Time-lapse microscopy of living cells

RBL cells were seeded at 2 × 10⁵ cells/chamber in eight-well chamber borosilicate coverglass systems (Thermo Fisher Scientific Waltham, MA). Cells were loaded with 1 mg/ml of FITC-dextran for 48 h. Images were acquired by a Leica Sp5 laser scanning confocal microscope, equipped with a heated chamber (37 °C) and CO₂ controller (4.8%) and a C-Apochromat 363/1.2 W Corr objective or using a Zeiss LSM Pascal confocal microscope using a Plan-apochromat 63° – NA 1.4 objective (Carl Zeiss MicroImaging) or Zeiss LSM 800 microscope. Image capture was performed using the standard time-series option (Carl Zeiss MicroImaging). Images and videos were generated and analyzed using the Zeiss LSM software and ImageJ software (W. Rasband, National Institutes of Health, Bethesda, MD). Long time-lapse image sequences were captured using the autofocusing function.