Regeneration and protection of beta cells in type 1 diabetes

T1D is an immune-mediated disease leading to the destruction of insulin producing cells and its frequency is increasing worldwide. As a result, islet cells are destroyed and, in the absence of insulin, glucose cannot enter the cells and accumulates in the blood. Replacement of the insulin producing cells (beta cells) represents the ultimate treatment for T1D. Recent advances in islet transplantation underscore the urgent need for developing alternatives to human tissue donors, which are scarce. Two possible approaches are the generation of insulin producing cells from embryonic or adult stem cells and the regeneration of endogenous beta cells. The overall aim of my PhD was to find out which of these approaches could be more feasible and which one could give the best results. The specific aim of the first part of this PhD was to study the best conditions for the isolation and culture of mesenchymal stem cells (MSCs) obtained from the bone marrow of non-obese diabetic (NOD) mice. MSCs represent one of the ideal sources that can be used for the generation of new insulin producing cells. The rationale behind this choice of experiment was that these cells will provide an unlimited source of autologous stem cells which can be transformed into insulin producing cells. At the same time we analyzed the potentiality of regeneration of the beta cells. This is a new and promising area of the research and it is important to determine its feasibility. It is therefore mandatory to arrange a marker that can be easly use to determine beta cell regeneration and following this line we set up our experiments on Reg genes and regeneration in NOD mice and also in human samples. Finally, during this PhD, I had the opportunity to meet Professor Terence Wilkin, Professor of Endocrinology & Metabolism at the University Medicine of Plymouth (UK), and together we set up a project on the Accelerator Hypothesis in the NOD mouse. This is a research project aimed to investigate mice exposed to different food availability, food restriction compared to the normal situation in which mice have free access to food (ad libitum), and how the age at onset of diabetes varied accordingly. Culled mice at diabetes diagnosis were dissected and pancreas retained for studies aimed at expression of Reg genes (Reg1, Reg2, Reg 3α, Reg3β, Reg 3γ, and Reg 3δ) associated with beta cell regeneration. Furthermore, with the present study, we tested the hypothesis that T1D can be delayed/prevented in the NOD mouse, by limiting weight gain (Accelerator Hypothesis) and therefore reducing the stress to the beta cells. Finally we tested the hypothesis that a diet with a lower protein and a greater starch amount could also impact disease development and beta cell regeneration.