Improved Coating of Pancreatic Islets With Regulatory T cells to Create Local Immunosuppression by Using the Biotin-polyethylene Glycol-succinimidyl Valeric Acid Ester Molecule

Abstract

Background We showed that T regulatory (Treg) cells can be attached to the surface of pancreatic islets providing local immunoprotection. Further optimization of the method can improve coating efficiency, which may prolong graft survival. In this study, we compared the effectiveness of two different molecules used for binding of the Tregs to the surface of pancreatic islets. Our aim was to increase the number of Treg cells attached to islets without compromising islets viability and function. Methods Cell surface of human Treg cells and pancreatic islets was modified using biotin-polyethylene glycol (-PEG-) -N-hydroxylsuccinimide (biotin-PEG-NHS) or -succinimidyl valeric acid ester (biotin-PEG-SVA). Then, islets were incubated with streptavidin as islet/Treg cells binding molecule. Treg cells were stained with CellTracker™ CM-DiL dye and visualized using Laser Scanning Confocal Microscope. The number of Treg cells attached per islets surface area was analyzed by Imaris software. The effect of coating on islet functionality was determined using Glucose-Stimulated Insulin Response (GSIR) assay. Results Coating procedure with biotin-PEG-SVA allowed for attaching 40% more Treg cells per 1 μm2 of islets surface. While viability was comparable, function of the islets after coating using biotin-PEG-SVA molecule was better preserved than with NHS molecule. GSIR was 62% higher for islets coated with biotin-PEG-SVA compared to biotin-PEG-NHS. Conclusion Coating of islets with Treg cells using biotin-PEG-SVA improves effectiveness with better preservation of the islet function. Improvement of the method of coating pancreatic islets with Treg cells, could further facilitate the effectiveness of this novel immunoprotective approach and translation into clinical settings.

Tailoring Common Hydrogels into 3D Cell Culture Templates

“…Here, we chose the acryl‐poly(ethylene‐glycol)‐succinimidyl‐valerate (APSV) photolinker as it is highly soluble in water and displays improved stability to hydrolysis compared to N ‐hydroxy‐succinimide (NHS) counterparts [ 33 ] making it overall more reliable.…”

Tissue‐engineering approaches in pancreatic islet transplantation

“…Furthermore, insulinotropic peptides, such as glucagon‐like peptide‐1 (GLP‐1), exendin‐4 (Ex‐4), or insulin‐like growth factor‐1 (IGF‐1), as well as proangiogenic factors and cells such as VEGF, platelet‐derived growth factor (PDGF), and endothelial cells (ECs), have been combined with these scaffolds and islets, in both in vitro (Kizilel et al, ; Lin & Anseth, ) and in vivo approaches (Brady et al, ; Farina et al, ; Hlavaty et al, ; Y. Li et al, ; Linn et al, ; Phelps, Headen, Taylor, Thulé, & García, ; Phelps, Templeman, Thulé & García, ), showing significant improvements in insulin secretion, islet survival, and engraftment. In other studies, immunosuppressive drugs (Haque, Jeong, & Byun, ; Pinto et al, ) or even immunomodulatory cells, such as regulatory T cells (Treg; Graham et al, ) or mesenchymal stem cells (MSCs; Borg et al, ; Gołąb et al, ; Marek et al, ), were combined with synthetic materials and used in vitro and in vivo to enhance their immunoprotective functions and subsequently prevent the immune reaction against nonautologous islets. Moreover, with the aim of “functionalizing” these synthetic scaffolds, that is, increasing their biocompatibility, they have been coupled with bioactive agents that increase the hydrophilicity of their surfaces (Liu, Holzwarth, & Ma, ).…”

Encapsulated Islet Transplantation: Where Do We Stand?

“…In 2006, Krol et al demonstrated that islets can be nanoencapsulated through a layer-by-layer approach using alternating layers of either polyallylamine hydrochloride or poly-diallyldimethylammonium chloride as polycations and polystyrene sulfonate as a polyanion [177]. Subsequent studies improved the layer-by-layer coating by using a biotin-PEG peptide conjugated with streptavidin in the PEG coating [178,179]. Nanoencapsulation of islets using alternate layers of phosphorylcholine-derived polysaccharides and algi-nate normalized blood sugar levels and reversed hyperglycemia in diabetic mice in an allotransplantation setting [180].…”