Figure 3: Collagen VI regulates SC activity in vitro.

(a) Quantification of Pax7⁺MyoD^–, Pax7⁺MyoD⁺ and Pax7^–MyoD⁺ cell populations on single wild-type and Col6a1^–/– myofibers fixed upon isolation (0 h) or following 72 h culture on matrigel-coated dishes in the presence or absence of purified native collagen VI. Data are shown as mean±s.e.m. of three independent replicates. The statistical analysis is provided in Table 1 (unequal variance Student’s t-test; n=10–22 myofibers, each group). (b) Three representative confocal images of cultured single myofibers and labeled with antibodies for Pax7 (green) and MyoD (light pink). Nuclei were stained with Hoechst (blue). Scale bar, 20 μm. (c) Confocal z-stack images of wild-type and Col6a1^–/– fibers grown on purified collagen VI and analyzed by immunofluorescence for collagen VI (light pink) and Pax7 (green). The insets show higher magnifications of the squared areas. Scale bar, 50 μm. (d) Quantification of apoptotic Pax7⁺ cells by TUNEL test in Col6a1^–/– single myofibers following 72 h culture on matrigel-coated dishes in the presence or absence of purified native collagen VI. Data are shown as mean±s.e.m. of two independent replicates (**P<0.01; unequal variance Student’s t-test; n=10 myofibers, each group). (e) Quantification of EdU⁺ cells, calculated as the percentage on Pax7⁺MyoD^–, Pax7⁺MyoD⁺ and Pax7^–MyoD⁺ cell populations, in Col6a1^–/– single myofibers after 72 h culture on matrigel-coated dishes in the presence or absence of purified native collagen VI. Data are shown as mean±s.e.m. of three independent replicates (**P<0.01; unequal variance Student’s t-test; n=10 myofibers, each group). Col VI, collagen VI; KO, Col6a1^–/–; MG, matrigel; WT, wild-type.