title: Glucose- and time-dependence of islet amyloid formation in vitro.
abstract: Islet amyloid contributes to the loss of beta-cell mass in type 2 diabetes. To examine the roles of glucose and time on amyloid formation, we developed a rapid in vitro model using isolated islets from human islet amyloid polypeptide (hIAPP) transgenic mice. Islets from hIAPP transgenic and non-transgenic mice were cultured for up to 7 days with either 5.5, 11.1, 16.7 or 33.3mmol/l glucose. At various time-points throughout the culture period, islets were harvested for determination of amyloid and beta-cell areas, and for measures of cell viability, insulin content, and secretion. Following culture of hIAPP transgenic islets in 16.7 or 33.3mmol/l glucose, amyloid formation was significantly increased compared to 5.5 or 11.1mmol/l glucose culture. Amyloid was detected as early as day 2 and increased in a time-dependent manner so that by day 7, a decrease in the proportion of beta-cell area in hIAPP transgenic islets was evident. When compared to non-transgenic islets after 7-day culture in 16.7mmol/l glucose, hIAPP transgenic islets were 24% less viable, had decreased beta-cell area and insulin content, but displayed no change in insulin secretion. Thus, we have developed a rapid in vitro model of light microscopy-visible islet amyloid formation that is both glucose- and time-dependent. Formation of amyloid in this model is associated with reduced cell viability and beta-cell loss but adequate functional adaptation. It thus enables studies investigating the mechanism(s) underlying the amyloid-associated loss of beta-cell mass in type 2 diabetes.
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and University of Washington, Seattle, WA 98108, USA. zraikas@u.washington.edu
authors.forename: Sakeneh
authors.initials: S
authors.lastname: Zraika
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Hull
authors.forename: Jayalakshmi
authors.initials: J
authors.lastname: Udayasankar
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Utzschneider
authors.forename: Jenny
authors.initials: J
authors.lastname: Tong
authors.forename: Fernando
authors.initials: F
authors.lastname: Gerchman
authors.forename: Steven E
authors.initials: SE
authors.lastname: Kahn
mesh_terms: D000682:Amyloid / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D007515:Islets of Langerhans; D008657:Metabolic Clearance Rate; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D013997:Time Factors
chemical_list: D000682:Amyloid; D005947:Glucose