31% of global deaths and are considered the main cause of death and disability worldwide. Stem cells from various sources have become attractive options for a range of cell-based therapies for smooth muscle tissue regeneration. However, for efficient myogenic differentiation, the stem cell characteristics, cell culture conditions, and their respective microenvironments need to be carefully assessed. This review covers the various approaches involved in the regeneration of vascular smooth muscles by conditioning human stem cells. This article delves into the different sources of stem cells used in the generation of myogenic tissues, the role of soluble growth factors, use of scaffolding techniques, biomolecular cues, relevance of mechanical stimulation, and key transcription factors involved, aimed at inducing myogenic differentiation. Impact statement The review article's main goal is to discuss the recent advances in the field of smooth muscle tissue regeneration. We look at various cell sources, growth factors, scaffolds, mechanical stimuli, and factors involved in smooth muscle formation. These stem cell-based approaches for vascular muscle formation will provide various options for cell-based therapies with long-term beneficial effects on patients.

Biomaterial application strategies to enhance stem cell-based therapy for ischemic stroke

BACKGROUND

Ischemic stroke is a condition in which an occluded blood vessel interrupts blood flow to the brain and causes irreversible neuronal cell death. Transplantation of regenerative stem cells has been proposed as a novel therapy to restore damaged neural circuitry after ischemic stroke attack. However, limitations such as low cell survival rates after transplantation remain significant challenges to stem cell-based therapy for ischemic stroke in the clinical setting. In order to enhance the therapeutic efficacy of transplanted stem cells, several biomaterials have been developed to provide a supportable cellular microenvironment or functional modification on the stem cells to optimize their reparative roles in injured tissues or organs.

AIM

To discuss state-of-the-art functional biomaterials that could enhance the therapeutic potential of stem cell-based treatment for ischemic stroke and provide detailed insights into the mechanisms underlying these biomaterial approaches.

METHODS

The PubMed, Science Direct and Scopus literature databases were searched using the keywords of “biomaterial” and “ischemic stroke”. All topically-relevant articles were then screened to identify those with focused relevance to in vivo, in vitro and clinical studies related to “stem cells” OR “progenitor cells” OR “undifferentiated cells” published in English during the years of 2011 to 2022. The systematic search was conducted up to September 30, 2022.

RESULTS

A total of 19 articles matched all the inclusion criteria. The data contained within this collection of papers comprehensively represented 19 types of biomaterials applied on seven different types of stem/progenitor cells, namely mesenchymal stem cells, neural stem cells, induced pluripotent stem cells, neural progenitor cells, endothelial progenitor cells, neuroepithelial progenitor cells, and neuroblasts. The potential major benefits gained from the application of biomaterials in stem cell-based therapy were noted as induction of structural and functional modifications, increased stem cell retention rate in the hostile ischemic microenvironment, and promoting the secretion of important cytokines for reparative mechanisms.

CONCLUSION

Biomaterials have a relatively high potential for enhancing stem cell therapy. Nonetheless, there is a scarcity of evidence from human clinical studies for the efficacy of this bioengineered cell therapy, highlighting that it is still too early to draw a definitive conclusion on efficacy and safety for patient usage. Future in-depth clinical investigations are necessary to realize translation of this therapy into a more conscientious and judicious evidence-based therapy for clinical application.

Endothelial and hematopoietic hPSCs differentiation via a hematoendothelial progenitor

Background

hPSC-derived endothelial and hematopoietic cells (ECs and HCs) are an interesting source of cells for tissue engineering. Despite their close spatial and temporal embryonic development, current hPSC differentiation protocols are specialized in only one of these lineages. In this study, we generated a hematoendothelial population that could be further differentiated in vitro to both lineages.

Methods

Two hESCs and one hiPSC lines were differentiated into a hematoendothelial population, hPSC-ECs and blast colonies (hPSC-BCs) via CD144⁺-embryoid bodies (hPSC-EBs). hPSC-ECs were characterized by endothelial colony-forming assay, LDL uptake assay, endothelial activation by TNF-α, nitric oxide detection and Matrigel-based tube formation. Hematopoietic colony-forming cell assay was performed from hPSC-BCs. Interestingly, we identified a hPSC-BC population characterized by the expression of both CD144 and CD45. hPSC-ECs and hPSC-BCs were analyzed by flow cytometry and RT-qPCR; in vivo experiments have been realized by ischemic tissue injury model on a mouse dorsal skinfold chamber and hematopoietic reconstitution in irradiated immunosuppressed mouse from hPSC-ECs and hPSC-EB-CD144⁺, respectively. Transcriptomic analyses were performed to confirm the endothelial and hematopoietic identity of hESC-derived cell populations by comparing them against undifferentiated hESC, among each other’s (e.g. hPSC-ECs vs. hPSC-EB-CD144⁺) and against human embryonic liver (EL) endothelial, hematoendothelial and hematopoietic cell subpopulations.

Results

A hematoendothelial population was obtained after 84 h of hPSC-EBs formation under serum-free conditions and isolated based on CD144 expression. Intrafemorally injection of hPSC-EB-CD144⁺ contributed to the generation of CD45⁺ human cells in immunodeficient mice suggesting the existence of hemogenic ECs within hPSC-EB-CD144⁺. Endothelial differentiation of hPSC-EB-CD144⁺ yields a population of > 95% functional ECs in vitro. hPSC-ECs derived through this protocol participated at the formation of new vessels in vivo in a mouse ischemia model. In vitro, hematopoietic differentiation of hPSC-EB-CD144⁺ generated an intermediate population of > 90% CD43⁺ hPSC-BCs capable to generate myeloid and erythroid colonies. Finally, the transcriptomic analyses confirmed the hematoendothelial, endothelial and hematopoietic identity of hPSC-EB-CD144⁺, hPSC-ECs and hPSC-BCs, respectively, and the similarities between hPSC-BC-CD144⁺CD45⁺, a subpopulation of hPSC-BCs, and human EL hematopoietic stem cells/hematopoietic progenitors.

Conclusion

The present work reports a hPSC differentiation protocol into functional hematopoietic and endothelial cells through a hematoendothelial population. Both lineages were proven to display characteristics of physiological human cells, and therefore, they represent an interesting rapid source of cells for future cell therapy and tissue engineering.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02925-w.

Integrative epigenomic and transcriptomic analysis reveals the requirement of JUNB for hematopoietic fate induction

Human pluripotent stem cell differentiation towards hematopoietic progenitor cell can serve as an in vitro model for human embryonic hematopoiesis, but the dynamic change of epigenome and transcriptome remains elusive. Here, we systematically profile the chromatin accessibility, H3K4me3 and H3K27me3 modifications, and the transcriptome of intermediate progenitors during hematopoietic progenitor cell differentiation in vitro. The integrative analyses reveal sequential opening-up of regions for the binding of hematopoietic transcription factors and stepwise epigenetic reprogramming of bivalent genes. Single-cell analysis of cells undergoing the endothelial-to-hematopoietic transition and comparison with in vivo hemogenic endothelial cells reveal important features of in vitro and in vivo hematopoiesis. We find that JUNB is an essential regulator for hemogenic endothelium specialization and endothelial-to-hematopoietic transition. These studies depict an epigenomic roadmap from human pluripotent stem cells to hematopoietic progenitor cells, which may pave the way to generate hematopoietic progenitor cells with improved developmental potentials.

Microfluidic processing of stem cells for autologous cell replacement

Autologous photoreceptor cell replacement is one of the most promising approaches currently under development for the treatment of inherited retinal degenerative blindness. Unlike endogenous stem cell populations, induced pluripotent stem cells (iPSCs) can be differentiated into both rod and cone photoreceptors in high numbers, making them ideal for this application. That said, in addition to photoreceptor cells, state of the art retinal differentiation protocols give rise to all of the different cell types of the normal retina, the majority of which are not required and may in fact hinder successful photoreceptor cell replacement. As such, following differentiation photoreceptor cell enrichment will likely be required. In addition, to prevent the newly generated photoreceptor cells from suffering the same fate as the patient's original cells, correction of the patient's disease‐causing genetic mutations will be necessary. In this review we discuss literature pertaining to the use of different cell sorting and transfection approaches with a focus on the development and use of novel next generation microfluidic devices. We will discuss how gold standard strategies have been used, the advantages and disadvantages of each, and how novel microfluidic platforms can be incorporated into the clinical manufacturing pipeline to reduce the complexity, cost, and regulatory burden associated with clinical grade production of photoreceptor cells for autologous cell replacement.