Cells were isolated from biopsies by collagenase digestion as described in detail in (20 (link)). Briefly, biopsies were cut into smaller pieces with sterile razor blades, placed in warm collagenase digestion media [1 mg/ml collagenase type II (Sigma-Aldrich C6885, St. Louis, MO, USA) in a 1:1 mixture of PBS and R15 [RPMI 1640 medium supplemented with 5mM l-glutamine, 50 U/ml penicillin, 50 μg/ml streptomycin, and 15% heat inactivated fetal bovine serum (Gemini Bio-Products, West Sacramento, CA, USA)] with 1 unit/ml DeoxyRibonuclease I (DNase) (Sigma) and shaken at 200 rpm in a 37°C incubator for 30 minutes. Samples were then expelled through a 16-gauge needle ten times and passed through a 70 μm cell strainer into fresh R15. The tissue collected on the strainer was placed in fresh collagenase digestion media with DNase and the cycle repeated four times. During subsequent rounds of digestion, the cell suspension was centrifuged and cell pellets resuspended in R15 and kept on ice. Pooled cells from serial digestions were used for analysis.