BACKGROUND: The transplantation of islets of Langerhans isolated from one donor pancreas can rarely release a diabetic recipient from insulin injections. The major reason is the destruction of 50%-60% of the transplanted tissue, which proceeds typically within a few hours after the insertion of the islets into the portal vein. Therefore, several groups have focused on development of an artificial site for islet transplantation. The main aim of the present study was to test the efficacy of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to evaluate the blood supply feeding the artificially created cavities for islet transplantation. METHODS: Two rounded devices were implanted: one device subcutaneously and the second one into the greater omentum of each animal. On the day of implantation as well as 1, 3, and 4 weeks later, we quickly injected the vascular specific MR contrast agent Vasovist (0.05 mL/100 g) intravenously. Penetration of the contrast agent was monitored by DCE-MRI. The influence of the contrast agent on the signal intensity observed within selected target areas was calculated with the use of ImageJ software. RESULTS: The penetration of the contrast agent was detected by the increase in signal intensity within implanted devices. The signal increase caused by the contrast compound was normalized to kidney tissue. On day of implantation of the device, no signal due to the contrast agent was detected in all devices. However, over the following weeks, there was an increase in signal detection within the omental device to 34%, 21%, and 14% of that of the kidney. Within the subcutaneously implanted devices there was an increase in signal detection up to 11%, 10%, and 7% of that detected in the kidney. CONCLUSIONS: The optimal time for transplantation of pancreatic islets into our omental device was 1 week after implantation of the scaffold. Also, the blood supply feeding the subcutaneous devices was regarded to be inadequate.

Diabetes Center Institute for Clinical and Experimental Medicine Prague Czech Republic

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The Optimal Timing for Pancreatic Islet Transplantation into Subcutaneous Scaffolds Assessed by Multimodal Imaging

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