Although model organisms have provided insight into the earliest stages of cardiac and hepatic vascularization, we know very little about this process in humans because of ethical restrictions and the technical difficulty of obtaining embryos during very early development. In this study, we demonstrate that micropatterned human pluripotent stem cell–derived gastruloids enable in vitro modeling of the earliest stages of vascularization. We identify a combination of vascular-inducing factors that give rise to cardiac vascularized organoids with a spatially organized and branched vascular network. To show the broader utility of our vascularization strategy, we use the same vascular-inducing factors to produce hepatic vascularized organoids. Our results suggest that a conserved developmental program generates the vasculature within different types of organs.

The common aldehyde dehydrogenase 2 (ALDH2) alcohol flushing variant known asALDH2*2affects ∼8% of the world’s population. Even in heterozygous carriers, this missense variant leads to a severe loss of ALDH2 enzymatic activity and has been linked to an increased risk of coronary artery disease (CAD). Endothelial cell (EC) dysfunction plays a determining role in all stages of CAD pathogenesis, including early-onset CAD. However, the contribution ofALDH2*2to EC dysfunction and its relation to CAD are not fully understood. In a large genome-wide association study (GWAS) from Biobank Japan,ALDH2*2was found to be one of the strongest single-nucleotide polymorphisms associated with CAD. Clinical assessment of endothelial function showed that human participants carryingALDH2*2exhibited impaired vasodilation after light alcohol drinking. Using human induced pluripotent stem cell–derived ECs (iPSC-ECs) and CRISPR-Cas9–correctedALDH2*2iPSC-ECs, we modeledALDH2*2-induced EC dysfunction in vitro, demonstrating an increase in oxidative stress and inflammatory markers and a decrease in nitric oxide (NO) production and tube formation capacity, which was further exacerbated by ethanol exposure. We subsequently found that sodium-glucose cotransporter 2 inhibitors (SGLT2i) such as empagliflozin mitigatedALDH2*2-associated EC dysfunction. Studies inALDH2*2knock-in mice further demonstrated that empagliflozin attenuatedALDH2*2-mediated vascular dysfunction in vivo. Mechanistically, empagliflozin inhibited Na⁺/H⁺-exchanger 1 (NHE-1) and activated AKT kinase and endothelial NO synthase (eNOS) pathways to ameliorateALDH2*2-induced EC dysfunction. Together, our results suggest thatALDH2*2induces EC dysfunction and that SGLT2i may potentially be used as a preventative measure against CAD forALDH2*2carriers.

FLNC truncating mutations ( FLNCtv ) are prevalent causes of inherited dilated cardiomyopathy (DCM), with a high risk of developing arrhythmogenic cardiomyopathy. We investigated the molecular mechanisms of mutant FLNC in the pathogenesis of arrhythmogenic DCM (a-DCM) using patient-specific induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs). We demonstrated that iPSC-CMs from two patients with different FLNCtv mutations displayed arrhythmias and impaired contraction. FLNC ablation induced a similar phenotype, suggesting that FLNCtv are loss-of-function mutations. Coimmunoprecipitation and proteomic analysis identified β-catenin (CTNNB1) as a downstream target. FLNC deficiency induced nuclear translocation of CTNNB1 and subsequently activated the platelet-derived growth factor receptor alpha (PDGFRA) pathway, which were also observed in human hearts with a-DCM and FLNCtv . Treatment with the PDGFRA inhibitor, crenolanib, improved contractile function of patient iPSC-CMs. Collectively, our findings suggest that PDGFRA signaling is implicated in the pathogenesis, and inhibition of this pathway is a potential therapeutic strategy in FLNC-related cardiomyopathies.

Messenger RNA (mRNA) vaccines against SARS-CoV-2 are highly effective and were instrumental in curbing the COVID-19 pandemic. However, rare cases of noninfective myocarditis, particularly in young males and typically after the second dose, have been observed. Here, we explore the mediators of this myocarditis to better understand and to enhance the safety of future mRNA vaccines. Through analysis of human plasma data and in vitro experiments with human macrophages and T cells, we identified increased C-X-C motif chemokine ligand 10 (CXCL10) and interferon-γ (IFN-γ) after exposure to BNT162b2 (Pfizer) or mRNA-1273 (Moderna). Neutralization of CXCL10 and IFN-γ during the second dose (21 days after the first dose) reduced vaccine-induced cardiac injury in mice. Neutralization also reduced cardiac stress markers such as the release of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and expression of inflammatory genes in human induced pluripotent stem cell (iPSC)–derived cardiac spheroids. When exposed to these cytokines in vitro, human iPSC-derived cardiomyocytes (iPSC-CMs) exhibited impaired contractility, arrhythmogenicity, and proinflammatory gene expression patterns. Genistein, a phytoestrogen implicated in reducing cardiovascular inflammation, mitigated these effects in iPSC-CMs. In mice exposed to these cytokines or receiving BNT162b2 vaccination, genistein treatment reduced cardiac injury markers and attenuated infiltration of neutrophils and macrophages into the heart. These findings implicate CXCL10–IFN-γ signaling as a contributor to myocardial injury in experimental models of mRNA vaccination and indicate that pharmacologic modulation, such as with genistein, may mitigate cytokine-driven injury.