Vascular smooth muscle cell apoptosis in intimal hyperplasia

 描述(申请人提供)：血管内膜增生是再狭窄的主要原因，再狭窄的发生率高得令人无法接受，尤其是在外周血管床。根据我们在大鼠颈动脉损伤模型上的发现，我们提出了一个非常规的假设，即直接血管干预诱导的血管平滑肌细胞(SMC)的凋亡影响包括内膜内皮细胞和动脉外膜细胞在内的整个血管壁。我们的数据表明，SMC通过蛋白激酶C-增量(PKCd)依赖的趋化因子的产生向外膜和血管内皮细胞传递信号。我们已经确定MCP-1是一种关键的旁分泌因子，SMC通过它来调节外膜成纤维细胞。通过将PKCd基因转移与MCP-1中和抗体相结合，我们阻止了成纤维细胞向内膜的迁移，并使PKCd对IH的抑制作用加倍。然而，加速血管内皮化的机制仍不清楚。在特定的目标I中，我们计划验证这样的假设，即凋亡的SMC通过驱动骨髓来源的细胞的募集来刺激再内皮化，而骨髓来源的细胞反过来通过分化或旁分泌效应促进内皮再生。我们还将测试CXCL7是否支持前内皮细胞的招募。在特定的目的II中，我们将测试表达PKCd的SMC产生的旁分泌效应是否是凋亡细胞的一般特性。在体外，我们将研究在生理相关刺激(如氧化应激和细胞因子)的诱导下，是否会产生旁分泌因子来吸引外膜成纤维细胞或骨髓来源的循环前血管生成细胞。在体内，我们将推动表达人白喉毒素受体的动脉平滑肌细胞凋亡，以期增强凋亡将减少SMC聚集，刺激外膜成纤维细胞迁移，但加速再内皮化。在特定的目标III中，我们将尝试翻译我们在初步研究中开发的PKCd修饰，通过刺激细胞凋亡和再内皮化，但抑制外膜成纤维细胞的流入来减轻内膜增生。总而言之，这是一个重要的和高度翻译的项目，可能会扩大我们对细胞死亡和治疗发展的知识。

 DESCRIPTION (provided by applicant): Intimal hyperplasia is a major cause of restenosis that occurs at an unacceptably high rate, particularly in peripheral vascular beds. Based on our findings made in a rat carotid injury model, we put forward an unconventional hypothesis that apoptosis of vascular smooth muscle cells (SMCs) induced by primary vascular intervention influences the entire vessel wall including intimal endothelial cells as well as cells of the arteral adventitia. Our data suggest that SMCs signal to the adventitia and endothelium through protein kinase C-delta (PKCd)-dependent production of chemokines. We have identified MCP-1 as a critical paracrine factor through which SMCs modulate adventitial fibroblasts. By combining PKCd gene transfer with an MCP-1 neutralizing antibody, we blocked fibroblasts from migrating into the intima and doubled the inhibitory effect of PKCd on IH. However, the mechanism underlying acceleration of re-endothelialization remains unclear. In Specific Aim I, we plan to test the hypothesis that apoptotic SMCs stimulate re- endothelialization by driving recruitment of bone marrow-derived cells which in turn contribute to endothelial regeneration through differentiation or paracrine effects. We will also test whether CXCL7 underlies the recruitment of pro-endothelial cells. In Specific Aim II, we will test whether the paracrine effects produced by PKCd-expressing SMCs are general properties of apoptotic cells. In vitro, we will examine whether induction of apoptosis with physiologically relevant stimuli such as oxidative stress and cytokines produce paracrine factors that attract adventitial fibroblasts or bone marrow-derived circulating proangiogenic cells. In vivo, we will drive arterial smooth muscle cells to apoptosis b expressing human diphtheria toxin receptor with an expectation that enhanced apoptosis will reduce SMC accumulation, stimulate migration of adventitial fibroblasts but accelerate re-endothelialization. In Specific Aim III, we will attempt to translate the PKCd modifications we developed in preliminary studies to attenuate intimal hyperplasia by stimulating apoptosis and re- endothelialization but suppressing influx of adventitial fibroblasts. In summary, this is a significant and highly translational project that is likely to expand our knowledge on cell death and therapeutic development.