Lonza’s aortic adventitial fibroblasts (AoAF) are isolated from the outer connective tissue layer of the aorta. The aortia is divided into three layers. The tunica intima is the inner endothelial layer, the tunica media is the layers of the smooth muscle cells, and the tunica adventitia is the outermost layer where the aortic adventitial fibroblasts (AoAF) are isolated from. Aortic adventitial fibroblasts (AoAF) are isolated from either ascending or descending aorta.