title: High Recovery of Functional Islets Stored at Low and Ultralow Temperatures.
abstract: BACKGROUND
  Poor recovery of islets upon cryopreservation is the main hurdle in islet banking. Pancreatic islets have a poor antioxidative defense mechanism, and exposure of islets to low temperature leads to oxidative stress.
  
  
  OBJECTIVE
  We aimed to investigate whether known compounds such as metformin, γ aminobutyric acid (GABA), docosahexanoic acid (DHA), or eicosapentaenoic acid (EPA) alone or in combination are capable of reducing oxidative stress for better islet recovery upon storage at suboptimal temperatures.
  
  
  METHODS
  Islets isolated from mouse pancreas were stored at low temperature (4°C) for 15 days and at ultralow temperature (-196°C) for 30 days with or without additives. After revival from cold storage, islets were assessed by using three methods: (1) specificity by dithizone (DTZ), (2) viability by fluorescein diacetate/propidium iodide (FDA/PI) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zolium bromide (MTT) assay, and (3) functionality by glucose-stimulated insulin secretion (GSIS). The oxidative status of the islets stored at suboptimal temperatures was determined by both intracellular free radical release (fluorometric analysis) and lipid peroxidation (enzymatic determination).
  
  
  RESULTS
  Supplementation with additives led to an improvement in islet survival upon storage at suboptimal temperatures, without depletion of insulin secretory activity, which was comparable to that of controls. The additives acted as cryoprotectants and antioxidants as revealed by high recovery of viable islets and reduction in total reactive oxygen species (ROS) and malonidealdehyde (MDA), respectively.
  
  
  CONCLUSIONS
  Our results demonstrate for the first time that supplementation with EPA, DHA, and metformin may lead to higher islet recovery from -196°C storage, enabling proper islet banking.
authors.affiliation: School of Regenerative Medicine, Manipal University, Bellary Road, Yelahanka, Bangalore 560065, India.
authors.forename: Bhawna
authors.initials: B
authors.lastname: Chandravanshi
authors.affiliation: School of Regenerative Medicine, Manipal University, Bellary Road, Yelahanka, Bangalore 560065, India.
authors.forename: Anandh
authors.initials: A
authors.lastname: Dhanushkodi
authors.affiliation: School of Regenerative Medicine, Manipal University, Bellary Road, Yelahanka, Bangalore 560065, India.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Bhonde
mesh_terms: D000818:Animals; D015925:Cryopreservation; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008687:Metformin / Q000494:pharmacology; D051379:Mice
chemical_list: D007328:Insulin; D008687:Metformin