Vascular smooth muscle cell apoptosis in intimal hyperplasia

 描述（由申请人提供）：内膜增生是再狭窄的主要原因，发生率高得不可接受，特别是在外周血管床中。基于我们在大鼠颈动脉损伤模型中的研究结果，我们提出了一个非传统的假设，即血管介入诱导的血管平滑肌细胞（SMC）凋亡影响整个血管壁，包括内膜内皮细胞以及动脉外膜细胞。我们的数据表明，平滑肌细胞通过蛋白激酶C-δ（PKCd）依赖的趋化因子的产生对外膜和内皮细胞发出信号。我们已经确定MCP-1作为一个关键的旁分泌因子，通过SMCs调节外膜成纤维细胞。通过结合PKCd基因转移与MCP-1中和抗体，我们阻止了成纤维细胞迁移到内膜，并加倍PKCd对IH的抑制作用。然而，促进再内皮化的机制尚不清楚。在特定目标I中，我们计划检验凋亡SMC通过驱动骨髓源性细胞的募集来刺激再内皮化的假设，骨髓源性细胞进而通过分化或旁分泌效应促进内皮再生。我们还将测试CXCL 7是否是促内皮细胞募集的基础。在特定目标II中，我们将测试PKCd表达SMC产生的旁分泌效应是否是凋亡细胞的一般特性。在体外，我们将研究是否诱导细胞凋亡与生理相关的刺激，如氧化应激和细胞因子产生旁分泌因子，吸引外膜成纤维细胞或骨髓来源的循环促血管生成细胞。在体内，我们将驱动表达人白喉毒素受体的动脉平滑肌细胞凋亡B，期望增强的凋亡将减少SMC积聚，刺激外膜成纤维细胞的迁移，但加速再内皮化。在特定目标III中，我们将尝试将我们在初步研究中开发的PKCd修饰转化为通过刺激细胞凋亡和再内皮化但抑制外膜成纤维细胞内流来减轻内膜增生。总之，这是一个重要的和高度转化的项目，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.