Mitogenic factors derived from extracellular matrix

The specific signals that trigger and promote regeneration of beta cells in situ within islets in living individuals are unknown but would be logical drug targets to increase beta cell regeneration and thereby restore beta cell mass in Type 1 diabetes. The major goals (deliverables) of this project will be to identify, characterize and validate novel factors that will increase beta cell regeneration and that may be suitable for development as drugs. This is a hypothesis driven, drug discovery project with specific milestones and timelines. The hypothesis driving this project is that factors able to enhance beta cell replication and/or recruitment/proliferation of beta cell progenitors are embedded within the extracellular matrix (ECM) from where they are liberated in vivo under appropriate circumstances including regeneration. These occult peptides that can also be liberated or derived from ECM in vitro may differ from one tissue to the next with any possibly impacting beta cells. The project will be a collaboration between two investigators: Stephen Badylak (co-PI) and Philippe Halban (PI). Dr. Badylak will prepare decellularized ECM from a variety of tissues/organs including the pancreas and islets. These ECMs will be digested enzymatically, exposed to living cells or hydrolyzed in order to generate crude fractions postulated to contain cryptic peptides with mitogenic and/or chemoattractant activity. The fractions will be shipped to Dr. Halban for bioassay. Rat islet cells and purified rat beta cells will be used initially for routine screening. Human islet cells and purified beta cells will be used only to confirm positive findings using rat cells due to their more limited supply. Each fraction will be tested for its ability to modulate cell replication or migration respectively, with identification in each instance of the cell type impacted. Any effect on insulin content and secretion will also be examined. Preliminary studies will be performed in order to indicate the signaling pathways that the factors activate and to provide some indication of the mode of action of these candidate drugs. Fractions showing biological activity in these assays will be further purified by Dr. Badylak in an iterative approach that will allow for the complete chemical characterization of active factors and their synthesis for revalidation and future mode of action studies allowing for possible drug development.