**4. Localisation of metalloproteinases in a vascular wall**

Metalloproteinases can be detected in all three layers of a vascular wall. Endothelium can produce MMP-1 and MMP-2. Smooth muscle cells (SMC) of both intima and media are the next source of MMPs. They can secrete MMP-2 and MMP-9. SMC can also produce TIMP-1 and TIMP-2. Adventitia is the layer where MMP-9 can be synthesized. Apart from these most studied metalloproteinases some other MMPs can be detected in a vascular wall: MT1- MMP, MMP-3, MMP-8, MMP-10, MMP-12 and MMP-13. Metalloproteinases are found not only in a wall of arterial wall, but in veins as well.

The balance between the expression of MMPs and TIMPs plays a vital role in preserving the proper and health state of the vascular wall. This equilibrium between activation and inactivation of MMPs is a part of a balance between synthesis and degradation of collagen and elastin, two proteins which have various properties and functions in the arterial wall. Both proteins are crucial for a proper function of the arterial wall. An interruption of these two balances may lead to a development of various vascular pathologies including atherosclerosis, formation of aneurysm and inflammation [3-5].
