Sex-specific angiogenic responses in endothelial cells—role of the pluripotency factor OCT4

The study investigates the sex-specific effects of the pluripotency factor OCT4 deficiency in endothelial cells (ECs) on angiogenesis. OCT4 is known for its role in embryonic stem cells, but we recently found that it plays a protective role in ECs during atherosclerosis. Herein, we utilized cultured mouse aortic ECs (MAECs) and several in vivo models, including skin wounding, melanoma tumor implantation, and hindlimb ischemia, to explore the role of OCT4 in angiogenesis in both male and female mice. Our findings revealed significant sexual dimorphism in wild type mice, along with sex differences in responses to OCT4 deficiency across all three in vivo models. Male mice with endothelial Oct4 knockout had faster skin wound healing, increased vascularization, and quicker blood flow recovery after hindlimb ischemia than wild-type mice. In contrast, female mice with endothelial Oct4 knockout experienced delayed wound healing, no significant change in blood flow recovery after hindlimb ischemia, and increased tumor growth. Mechanistically, MCP1, a key angiogenic chemokine, was differentially regulated in male and female Oct4 knockout compared to wild-type MAECs, suggesting OCT4-dependent regulation of MCP1 as a critical mechanism for sex differences in angiogenic responses. RNA sequencing (RNAseq) analysis revealed distinct gene expression profiles in male and female MAECs upon OCT4 deficiency. Notably, female ECs exhibited upregulation of pro-inflammatory genes, which, although modest relative to their already elevated baseline, may contribute to the enhanced tumor growth observed in mutant females. In contrast, male ECs exhibited increased expression of cell cycle- and angiogenesis-related genes, correlating with their enhanced angiogenic responses. Overall, the research provides novel insights into the sex-specific functional role of OCT4 in ECs during angiogenesis and emphasizes the need for developing sex-specific EC-targeting therapeutic strategies for cardiovascular diseases and cancer.