Abstract 3547: Transforming Growth Factor-Beta 1 Transfected Vascular Smooth Muscle Cells Induce Endothelial Differentiation In Normal But Not Marfan Syndrome Vascular Smooth Muscle Cells
We have previously shown over-expression of TGF-beta isoforms in thoracic aortic aneurysm tissue (TAA) and cultured vascular smooth muscle cells (VSMC) derived from Marfan syndrome (MFS) subjects. To determine the importance of VSMC TGF-beta expression in regulation of vascular progenitor cell activation in response to injury we transiently transfected normal VSMC with pMAM-neoTGF-beta1. Transfection of two VSMC cultures resulted in increased expression of active TGF-beta 1 in the conditioned media as assessed by Western blot. Furthermore zymography study showed increased MMP-2 activity in transfected VSMC similar to increased MMP-2 activity in MFS VSMC. Semi quantitative analysis of MMP-2 and MMP-9 immunohistochemical staining in transfected normal cells compared to non-transfected normal VSMC showed increased MMP-2 expression (strong vs moderate) but only slight increase of MMP-9 expression (moderate/strong vs. moderate). Incubation of circulating monocytes for 48 h with the conditioned media from transfected normal VSMC resulted in enhanced monocyte differentiation into endothelial cells (EC) with increased percentage of CD31 positive cells (75%–100% CD31+) in comparison to 50% CD31+ when incubated in endothelial growth media only. Interestingly incubation of normal VSMC with MFS VSMC conditioned media resulted in no CD31+ cells. This study suggests that in VSMC derived from normal subjects increased active TGF-beta1 induced monocyte differentiation into EC. In MFS however increased TGF-beta 1 expression inhibited EC differentiation suggesting the presence of altered TGF-beta in MFS. The functional alteration is likely to be associated with the lack of inflammatory infiltration and fibrosis in MFS TAA.