PEDF在血管再狹窄化的治療效果及相關機制

Abstract

藥物釋放型支架(Drug eluting stent)是目前用來治療因動脈粥狀硬化導致血管阻塞的主要方式，藥物可藉由抑制血管中層平滑肌細胞移行增生的特性達到抗血管內膜增生(Neointima hyperplasia)，而此技術已應用在超過百萬名心血管疾病患者中。但近年來，許多臨床報告指出藥物釋放型支架會嚴重地延緩病人血管再內皮化(Re-endothelialization)及影響內皮正常功能，造成病患在晚期有血栓形成、支架再狹窄、血管功能喪失等等併發症，甚至存在較高的死亡率。因此，抑制血管內膜增生及加速血管再內皮化是目前發展藥物釋放型支架的新方針。色素上皮衍生因子(Pigment epithelium-derived factor , PEDF)為多功能性的分泌型蛋白質，在心血管疾病方面已被證實具有抗發炎、抗氧化及抗平滑肌增生的功用，因此本實驗目的是探討PEDF是否能成為發展藥物釋放型支架的新方向。在體外實驗，我們利用人類臍帶靜脈內皮細胞及臍帶間質內皮前驅細胞作為探討血管再內皮化的機制；大鼠主動脈平滑肌細胞及巨噬細胞RAW264.7則用來進行抗增生、抗發炎試驗。體內實驗則利用血管內皮損傷模式觀察血管再內皮化及血管內膜增生。本篇實驗中另加入臨床用藥Sirolimus作為比較組。初步實驗結果顯示，在血管內皮研究中，PEDF能有效增加內皮細胞增生移行、誘導內皮前驅細胞產生趨化性及貼附能力，並於動物實驗中觀察到PEDF促使內皮前驅細胞釋放和加速血管再內皮化。另在血管內膜增生相關實驗顯示PEDF能藉由抗細胞增生及抗發炎特性達到抑制血管內膜增生，同時PEDF也具抗血管氧化壓力能力。而Sirolimus同樣地具有抗血管內膜增生能力，但會導致血管氧化壓力上升、延緩血管再內皮化、抑制內皮細胞功能。總結本篇實驗，PEDF具有抑制血管內膜增生、加速血管再內皮化和促進血管細胞功能的特性，期望未來能成為新的潛力藥物。

Drug-euting stents (DES) are the devices developed for preventing SMC proliferation-mediated restenosis and have been used in millions of patients with Coronary artery disease (CHD). However, in recent year, clinical reports reveal that DES severely impair endothelial functions and delay re-endothelialization. These cause the increased risk of in-stent restenosis, late thrombosis and even mortality in patients. Pigment epithelium-derived factor (PEDF), a cytokine which isolate from retina pigment epithelial cells, has the multiple functions of potential neuronal differentiating activity, anti-inflammation, and smooth muscle growth inhibition. The aim of the study is to investigate whether PEDF has beneficial effects in vascular system and thus may be a new strategy in developing DES. In vitro, we use Human Umbilical Vein Endothelial Cell (HUVEC) and Endothelial Precursor Cell (EPC), which are important roles in endothelial recoverage, as part of cell models; Using Rat Aortic Smooth Muscle Cell (RASMC) and RAW264.7 cell as another part studies proliferation and inflammation. Under different condition, cells are individually treated with PEDF and Sirolimus, a drug widely used in DES, as a comparison. In vivo, we use wire injury model in C57/B6 mice to study the effect of re-endothelialization within Saline, PEDF and Sirolimus group. The preliminary data shows that PEDF effectively enhances cell growth, migration and homeostasis in HUVEC as well as increasing the capacity of migration and adhesion in EPC. In vitro, day 5 after injury, PEDF significantly increases CD133, CD34 and SSEA-1 positive cell in peripheral blood cell, which suggests that PEDF mobilizes endothelial progenitor cells from bone marrow; Day 7 after injury, PEDF group has nearly achieved complete re-endothelialization and further shows the lower oxidative stress compared to saline group at day 28 after injury. Moreover, PEDF has the well-known capability to inhibit the proliferation of SMC and inflammation in both SMC and RAW264.7 cell. Instead, Sirolimus not only triggers the inhibition of endothelial normal functions but abnormal increment of cell senescence in cell model. Sirolimus treated mice also have the highest level of oxidative stress in injuryed artery. In conclusion, via accelerated re-endothelialization and protection of vascular cells, PEDF may have the potential to prevent in-stent restenosis and be a new trend in developing DES.