Fig. 4. GFP⁺/CD45^– cells from regenerating muscle appear myogenic in vitro. (A,B) Following FACS sorting, GFP⁺/CD45^– cells from SP-transplanted mice analyzed 5 days after CTX damage were cultured alone in proliferation medium. (A) Observation by phase contrast microscopy showed that these cells displayed a myogenic morphology (arrows), and (B) visualization by fluorescence microscopy revealed that cells with this morphology were, indeed, donor-derived, GFP⁺ (arrows). (C,D) Expression of myogenic markers by isolated GFP⁺/CD45^– cells from multiple time points co-cultured in 1:1 ratio with C2C12 myoblasts. (C) MyoD staining (red) performed on GFP⁺/CD45^– cells from a WBM-transplanted mouse 5 days post-CTX injury revealed that these cells can express this muscle marker when cultured in a myogenic environment (arrows). (D) Desmin staining (red) showed that even 7 weeks after CTX injection, the regenerated muscle still contains mononuclear cells capable of adopting myogenic markers. DAPI stained in blue.