Fig. 2.

Two-photon imaging of islet morphology and viability in microfluidics. Islets were pre-loaded with Hoechst 33342 and Fluo-4 for nuclear identification and intracellular Ca²⁺ detection, respectively. Viability was detected by adding annexin V in the flowing medium. a, b Images of single islets, intact (a) or subjected to mechanical stress (b), within a microfluidic channel (see video 1). From top left: morphology (transmitted light), nuclei (blue), intracellular Ca²⁺ (green), and mortality (red). c, d Plots of intracellular Ca²⁺ oscillations in the same islets shown in a, b, respectively, constantly perfused with buffer containing stimulatory glucose concentration (11 mM). Zero-centered raw data. Annexin-V⁺ cells from the stressed islets do not display oscillatory Ca²⁺ activity, as detected by Fluo-4