Project description:Background: Biological-sex differences play a vital role in cardiovascular diseases, including atherosclerosis. The endothelium is a critical contributor to cardiovascular pathologies since endothelial cells (EC) regulate vascular tone, redox balance, and inflammatory reactions. Although EC activation and dysfunction play an essential role in the early and late stages of atherosclerosis development, little is known about sex-dependent differences in EC. Methods: We used aortic EC that was isolated from 13-week-old female and male mice as well as EC-lineage tracing (Cdh5-CreERT2 Rosa-YFP) atherosclerotic Apoe‒/‒ mice to investigate the biological sexual dimorphism of the EC functions in vitro and in vivo. RNA sequencing (RNAseq) analyses were performed on male and female mouse aortic EC and human lung EC. Results: In vitro, female mouse aortic EC (F_MAEC) showed more apoptosis and higher cellular ROS levels, lower mitochondrial membrane potential (ΔΨm), and lower levels of mitochondrial transcription factor A (TFAM) than male aortic EC (M_MAEC). Additionally, F_MAEC had decreased angiogenic potential (tube formation, cell viability, and proliferation) compared to M_MAEC. In vivo, female mice had significantly higher lipid accumulation within the aortas, less efficient outward vessel remodeling, and lower endothelial-mediated vasorelaxation than males. Using the EC-lineage tracing approach, we found that female lesions had significantly lower rates of intraplaque neovascularization and Endothelial-to-Mesenchymal (EndoMT) transition within advanced atherosclerotic lesions but higher incidents of missing EC lumen coverage and higher levels of oxidative products and apoptosis. RNAseq analyses revealed that both mouse and human female EC had higher expression of genes associated with inflammation and apoptosis and lower expression of genes related to angiogenesis and oxidative phosphorylation than male EC. Conclusions: Our study delineates critical sex-specific differences in EC relevant to pro-inflammatory, pro-oxidant, and angiogenic characteristics, which are entirely consistent with a vulnerable phenotype in females. Our results provide a biologic basis for sex-specific pro-atherosclerotic mechanisms.

Project description:Historically, lower incidence of CVD and related deaths in women compared to men of the same age has been attributed to female sex hormones, particularly estrogen and its receptors. Autologous Bone marrow stem cell (BMSC) clinical trials for cardiac cell therapy overwhelmingly included male patients; however, meta-analysis data on these trials suggest a better functional outcome in women compared to men. Direct comparison of gender-specific cardiac reparative activity and estrogen-independent mechanisms that regulate gender-specific dimorphisms of BMSC has not been studied. This study was designed to identify sex hormone-independent mechanisms that regulate superior reparative properties of female endothelial progenitor cells (EPCs) post-MI, particularly epigenetic mechanisms. Male (M), female (F), and ovariectomized female (OVX) mice-derived EPCs were subjected to a series of molecular and epigenetic analyses followed by in vivo functional assessments of cardiac repair. RNA sequencing and other quantitative assays showed a similar genetic profile between F-EPCs and OVX-EPCs, distinct from M-EPCs that displayed significant up-regulation of inflammation-related genes. F-EPCs and OVX EPCs secrete higher levels of proangiogenic factors, lower levels of proinflammatory cytokines and show better cardiac reparative activity after intra-cardiac injections in a male mouse model of myocardial infarction (MI). Epigenetic sequencing revealed a marked difference in the occupancy of the gene repressive H3K9me3 mark, particularly at transcription start sites of key angiogenic and proinflammatory genes in male EPCs compared to female and ovariectomized EPCs. Our study unveiled that functional gender dimorphism in EPCs is, in part, mediated by differential epigenetic regulation of the proinflammatory and anti-angiogenic gene CCL3, orchestrated by the control of H3K9me3 by histone methyltransferase, G9a/Ehmt2. Our research highlights the importance of considering gender of donor cells for progenitor based tissue repair.

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Senescence and Inflamm-Aging Are Associated With Endothelial Dysfunction in Men But Not Women With Atherosclerosis

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