胰岛素纳米粒温敏水凝胶缓释系统治疗早期糖尿病性视网膜病变的实验研究

Diabetic retinopathy (DR) is one of the major ocular diseases leading to blindness worldwide. Early treatment is important to prevent the development of DR. Insulin is the key drug in the treatment of diabetes mellitus. Intensive insulin treatment could effectively control blood sugar. However, the treatment results in the occurrence and progression of DR in some patients. It was demonstrated that topically intravtreal injection of insulin is proved to reduce and delay the development of DR in animal models. In order to maintain therapeutic insulin concentration in vitreous and retina, frequent intravitreal injections are required because of the short half-life of insulin. The repeated injections may increase complications due to the invasive procedure, such as cataract formation, vitreous hemorrhage, and endophthalmitis. In our previous study, we combined the nanotechnology and thermosensitive hydrogel sustained release system, and formed a novel insulin-loaded nanoparticle thermosensitive hydrogel system (INTHS), which had a stable release profile of more than 60 days. The sustained release system was subconjunctivally injected in diabetic rats. The results showed neuroprotective. In addition, INTHS is tissue compatible and biodegradable, as well as phase-transition from room temperature to body temperature (form solution of gel). Based on the former investigation, in this study, we plan to develop INTHS and explore in vitro release profile, stability, safety, bioactivity, and in vivo safety and long acting effects on the prevention of DR by subconjunctival iniection.

糖尿病性视网膜病变（DR）早期治疗是关键，单纯控制血糖无法阻止DR的发生、发展。研究发现胰岛素除具有降血糖作用外，还具有中枢神经保护作用，局部玻璃体腔注射可减少、延缓DR的发生。然而胰岛素半衰期短需频繁注射，玻璃体腔注射并发症多，局部直接注射胰岛素药物浓度峰对视网膜有毒性作用等。我们创新性地将纳米粒缓释和温敏水凝胶缓释二者相结合，制备成胰岛素纳米粒温敏水凝胶缓释系统（INTHS），并首次将该INTHS直接注射到结膜下，在眼球体温作用下，常温液态INTHS转变成凝胶态并缓慢生物降解，从而达到持久、稳定释放胰岛素。结合前期研究，本课题拟开发这种胰岛素缓释系统（INTHS），探讨其体外释放曲线、稳定性、生物安全性和生物学活性；并将INTHS注射到大鼠结膜下，探讨该缓释系统在眼内的释放情况、生物安全性以及对早期DR的视网膜保护效果，为DR患者提供新的治疗思路。

糖尿病性视网膜病变（DR）早期治疗是关键，单纯控制血糖无法阻止DR的发生、发展。研究发现胰岛素除具有降血糖作用外，还具有中枢神经保护作用，局部玻璃体腔注射可减少、延缓DR的发生。然而胰岛素半衰期短需频繁注射，玻璃体腔注射并发症多，局部直接注射胰岛素药物浓度峰对视网膜毒性作用大等。我们创新性地将纳米粒缓释和温敏水凝胶缓释二者相结合，制备成胰岛素纳米粒温敏水凝胶缓释系统（INTHS），并首次将该INTHS直接注射到糖尿病大鼠结膜下，在眼球体温作用下，常温液态INTHS转变成凝胶态并缓慢生物降解，从而达到持久、稳定释放胰岛素。研究目的在于分析该缓释系统对大鼠早期糖尿病性视网膜病变的保护效果。结果显示，正常大鼠结膜下注射INHTS可以达到缓慢释放胰岛素的作用，且释放持久、稳定，其组织相容性好，不影响正常视网膜功能。结膜下注射INTHS可以有效保护糖尿病引起的视网膜神经细胞的凋亡、视网膜超微结构的改变，抑制高血糖引起的视网膜GFAP、VEGF和Occludin表达的上调，从而有效保护视网膜的功能。本研究为胰岛素应用于早期糖尿病性视网膜病变提供了实验基础和治疗新思路，也为眼内小分子蛋白类药物给药提供了可供选择的给药新方式。