Hypoxic tubular epithelial cells regulate the angiogenesis of HMEC-1 cells via mediation of Rab7/MMP-2 axis

RAS protein activator-like 2 (RASAL2) initiates peritubular capillary rarefaction in hypoxic renal interstitial fibrosis

The progression of chronic kidney disease (CKD) often involves renal interstitial fibrosis (RIF) and subsequent loss of peritubular capillaries (PTCs), which enhances disease severity. Despite advancements in our understanding of fibrosis, effective interventions for reversing capillary loss remain elusive. Notably, RIF exhibits reduced capillary density, whereas renal cell carcinoma (RCC) shows robust angiogenesis under hypoxic conditions. Using RNA sequencing and bioinformatics, we identified differentially expressed genes (DEGs) in hypoxic human renal tubular epithelial cells (HK-2) and renal cancer cells (786-0). Analysis of altered Ras and PI3K/Akt pathways coupled with hub gene investigation revealed RAS protein activator-like 2 (RASAL2) as a key candidate. Subsequent in vitro and in vivo studies confirmed RASAL2's early-stage response in RIF, which reduced with fibrosis progression. RASAL2 suppression in HK-2 cells enhanced angiogenesis, as evidenced by increased proliferation, migration, and branching of human umbilical vein endothelial cells (HUVECs) co-cultured with HK-2 cells. In mice, RASAL2 knockdown improved Vascular endothelial growth factor A (VEGFA) and Proliferating cell nuclear antigen (PCNA) levels in unilateral ureteral occlusion (UUO)-induced fibrosis (compared to wild type). Hypoxia-inducible factor 1 alpha (HIF-1α) emerged as a pivotal mediator, substantiated by chromatin immunoprecipitation (ChIP) sequencing, with its induction linked to activation. Hypoxia increased the production of RASAL2-enriched extracellular vesicles (EVs) derived from tubular cells, which were internalized by endothelial cells, contributing to the exacerbation of PTC loss. These findings underscore RASAL2's role in mediating reduced angiogenesis in RIF and reveal a novel EV-mediated communication between hypoxic tubular- and endothelial cells, demonstrating a complex interplay between angiogenesis and fibrosis in CKD pathogenesis.

ADSC-derived exosomes attenuate myocardial infarction injury by promoting miR-205-mediated cardiac angiogenesis

BACKGROUND

Acute myocardial infarction is a major health problem and is the leading cause of death worldwide. Myocardial apoptosis induced by myocardial infarction injury is involved in the pathophysiology of heart failure. Therapeutic stem cell therapy has the potential to be an effective and favorable treatment for ischemic heart disease. Exosomes derived from stem cells have been shown to effectively repair MI injury-induced cardiomyocyte damage. However, the cardioprotective benefits of adipose tissue-derived mesenchymal stem cell (ADSC)-Exos remain unknown. This study aimed to investigate the protective effects of exosomes from ADSC on the hearts of MI-treated mice and to explore the underlying mechanisms.

METHODS

Cellular and molecular mechanisms were investigated using cultured ADSCs. On C57BL/6J mice, we performed myocardial MI or sham operations and assessed cardiac function, fibrosis, and angiogenesis 4 weeks later. Mice were intramyocardially injected with ADSC-Exos or vehicle-treated ADSCs after 25 min following the MI operation.

RESULTS

Echocardiographic experiments showed that ADSC-Exos could significantly improve left ventricular ejection fraction, whereas ADSC-Exos administration could significantly alleviate MI-induced cardiac fibrosis. Additionally, ADSC-Exos treatment has been shown to reduce cardiomyocyte apoptosis while increasing angiogenesis. Molecular experiments found that exosomes extracted from ADSCs can promote the proliferation and migration of microvascular endothelial cells, facilitate angiogenesis, and inhibit cardiomyocytes apoptosis through miRNA-205. We then transferred isolated exosomes from ADSCs into MI-induced mice and observed decreased cardiac fibrosis, increased angiogenesis, and improved cardiac function. We also observed increased apoptosis and decreased expression of hypoxia-inducible factor-1α and vascular endothelial growth factor in HMEC-1 transfected with a miRNA-205 inhibitor.

CONCLUSION

In summary, these findings show that ADSC-Exos can alleviate cardiac injury and promote cardiac function recovery in MI-treated mice via the miRNA-205 signaling pathway. ADSC-Exos containing miRNA205 have a promising therapeutic potential in MI-induced cardiac injury.

WITHDRAWN: The Role of the Vascular Niche in Organ Fibrosis and COVID-19-Related Organ Damage and the Countermeasures adopted by Chinese and Western Medicine

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