Matrix metalloproteinase activation predicts amelioration of remodeling after dietary modification in injured arteries

Objective- To establish and validate early noninvasive imaging of matrix metalloproteinase (MMP) activation for monitoring the progression of vascular remodeling and response to dietary modification. Methods and results- Apolipoprotein E mice that were fed a high-fat diet underwent left common carotid artery wire injury. One week after surgery, a group of animals were withdrawn from the high-fat diet. The other group of animals continued that diet throughout the study. Micro single-photon emission computed tomographic (microSPECT)/CT imaging with RP805 (a Tc-labeled tracer targeting activated MMPs) was repeatedly performed at 2 and 4 weeks after surgery. Histological analysis at 4 weeks showed significant left carotid neointima formation, monocyte/macrophage infiltration, and upregulation of several MMPs, which were ameliorated by withdrawal from the high-fat diet. In vivo microSPECT/CT images visualized significant RP805 uptake, reflecting MMP activation, in the injured carotid arteries. MMP activation was reduced as early as 1 week after withdrawal from the high-fat diet and significantly correlated with neointimal area at 4 weeks after surgery. Conclusion- MMP activation predicts the progression of vascular remodeling and can track the effect of dietary modification after vascular injury.