Rm5201

For isolation of cell populations, tibialis anterior, quadriceps and gastrocnemius muscles were collected uninjured or 3 days after glycerol injection and digested with Dispase II (2.5 U/ml) (Roche), Collagenase B (0.2%) (Roche) and MgCl2 (5 mM) at 37 °C. Cells were then incubated at 4 °C for 30 min with antibodies against CD45 (Invitrogen, MCD4501 or MCD4528; dilution for both 1/25), CD31 (Invitrogen, RM5201 or RM5228; dilution for both 1/25), CD11b (Invitrogen, RM2801 or RM2828; dilution for both 1/25), CD34 (BD Biosciences, 560230 or 560238; dilution for both 1/60), Ly-6A–Ly-6E (Sca1) (BD Biosciences, 561021; dilution 1/150), α7-integrin (R&D, FAB3518N; dilution 1/30) and CD140a (eBioscience, 12–1401–81 or 17–1401–81; dilution for both 1/30). Antibody validation is provided on the manufacturer’s website. Specific cell subsets were isolated with a Beckman Coulter Astrios Cell sorter as described below and represented in supplementary figures S1 and S3A. MuSCs were identified as CD31⁻/CD11b⁻/CD45⁻/Sca1⁻/CD34⁺/Integrin α7⁺ and Fibro/Adipogenic progenitors (FAPs) were identified as CD31⁻/CD11b⁻/CD45⁻/Sca1⁺/CD34⁺/PDGFRα⁺. Lineage positive cells (Lin+) were identified as: CD31⁺/CD11b⁺/CD45⁺. CD31⁻/CD11b⁻/CD45⁻/Sca1⁺/CD34⁺/PDGFRα⁻ cells were also collected and named PDGFRα⁻ cells.