Thursday, November 21, 2024
11/21/2024
DESCRIPTION (provided by applicant): The function of pancreatic beta-cell cells is a key issue in diabetes mellitus, but can only be assessed indirectly. Currently, several aspects regarding beta-cell mass remain to be elucidated, for example: (1) Is the total beta-cell mass at the onset of type 2 diabetes diminished or not, (2) how does the beta-cell mass develop during the course of the disease, (3) which factors affect beta-cell mass, and (4) how does beta-cell mass relate to the response to therapy. Futhermore, it would be of great interest to measure beta-cell mass after islet-transplantation. Research is hampered by the fact that no reliable methods exist to assess and quantify human beta-cell mass in vivo. If beta-cell mass could be determined by a non-invasive method, this would be of a tremendous asset in advancing this field of research. We have developed a radiolabeled agent (DOTA-Lys40-Exendin 4) that allows specific beta-cell imaging. In mice the tracer shows uptake of approximately 9% of the injected activity per gram of pancreas tissue. This specific tracer is therefore a promising tool for in vivo beta-cell imaging in humans.Under this grant proposal, we will develop a Ga-68 labeled DOTA-Exendin compound for imaging of beta-cells in vivo with positron emission tomography (PET). The use of a positron emitter such as Ga-68 will offer a number of advantages over conventional nuclear medicine imaging: 1. high spatial resolution, 2. accurate quantification, 3. exact localization of the pancreas / the beta-cell areas by use of an integrated PET/CT scanner (CT=computed tomography), even if pancreatic tracer uptake is decreased after beta-cell loss. In comparison to Magnetic Resonance Imaging (MRI), the approach is very sensitive and will not require direct labeling of beta-cells for imaging purposes. Direct labeling (for example with iron) can only be done in beta-cell transplantation (prior to islet transplantation) but is not suitable for imaging of pancreatic beta-cells in vivo. In this project, we will investigate the correlation of uptake of the Ga-68-labeled DOTA-Exendin and beta-cell mass in different animal models of diabetes. Upon succesful pre-clinical development of the tracer, pilot studies in humans will be conducted. Apart from proof-of-principle studies in healthy volunteers and diabetes type I and II patients, a dosimetric method will be established to simply and reliably quantify beta-cell mass by PET imaging.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).
