Project description:The etiology of aortic aneurysms is poorly understood, but it is associated with atherosclerosis, hypercholesterolemia, and abnormal transforming growth factor β (TGF-β) signaling in smooth muscle. Here, we investigated the interactions between these different factors in aortic aneurysm development and identified a key role for smooth muscle cell (SMC) reprogramming into a mesenchymal stem cell (MSC)-like state. SMC-specific ablation of TGF-β signaling in Apoe-/- mice on a hypercholesterolemic diet led to development of aortic aneurysms exhibiting all the features of human disease, which was associated with transdifferentiation of a subset of contractile SMCs into an MSC-like intermediate state that generated osteoblasts, chondrocytes, adipocytes, and macrophages. This combination of medial SMC loss with marked increases in non-SMC aortic cell mass induced exuberant growth and dilation of the aorta, calcification and ossification of the aortic wall, and inflammation, resulting in aneurysm development.
Project description:Smooth muscle cell TGFβ signaling is one of the primary drivers of smooth muscle cell maturation. Inhibition of smooth muscle cell TGFβ signaling in hyperlipidemic mice induces vessel wall inflammation and vessel wall dilation/dissection and leads aortic aneurysm. We performed bulk RNAseq method to examine smooth muscle cell gene expression profile using fresh human tissues from normal aortic media smooth muscle cells and aneurysm aortic media smooth muscle cells.
