After 3 days of maintenance, islets were diluted to plate an average 3 islets per well for subsequent analysis in 96-multiwell RAFTTM (3D) plates according to the instructions of the manufacturer (TAP Biosystems, Lonza, Cologne, Germany). Briefly, islets were dispensed in the chilled mixed collagen solution of the RAFTTM kit (containing 2.8 ml 10X MEM medium, 22.4 ml 2 mg/ml rat tail collagen type I, 1.624 ml neutralizing solution and 1.2 ml islets for 96-well tissue culture plate) according to the RAFT TM protocol. We plated 240 µl mixed collagen solution per well and incubated the plate at 37 °C to form a hydrogel for 15 min. Then we placed the RAFTTM absorbers on the top of the hydrogel in a laminar flow hood at room temperature (RT) for 15 min. After removing the absorbers we immediately loaded 200 µl MES medium per well. Medium was replaced on every third day.