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

描述（由申请人提供）：基因治疗在糖尿病肾病的背景下有着巨大的希望，尽管该领域的具体进展很难实现。具体而言，已知生长因子TGF-2在肾小球基质扩张和肾小球纤维化进展中起关键作用，并且通过中和抗体抑制TGF-2活性在几种糖尿病肾病动物模型中显示出惊人的功效。然而，与分子治疗的许多靶点一样，TGF-2与许多体细胞过程密切相关，脱靶抑制可能会造成严重的有害影响。TGF-2疗法可以专门针对受损的肾脏，这可能是使肾脏疾病的基因治疗成为现实的关键突破。在目前的提案中，我们的目标是开发一种新的基于微泡的靶向TGF-2基因治疗的递送载体。我们已经开发了一种微泡，它可以与质粒或siRNA的有效载荷结合，并通过选择结合靶向配体靶向糖尿病肾脏。这些药物可以静脉注射，通过无创超声成像监测其在肾脏内的积累。siRNA载荷的释放和转移到目标肾小球细胞是通过对肾脏施加高功率超声能量介导的，这会导致微泡的快速破坏和邻近细胞的短暂穿孔。剩余的非靶向药物被清除到肝脏、脾脏和肺部，在那里，通过通货紧缩的药物破坏使任何残留的siRNA暴露于内源性核酸酶，从而潜在地减少脱靶效应。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递送策略。将纵向评估TGF-2敲除和系膜基质扩张的减少。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中的毒性和生物分布。我们预计，上述目标的成功完成将证明这种靶向给药技术治疗糖尿病肾病的有效性，并为Targeson的下一阶段临床应用开发提供关键数据。

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. PUBLIC HEALTH RELEVANCE: Few techniques for targeted gene therapy are available, especially in deep tissues such as the kidney. This project will examine the ability of a targeted ultrasound-based technique to deliver a therapeutic siRNA to diabetic kidney, and determine whether this strategy is able to ameliorate glomerular fibrosis in animal models of the disease.