Intraluminal delivery of thrombospondin‐2 small interfering RNA inhibits the vascular response to injury in a rat carotid balloon angioplasty model

In an effort to inhibit the response to vascular injury that leads to intimal hyperplasia, this study investigated the in vivo efficacy of intraluminal delivery of thrombospondin‐2 (TSP‐2) small interfering RNA (siRNA). Common carotid artery (CCA) balloon angioplasty injury was performed in rats. Immediately after denudation, CCA was transfected intraluminally (15 min) with one of the following: polyethylenimine (PEI)+TSP‐2 siRNA, saline, PEI only, or PEI+control siRNA. CCA was analyzed at 24 h or 21 d by using quantitative real‐time PCR and immunohistochemistry. TSP‐2 gene and protein expression were significantly up‐regulated after endothelial denudation at 24 h and 21 d compared with contralateral untreated, nondenuded CCA. Treatment with PEI+TSP‐2 siRNA significantly suppressed TSP‐2 gene expression (3.1‐fold) at 24 h and TSP‐2 protein expression, cell proliferation, and collagen deposition up to 21 d. These changes could be attributed to changes in TGF‐β and matrix metalloproteinase‐9, the downstream effectors of TSP‐2. TSP‐2 knockdown induced anti‐inflammatory M2 macrophage polarization at 21 d; however, it did not significantly affect intima/media ratios. In summary, these data demonstrate effective siRNA transfection of the injured arterial wall and provide a clinically effective and translationally applicable therapeutic strategy that involves nonviral siRNA delivery to ameliorate the response to vascular injury.—Bodewes, T.C.F., Johnson, J.M., Auster, M., Huynh, C., Muralidharan, S., Contreras, M., LoGerfo, F. W., Intraluminal delivery of thrombospondin‐2 small interfering RNA inhibits the vascular response to injury in a rat carotid balloon angioplasty model. FASEB J. 31, 109–119 (2017) www.fasebj.org