PT  - JOURNAL ARTICLE
AU  - Roberts, Sheryl
AU  - Khera, Eshita
AU  - Choi, Crystal
AU  - Navaratna, Tejas
AU  - Grimm, Jan
AU  - Thurber, Greg M.
AU  - Reiner, Thomas
TI  - Optoacoustic imaging of Glucagon-like Peptide 1 Receptor with a near-infrared exendin-4 analog
AID  - 10.2967/jnumed.120.252262
DP  - 2020 Oct 01
TA  - Journal of Nuclear Medicine
PG  - jnumed.120.252262
4099  - http://jnm.snmjournals.org/content/early/2020/10/23/jnumed.120.252262.short
4100  - http://jnm.snmjournals.org/content/early/2020/10/23/jnumed.120.252262.full
AB  - Limitations in current imaging tools have long challenged the imaging of small pancreatic islets in animal models. Here, we report the first development and in vivo validation testing of a broad spectrum and high absorbance near infrared optoacoustic contrast agent, E4x12-Cy7. Our near infrared tracer (E4x12-Cy7) is based on the amino acid sequence of exendin-4 and targets the glucagon-like peptide-1 receptor (GLP-1R). Cell assays confirmed that E4x12-Cy7 has a high binding affinity (IC50 = 4.6 ± 0.8 nM). Using the multi-spectral optoacoustic tomography (MSOT), we imaged E4x12-Cy7 and optoacoustically visualized β-cell insulinoma xenografts in vivo for the first time. In the future, similar optoacoustic tracers that are specific for β-cells and combines optoacoustic and fluorescence imaging modalities could prove to be important tools for monitoring the pancreas for the progression of diabetes.