Development of Anti-Fouling Peptide-Nanoparticle Conjugates for the Delivery of siRNA to Fractures

小干扰RNA（siRNA）是一类有前途的药物，但受到递送挑战的限制。裸体 siRNA在体内具有差的细胞摄取和快速降解，因此siRNA通常在体内施用。 纳米颗粒（NP）制剂。为了规避降解和吸收不良的细胞外屏障， 细胞内溶酶体运输，我们的实验室率先开发pH响应阳离子二嵌段 用于siRNA递送的三元共聚物纳米颗粒（pHCNPs），其极大地改善了siRNA治疗效果。 功效siRNA-pHCNP的局部体内递送在骨和其他组织中显示出前景，但许多研究表明， 包括许多肌肉骨骼系统的疾病需要全身给药。的全身递送 NPs由于血清吸附而受到阻碍，导致单核吞噬细胞系统（MPS）摄取和不良的细胞毒性。 循环时间，并可能增强免疫原性。事实上，许多被批准的siRNA-NP治疗剂 或在发展的晚期阶段利用MPS在肝脏中的积累，靶向肝脏疾病。 减少蛋白质-NP相互作用是改善siRNA-NP的全身递送以到达其他靶点的关键 组织中纳米颗粒的聚乙二醇（PEG）修饰（PEG化）是目前减少蛋白质的标准 吸附，但它也通过阻碍摄取降低NP功效，并可能诱导免疫应答 因为抗PEG抗体两性离子（ZI）部分在减少蛋白质吸附方面显示出巨大的前景 并且对NP功能特性的破坏性小于PEG。仿生ZI肽（ZIPs）是一种生物活性肽。 有前途的新方法，以改善聚合物NP药代动力学性质。特别是，半随机 ZIPs（srZIPs）允许半独立于氨基酸组成的电荷序列测试。这些 属性完全导致假设，半随机ZIPs（srZIPs）设计与低 聚集潜力可用于修饰NP以改善体循环和siRNA递送 通过减少NP-血清蛋白相互作用。我们将从三个方面来检验这个假设。在目标1中，我们 产生srZIP-pHCNP缀合物的文库，以测试与 天然pHCNP和PEG-pHCNP。在目标2A中，我们将使用靶细胞在体外测试这些缀合物 在目的2B中，我们将评估在骨髓间充质干细胞（间充质干细胞）和MPS细胞（巨噬细胞）中的改善， pHCNP缀合物在体内的循环时间。在目标3中，我们将使用已建立的小鼠股骨骨折 研究携带治疗性抗WWP 1 siRNA（WW结构域）的pHCNP的骨折累积的模型 含有E3泛素蛋白连接酶1，一种骨折愈合的负调节因子），我们已经证明， 使用局部递送方法加速骨折愈合。在该项目完成后，我们预计 为了鉴定新的基于肽的抗聚集方法，用于在聚合物中递送siRNA， 纳米颗粒，为未来肌肉骨骼应用的siRNA全身递送奠定基础， 超越。

Small interfering RNA (siRNA) are a promising class of drugs that are limited by delivery challenges. Naked siRNA has poor cellular uptake and rapid degradation in vivo, thus siRNA is typically administered in nanoparticle (NP) formulations. To circumvent extracellular barriers of degradation and poor uptake as well as intracellular lysosomal trafficking, our lab pioneered the development of pH-responsive cationic diblock tercopolymer nanoparticles (pHCNPs) for the delivery of siRNA, which greatly improve siRNA therapeutic efficacy. Local in vivo delivery of siRNA-pHCNPs has shown promise in bone and other tissues, but many diseases, including many of the musculoskeletal system require systemic administration. Systemic delivery of NPs is hampered due to serum adsorption, leading to mononuclear phagocyte system (MPS) uptake and poor circulation times, and may potentiate immunogenicity. In fact, many siRNA-NP therapeutics that are approved or in late stages of development take advantage of MPS accumulation in liver, targeting hepatic diseases. Reducing protein-NP interactions is key to improving the systemic delivery of siRNA-NPs to reach other target tissues. Poly(ethylene glycol) (PEG) modification (PEGylation) of NPs is the current standard to reduce protein adsorption, but it also reduces NP efficacy by hampering uptake and may induce immunological responses due to anti-PEG antibodies. Zwitterionic (ZI) moieties have shown great promise in reducing protein adsorption and are less disruptive to NP functional characteristics than PEG. Biomimetic ZI peptides (ZIPs) are a promising new approach to improve polymeric NP pharmacokinetic properties. In particular, semi-randomized ZIPs (srZIPs) allow testing of charge sequence semi-independently of amino acid composition. These attributes altogether lead to the hypothesis that semi-randomized ZIPs (srZIPs) designed with low aggregation potential can be used to modify NPs to improve systemic circulation and siRNA delivery by reducing NP-serum protein interactions. We will test this hypothesis in three ways. In Aim 1, we will generate a library of srZIP-pHCNP conjugates to test the effects on serum-induced aggregation compared to naïve pHCNPs and PEG-pHCNPs. In Aim 2A, we will test these conjugates in vitro using target cells (mesenchymal stem cells) and in MPS cells (macrophages), and in Aim 2B we will evaluate improvements in circulation times of the pHCNP conjugates in vivo. In Aim 3 we will use an established mouse femur fracture model to investigate fracture accumulation of pHCNP bearing therapeutic anti-WWP1 siRNA (WW Domain Containing E3 Ubiquitin Protein Ligase 1, a negative regulator of fracture healing), which we have shown to expedite bone fracture healing in using a local delivery approach. At the completion of this project, we expect to identify new peptide-based anti-aggregation approaches for the delivery of siRNA in polymeric nanoparticles, laying the foundation for future systemic delivery of siRNA for musculoskeletal applications and beyond.