ROLE OF VASCULAR SMOOTH MUSCLE CELLS IN VASCULAR DISEASE

血管内皮细胞的迁移、增殖和新生内膜积聚 平滑肌细胞（VSMC）是发育中的关键事件， 许多血管疾病的进展和可预测的后果 对血管的机械损伤。 体内的VSMC被 通过并嵌入细胞外基质（ECM）， 在迁移过程中。 在许多其他细胞类型中，跨ECM的迁移 这些障碍包括局部破坏或退化， 细胞外蛋白酶的屏障。 这类蛋白酶的原理 是属于基质金属蛋白酶（MMP）家族的那些。 使用体外测定来监测和操纵VSMCs的能力 降解一个确定的ECM屏障，因为他们迁移到一个 化学引诱物，我们证明了从大鼠分离的VSMCs 并保持在增殖或“合成”状态 易于迁移通过重组基底的ECM屏障 膜的 血清饥饿/分化的VSMCs向 化学引诱物在存在和不存在下， 屏障小于增殖屏障的20%（p <0.001） 细胞 MMP表达在肿瘤细胞迁移过程中的重要性 通过重组BM的“合成”VSMC被证明使用 一种模拟所有MMP的抑制性前肽区的肽。 这种肽阻断了增殖细胞通过 屏障降低80%以上（p <0.005），但无显著性差异 影响在没有屏障的情况下发生的迁移。 同样地，能够中和72 kD的抗血清也可用于免疫小鼠。 IV型胶原酶（MMP-2）也抑制了通过 屏障，而不显著影响细胞在 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主要MMP 细胞 血清饥饿/分化的VSMCs表达的MMP 2活性 如通过荧光肽裂解测定所测量的， 在增殖的血管平滑肌细胞中测量。 这些结果证明 VSMCs迁移通过ECM屏障的成分类似于 这种能力是由 细胞的表型状态

The migration, proliferation, and neointimal accumulation of vascular smooth muscle cells (VSMCs) are key events in the development and progression of many vascular diseases and a predictable consequence of mechanical injury to 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 chemoattractant, we demonstrate the 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 serum-starved/differentiated VSMCs toward the chemoattractant both in the presence and in the absence of the barrier is less than 20% (p less than 0.001) that of proliferating cells. The importance of MMP expression during the migration of "synthetic" VSMCs through the reconstituted BM was demonstrated using a peptide that mimics the inhibitory propeptide region of all MMPs. This peptide blocked migration of proliferating cells through the barrier by more than 80% (p less than 0.005), but did not significantly affect migration that occurred in the absence of the barrier. Likewise, antisera capable of neutralizing the activity of the 72 kD type IV collagenase (MMP-2) also inhibited migration through the barrier, without significantly affecting the migration of cells 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. These results demonstrate that VSMCs migrate through an ECM barrier similar in composition to one that normally surrounds them and that this ability is regulated by the phenotypic state of the cell.