Albumin from bovine serum fraction 5

INS1(832/13) pancreatic β cells⁶⁰ (link) were cultured in RPMI medium (11 mM glucose) supplemented with 10% (v/v) fetal calf serum, 20 mM HEPES, 50 μM beta-mercaptoethanol plus penicillin (100 units/mL) and streptomycin (0.1 mg/mL) at 37°C in an atmosphere of humidified air (95%) and CO₂ (5%). EndoC-βH1 cells were kindly provided by Dr. Philippe Ravassard (CRICM CNRS UMR 7225, Paris, France) and grown in serum-free DMEM (Life Technology) containing low glucose (1 g/L), 2% (w/v) albumin from bovine serum fraction V (Roche Diagnostics), 50 μM β-mercaptoethanol, 10 mM nicotinamide (VWR), 5.5 μg/mL transferrin (Sigma-Aldrich), 6.7 ng/mL sodium selenite (Sigma-Aldrich), penicillin (100 units/mL), and streptomycin (100 μg/mL).

The human pancreatic beta cell line EndoC-βH1 (courtesy of Professor Erik Renstrom, Lund University) was grown in a culture plate coated with 2 μg/mL of fibronectin (Sigma-Aldrich, St Louis, MO, USA)/1% extracellular matrix (ECM, Sigma-Aldrich, St Louis, MO, USA) and cultured at 37 °C and 5% CO₂ in low-glucose (1 g/L) Dulbecco’s Modified Eagle Medium (DMEM, Gibco, Thermo Fisher Scientific, Waltham, MA, USA) with 2% albumin from bovine serum fraction V (Roche Diagnostics), 50 µM 2-mercaptoethanol (Sigma-Aldrich, St Louis, MO, USA), 10 mM nicotinamide (Sigma-Aldrich, St Louis, MO, USA), 5.5 μg/mL transferrin (Sigma-Aldrich, St Louis, MO, USA), 6.7 ng/mL sodium selenite (Sigma-Aldrich), and penicillin (100 units/mL)/streptomycin (100 μg/mL) (Gibco, Thermo Fisher Scientific, Waltham, MA, USA).