PLGA-S1P纳米粒涂层支架预防支架内再狭窄的作用及其机制研究

Our previous study found that sphingosine-1-phosphate (S1P) can induce endothelial cell migration and capillary-like tube formation. S1P can also stimulate endothelial cell proliferation and inhibit endothelial cell apoptosis in vitro. One group published that physiological concentration or greater concentration of S1P potently inhibited smooth muscle cells (SMCs) migration. Compared with the traditional surgery intervention, the stent implantation has much more advantages, however the treatment of patients with in-stent restenosis (ISR) remains a challenge. Microspheres made from poly (lactic-co-glycolic acid) (PLGA) has been successfully employed as a controlled drug delivery system for sustained release of various drugs. In order to prevent ISR, we propose to use PLGA as a drug carrier and improve the preparation process of PLGA-S1P nanoparticles, then we coat the bare metal stent by using appropriate amount of PLGA-S1P nanoparticles, and after that implant the PLGA-S1P coated stents into the iliofemoral arteries of rabbit ASO animal model. We assume that after we implant the PLGA-S1P coated stents, the PLGA will gradually hydrolyze to achieve sustained release of embedded S1P in the local artery, and the optimal concentration of S1P will induce the endothelialization and inhibit the SMCs over-proliferation, thus prevent the ISR. We plan to measure the mRNA expression of VEGF, PDGF-B and SDF-1, and plan to study Akt/ERK-eNOS pathway to investigate the effects and mechanisms of PLGA-S1P on ISR. Our results may represent a promising strategy for endoluminal stent therapy.

课题组前期工作发现1-磷酸鞘氨醇（S1P）可以诱导内皮细胞迁移和毛细血管样管形成。离体实验研究结果表明S1P具有诱导内皮细胞增殖、抑制内皮细胞凋亡以及抑制平滑肌细胞迁移等作用。本课题针对血管内支架置入术后再狭窄问题，提出将聚乳酸-羟基乙酸共聚物（PLGA）包被的S1P涂于金属裸支架表面预防支架置入术后再狭窄的设想。为验证此设想，拟将涂覆适量PLGA-S1P纳米粒缓释制剂的金属血管内支架置入动脉粥样硬化动物模型髂股动脉内，通过PLGA缓慢降解释放S1P，诱导支架置入部位血管内皮化，抑制平滑肌细胞过度增殖，从而达到抑制支架置入术后再狭窄的目的，通过测定VEGF、PDGF-B、SDF-1等多种细胞因子的表达以及Akt/ERK-eNOS通路，探讨PLGA-S1P预防支架内再狭窄的作用与机制。本课题为预防外周动脉狭窄/闭塞性疾病支架置入术后再狭窄提供更有价值的理论与实验依据。

本课题针对血管内支架置入术后再狭窄问题，提出将S1P与环糊精制成包合物，然后载入PLGA成功制备PLGA-S1P纳米粒，作为金属裸支架的表面涂层材料，制成药物缓释涂层支架置入下肢动脉粥样硬化动物模型髂股动脉内，通过PLGA的缓慢降解不断向支架置入部位释放S1P，增加局部组织S1P的浓度，诱导支架置入部位的内皮化，并且抑制平滑肌细胞的过度增殖，进而达到抑制支架置入术后再狭窄的目的，该研究结果将为预防外周动脉狭窄/闭塞性疾病的介入治疗提供理论与实验依据，并为研制国产支架的研发提供理论依据。首先我们在制备S1P和环糊精包合物的过程中发现，环糊精本身具有促内皮化的作用，其机制是通过上调VEGF-A，PDGF-BB，FGF-2和TGF-b1等生长因子的表达，激活eNOS通路来实现的；其次我们进行了药物涂层支架的制备，经电镜扫描观察支架表面形貌，所得涂层光滑；再次，课题组进行了药物涂层支架的体内预实验研究，支架置入新西兰大白兔股动脉14天随访，DSA下可见支架仍在原左侧髂股动脉处，无移位；最后，课题组成员发明了一种直径不断增大的兔新型腹主动脉瘤模型以及在下肢缺血性疾病中S1P相关受体基因表达表达的研究中发现S1PR2受体激动剂可能会成为涂层支架的候选药物，该研究为S1P涂层支架进一步研究奠定了理论基础。