MATRIX METALLOPROTEINASES OF VASCULAR WALL CELLS ARE INCREASED IN BALLOON-INJURED RAT CAROTID-ARTERY

Purpose: Although matrix metalloproteinase (MMP) expression has been c orrelated with proliferation and migration of various tumor cells, the relation between MMP expression and smooth muscle cell (SMC) prolifer ation and migration has not been established. Methods: We measured MMP expression (gelatin, casein, and elastin zymography) by vascular wall cells in balloon-injured carotid artery during the period of medial S MC proliferation, migration of SMC from the media to the intima, and s ubsequent intimal SMC proliferation. Results: The 72 and 64-kd gelatin ases (presumably 72 kd type TV collagenase or MMP 2) were constitutive ly expressed in normal carotid arteries, and the activated (59 and 54 kd) forms of this enzyme were increased at 5 days when SMCs start to m igrate. A 92 kd gelatinase (presumably 92 kd type TV collagenase or MM P 9) was increased at 24 hours, when SMCs entered the growth cycle, an d decreased thereafter. A low-molecular-weight metalloproteinase with elastolytic activity was present in the adventitia, and the activity w as increased at 5 days after surgery. Conclusions: These results sugge st that the 72 kd and 92 kd gelatinases may be involved in basement me mbrane and matrix degradation in the media in relation to SMC prolifer ation and migration, whereas the low-molecular-weight metalloproteinas e may have a role in elastin turnover in the adventitia.