ROLE OF VASCULAR SMOOTH MUSCLE CELLS IN VASCULAR DISEASE

血管平滑肌细胞的迁移、增殖和新生内膜积聚 肌肉细胞（VSMCs）是发生和发展的关键事件， 许多血管疾病和机械损伤的可预测后果， 血管。 体内的VSMC被包围并嵌入在 细胞外基质（ECM），其在迁移期间必须穿过。 在 许多其他类型的细胞，跨ECM屏障的迁移涉及局部 这些屏障被胞外蛋白酶破坏或降解。 这些蛋白酶中的主要是那些属于基质的蛋白酶 金属蛋白酶（MMP）家族。 使用体外测定来监测和 操纵VSMC降解限定的ECM屏障的能力，因为它们 向化学引诱物迁移，我们证明了从 大鼠胸主动脉，并保持在增殖或“合成” 状态容易迁移通过重构基底ECM屏障 膜的 生长停滞/分化的VSMCs向血管平滑肌细胞的迁移 在存在和不存在屏障的情况下， 低于增殖期细胞的20%（p<0.001）。 一种肽， 所有MMPs和抗血清的抑制性前肽区 中和72 kD IV型胶原酶（MMP-2）的活性， 增殖细胞通过屏障的迁移超过80% （p<0.005），但并没有显著影响发生在 没有障碍。北方印迹和酶谱分析表明， MMP 2是这些细胞表达和分泌的主要MMP。 MMP2 血清饥饿/分化的VSMCs表达的活性，通过 荧光肽裂解测定小于5%的测量中， 增殖血管平滑肌细胞膜型MMP（MT-MMP），最近描述的一种 整合质膜蛋白激活MMP-2，是差异 在VSMC中表达。特别是，增殖（迁移）VSMC表达2 MT-MMP mRNA是分化/生长停滞细胞的3倍。 在 相反，MMP-2 mRNA似乎相等地表达。这些结果 证明VSMC迁移通过ECM屏障， 这种能力是由 细胞表型状态和MT-MMP可能是重要的 VSMC中MMP-2蛋白水解级联的调节剂。

The migration, proliferation, and neointimal accumulation of vascular smoot muscle cells (VSMCs) are key events in the development and progression of many vascular diseases and a predictable consequence of mechanical injury t the blood vessel. VSMCs in vivo are surrounded by and embedded in extracellular matrices (ECMs) that must be traversed during migration. In many other cell types, migration across ECM barriers involves the local destruction or degradation of these barriers by extracellular proteases. Principle among such proteases are those belonging to the matrix metalloproteinase (MMP) family. Using an in vitro assay to monitor and manipulate the ability of VSMCs to degrade a defined ECM barrier as they migrate toward a chemo-attractant, we demonstrate that VSMCs isolated from the rat thoracic aorta and maintained in a proliferating or "synthetic" state readily migrate through an ECM barrier of reconstituted basement membrane. The migration of growth arrested/ differentiated VSMCs toward th chemoattractant both in the presence and in the absence of the barrier is less than 20% (p<0.001) that of proliferating cells. A peptide that mimics the inhibitory propeptide region of all MMPs and antisera caple of neutralizing the activity of the 72 kD Type IV collagenase (MMP-2) blocked migration of proliferating cells through the barrier by more than 80% (p<0.005), but did not significantly affect migration that occurred in the absence of the barrier. Northern blotting and zymogramic analyses indicate that MMP2 is the principal MMP expressed and secreted by these cells. MMP2 activity expressed by serum starved/differentiated VSMCs as measured by a fluorescent peptide cleavage assay was less than 5% of that measured in proliferating VSMCs. Membrane-type MMP (MT-MMP), a recently described integral plasma membrane protein that activates MMP-2, is differentially expressed in VSMCs. Specifically, proliferating (migratory) VSMCs express 2 3 fold more MT-MMP mRNA than differentiated/growth arrested cells. In contrast, MMP-2 mRNA appears to be equally expressed. These results demonstrate that VSMCs migrate through an ECM barrier similar in compositio to one that normally surrounds them and that this ability is regulated by the phenotypic state of the cell and that MT-MMP may be an important regulator of the MMP-2 proteolytic cascade in VSMC.