Stromal vascular fraction cells (University Hospital, Basel, Switzerland)

Adipose tissue, isolated by liposuction or excision, was finely minced. Samples were digested with collagenase type II (355 U/mg) for 60–90 min at 37 °C. After centrifugation at 190 g for 10 min, the lipid-rich layer was discarded and the cellular pellet was washed once with phosphate buffered saline (PBS). Red blood cells were lysed by incubation for 2 min, in a solution of ammonium chloride (0.15 m), potassium hydrogen carbonate (1 mm) and EDTA (0.1 mm). The resulting SVF cells were then resuspended in complete medium (CM), consisting of α-MEM supplemented with fetal bovine serum (10%), HEPES (1%), sodium pyruvate (1%) and penicillin-streptomycin-glutamin solution (1%).

For monolayer expansion, SVF cells were seeded at a density of 2 × 10³ cells/cm² onto tissue culture plates, cultured in CM supplemented with FGF-2 (5 ng/mL).  Cells were serially replated onto new dishes at a density of 3 × 10³ cells/cm² when reaching subconfluence.