Bioactive Gels that Promote Long-Term Islet Survival and Function

描述(申请人提供)：生物材料科学的最新进展表明，有机会为胰岛输送创造合成的壁龛，不仅提供允许短期胰岛存活的物理屏障，而且提供生物控制的微环境，积极促进长期胰岛存活和功能，同时通过生物化学调节免疫反应的局部影响。我们假设，合成的聚乙二醇水凝胶壁龛，用关键的细胞外基质分子修饰以促进胰岛功能，并通过生物信号抑制免疫系统应激造成的细胞损伤，将支持移植胰岛的长期存活和功能。为了验证这一假设，将合成引入细胞-细胞和细胞-基质相互作用的凝胶利基环境，并监测对胰岛移植治疗的总体成功至关重要的功能：细胞生存和代谢活动，对葡萄糖和其他刺激的胰岛素分泌的响应，以及将这些细胞外刺激转化为胰岛素释放的细胞内事件的分析，如细胞内钙浓度(目标1)。通过这些实验，我们将确定“允许的”水凝胶化学，定义为支持胰岛在体外1个月的存活和功能的化学。目标2将测试这些允许配方在生理压力下支持胰岛功能的能力。激活的胰岛特异性T细胞株将用于与胶囊的共同培养，以评估聚乙二醇胶囊的免疫保护能力。凝胶的生物物理性质(例如，交联密度)将有所不同，并将检查低氧的相对作用。有了这些认识，这些允许凝胶配方将进一步用免疫调节抗体和酶以及抗炎抗氧化酶来建立新的策略，通过局部抑制宿主免疫和炎症反应的细胞的影响来积极促进胰岛功能和长期生存。这些研究建立在从目标2获得的知识的基础上，目标2确定了最紧迫的细胞压力，并为选定的胶囊功能修改提供了方向框架(目标3)。最后，支持和保护胰岛存活和功能的“促进型”凝胶载体的有效性将在糖尿病动物模型中进行测试(目标4)。这项建议旨在制备结合信号的生物材料设备，以积极促进胰岛素产生细胞的功能，并提高移植到糖尿病患者体内的设备的性能。如果成功，这一策略将延长移植的胰腺组织的持续时间和功能，而不需要终身服用免疫抑制药物。

DESCRIPTION (provided by applicant): Recent advances in biomaterial science suggest opportunities to create synthetic niches for islet delivery that not only provide a physical barrier to permit short-term islet survival, but a biologically-controlled microenvironment that actively promotes long-term islet survival and function while biochemically modulating the local effects of the immune response. We hypothesize that a synthetic poly(ethylene glycol) (PEG) hydrogel niche, modified with critical extracellular matrix molecules to promote islet function and biological signals to suppress cell damage from stresses of the immune system, will support the long-term survival and function of transplanted islets. To test this hypothesis, gel niches that introduce both cell-cell and cell-matrix interactions will be synthesized, and functions critical to the overall success of islet transplantation therapies will be monitored: cell survival and metabolic activity, insulin secretion in response to glucose and other stimuli, and analysis of intracellular events that translate these extracellular stimuli into insulin release, such as intracellular calcium concentration (Aim 1). Through these experiments, we will identify `permissive' hydrogel chemistries, defined as ones that support islet survival and function over the course of 1 month in vitro. Aim 2 will test the ability of these permissive formulations to support islet function under physiological stress. Activated islet-specific T cell lines will be used in co-culture with the capsules to evaluate the immunoprotective capabilities of the PEG capsule. The biophysical properties (e.g., crosslinking density) of the gels will be varied, and the relative role of hypoxia will be examined. With this understanding, these permitting gel formulations will be further modified with immune modulatory antibodies and enzymes and anti-inflammatory anti-oxidative enzymes to establish new strategies to actively promote islet function and long-term survival by locally suppressing the effects of the cells of the host immune and inflammatory responses. These studies build on the base of knowledge gained from Aim 2, which identifies the cellular stresses that are most pressing and provides the directional framework for selected functional modifications of the capsule (Aim 3). Finally, the effectiveness of the `promoting' gel carriers that support and protect islet survivability and function will then be tested in a diabetic animal model (Aim 4).This proposal aims to prepare biomaterial devices that incorporate signals to actively promote the function of insulin-producing cells and improve the performance of devices transplanted into diabetic patients. If successful, this strategy will prolong the duration and function of transplanted pancreatic tissue without the need for life-long administration of immunosuppressive drugs.