Optical Imaging of Beta-Cell Function and Engraftment

描述（由申请人提供）：一旦埃德蒙顿小组正式宣布前七次成功的移植，用胰岛移植治疗1型糖尿病的临床实用性就变得明显了，而不需要外源性胰岛素替代。这项研究证明了两个主要观点：改进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体来获得适当的细胞群来治疗一个受体。显然，分离过程中的坏死和凋亡过程显著减少了可获得的功能性细胞团的数量。即使有适当的胰岛细胞质量，胰岛移植仍然容易受到自身免疫和同种免疫排斥。为了保护移植物免受这些过程的负面影响，埃德蒙顿团队使用了一种强效免疫抑制药物的鸡尾酒。接受者需要在其整个生命周期内维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脏和肝脏功能。这种担心是一个主要因素，阻碍了该方案的常规临床应用，以防止免疫排斥的胰岛移植在年轻的糖尿病患者。相比之下，耐受诱导策略，而不是免疫抑制，似乎是治疗儿童糖尿病的有利方法。在研究不同致耐受性方案的尝试中，能够在体内跟踪活化T细胞的活性以及对移植胰岛造成的损伤将变得极其重要。我们在此提出的成像系统对于更快地获得从干预啮齿动物到合理的人体试验所需的知识肯定是有价值的。这些方法应允许在活动物中进行非侵入性活细胞成像。我们提出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物在生理自荧光背景之上是可检测的，但具有足够的区分性（例如，绿色对红色）以允许同时监测不同的细胞类型。这些构成了本申请的主要目标，也是我们将仔细评估致耐受性方法可行性的基础。

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.