Fluorescent Probes for Tracking Insulin Secretion in Therapeutic and Diagnostic Devices

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 DESCRIPTION (provided by applicant): Significance: Type 1 and Type 2 Diabetes Mellitus (T1D and T2D) are becoming an increasing burden on socioeconomic resources with surging patient numbers all over the world. Insulin-dependent treatment regimen such as regular insulin injections are well established but have been associated with a negative impact on the patients' quality of life with a variety of long-term complications. The search for insulin-independent treatment options has been an important, albeit elusive, scientific goal for over 40 years with promising results particularly in the field of pancreatic islet transplantation. Here, grafting of either entire cadaveric pancreases or encapsulated islets comprised of insulin producing beta cells in a protective capsule has been the main focus of research. However, usable cadaveric pancreatic tissue is hard to acquire with graft success mostly limited by the cellular survival of the beta cells. Another issue that needs to be addressed is how to select functional islets based on their insulin release activity, in order to achieve a more consistent and more predictable transplant outcome, and to help patients maintain insulin independence over a longer period of time. No simple method with high efficacy exists to date that could be useful in this monitoring process to quantify insulin secretion of individual islets. Furthermore, such a technique can also be adapted to gain diagnostic information in an effort to monitor insulin secretion efficiently when determining diabetes progression and etiology. Hypothesis: We hypothesize that the use of our fluorescent imaging agent, namely ZIMIR, has the ability to solve these therapeutic and diagnostic problems when used in technologies such as fluorescence-activated cell sorting (FACS) or in ZIMIR-functionalized optical fibers. Preliminary Data: We have demonstrated that ZIMIR represents the vanguard of a zinc sensitive fluorescent agent with the ability to label beta cells and image insulin secretion, both essential features for the screening of functional islets, encapsulated islets, or beta cells. Furthermore, we showed that ZIMIR is sensitive enough to quantify a concentration increase of Zn2+ that can be detected by fluorescence at the portal vein and directly correlated to insulin secretion, a crucial prerequisite for the design of a devic that can quantify insulin secretion in vivo. Specific Aims: The key objectives in Phase I entail th synthesis, purification and characterization of a large amount of ZIMIR (Aim 1) and ZIMIR-maleimide (Aim 2). The latter will be used in Phase II for the functionalization of modified optica fibers comprised of silicon dioxide. These fibers will then be used to construct a fiber photometry instrument for the detection of Zn2+, validated in vitro and in vivo. ZIMIR will be used in Phase I for preclinical testing of the agent to find use in islet sorting using FACS with subsequent transplantation experiments. Overall Impact: Together, these technologies developed by VitalQuan will demonstrate the utility of ZIMIR in iselt cell sorting applications to increase isle graft success rates and will also establish unprecedented studies designed for in vivo insulin tracking. Taken in concert, these applications will accelerate the commercialization of ZIMIR for clinical use in diabetes research and treatment.