This page contains exclusive content for the member of the following sections: TTS, IPITA. Log in to view.
Presenter: J., Lakey, Orange, USA
Authors: A. Garcia, C. Constantinescu, M. Pan, G. Chandy, J. Muhkerjee, J. Lakey
In vitro labeling versus in vivo labeling of islets for PET Imaging after islet transplantation
A. Garcia1, C. Constantinescu1, M. Pan1, G. Chandy1, J. Muhkerjee1, J. Lakey2
1 University of California Irvine, Psychiatry and Human Behavior, Orange, USA; 2 University of California Irvine Medical Center, Surgery, Orange, USA
Objective: The ability to accurately monitor transplanted islets noninvasively would represent a tremendous advancement in the field of islet transplantation. We have focused on F allypride, a selective dopamine D2/D3 receptor antagonist.18F labeled fallypride is a clinical radiotracer for use in biomedical imaging using positron emission tomography (PET) . The aim of this study was to compare18F-fallypride labeling of islets and subsequent PET imaging of islets by either labeling the islets before transplantation or in vivo labeling after islet transplantation in the rodent model.
Methods: Islets were isolated from male Lewis rats using standard methods. In the first experiment, 1500 islets (IEQ) were transplanted into the spleen after prelabeling with 0.185 MBq/ml18F-fallypride incubation for 1 hr at 37oC and then immediately imaged over a 2 hr period using an Inveon MicroPET/microCT imaging system (Siemens Inc). The second experimental group placed unlabeled islets (1500 IEQ) into the spleen, followed by i.v. injection of18F-fallypride, and 2 hr microPET /microCT scan. Images were processed and compared to reference scans of muscle and prelabeled splenocytes transplanted into the spleen.
Results: Prelabeled transplanted islets (group 1) were clearly visible using the MicroPET/microCT imaging. In the unlabeled islet transplant experiment (group 2),18F-fallypride activity was detected in the region of the abdomen where the spleen was located.18F-fallypride activity in the transplant site increased significantly during the scan while18F-fallypride activity in the muscle remained low, with a ratio of islet transplant site / muscle of >5.
Conclusions: This study demonstrates the feasibility of transplanting unlabeled islets with subsequent labeling via systemic intravenous administration of18 F-fallypride for imaging transplanted islets in the rodent model. Longitudinal time course studies in the transplant model and evaluation in a large animal model are the next steps in moving this technology forward.
By viewing the material on this site you understand and accept that:
The Transplantation Society
International Headquarters
740 Notre-Dame Ouest
Suite 1245
Montréal, QC, H3C 3X6
Canada