Fig. 3

MSNPs biodistribute to regenerating myofibers in dystrophic muscle. A–B. Staining of muscle regeneration. Tiled images of gastrocnemius, quadriceps, and tibialis anterior muscles shows varying levels of regeneration across and corresponds with MSNP biodistribution. Scale bars represents 500 μm. B–C. Time course of MSNP biodistribution to skeletal muscle. MSNPs packaged with NIR labeled protein bio-distribute to skeletal muscle by 1 h and are cleared by 48 h. IVIS of skeletal muscle tissue at 1, 24, and 48 h post MSNP systemic delivery (50 mg/kg). Staining shows MSNPs (white), regenerating myofibers (a-SMA, red), capillaries (Cd31, green), and nuclei (DAPI, blue). Scale bars represent 20 μm. Color code: Red, vascular smooth-muscle cells stained with anti-alpha smooth muscle actin (α-SMA) antibody, nuclear stained with DAPI; white, NIR MSNPs. Co-staining of Cd68 + macrophages (green) with MSNPs (white) shows greater than 90% co-localization at 24 h post systemic injection