Fig 2: ASCs leave the ScAT and infiltrate injured muscle.A Time course evaluation of murine in vitro ASC chemotaxis in response to plasma isolated from Ctrl, CTX- and Gly-injured animals at 1 dpi. n = 5 (Ctrl), 3 (Gly) and 4 (CTX) animals over three independent experiments. B In vitro human ASCs (of three individuals) chemotaxis in response to serum of six individuals collected 1 hour after an acute bout of continuous exercise (60% VO2 max). C Correlation of human ASC chemotaxis with 1h-post exercise GDF-15 blood levels. n = 6 serums tested on 1 or 2 sets of ASC over three independent experiments. D Model of ScAT grafting from CD34-GFP mouse into WT C57Bl/6 mice (left panel), the figure was partly generated using Servier Medical Art, provided by Servier, licensed under a Creative Commons Attribution 3.0 unported license. Immunohistofluorescence image of the ScAT depot 7 days post-graft surgery (right panel, bar scale 200 μm). E Flow cytometry analysis of the SVF from Gly-injured muscle of the grafted mice (1 dpi), GFP+/CD45−/CD31− are scated on an histogram for Sca-1 intensity. F–H Immunohistological analysis of Gly-injured (1 dpi) quadriceps in grafted mice with KikGR ScAT in situ (green arrowheads point KikGR+/CD140α+/CD45− (F), KikGR+/ Podoplanin+/CD31− cells (G) or KikGR+/CD140α+/Sca-1+ (H)). Bar scale 10 μm. Results are expressed as mean ± SEM; *p < 0.05.

Fig 3: FAPs content increases within 24 h after muscle injury.A, B Myofiber damage was induced by intramuscular injection of glycerol (Gly) or cardiotoxin (CTX) into the quadriceps. FAP number was quantified in quadriceps-derived SVF by flow cytometry (with the markers CD31, CD45, Sca-1, CD34, CD140α, and podoplanin) from 1 to 9 dpi and compared between control (uninjured, Ctrl), Gly or CTX injected animals (A, B) as well as in contralateral non-injured quadriceps (B) For A, n = 62 (Ctrl) animals over nine independent experiments at 0 dpi, n = 28 (Gly) and 7 (CTX) animals over four independent experiments at 1 dpi, n = 3 (Gly and CTX) animals over three independent experiments at 3, 7 and 9 dpi. For B, n = 62 (Ctrl), 19 (Gly), 6 (CTX) animals over 9, 3, and 3 independent experiments, respectively. C Detection of in vivo Edu incorporation detected by flow cytometry in FAPs of control and injured animals (Gly, 1 dpi). n = 8 animals at all time points over three independent experiments. D Representative confocal images and immunohistological analysis of injured (Gly and CTX) quadriceps at 1 dpi and quantification of Sca-1+/Podoplanin+/CD45− cells in situ. n = 4 (Ctrl and Gly) and 5 (CTX) animals over three independent experiments. Bar scale 50 μm. E, F Clonogenic (E) and adipogenic (F) assays were performed on total SVF isolated from control or injured (Gly and CTX) muscle at 1 dpi. For E, n = 12 (Ctrl) and 5 (Gly and CTX) animals over three independent experiments. F n = 8 (Ctrl) and 14 (Gly), and 6 (CTX) animals over four independent experiments. G Representative phase contrast images of Ctrl, Gly, or CTX muscle-derived SVF cells under adipogenic culture conditions. Cells were fixed at day 4 and stained with Oil red O. Bar scale 50 μm. H mRNA expression of adipogenic markers measured on total SVF isolated from control or injured (Gly and CTX) muscle at 1 dpi. n = 7 (Gly and CTX) animals over four independent experiments. Results are expressed as a percentage of non-injured control animals with mean ± SEM; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 vs Ctrl.