Cytoprotection of PEG-modified adult porcine pancreatic islets for improved xenotransplantation.
Functional poly(ethylene glycol) (PEG) derivatives, including monosuccinimidyl PEG (MSPEG) with molecular weight (MW) of 2000 (2 kDa) as well as 5 kDa and disuccinimidyl PEG (DSPEG) with MW of 3 and 6 kDa, were synthesized and characterized. They were used to modify the surface of adult porcine islets for cytoprotection. The islets were isolated, purified and modified with functional PEG. Untreated porcine islets were used as control. An in vitro human antibody/complement-mediated cytotoxicity test based on the release of intracellular lactate dehydrogenase was used to evaluate cytotoxicity of human serum to the modified islets. In vitro cell viability was assessed using membrane-integrity straining and islet metabolism in culture. In vitro islet functionality was evaluated by glucose-stimulated insulin release of islets in static incubation with human serum. In vivo islet functionality was evaluated by monitoring non-fasting blood glucose level in streptozotocin-induced diabetic (SCID) immunocompromized mice after intraportal transplantation of porcine islets. Results show that all the PEG derivatives used in the study showed significant in vitro and in vivo cytoprotections against cytotoxic effects elicited by human serum and diabetic SCID mice, respectively, to porcine islets. DSPEG derivatives combined with human albumin exhibited a better cytoprotection, as compared to MSPEG ones, due to the capacity of the succinimidyl groups to selectively react with amino groups of the albumin under physiological conditions. The effects of both MW and concentration of the PEG derivatives on cytoprotection were significant. It appears that this novel biotechnology will be an attractive approach for improved xenotransplantation of islets.
Department of Biomedical Engineering, University of Alabama at Birmingham, 370 Hoehn Building, 1075 13th Street South, Birmingham, AL 35294-4440, USA. dxie@eng.uab.edu
Dong
D
Xie
Cheryl A
CA
Smyth
Christopher
C
Eckstein
Guadalupe
G
Bilbao
Jimmy
J
Mays
Devin E
DE
Eckhoff
Juan L
JL
Contreras
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001786:Blood Glucose / Q000032:analysis; D002417:Cattle; D002478:Cells, Cultured; D019610:Cytoprotection / Q000502:physiology*; D003921:Diabetes Mellitus, Experimental / Q000097:blood* / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016381:Islets of Langerhans Transplantation / Q000379:methods*; D008297:Male; D008422:Materials Testing; D051379:Mice; D016513:Mice, SCID; D019397:Pancreas, Artificial; D011092:Polyethylene Glycols / Q000737:chemistry*; D023822:Tissue Engineering / Q000379:methods*; D014183:Transplantation, Heterologous
D001672:Biocompatible Materials; D001786:Blood Glucose; D011092:Polyethylene Glycols