Adenovirus-mediated gene transfer of the human tissue inhibitor of metalloproteinase-2 blocks vascular smooth muscle cell invasiveness in vitro and modulates neointimal development in vivo

Background - Endovascular injury induced by balloon withdrawal leads to the increased activation of matrix metalloproteinases (MMPs) in the vascular wall, allowing smooth muscle cells (SMCs) to digest the surrounding extracellular matrix (ECM) and migrate from the media into the intima. The objective of this study was to examine the effects of a replication-deficient adenovirus carrying the cDNA for human tissue inhibitor of metalloproteinase- 2 (AdCMV.hTIMP-2) on SMC function in vitro and neointimal development in the injured rat carotid artery. Methods and Results - Infection of cultured rat aortic SMCs at a multiplicity of infection of 100 with AdCMV.hTIMP-2 resulted in high-level expression of hTIMP-2 mRNA and protein secretion into the medium. Conditioned media (CM) from AdCMV.hTIMP-2-infected but not control virus (AdCMV.null or AdCMV.βgal)-infected SMCs inhibited MMP-2 activity on gelatin zymograms as well as the chemoattractant-directed migration of SMCs across reconstituted basement membrane proteins in the Boyden chamber assay. In contrast, AdCMV.hTIMP-2 CM had no effect on chemoattractant-directed migration of SMCs occurring in the absence of an ECM barrier or on the proliferation of cultured neointimal SMCs. Delivery of AdCMV.hTIMP-2 (2.5 X 10⁹ pfu) to the carotid artery wall at the time of balloon withdrawal injury inhibited SMC migration into the intima by 36% (P<0.05) at 4 days and neointimal area by 53% (P<0.01) at 8 days and by 12% (P=NS) at 21 days after injury. AdCMV.hTIMP-2 had no effect on medial area. Conclusions - Adenovirus- mediated hTIMP-2 gene transfer inhibits SMC invasiveness in vitro and in vivo and delays neointimal development after carotid injury.