These studies build upon previous findings by our group, which establish that pancreatic islets avidly take up superparamagnetic nanoparticles, following in vitro incubation, and retain the nanoparticulate label for an extended time-frame (months), without impairment of islet viability and function (32,33). and near-infrared fluorescence optical imaging and results in down-regulation of the target gene. == Conclusions == These results illustrate the value of our approach in overcoming the challenges associated with genetic modification of intact pancreatic islets in a clinically acceptable manner. Furthermore, an added advantage of our technology derives from the combined capability of our magnetic nanoparticles for siRNA delivery and magnetic labeling of pancreatic islets. Keywords:magnetic resonance imaging, optical imaging, rna interference, pancreatic islets == Introduction == In view Mouse monoclonal to CD32.4AI3 reacts with an low affinity receptor for aggregated IgG (FcgRII), 40 kD. CD32 molecule is expressed on B cells, monocytes, granulocytes and platelets. This clone also cross-reacts with monocytes, granulocytes and subset of peripheral blood lymphocytes of non-human primates.The reactivity on leukocyte populations is similar to that Obs of the importance of the beta-cell as a core effector of metabolic control and the profound repercussions of beta-cell pathology on human health, the acquisition of tools for the regulation of beta-cell function represents a key research and clinical priority. One very promising and widely explored approach towards this goal involves modification of the gene expression profile of the beta cell. To this end, numerous reports in the literature describe the application of gene transfer in beta-cell derived cell-lines for the study of beta-cell differentiation (1-3), beta-cell function (2,4-7), immunorecognition in the pathogenesis of type 1 diabetes (8), and the mechanisms behind the pathogenesis of type 2 diabetes (9), to name a few. In the context of gene therapy for diabetes, several ideas have shown promise, including stimulation of beta-cell growth, induction of beta-cell differentiation and regeneration, genetic engineering of non-beta cells to produce insulin, and transplantation of designed beta cells (10). However, in many cases, the behavior of beta-cell derived lines is not mirrored by that of whole islets (5,11), underscoring the benefit of studying the beta-cell in its native environment. Partially in response to this concern, attempts have been made to transfect/transduct intact islets, using lipid-mediated plasmid delivery (12,13), as well as adeno- (14-17), adeno associated- (18-21), and lentiviral vectors (16,22,23). Gene transfer to intact pancreatic islets is particularly challenging, due to the fact that they exist as clusters of 1002,000 cells, making physical access to the core of the islet difficult. In general, most studies report that primarily cells localized in the islet periphery become efficiently transduced/transfected (14,16,17,20). With specific relevance to the present study, recombinant adenovirus has been used for the delivery of shRNA to intact pancreatic islets, with the goal of endogenous gene suppression, through the mechanism of RNA interference (24). However, viral or transfection agent-mediated delivery has been directly associated with cytotoxicity (22,25,26) and/or immunogenicity (27), diminishing enthusiasm towards this approach for gene transfer to intact islets, particularly in the context of autoimmune dysfunction, as seen in type 1 diabetes. The attraction of using RNA interference to silence gene expression in pancreatic islets extends from the relative ease of siRNA delivery using nonviral means, the major prerequisite being delivery of the siRNA duplex to the cytosol. Even though the ensuing silencing effect is usually transient, it is still relatively long-lasting. In non-dividing or slowly-dividing cells, knockdown can persist for 3-4 weeks (28). Furthermore, the loss of silencing is mainly a function of siRNA dilution, rather than degradation (28), Tafamidis meglumine implying that if one designed an approach to retain the siRNA molecule inside the cell for a prolonged time period, they could extend the longevity of the knock-down even further. In agreement with these conclusions, two reports exist of the nonviral liposomal (29) and transfection-agent mediated (30) delivery of siRNA to intact pancreatic islets. The idea behind the latter approach is based on Tafamidis meglumine the known capacity of hydrodynamic injection to efficiently deliver siRNA to well-vascularized organs. However, the invasiveness of this method for in vivo transfection makes its clinical application not feasible (31). In the present study, we attempted to extend the potential of RNA interference for modification of the gene expression profile of pancreatic islets. Our approach explores the application of superparamagnetic nanoparticulate carriers to deliver siRNA inside the islet cells, coupled with the simultaneous magnetic labeling of the islets allowing for their further tracking by MRI. These studies build upon previous findings by our group, which establish that pancreatic islets avidly take up superparamagnetic nanoparticles, following in Tafamidis meglumine vitro incubation, and retain the nanoparticulate label.