Optical Imaging of Beta-Cell Function and Engraftment

描述(申请人提供)：埃德蒙顿集团正式宣布首7例成功的胰岛移植后，通过胰岛移植治疗1型糖尿病患者的临床实用性就变得明显起来，从而避免了外源性胰岛素替代的需要。这项研究证明了两个要点：改进的胰岛分离程序和移植方式的技术可行性；第二，需要一个以上的同种异体供者才能获得合适的细胞团来治疗一个受者。显然，分离过程中的坏死和凋亡过程极大地减少了可获得的功能性细胞团的数量。即使有适当的细胞量，胰岛移植仍然容易受到自身免疫和同种异体免疫排斥反应的影响。为了保护移植物免受这些过程的负面后果，埃德蒙顿研究小组使用了一种有效的免疫抑制药物的鸡尾酒。接受者被要求在他们的一生中保持这种免疫抑制方案。然而，这种疗法确实存在毒性风险，因为长期使用这种鸡尾酒会损害肾和肝功能。这一担忧是阻碍将该方案引入常规临床用于预防年轻糖尿病患者胰岛移植免疫排斥反应的主要因素。相比之下，耐受性诱导策略，而不是免疫抑制，似乎是治疗儿童糖尿病的有利方法。为了研究不同的耐受方案，能够在体内跟踪激活的T细胞的活动，同时对移植的胰岛造成损害，这将变得极其重要。我们在这里提出的成像系统对于更快地获得从干预啮齿动物到理性人体试验所需的知识肯定是有价值的。这些方法应该可以在活体动物中进行非侵入性的活细胞成像。我们建议开发一种基于光学荧光和发光的系统，其中荧光和发光标记可以在生理自身荧光背景之上检测到，但具有足够的区分性(例如，绿色和红色)，以允许同时监测不同类型的细胞。这些构成了这项应用的主要目标，并将在此基础上仔细评估我们的耐受性方法的可行性。

DESCRIPTION (provided by applicant): The clinical practicality of treating type 1 diabetics with islet transplants obviating the need for exogenous insulin replacement became evident once the first seven successful transplants were officially announced by the Edmonton group. This study proved two major points: the technical feasibility of improved islet isolation procedures and transplantation modalities and second, that more than one allogeneic donor is required to obtain an appropriate ¿-cell mass to treat one recipient. Apparently, necrotic and apoptotic processes during the isolation procedure dramatically reduce the number of functional ¿-cell mass obtainable. Even with an appropriate ¿-cell mass, islet transplants are still susceptible to autoimmune and alloimmune rejection. To protect the graft against the negative consequences of these processes, the Edmonton team used a cocktail of potent immunosuppressive drugs. The recipients are required to maintain this regimen of immunosuppression for their entire lifetime. However, this therapy does pose toxicity risks in that prolonged use of this cocktail can impair kidney and liver function. This concern is a major factor that impedes the introduction of this regimen for routine clinical use to prevent immune rejection of islet transplants in young diabetics. In contrast, tolerance induction strategies, rather than immunosuppression, appear to be the favorable approach to treat children with diabetes. In an attempt to study different tolerogenic protocols, it will become extremely important to be able to follow in vivo the activities of activated T cells simultaneously with the damage inflicted to the transplanted islets. The imaging system we are proposing herein will certainly be valuable to more quickly acquire the knowledge needed to progress from intervening in rodents to rational human trials. These methods should allow non-invasive live cell imaging in live animals. We propose the development of an optical fluorescence and luminescence-based system where the fluorescent and luminescent markers are detectable above physiologic self-fluorescent backgrounds, yet sufficiently discriminative (e.g., green versus red) to allow the monitoring of different cell types simultaneously. These constitute the main goals of this application and the basis upon which the feasibility of our tolerogenic approaches will be carefully evaluated.