Local gene transfer of tissue inhibitor of metalloproteinase-2 influences vein graft remodeling in a mouse model

Recently, we established a new mouse model of vein graft arteriosclerosis b y grafting vena cava to carotid arteries. In many respects, the morphologic al features of this murine vascular graft model resemble those of human ven ous bypass graft disease. Using this model, we studied the effects of local gene transfer of tissue inhibitor of metalloproteinase-2 (TIMP-2) on vein graft remodeling. Mouse isogeneic vessels of the vena caval veins were graf ted end to end into carotid arteries, then enveloped with the replication-d efective recombinant adenoviruses overexpressing human TIMP-2 (RAdTIMP-2) o r beta -galactosidase (RAdLacZ) at 1 x 10(10) plaque-forming units/mL in a total volume of 50 muL, and incubated at room temperature for 20 minutes. I n the untreated group, vessel wall thickening was observed as early as I we ek after surgery and progressed to 4- to 10-fold the original thickness in grafted veins at 4 and 8 weeks, respectively. RAdLacZ vector treatment sign ificantly enhanced neointimal lesions at 8 weeks, which was completely bloc ked by RAdTIMP-2 gene overexpression. Interestingly, RAdTIMP-2 gene transfe r resulted in a reduction in vessel diameter of grafted veins compared with ungrafted veins (819 +/- 96 versus 624 +/- 67 mum, respectively; P <0.05). Maximal beta -galactosidase activity was found at 2 weeks and was detectab le until 4 weeks after gene transfer. Double immunofluorescence studies dem onstrated that cells overexpressing TIMP-2 were mostly localized in the adv entitia and were MAC-1-positive monocytes/macrophages but not smooth muscle cells. Furthermore, the activity of matrix metalloproteinases was markedly decreased in the vessel walls treated with RAdTIMP-2 compared with that in the untreated control group and the RAdLacZ-treated group. Thus, this mous e model has been proven to be useful in gene transfer studies. Our findings demonstrate that local TIMP-2 gene transfer significantly reduces vein gra ft diameter, ie, remodeling, to an artery-like vessel via inhibition of mat rix metalloproteinase activity.