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Management of chronic kidney disease (CKD) remains a major challenge due limited therapeutic options to reverse fibrosis, which is a critical feature in CKD. Partial epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells (TECs) is a key driver of fibrosis, and has become an important focus for kidney protection strategies. Blood platelets, a major source of circulating transforming growth factor beta (TGF-β), are implicated in pathogenesis of CKD, but their involvement in EMT and kidney fibrosis remains uncertain. Methods: We used two mouse models of renal fibrosis—diabetic kidney disease (DKD) and unilateral ureter obstruction (UUO)—to examine the connection between platelets, partial EMT, and fibrosis. Platelet inhibition or depletion was performed to assess EMT, cell cycle arrest, and fibrosis. In vitro, platelets were applied to TECs and kidney organoids. To determine the role of TGF-β signaling, we used TGF-βRI inhibitor. Expression of EMT, and fibrosis markers, as well as TGF-β1 signaling, were analyzed using western blot, reverse transcription quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and immunostaining. Results: In both animal models, platelet inhibition or depletion resulted in reduced expression of cell cycle arrest marker p21, partial EMT and fibrosis. In vitro, activated platelets stimulated cell cycle arrest, EMT, and fibrosis in TECs and kidney organoids. Chronically injured TECs experience cell-cycle arrest which promote a paracrine EMT program in TECs, jointly leading to fibrosis. This platelet-mediated effect on cell cycle arrest and EMT was driven by TGF-β1 signaling, as selective inhibition of the TGF-β receptor rescued these dysfunctional phenotypes. Conclusions: Our study demonstrates that platelets activate the TGF-β1 pathway, leading to cell cycle arrest, EMT and renal fibrosis. These findings suggest that antiplatelet therapies may have potential renoprotective effects by protecting tubular homeostasis, attenuating partial EMT and fibrosis.

Propionic acidemia (PA) is a metabolic disorder caused by a deficiency of the mitochondrial enzyme propionyl-CoA carboxylase (PCC) due to mutations in the PCCA or PCCB genes, which encode the two PCC subunits. PA may lead to several types of cardiomyopathy and has been linked to cardiac electrical abnormalities such as QT interval prolongation, life-threatening arrhythmias, and sudden cardiac death. To gain insights into the mechanisms underlying PA-induced proarrhythmia, we recorded action potentials (APs) and ion currents using whole-cell patch-clamp in ventricular-like induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) from a PA patient carrying two pathogenic mutations in the PCCA gene (p.Cys616_Val633del and p.Gly477Glufs*9) (PCCA cells) and from a healthy subject (healthy cells). In cells driven at 1 Hz, PCC deficiency increased the latency and prolonged the AP duration (APD) measured at 20% of repolarization, without modifying resting membrane potential or AP amplitude. Moreover, delayed afterdepolarizations appeared at the end of the repolarization phase in unstimulated and paced PCCA cells. PCC deficiency significantly reduced peak sodium current (INa) but increased the late INa (INaL) component. In addition, L-type Ca2+ current (ICaL) density was reduced, while the inward and outward density of the Na+/Ca2+ exchanger current (INCX) was increased in PCCA cells compared to healthy ones. In conclusion, our results demonstrate that at the cellular level, PCC deficiency can modify the ion currents controlling cardiac excitability, APD, and intracellular Ca2+ handling, increasing the risk of arrhythmias independently of the progressive late-onset cardiomyopathy induced by PA disease.

Cardiac cellular fate transition holds remarkable promise for the treatment of ischemic heart disease. We report that overexpressing two transcription factors, Sall4 and Gata4, which play distinct and overlapping roles in both pluripotent stem cell reprogramming and embryonic heart development, induces a fraction of stem-like cells in rodent cardiac fibroblasts that exhibit unlimited ex vivo expandability with clonogenicity. Transcriptomic and phenotypic analyses reveal that around 32 ± 6.4% of the expanding cells express Nkx2.5, while 13 ± 3.6% express Oct4. Activated signaling pathways like PI3K/Akt, Hippo, Wnt, and multiple epigenetic modification enzymes are also detected. Under suitable conditions, these cells demonstrate a high susceptibility to differentiating into cardiomyocyte, endothelial cell, and extracardiac neuron-like cells. The presence of partially pluripotent-like cells is characterized by alkaline phosphatase staining, germ layer marker expression, and tumor formation in injected mice (n = 5). Additionally, significant stem-like fate transitions and cardiogenic abilities are induced in human cardiac fibroblasts, but not in rat or human skin fibroblasts. Molecularly, we identify that SALL4 and GATA4 physically interact and synergistically stimulate the promoters of pluripotency genes but repress fibrogenic gene, which correlates with a primitive transition process. Together, this study uncovers a new cardiac regenerative mechanism that could potentially advance therapeutic endeavors and tissue engineering.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-024-73975-8.