Multimodality Imaging of β-Cells in Mouse Models of Type 1 and 2 Diabetes

OBJECTIVE-beta-Cells that express an imaging reporter have provided powerful tools for studying beta-cell development, islet transplantation, and beta-cell autoimmunity. To further expedite diabetes research, we generated transgenic C57BL/6 MTP-TF mice that have a mouse insulin promoter (MIP) driving the expression of a trifusion (TF) protein of three imaging reporters (luciferase/enhanced green fluorescent protein/HSV1-sr39 thymidine kinase) in their beta-cells. This should enable the noninvasive imaging of beta-cells by charge-coupled device (CCD) and micro-positron emission tomography (PET), as well as the identification of beta-cells at the cellular level by fluorescent microscopy. RESEARCH DESIGN AND METHODS-MIP-TF mouse beta-cells were multimodality imaged in models of type 1 and type 2 diabetes. RESULTS MIP-TF mouse beta-cells were readily identified in pancreatic tissue sections using fluorescent microscopy. We show that MIP-TF beta-cells can be noninvasively imaged using microPET. There was a correlation between CCD and microPET signals from the pancreas region of individual mice. After low-dose streptozotocin administration to induce type 1 diabetes, we observed a progressive reduction in bioluminescence from the pancreas region before the appearance of hyperglycemia. Although there have been reports of hyperglycemia inducing proinsulin expression in extrapancreatic tissues, we did not observe bioluminescent signals from extrapancreatic tissues of diabetic MIP-TF mice. Because MIP-TF mouse beta-cells express a viral thymidine kinase, ganciclovir treatment induced hyperglycemia, providing a new experimental model of type 1 diabetes. Mice fed a high-fat diet to model early type 2 diabetes displayed a progressive increase in their pancreatic bioluminescent signals, which were positively correlated with area under the curve-intraperitoneal glucose tolerance test (AUC-IPGTT). CONCLUSIONS MIP-TF mice provide a new tool for monitoring beta-cells from the single cell level to noninvasive assessments of beta-cells in models of type I diabetes and type 2 diabetes. Diabetes 60:1383-1392, 2011