XXXX Induces a Quiescent Phenotype and Inhibits Migration in Vascular Smooth Muscle Cells In  Vitro.

@entity1 @entity556 @entity1373 @entity9820 @entity1317 @entity850
BACKGROUND: Loss of critical endothelial cell function and subsequent vascular smooth muscle cell (VSMC) migration is central to the pathology of injury-induced neointimal @entity1373 and recurrent @entity850 . @entity9820 (TM), well known for its function as an endothelial surface anticoagulant, may have an unknown direct effect on VSMC physiology that would be lost after injury. Here, we examined a novel effect of TM on VSMC by testing the hypothesis that direct application of TM induces favorable changes to the morphology of VSMC and inhibits their migration. METHODS: Primary @entity1 VSMC were harvested using the explant technique and used in early passage (1-4) for all experiments. Laser-scanning confocal fluorescent imaging was performed to assess the effect of soluble TM on VSMC morphology. In  vitro, migration of VSMC was measured using: (1) a 4-hr modified Boyden chemotaxis assay and (2) a 24-hr electric cell-substrate impedance sensing injury migration assay. Migration experiments were conducted with VSMC exposed to increasing doses of soluble recombinant TM. Recombinant @entity556 served as a positive control and serum-free media as a negative control for all experimentation. Data were analyzed using a Student's t-test or repeated measures analysis of variance where appropriate (a  <  0.05). RESULTS: VSMC exposed to TM clearly demonstrated a quiescent morphology with organized stress fibers consistent with a quiescent, differentiated, contractile phenotype; whereas, @entity556 stimulation led to an activated, dedifferentiated, synthetic phenotype. VSMC demonstrated a low, baseline level of migration in unstimulated serum-free conditions. @entity556 significantly stimulated VSMC migration as expected. TM, independent of @entity556 , significantly inhibited baseline VSMC migration in a dose-response fashion. The maximal inhibition was observed at (5   g/mL) with 70% reduction (56      1.7 vs. 18      3.5  cells/5 high-power fields, P  =  0.0005). CONCLUSIONS: TM has a direct effect on VSMC resulting in a quiescent, differentiated and contractile phenotype, and inhibition of migration. This effect is independent of the presence of @entity556 . These findings provide new knowledge in understanding the pathophysiology of @entity1317 and support a strategy focused on restoring key endothelial function to prevent intimal @entity1373 .
