title: Poly(ethylene glycol) cross-linked hemoglobin with antioxidant enzymes protects pancreatic islets from hypoxic and free radical stress and extends islet functionality.
abstract: The objective of this study was to investigate the efficiency of multifunctional poly(ethylene glycol)-based hemoglobin conjugates crosslinked with antioxidant enzymes for their ability to protect an oxygen carrier (hemoglobin) and insulin secreting islets from the combination of hypoxic and free radical stress under simulated transplantation conditions. In this study, RINm5F cells and isolated pancreatic islets were challenged with oxidants (H(2)O(2) or xanthine and xanthine oxidase) and incubated with conjugates (hemoglobin-hemoglobin or superoxide dismutase-catalase-hemoglobin) in normoxia (21% oxygen) or hypoxia (6% or 1% oxygen). Hemoglobin protection, intracellular free radical activity and cell viability in RINm5F cells measured by methemoglobin, dichlorofluorescein-diacetate, and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, respectively, showed that cells were better protected by conjugates containing antioxidant enzymes. Insulin secretion from islets and qualitative confocal evaluation of viability showed beta cells were protected by conjugates containing antioxidant enzymes when exposed to induced stress. Our study suggested that antioxidant enzymes play a significant role in hemoglobin protection and thus extended cell protection.
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah 84108, USA.
authors.forename: Venkatareddy
authors.initials: V
authors.lastname: Nadithe
authors.forename: Deepa
authors.initials: D
authors.lastname: Mishra
authors.forename: You Han
authors.initials: YH
authors.lastname: Bae
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D002417:Cattle; D015687:Cell Hypoxia / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004912:Erythrocytes / Q000201:enzymology / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008706:Methemoglobin / Q000378:metabolism; D018613:Microscopy, Confocal; D018384:Oxidative Stress / Q000187:drug effects*; D010088:Oxidoreductases / Q000097:blood; D010100:Oxygen / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D023822:Tissue Engineering
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D006454:Hemoglobins; D007328:Insulin; C109960:PEG-hemoglobin; D011092:Polyethylene Glycols; D008706:Methemoglobin; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D010100:Oxygen