Immunosuppression-free islet transplantation via localized immunomodulatory exosome tethering

项目摘要/摘要 临床胰岛移植是治疗胰岛素依赖型糖尿病患者的一种有前途的治疗方法， 通过恢复天然胰岛素信号来消除长期继发性并发症的可能性。在临床上 已有的成功证明了通过胰岛替代实现胰岛素独立的可行性。 治疗上，长期免疫抑制疗法的必要性限制了这种疗法的广泛适用性 程序，因为与慢性免疫抑制相关的实质性风险超过了糖尿病的风险 相关的病症。因此，人们对大胶囊器件的开发非常感兴趣，以 将移植细胞从受体免疫系统中分离出来，目的是通过 直接的抗原提呈途径。虽然这种策略会降低对移植物的免疫反应， 胶囊化不能阻止脱落抗原的扩散，脱落抗原通过间接抗原激活免疫细胞。 最终靶向并摧毁移植细胞的呈递途径。因此，一种协同方法可以 需要大胶囊化来充分改善对胰岛移植物的免疫反应。 胎盘微环境是局部的、正常的生理的独特的生物学例子。 母胎界面滋养细胞通过两种机制维持耐受性：(1)形成屏障 以防止异体组织与宿主接触，以及(2)局部呈现和分泌 免疫调节因子诱导耐受性、先天和获得性免疫细胞。一种有效的方法，通过它 滋养层细胞通过分泌的外切体传递免疫调节有效载荷。我们的目标是模仿这两个 免疫隔离水凝胶包裹胰岛介导滋养层细胞耐受的机制 并将免疫调节性滋养细胞来源的外切体拴在装置表面。 我们假设，免疫调节滋养层细胞来源的外切体在 合成水凝胶大胶囊装置的表面将与免疫隔离协同作用产生 对移植物的局部免疫耐受。我们预计，局部化的外切体呈现将导致局部 通过在移植部位诱导产生耐受性的先天免疫细胞和适应性免疫细胞来产生对移植物的耐受性。 在水凝胶装置内的包裹将防止直接的抗原提呈和表面结合的外切体。 将诱导产生耐受性的抗原提呈细胞，通过间接抗原识别防止免疫破坏。 这些假设将在以下具体目标的实验中得到解决：(1)工程师和 免疫调节外切体呈递合成水凝胶大胶囊化装置； 免疫调节性大胶囊装置对局部移植物免疫环境的影响。我们 预计这项研究将证明耐受性滋养细胞外体的免疫抑制能力， 以及它们与胰岛包裹的协同作用的潜力。

PROJECT SUMMARY/ABSTRACT Clinical islet transplantation is a promising treatment for insulin-dependent diabetic patients, with the potential to eliminate long-term secondary complications by restoring native insulin signaling. While clinical successes have demonstrated the feasibility of achieving insulin independence through islet replacement therapy, the necessity of a long-term immunosuppressive regimen limits the widespread applicability of this procedure, as the substantial risk associated with chronic immunosuppression outweighs the risk of diabetes associated morbidities. As a result, there is great interest in the development of macroencapsulation devices to isolate transplanted cells from the recipient immune system, with the intent to eliminate immune recognition via the direct antigen presentation pathway. While this strategy can reduce immune response to the graft, encapsulation cannot prevent the diffusion of shed antigens, which activate immune cells via the indirect antigen presentation pathway to ultimately target and destroy the transplanted cells. As such, a synergistic approach to macroencapsulation is required to fully ameliorate the immune response to islet grafts. The placental microenvironment is a unique biological example of localized, normal physiological tolerance, maintained by trophoblasts at the fetal-maternal interface via two mechanisms: (1) creating a barrier to prevent contact between allogeneic tissue and host, and (2) localized presentation and secretion of immunomodulatory factors to induce tolerogenic innate and adaptive immune cells. One potent method by which trophoblasts deliver immunomodulatory payloads is via secreted exosomes. We aim to mimic these two mechanisms of trophoblast-mediated tolerance through encapsulating islets in an immunoisolating hydrogel device and tethering immunomodulatory trophoblast-derived exosomes to the device surface. We hypothesize that localized presentation of immunomodulatory trophoblast-derived exosomes at the surface of a synthetic hydrogel macroencapsulation device will synergize with immunoisolation to produce localized immune tolerance to the graft. We anticipate that localized exosome presentation will result in local tolerance to the graft by inducing tolerogenic innate and adaptive immune cells at the site of transplantation. Encapsulation within the hydrogel device will prevent direct antigen presentation, and surface-bound exosomes will induce tolerogenic antigen presenting cells, preventing immune destruction via indirect antigen recognition. These hypotheses will be addressed in the experiments of the following Specific Aims: (1) Engineer an immunomodulating exosome-presenting synthetic hydrogel-based macroencapsulation device; and (2) Evaluate immunomodulatory macroencapsulation device impact on the localized graft immune environment. We anticipate that this study will demonstrate the immunosuppressive capacity of tolerogenic trophoblast exosomes, and their potential for synergy with islet encapsulation.