Engineering Ultrathin Immunomodulatory Coatings for Islet Encapsulation

描述（由申请人提供）：临床胰岛移植（CIT），将同种异体胰岛输注到肝脏中，通过提供基于细胞的手段来模拟对葡萄糖的正常生理反应，在长期治疗2型糖尿病中显示出显著的前景。虽然有希望，但由于植入后功能受损和胰岛丢失而受到抑制。这种损失归因于对移植物的强烈炎症和免疫反应，主要由细胞表面蛋白和抗原引起。在本申请中，我们看到通过将胰岛包封在新的聚合物层中来最小化导致胰岛移植失败的有害宿主反应。超薄涂层是通过生物正交化学手柄功能化的生物材料的共价逐层组装产生的。通过胰岛细胞簇表面上聚合物层的受控共价连接，所得稳定胶囊比标准实践小500倍;因此，空隙体积显著减少，营养转运和葡萄糖传感不受影响。此外，这些层的组成、结构、厚度和功能可以在纳米尺度上复杂地控制。一旦制造，这些生物活性层作为理想的细胞表面工程平台，从而能够动态地与植入物-宿主界面相互作用的生物活性基序可以被拴系。因此，惰性生物材料层可以转化为能够主动改变局部植入环境的生物活性表面。我们假设，共价稳定，包被，通过共价层层组装产生，将提高胰岛植入和功能的持续时间，通过掩蔽主机识别的表面抗原和蛋白质，而不赋予营养或胰岛素扩散的限制。此外，能够抑制免疫应答的生物活性剂的束缚将进一步增强移植胰岛的长期存活。为了验证这一假设，将在胰岛表面产生生物稳定的、共价连接的生物膜 使用能够掩蔽表面抗原和炎性蛋白的生物相容性聚合物（Aim 1）。此外，将用能够在移植物界面处引导宿主先天性和适应性免疫应答的免疫调节剂使生物相容性涂层的表面功能化（目的2）。将在体外和糖尿病鼠模型中评价目的。设计有效的策略来在胰岛表面上构建能够表达活性免疫调节剂的定制纳米薄层，可以在没有慢性全身性免疫抑制的情况下显着提高胰岛移植物的功效和长期稳定性。

DESCRIPTION (provided by applicant): Clinical islet transplantation (CIT), the infusion of allogeneic islets into the liver, has shown significant promise in the long-term treatment of Type diabetes by providing a cell-based means to mimic the normal physiological response to glucose. While promising, it is dampened by the impaired function and loss of islets following implantation. This loss is attributed to strong inflammatory and immunological responses to the transplant, primarily instigated by cell surface proteins and antigens. In this application, we see to minimize detrimental host responses that lead to islet engraftment failure by encapsulating the islets in novel ultrathin polymeric layers. Ultrathin coatings are generated through the covalent layer-by-layer assembly of biomaterials functionalized with bioorthogonal chemical handles. Through the controlled, covalent linking of polymers layers on the islet cell cluster surface, resulting stable capsules are on the order of 500-fold smaller than standard practices; thus, void volumes are dramatically reduced and nutritional transport and glucose sensing are unaffected. Further, the composition, structure, thickness, and function of these layers can be intricately controlled on the nanometer scale. Once fabricated, these ultrathin layers serve as ideal platforms for cell surface engineering, whereby bioactive motifs capable of dynamically interacting with implant-host interface can be tethered. As such, the inert biomaterial layer can be converted to a bioactive surface capable of actively altering the localized implant environment. We hypothesize that covalently stabilized, ultrathin coatings, generated via covalent layer-by-layer assembly, will enhance islet engraftment and functional duration by masking host recognition of surface antigens and proteins, without imparting limitations on nutrient or insulin diffusion. In addition, the tethering of bioactive agents capable of instructin immune responses will further enhance long-term survival of the transplanted islets. To test this hypothesis, biostable, covalently-linked, ultrathin coatings will be generated on the islet surface using biocompatible polymers capable of masking surface antigens and inflammatory proteins (Aim 1). Additionally, the surface of ultrathin coatings will be functionalized with immunomodulatory agents capable of directing host innate and adaptive immune responses at the transplant interface (Aim 2). Aims will be evaluated both in vitro and in diabetic murine models. The design of effective strategies to build tailored nano-thin layers on the islet surface capable of expressing active immunomodulatory agents could significantly improve the efficacy and long-term stability of islet transplants in the absence of chronic, systemic immunosuppression.