CTGF is a Marker of Promigratory Subpopulation of Human Vascular Smooth Muscle Cells: Target for Treatment of Intimal Hyperplasia

Abstract

identity are plastic, and changes are found similar to those previously reported in human vein graft adaptation and animal models. These bioreactors adequately mimic the human arterial environment and enable testing of potential therapeutic agents directed against neointimal hyperplasia. Introduction and objectives:Understanding the processes that control vascular smooth muscle cell (VSMC) phenotypic modulation and determining which subpopulation of VSMCs migrate is critical for the design of treatment of intimal hyperplasia. Connective tissue growth factor (CTGF) has recently been reported to be upregulated in a variety of fibrotic disorders. We hypothesize that CTGF is a marker of a dedifferentiated VSMCs and therefore a target for treatment of intimal hyperplasia.Methods: Western blot analysis was used to determine protein expression. Bowden chambers were used for VSMC migration. Magnetic beads were labeled with CTGF antibody according to the manufacture's protocol. Porcine carotid arteries were microdissected into inner layer (intima/media) and outer layer (media/adventitia). VSMCs were transfected with myr-AKT1 using the nucleofection technique. Pig iliac arteries were injured and organ-cultured for 7 days.Results: Intimal hyperplastic VSMCs had higher baseline CTGF expression than normal VSMCs. VSMCs in the inner intimal/medial layer had increased differentiation markers. Outer medial/adventitial layer VSMCs had decreased contractile protein expression and increased CTGF expression. Balloon injury led to increased expression of CTGF in a subpopulation of VSMC as well as CTGF expression in cells within the intimal hyperplastic lesion. Intimal hyperplasia was recapitulated by addition of exogenous CTGF. High-expressing CTGF VSMCs (magnetic bead isolated) had decreased contractile protein expression and increased extracellular matrix expression. CTGF-positive VSMCs had 60% increased migration. Exogenous CTGF increased VSMC migration in a dose-dependent manner. Overexpression of myr-AKT1 increased CTGF and collagen IV expression in VSMCs.Conclusions: CTGF is an important regulator of VSMC migration and vascular remodeling through AKT1. CTGF is overexpressed in a subpopulation of VSMCs, which may be the promigratory cells that populate intimal hyperplasia lesions. These data will allow for more targeted therapies for intimal hyperplasia.