Single cell suspensions were prepared from dorsal skin as previously described (12 (link)), and skin tissue was sliced into smaller pieces and digested for 1.5 hours at 37 °C with a solution of RPMI + 10mM Hepes + 0.05% DNase I (Sigma-Aldrich) + 0.27% collagenase type XI (Sigma-Aldrich) + 0.027% hyaluronidase type IV-S (Sigma-Aldrich).