新型生物材料团聚体释放NGF和FGF-2对糖尿病神经病变的神经血管作用的研究

Diabetic neuropathy is one of the common complications of diabetes, there is strong vascular link in diabetic neuropathy. To effectively treat neuropathy, microvascular diseases also need to be addressed. Most growth factor therapies are limited by the lack of an appropriate delivery system, and almost all focuses on one growth factor alone. Therefore, we postulate that controlled local release of NGF and FGF-2 will synergistically treat neuropathy and the underlying microvascular defect. We expect that the regenerated nerve and vascular tissue will positively reinforce each other and represent a powerful new therapeutic approach to treating diabetic neuropathy. We have previously shown that polycation molecular weight controls the release rate of FGF-2: larger polycations compete more favorably for heparin and increase the growth factor release rate. Our group found the polycations(PEAD) will compete more efficiently for heparin to grwoth factors, so we developed the [PEAD:heparin] and we found the charge density with a fixed molecular weight will lead to NGF and FGF-2 release and keep the bioactivity of growth factor. Based on the strong preliminary data, we expect [PEAD:heparin] to offer appropriate heparin binding and growth factor release. We will optimise the [PEAD：heparin：(NGF+FGF-2)] drug delivery systems, and evaluate the effect and the role in the regeneration of the nerves and blood vessels by cellular and animal models. This project will give a potential clinical applications for diabetic neuropathy.

糖尿病性神经病变是常见的糖尿病并发症，其病变神经周围也存在复杂的血管网络，为了有效地治疗神经病变，微血管疾病也必须解决。目前利用生长因子治疗神经血管疾病仍缺乏好的药物递送系统，且都是应用单一生长因子。我们推测通过生物材料控制局部释放神经生长因子(NGF)和碱性成纤维细胞生长因子(FGF-2)将协同治疗神经病变和微血管损伤，从而开发出新的治疗糖尿病神经病变的方法。课题组前期开发的多聚阳离子PEAD可与肝素竞争结合生长因子，因此我们开发了[PEAD:肝素] 团聚体，结果显示[PEAD:肝素]可通过调整其分子量和电荷数来控释FGF-2或NGF，并保持其生物活性。本项目是在前期基础上通过[PEAD：肝素]控制NGF和FGF-2的释放和活性，进一步优化[PEAD：肝素：(NGF+FGF-2)]药物递送系统，并利用细胞和动物模型评价其对神经血管的再生作用，探讨分子机制，为其潜在的临床应用奠定理论基础。

外周神经系统疾病，包括糖尿病外周神经病变 (DPN) 和外周神经损伤 (PNI) 均是临床上多见但难以治愈的疾病。医学上通过控住血糖缓解DPN的发生发展，通过显微缝合术或自体神经移植修复离断的外周神经。但这些修复手段均存在一定的缺陷，外周神经病变的恢复效果主要取决于神经再生的程度和周围血管网络改善，已有研究证实神经生长因子 (NGF) 和碱性成纤维细胞生长因子 (FGF-2) 对神经的再生和血管网络的形成均具有良好的促进效果，但二者半衰期短暂在体内易被各蛋白酶类的水解，故寻找一种能保护二者活性并缓控其释放的药物递送系统迫在眉睫。本项目将一种多聚阳离子PEAD通过肝素将NGF和bFGF联合制备一种新型生物材料团聚体 [PEAD：肝素：(NGF+FGF-2)]。体内研究结果显示该团聚体能有效地促进DPN大鼠运动和感觉功能的恢复，抑制病变神经的脱髓鞘化和结构紊乱，提高神经内施旺细胞 (SCs) 的存活，其作用机制与抑制内质网应激 (ERS)诱导的细胞凋亡密切相关，效果显著优于连续注射等计量的生长因子 。同时，我们将 [PEAD：肝素：NGF] 或 [PEAD：肝素：bFGF] 团聚体注射入PNI大鼠的损伤神经区域，利用脚步印迹、透射电镜、免疫印迹和免疫荧光等手段评价该团聚体对PNI的改善效果，结果显示，该类团聚图能够有效地促进PNI大鼠神经功能和结构的改善，包括提高运动和感觉的能力，促进轴突和髓鞘的再生，上调神经内结构和功能蛋白的表达，增强轴突和SCs的共生关系并逆转腓肠肌的萎缩。我们的研究结果还证实抑制ERS的过度激活可通过P13K/AKT/GSK3β和ERK1/2信号通路调控，NGF能够加速髓鞘碎片的清进且这种效应是通过调控p75NTR/AMPK/mTOR信号通路来促进SCs内自噬水平的表达。我们的研究结果为DPN和PNI的治疗提供了新的途径。通过本项目发表SCI论文9篇（IF>5, 6篇），申请发明专利1项，参与获得教育部自然科学一等奖一项。