Endothelial progenitor cells (EPCs) contribute to blood vessel formation. Canonical Wnt signaling plays an important role in physiological and pathological angiogenesis and EPC fate regulation. However, the mechanism for Wnt signaling to regulate EPC fate in neovascularization (NV) has not been clearly defined. Here, we showed that very low-density lipoprotein receptor knockout (Vldlr^−/−) mice, a model of ocular NV induced by Wnt signaling overactivation, have increased EPC numbers in the bone marrow, blood, and retina, as well as an elevated mitochondrial membrane potential indicating higher mitochondrial function of EPCs in the circulation. Isolated EPCs from Vldlr^−/− mice showed overactivated Wnt signaling, correlating with increased mitochondrial function, mass, and DNA copy numbers, compared with WT EPCs. Our results also demonstrated that Wnt signaling upregulated mitochondrial biogenesis and function, while inhibiting glycolysis in EPCs, which further decreased EPC stemness and promoted EPCs to a more active state toward differentiation, which may contribute to pathologic vascular formation. Fenofibric acid, an active metabolite of fenofibrate, inhibited Wnt signaling and mitochondrial function in EPCs and decreased EPC numbers in Vldlr^−/−mice. It also decreased mitochondrial biogenesis and reactive oxygen species production in Vldlr^−/− EPCs, which may be responsible for its therapeutic effect on diabetic retinopathy. These findings demonstrated that Wnt signaling regulates EPC fate through metabolism, suggesting potential application of the EPC metabolic profile as predictor and therapeutic target for neovascular diseases. Stem Cells  2019;37:1331–1343

Dysregulated blood vessel formation is an important pathological feature in multiple diseases such as neovascular eye diseases and cancer. Endothelial progenitor cells (EPCs) are generated in the bone marrow, transported to target tissues through the blood, and differentiate into endothelial cells to form new vessels. This study found that EPC metabolic profile is a direct determinant of EPC fate. The Wnt signaling pathway regulates EPC metabolism, EPC fate, and subsequently, new vessel formation. These findings reveal a new function of Wnt signaling in regulating mitochondrial function in EPCs. This study also suggests a potential significance of EPC metabolic profile as a diagnostic marker and therapeutic target for diseases caused by abnormal blood vessel formation.