Non-invasive Beta-cell Imaging: Visualization, Quantification, and Beyond

• Published in: Frontiers in endocrinology (Lausanne) 2021-06, Vol.12, p.714348-714348
• Main Authors: Murakami, Takaaki, Fujimoto, Hiroyuki, Inagaki, Nobuya
• Format: Article
• Language: English
• Subjects: Animals; beta-cell imaging; Diabetes Mellitus - diagnostic imaging; Diabetes Mellitus - metabolism; Diabetes Mellitus - pathology; Endocrinology; exendin; glucagon-like peptide-1; Humans; Insulin-Secreting Cells - metabolism; Insulin-Secreting Cells - pathology; positron emission tomography; Positron-Emission Tomography - methods; Radiopharmaceuticals - metabolism; single photon emission computed tomography; Tomography, Emission-Computed, Single-Photon - methods; β-cell mass
• ISSN: 1664-2392; 1664-2392
• DOI: 10.3389/fendo.2021.714348

Pancreatic beta (β)-cell dysfunction and reduced mass play a central role in the development and progression of diabetes mellitus. Conventional histological β-cell mass (BCM) analysis is invasive and limited to cross-sectional observations in a restricted sampling area. However, the non-invasive evaluation of BCM remains elusive, and practical and clinical techniques for β-cell-specific imaging are yet to be established. The lack of such techniques hampers a deeper understanding of the pathophysiological role of BCM in diabetes, the implementation of personalized BCM-based diabetes management, and the development of antidiabetic therapies targeting BCM preservation and restoration. Nuclear medical techniques have recently triggered a major leap in this field. In particular, radioisotope-labeled probes using exendin peptides that include glucagon-like peptide-1 receptor (GLP-1R) agonist and antagonist have been employed in positron emission tomography and single-photon emission computed tomography. These probes have demonstrated high specificity to β cells and provide clear images accurately showing uptake in the pancreas and transplanted islets in preclinical and clinical studies. One of these probes, indium-labeled exendin-4 derivative ([Lys ( In-BnDTPA-Ahx)]exendin-4), has captured the longitudinal changes in BCM during the development and progression of diabetes and under antidiabetic therapies in various mouse models of type 1 and type 2 diabetes mellitus. GLP-1R-targeted imaging is therefore a promising tool for non-invasive BCM evaluation. This review focuses on recent advances in non-invasive β-cell imaging for BCM evaluation in the field of diabetes; in particular, the exendin-based GLP-1R-targeted nuclear medicine techniques.