Fig. 4: Transgene-free iMPCs restore DYSTROPHIN expression in DMD mice.

a A schematic illustrating transplantation strategy of transgene-free iMPCs into dystrophic Tibialis Anterior (TA) muscles of DMD mice. b Representative immunofluorescence images of DYSTROPHIN in TA muscle cross-sections at 4 weeks post iMPC transplantation. PBS injection was used as a negative control. Scale bar, 1 mm; scale bar inlay, 200 μm. c Quantification of DYSTROPHIN⁺ fibers per cross-section in TA muscles engrafted with PBS or iMPCs treated with or without DLL1. Data are shown as mean ± SD. N = 2 iMPC lines, each transplanted four independent times into TA muscles as indicated by color coding. Significance was determined by two-tailed unpaired t tests. d Percentage of DYSTROPHIN⁺ area as calculated per total TA area. Related to (b). e Immunofluorescence image depicting a rare donor-derived PAX7-nGFP⁺ cell within a restored DYSTROPHIN⁺ area in a transplanted TA. Scale bar, 10 μm. f A schematic illustrating transplantation strategy of transgene-free iMPCs treated with SP, CP or SP + CP for 7 days prior to engraftment into TA muscles of DMD mice. g FACS analysis of an iMPC clone subjected to the indicated conditions for 10 days. h Representative immunofluorescence images of DYSTROPHIN in TA muscles 4 weeks after transplantation. Scale bar, 500 μm; scale bar inlay, 100 μm. i Quantification of DYSTROPHIN⁺ fibers per TA muscle cross-section engrafted with PBS or iMPCs treated with the indicated small molecules. Data are shown as mean ± SD. N = 2 iMPC lines, each transplanted four independent times into TA muscles as indicated by color coding. Significance was determined by two-tailed unpaired t tests. j Percentage of DYSTROPHIN⁺ area as calculated per total TA area. Related to (h). k A model summarizing the findings of this study.