Muscle Injury and Immune Cell Isolation

WT or Nur77 KO mice were anesthetized with 2.5% isoflurane using a SomnoSuite device. After anesthesia, muscle damage was induced in the tibialis anterior (TA) muscle by injecting 50 µL of 12 µM cardiotoxin (Latoxan, Valence, France) in phosphate-buffered saline (PBS). Mice were sacrificed and muscles were collected on days 2, 3, and 4 post-injury and processed for cell and mRNA analysis. TA muscles were dissociated in RPMI containing 0.2% collagenase II (Thermo Fisher Scientific, Waltham, MA, USA) at 37°C for 1 h and filtered through a 100 µm and then a 40 µm filter. Muscle-derived CD45⁺ cell isolation was carried out as described earlier (50 (link)). CD45⁺ cells were separated using magnetic sorting (Miltenyi Biotec, Gladbach, Germany).