Graft revascularization is essential for non-invasive monitoring of transplanted islets with radiolabeled exendin.
Islet transplantation is a novel promising strategy to cure type 1 diabetes. However, the long-term outcome is still poor, because both function and survival of the transplant decline over-time. Non-invasive imaging methods have the potential to enable monitoring of islet survival after transplantation and the effects of immunosuppressive drugs on transplantation outcome. (111)In-labeled exendin-3 is a promising tracer to visualize native and transplanted islets by SPECT (Single Photon Emission Computed Tomography). In the present study, we hypothesized that islet microvasculature plays an important role determining the uptake of exendin-3 in islets when monitoring transplant survival. We observed (111)In-exendin-3 accumulation in the transplant as early as three days after transplantation and an increase in the uptake up to three weeks post-transplantation. Islet-revascularization correlated with the increase in (111)In-exendin-3 uptake, whereas fully re-established islet vasculature coincided with a stabilized uptake of the radiotracer in the transplant. Here, we demonstrate the importance of islet vasculature for in vivo delivery of radiotracers to transplanted islets and we demonstrate that optimal and stable uptake of exendin four weeks after transplantation opens the possibility for long-term monitoring of islet survival by SPECT imaging.
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Wael A
WA
Eter
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Desirée
D
Bos
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Cathelijne
C
Frielink
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Otto C
OC
Boerman
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Maarten
M
Brom
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Martin
M
Gotthardt
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D003922:Diabetes Mellitus, Type 1 / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D006085:Graft Survival; D006801:Humans; D007205:Indium Radioisotopes / Q000008:administration & dosage / Q000737:chemistry; D016381:Islets of Langerhans Transplantation / Q000000981:diagnostic imaging*; D051379:Mice; D010455:Peptides / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D011859:Radiography; D015899:Tomography, Emission-Computed, Single-Photon
D007205:Indium Radioisotopes; D010455:Peptides; C066448:exendin 3