C57bl 10scsn dmdmdx j mice

Bic/miR-155^−/− mice in a 129-C57BL/6 mixed background were described previously.^{38 (link)} miR-155-KO mice were generated by mating miR-155^+/− male and female mice. C57BL/10ScSn-Dmd_mdx/J mice were purchased from Jackson Laboratory (Bar Harbor, ME, USA). All animals were housed in sterile, pathogen-free isolation cages. Previously described primers for genotyping of miR-155 and mdx were used.^{42 (link), 78 (link)} All experiments with mice were performed according to protocols approved by the Institutional Animal Care and Use Committees of Boston Children's Hospital.

All animal procedures were performed in accordance with protocols approved by the Institutional Animal Care and Use Committee of the University of Maryland, School of Medicine. Freshly isolated soleus muscles were collected from young (~2 months) and old (~14 months) adult male wild type C57BL/6Scsn/J and dystrophic mdx C57BL/10Scsn-Dmd mdx/J mice (Jackson Laboratories, Bar Harbor, ME), and flash frozen in liquid nitrogen. For each experiment, four to seven (n = 4–7) different soleus muscles were used per animal group.

Male C57BL/10ScSn-Dmd^mdx/J mice (n = 10, JAX no. 001801) and age-matched male C57BL/10ScSnJ mice (n = 10, JAX no. 000476) were purchased from Jackson Laboratories. The C57BL/10ScSn-Dmd^mdx/J mouse is a model of DMD. Animals were acclimated for a minimum of 3 days prior to imaging. Animals were housed in pairs except after imaging when animals were single-housed to allow for radiation decay. Rodent chow (Lab Diet® Certified Rodent Diet no. 5002, PMI Nutrition International, Inc.) and tap water were available ad libitum. All applicable institutional and/or national guidelines for the care and use of animals were followed. All study procedures were approved by the Institutional Animal Care and Use Committee of MPI Research (Mattawan, MI) or Invicro, LLC (Boston, MA).

C57BL/6J (RRID:IMSR_JAX:000664) and C57BL/10ScSn-Dmd^mdx/J mice (RRID:IMSR_JAX:001801), hereafter referred to as wt and mdx mice, respectively, were purchased from the Jackson Laboratory.
Mice were bred respecting the standard animal facility procedures, and all the procedures were conducted in accordance with rules of good animal experimentation I.A.C.U.C. n°432 of 12 March 2006 and under ethical approval released on 23/October/2017 from the Italian Ministry of Health, protocol #820/2017-PR.
For muscle injury, 45-day-old wt and mdx mice were anesthetized with an intramuscular injection of saline solution containing ketamine (5 mg/mL) and xylazine (1 mg/mL) prior to the intramuscular administration of 20 μL of 10 μM cardiotoxin solution, isolated from Naja Pallida (Latoxan L8102, Portes les valence, France), into tibialis anterior, quadriceps, and gastrocnemius muscles.

Animal studies were approved by the Institutional Animal Care and Use Committee at the Medical College of Wisconsin (approval no. #3547). All mice in this study were 10- to 12-week-old female C57BL/10ScSn-Dmdmdx/J mice (The Jackson Laboratory). All animals were handled in compliance with Institutional Animal Care and Use Committee guidelines as well as local, national and international regulations and guidelines.