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Aging‐induced dysregulation of Dicer1‐dependent microRNA expression impairs angiogenic capacity of rat cerebromicrovascular endothelial cells

Age‐related impairment of angiogenesis is likely to play a central role in cerebromicrovascular rarefaction and development of vascular cognitive impairment. To test the hypothesis that dysregulation of Dicer1 impairs endothelial angiogenic capacity in aging, primary cerebromicrovascular endothelial cells(CMVEC) were isolated from young (3 mo) and aged (24 mo) F344xBN rats. In aged CMVECs Dicer1 was down‐regulated and its expression was increased by treatment with PEG‐catalase. Compared to young cells aged CMVECs exhibited altered miRNA expression profile, which was associated with impaired proliferation, adhesion to vitronectin, collagen and fibronectin, cellular migration and impaired ability to form capillary‐like structures. Overexpression of Dicer1 in aged CMVECs partially restored miRNA expression profile and significantly improved angiogenic processes. In young CMVECs down‐regulation of Dicer1 (siRNA) resulted in altered miRNA expression profile associated with impaired proliferation, adhesion, migration and tube formation, mimicking the aging phenotype. Collectively, Dicer1 is essential for normal endothelial angiogenic processes, suggesting that age‐related dysregulation of Dicer1‐dependent microRNA expression may be a potential mechanism underlying impaired angiogenesis and cerebromicrovascular rarefaction in aging.