Notably, the specific elimination of CD34+ cell‐derived Periostin+ myofibroblasts in dual recombinase‐based lineage tracing (Cd34‐Dre;Postn‐CreERT2;Dou‐tdT‐DTR) mice further confirms the functional contribution of CD34+ cell‐derived Periostin+ myofibroblasts to adventitial fibrous collar formation within aortic aneurysms, and their beneficial effects in preventing abdominal aortic rupture and increasing animal survival. Here, POSTN is linked to aortic aneurysm.