Engineering Ultrathin Immunomodulatory Coatings for Islet Encapsulation

描述(申请人提供)：临床胰岛移植(CIT)，将同种异体胰岛注入肝脏，通过提供一种基于细胞的方法来模拟对葡萄糖的正常生理反应，在长期治疗2型糖尿病方面显示出巨大的前景。虽然很有希望，但由于植入后胰岛功能受损和丢失，它受到了抑制。这种损失归因于对移植的强烈炎症和免疫反应，主要是由细胞表面蛋白和抗原引发的。在这一应用中，我们看到通过将胰岛包裹在新的超薄聚合物层中，将导致胰岛植入失败的有害宿主反应降至最低。超薄涂层是通过生物正交化学手柄功能化的生物材料逐层共价组装而成的。通过胰岛细胞团表面聚合物层的受控共价连接，得到的稳定胶囊比标准做法小约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，这些层的成分、结构、厚度和功能可以在纳米尺度上复杂地控制。一旦制成，这些超薄层就成为细胞表面工程的理想平台，从而能够与植入物-宿主界面动态相互作用的生物活性基序可以被拴住。这样，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。我们推测，通过层层共价组装产生的共价稳定的超薄涂层，将通过掩盖宿主对表面抗原和蛋白质的识别而增强胰岛植入和功能持续时间，而不会限制营养或胰岛素的扩散。此外，能够指示免疫反应的生物活性物质的捆绑将进一步提高移植胰岛的长期存活率。为了验证这一假设，将在胰岛表面产生生物稳定的、共价连接的超薄涂层。 使用能够掩盖表面抗原和炎症蛋白的生物相容聚合物(目标1)。此外，超薄涂层的表面将使用免疫调节剂进行功能化，这些免疫调节剂能够在移植界面引导宿主先天和获得性免疫反应(目标2)。AIMS将在体外和糖尿病小鼠模型中进行评估。设计有效的策略在胰岛表面构建能够表达活性免疫调节剂的量身定制的纳米薄层，可以在没有慢性全身免疫抑制的情况下显著提高胰岛移植的有效性和长期稳定性。

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.