MMP9 and Aortic dissection: In contrast, the former researchers[13] showed that the expression of MMP-2 and TIMP-2 in aortic samples from patients with acute aortic dissection were significantly lower than in aortic samples from patients undergoing coronary artery bypass, implied that an imbalance between TIMP-2/MMP-2 and TIMP-2/MMP-9 might play an important role in the onset of aortic dissection.