Molecular Shielding of Pancreatic Islets Using PEG Dendron for Immunoprotection

Abstract

As a new approach to islet transplantation, biocompatible poly(ethylene glycol) (PEG) derivatives were chemically grafted onto the surface of pancreatic islet. The aim of this study was to determine the optimal PEG dendron grafting condition to completely cover the surface of islet while maintaining high cell viability after PEGylation. Densely modified islet surface could effectively inhibit immune cell infiltration. FITC labeled PEG dendrons were used to determine the optimal PEG dendron concentration and incubation time. According to the images obtained from scanning electronic microscope (SEM), 1% (w/v) was the optimal concentration for surface modification of islet and 1 h incubation time was the optimal condition for covering the surface of islets. The viability and functionality of PEG dendron modified islets were almost similar to those of the unmodified islets. In addition, islet surface modification with PEG dendron effectively inhibited the immune cell infiltration even after 7 days of co-culture with splenocytes. The overall results showed that islet surface modification using PEG dendron did not affect the function of islets while effectively inhibiting immune cell activation and infiltration. In conclusion, when PEG dendron grafting was performed for 1 h using 1% PEG dendron, the surface of islet was completely covered without affecting the viability and the functionality of islets. Therefore, PEG dendrons can be used as surface camouflage material to reduce immune response without increasing the islet size when infused via portal vein.