Theranostic system for targeted, sustained-delivery with quantitative "hot spot" MPI of magnetic extracellular vesicles

治疗性细胞的移植具有治愈或缓解各种疾病的巨大潜力。在 在临床上，细胞移植物通常在移植后的短时间内死亡或停止功能。一个新兴 一种策略是使用来源于间充质干细胞（MSC）的细胞外囊泡（EV）作为佐剂 细胞疗法然而，在有效地将电动汽车输送到目标地点并在目标地点保持电动汽车方面仍然存在挑战， 以及无法使用临床相关的生物分布和药代动力学特征来阐明EV的生物分布和药代动力学特征。 工具.此外，一些新的研究表明，多次输送电动汽车对治疗结果至关重要， 这是目前临床给药途径难以实现的。我们建议发展治疗诊断学， 可注射微球体EV给药系统（EFDS），用于EV的局部、靶向和持续给药， 能够用磁粒子成像（MPI）在体内跟踪EV。我们的EFDS采用模块化设计， 系统的每个主要部件可以独立地修改以适合不同的目的。我们的兴趣在于 在胰岛移植治疗1型和晚期2型糖尿病中。两种设计的EVDS - LipoCap 和MICap -被提议。LipoCaps（500 μm）可以通过门静脉输注到肝脏中（临床测试 胰岛移植方案）用于与胰岛共植入，或用于移植后的随访剂量。MICaps (900μm）适用于体积较大的植入部位，如腹腔。两种设计 目的是获得一个本地的，持续的交付电动汽车的岛屿。LipoCaps和MICaps将由超纯化的 藻酸盐是FDA批准的食品、化妆品和药品的赋形剂。为了尽量减少非- 从藻酸盐基质释放后，附近脂肪和组织的特异性摄取，EV将被装载在胰岛内， 在藻酸盐包封之前靶向脂质体。这将通过将脂质体缀合至 exendin-4是胰高血糖素样肽-1受体的配体，在胰岛细胞表面大量表达 β细胞此外，电动汽车将标记临床级超小超顺磁性氧化铁 纳米颗粒（USPIO）以促进MPI成像。MPI是一种提供“热点”的新兴模态 可视化以及EV定量，非常类似于PET和SPECT，而不使用放射性试剂。 与1H MRI不同，来自血池和运动效应的背景伪影不是MPI的问题。MPI是 据报道，比19 F MRI和CT更敏感，因此可能会减少引入的标签数量 植入病人体内MPI可以告知医生EV的时间和空间行为，这反过来可以 提供定制EV治疗。为了系统地研究该项目的可行性，有三个具体目标 1）合成和表征携带MSC-EV的LipoCaps和MICaps，并测试它们的活性。 2）建立一种USPIO标记方法， EV特性，同时最大化MPI检测灵敏度; 3）为了测试所提出的EVDS是否可以改善胰岛功能， 免疫缺陷NU/J小鼠的存活和功能，同时通过MPI进行跟踪。

Transplantation of therapeutic cells holds great potential to cure or provide relief to various ailments. In the clinic, cell grafts often perish or cease to function within a short period post-transplantation. An emerging strategy is the use of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) as an adjuvant to cell therapy. However, there remain challenges for effective EV delivery to and retention at the target sites, and the inability to elucidate the biodistribution and pharmacokinetic profiles of EVs using a clinically relevant tool. Moreover, a few new studies indicated that multiple deliveries of EVs are essential for therapeutic outcomes, which are hard to accomplish using the current clinical administration routes. We propose to develop theranostic, injectable microspheroid EV-delivery systems (EVDS) for local, targeted, and sustained-delivery of EVs while enabling EV tracking in vivo with magnetic particle imaging (MPI). The design of our EVDS is modular where each main component of the system can be independently modified to suit different purposes. Our interest lies in pancreatic islet transplantation to treat type 1 and advanced type 2 diabetes. Two designs of EVDS – LipoCap and MICap – are proposed. LipoCaps (500 μm) can be infused into the liver via the portal vein (a clinically tested islet transplantation protocol) for co-implantation with islets, or for follow-up doses post-transplantation. MICaps (900 µm) are appropriate for implant site with larger volumes, such as the intraperitoneal cavity. Both designs aim to obtain a local, sustained delivery of EVs to islets. LipoCaps and MICaps will be composed of ultrapurified alginate, an FDA-approved excipient of food, cosmetic and pharmaceutical products. In order to minimize non- specific uptake by nearby fat and tissues after the release from alginate matrix, EVs will be loaded inside islet- targeting liposomes prior to alginate encapsulation. This will be achieved by conjugating the liposomes to exendin-4, a ligand of glucagon-like peptide-1 receptors which are abundantly expressed on the surface of islet beta cells. In addition, EVs will be labeled with clinical-grade ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) to facilitate imaging by MPI. MPI is an emerging modality that provides “hot spot” visualization as well as EV quantification, much alike to PET and SPECT without the use of radioactive agents. Unlike 1H MRI, background artifacts from blood pools and motion effects are not an issue with MPI. MPI is reported to be more sensitive than 19F MRI and CT, and therefore may reduce the quantity of labels introduced into the patients. MPI may inform physicians on the temporal and spatial behavior of EVs which, in turns, may afford EV therapy to be customized. To systemically investigate the feasibility of the project, three specific aims are proposed: 1) To synthesize and characterize LipoCaps and MICaps carrying MSC-EVs, and to test their effects on human islets’ survival and function in vitro; 2) To develop a USPIO-labeling method that will preserve EV properties while maximizing MPI detection sensitivity; 3) To test if the proposed EVDS can improve islet survival and function in immunodeficient NU/J mice while being tracked by MPI.