Dystrophin-positive fibers before and after HCT and at autopsy. Immunofluorescence staining was performed on muscle tissue sections from pre- and posttransplantation biopsies; necropsy and wild-type dogs were used as positive controls. Sartorius from (A) before HCT and (B) bicep from necropsy; (C) diaphragm from necropsy; (D) sartorius muscle from wild-type dog. Normal mouse immunoglobulin G (IgG; Invitrogen) was used as negative control (not shown). Nonfixed sections were blocked in 3% bovine serum albumin in 1 × Dulbecco phosphate-buffered saline (PBS; Gibco) and incubated for 60 minutes at room temperature with mouse anti–human dystrophin monoclonal antibody (NCL-DYS2, 20 μg/mL; Novocastra Laboratories). Sections were then rinsed 3 times for 15 minutes in PBS and incubated in the dark for 30 minutes at room temperature with rabbit anti–mouse Rhodamine-conjugated secondary antibody (1:100 dilution; Invitrogen). Preparations were counterstained with 4′, 6-diamidino-2-phenylindole (DAPI; Sigma). Sections were then rinsed in PBS (3 × 15 minutes) and mounted in Vectashield (Vector Laboratories). Fields were chosen to show rare positive fibers. Original magnification × 20.