NIDDK Programs
To harness the therapeutic potential of stem cells for the treatment of diabetes novel technologies will need to be developed. First, stem cells will be have to be isolated and expanded. Second, the stem cells will have to undergo directed and controlled differentiation toward the beta-cell lineage. Finally, fully functional beta-cells must be isolated from the resulting complex mixes of cells. In this application, we propose to develop reagents that will assist in the further development of all three of these steps. We will generate a comprehensive panel of monoclonal antibodies directed against cell surface epitopes of murine, primate and human pancreatic cells. These antibodies will permit the fractionation of pancreatic cell suspensions using fluorescence activated cell sorting and/or magnetic bead panning. This approach can be used to isolate pancreatic stem cells (step 1) as well as for the purification of differentiated progeny before therapeutic transplantation (step 3). In addition, this proposal is designed to identify the network of genes controlled by the pancreatic transcription factor, PDX-1. Evidence suggests that the family of protein-coding genes under the control of PDX-1 defines many of the phenotypic characteristics of differentiated beta cells. Although a few of these genes have been identified, the full constellation of PDX-1 responsive targets is unknown. We propose that PDX-1 also drives the expression of non-coding genes that are equally important for regulating beta cell function (steps 2&3). Definition of both families of targets is required for a complete understanding of beta cell biology and pathophysiology.
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· Investigators: David Harlan, Eric Liu†, Klaus Pechhold†, Kristina Rother†
Investigators within the NIDDK Islet and Autoimmunity Branch (IAB), along with intramural and extramural collaborators, are involved in several ongoing projects to assess the capacity of putative beta cell progenitor cells to differentiate into functionally relevant and physiologically regulated insulin producing cells. Toward that end, and depending upon the progenitor cell source, IAB investigators have developed a mouse model (described at previous BCBC retreats) specifically designed to promote in vivo differentiation of the putative beta cell progenitor. For instance, in that mouse, immune mediated destruction of the endogenous beta cells can be carefully regulated such that the killing takes place over weeks (to create an increasing need for new beta cell function) and such that new beta cells created from the progenitor would not be susceptible to the immune mediated killing. We have also developed a non-human primate model (also described at previous retreats) for testing potential islet progenitors- and experiments testing cells grown in vitro by our intramural collaborator (Dr. Marvin Gershengorn) are underway. Last, we have two clinical protocols, one under way and one in the late planning phase, to test whether pancreatic insulin producing capacity can recover in patients with long standing type 1 diabetes mellitus. With regard to the latter clinical trials, we are careful to not list as an endpoint recovery of beta cell mass, since we acknowledge that mass cannot, as of today, be measured. We are also, therefore, testing a novel imaging technique we believe holds promise for assessing beta cell mass in vivo.
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† - External investigator
