C57bl 6n male mice

All animal experiments were performed in compliance with the institutional guidelines for the care and use of laboratory animals. The protocol was approved by the IZUMO Campus Animal Care and Use Committee of Shimane University (permission number: IZ26-7). C57BL/6N male mice were purchased from CLEA Japan, Inc. (Osaka, Japan). C57BL/6N-IL-33^−/− mice (CDB0631K)^{47 (link)} were obtained from RIKEN CDB (Kobe, Japan) (http://www.cdb.riken.jp/arg/mutant%20mice%20list.html) and inbred at the institutional animal facility. These mice were maintained under specific pathogen-free conditions at a controlled temperature of 23±2 °C, relative humidity 55±10%, and with a 12-h light–dark cycle. The mice were intermittently checked for health throughout the entire experimental period after tumour injection. Mice were killed by CO₂ inhalation at the end of the study.

MSCs were collected from 8‐week‐old C57BL/6‐Tg (CAG‐EGFP) male mice (Japan SLC Inc., Shizuoka, Japan) and cultured as described above. Surgical procedures were performed on 8‐week‐old C57BL/6N male mice (CLEA Japan Inc., Tokyo, Japan). The recipient animals were anesthetized using 2% isoflurane. Following anesthesia, posterior biceps femoral (PBF) muscles were opened aseptically, a slit of 2 mm (width) × 3 mm (depth) was made using a scalpel. The mice were subsequently injected into the slit with 1 × 10⁵ MSCs from EGFP mice suspended in 2 μL of PBS. After 2 days, the mice were euthanized and the PBF muscles were collected for FACS assessment.