Ultrasound-triggered delivery of siRNA as treatment for diabetic kidney disease

描述(申请人提供)：糖尿病肾病背景下的基因治疗具有巨大的前景，尽管该领域的具体进展一直难以实现。明确地说，生长因子转化生长因子-2在肾小球基质扩张和肾小球纤维化的进展中起关键作用，中和抗体抑制转化生长因子-2的活性在几种糖尿病肾病动物模型中显示出显著的效果。然而，与分子治疗的许多靶点一样，转化生长因子-2与许多躯体过程密切相关，靶外抑制可能会造成严重的有害影响。通过这种方法，转化生长因子-2治疗可以专门针对受损的肾脏，这可能在实现肾脏疾病的基因治疗方面提供关键突破。在目前的方案中，我们的目标是开发一种新型的基于微泡的靶向转化生长因子-2基因治疗载体。我们已经开发了一种微泡，它可以与有效负载的质粒或siRNA结合，并通过选择素结合的靶向配体靶向糖尿病肾脏。这些药物可以静脉给药，它们在肾脏内的蓄积通过非侵入性超声成像进行监测。SiRNA有效载荷的释放和转移到靶向的肾小球细胞是通过对肾脏施加高功率超声波能量来调节的，这会导致微泡的快速破坏和相邻细胞的瞬时穿孔。剩余的非靶向制剂被清除到肝脏、脾和肺，在那里，通货紧缩对制剂的破坏使任何残留的siRNA暴露于内源性核酸酶，从而潜在地减少非靶向效应。我们的目标是在几种临床相关的糖尿病小鼠模型中评估这种靶向siRNA传递策略。对转化生长因子-2的抑制和系膜基质扩张的减少，将进行纵向评估。我们还将系统地评估该制剂的有效载荷能力和稳定性，并评估其在啮齿动物体内的毒性和生物分布。我们预计，拟议目标的成功完成将证明这种定向递送技术在治疗糖尿病肾脏疾病方面的有效性，并为Targeson提供进入临床使用的下一阶段开发所需的关键数据。

DESCRIPTION (provided by applicant): Gene therapy in the context of diabetic kidney disease holds tremendous promise, although concrete progress in the field has been difficult to achieve. Specifically, the growth factor TGF-2 is known to play a critical role in glomerular matrix expansion and progression of glomerular fibrosis, and inhibition of TGF-2 activity by neutralizing antibodies has shown striking efficacy in several animal models of diabetic kidney disease. However, as is the case with many targets of molecular therapy, TGF-2 is strongly implicated in numerous somatic processes, and off-target inhibition may pose severe detrimental effects. Means by which TGF-2 therapy could be targeted specifically to the impaired kidney could offer a critical breakthrough in making gene therapy for kidney disease a reality. In the current proposal, we aim to develop a novel microbubble-based delivery vehicle for targeted TGF-2 gene therapy. We have developed a microbubble that can be conjugated with a payload of plasmid or siRNA, and targeted to the diabetic kidney by means of a selectin-binding targeting ligand. These agents can be administered intravenously, and their accumulation within the kidney monitored by non-invasive ultrasound imaging. Release of the siRNA payload and transfer into the targeted glomerular cells is mediated by application of high-power ultrasound energy specifically to the kidneys, which causes rapid destruction of the microbubbles and a transient poration of the adjacent cells. Remaining untargeted agents are cleared to the liver, spleen, and lung, where agent destruction by deflation exposes any residual siRNA to endogenous nucleases, thus potentially reducing off-target effects. We aim to evaluate this targeted siRNA delivery strategy in several clinically-relevant mouse models of diabetes. TGF-2 knock-down, and reduction in mesangial matrix expansion, will be assessed longitudinally. We will also systematically assess the payload capacity and stability of the agent, and evaluate toxicity and biodistribution in rodents. We anticipate that successful completion of the proposed aims will demonstrate efficacy of this targeted delivery technology for treatment of diabetic kidney disease, and provide Targeson with critical data needed to advance to the next stage of development for clinical use.