Project 457552

In the pancreas, alpha-cells release glucagon (which causes blood sugar to go up) and beta-cells release insulin (which causes blood sugar to go down); and for the control of blood sugar, secretion of these 2 hormones has to be perfectly balanced. The problem in type 1 diabetes (T1D) is not only that beta cells are destroyed, but also alpha-cells lose their ability to release glucagon appropriately to a lowering in blood sugar levels ("glucose blindness"), which can cause life-threatening low blood sugar (hypoglycemia) after insulin injections. No treatment has been developed to regulate glucagon secretion and the scientific community still doesn't know what goes awry with the alpha-cells in T1D, mainly because of lack of adequate technical tools to study human alpha-cells under these conditions. Here, we will obtain pancreas tissues from diabetic and non-diabetic donors through the nPOD network and prepare living slices to interrogate alpha cells. Using advanced fluorescence microscopy, we will measure calcium (Ca2+) response and glucagon secretion in alpha-cells in response to different glucose concentrations (ranging from 1 mM to 20 mM). We will utilize a custom-made microfluidic device that enables us to hold the slices during the imaging while exchanging the media. Applying these tools together, we will investigate pancreatic alpha- cells in the following manner: (1) first determine how glucagon is normally released, which is surprisingly unclear, (2) why glucagon is not released properly in T1D, and then 3) determine if there are ways to fix this process. Our work will elucidate normal alpha-cell physiology and its defects in T1D, and how neighboring islet cells normally communicate with each other and become un-neighbourly to pathologically influence each other in T1D. We can then manipulate alpha cell defects and/or rectify the defective crosstalk between islet cells in T1D, which will reveal new paradigms in treating T1D.