Fig 1.
SB431542 reduces rotator cuff muscle fibrosis after injury.
(a-d) Representative Masson trichrome stain of supraspinatus muscle sections at 6 weeks, scale bar = 50μm. (e) Quantification of injured muscle fibrosis indices at 2 and 6 weeks from 4 whole muscle sections/animal (N = 4/group) imaged at 5X magnification, *p<0.05.
Fig 2.
SB431542 reduces rotator cuff muscle fatty infiltration after injury.
(a-d) Representative oil red-O stain of supraspinatus muscle sections at 6 weeks, scale bar = 50μm. (e) Quantification of injured muscle fat index indices at 6 weeks from 4 whole muscle sections/animal (N = 4/group) imaged at 5X magnification, *p<0.05.
Fig 3.
SB431542 decreases supraspinatus weight loss after injury.
Graph shows average wet weight of freshly harvested supraspinatus muscles from both vehicle and treatment groups (N = 8/group). **p<0.01.
Fig 4.
SB431542 decreases expression of fibrotic, adipogenic, and atrophy-related genes.
(a) Fold change of α-SMA in injured muscle, SB431542 treatment compared to vehicle. (b) Fold changes of PPARγ and SREBP-1. (c) Fold change of atrogin-1. (d) Fold change of PAI-1. N = 6 animals/group, 3 technical replicates/animal. *p<0.05, **p<0.01, ***p<0.005.
Fig 5.
SB431542 reduces PDGFRα+ cell number in injured muscle.
(a-d) representative supraspinatus muscle sections from PDGFRα-GFP reporter mice counterstained with DAPI, scale bar = 25 μm. (e) ImageJ quantification of PDGFRα+ cells/mm2 from 4 representative fields of view imaged at 20X magnification per animal (N = 3/group). *p<0.05.
Fig 6.
SB431542 decreases CD31-/CD45-/a7-/sca1+ FAP cell number at 2 weeks.
(a) Representative flow cytometry overlay plots of cells sorted from vehicle group (upper plot) and SB431542 treatment group (lower plot); N = 8 supraspinatus, 8 infraspinatus pooled per group. Gate indicates sca1+, a7 integrin- FAP cells out of the CD31-/CD45- population. (b) Quantification of total CD31-/CD45-/a7-/sca1+ cell number per mg of sorted tissue. (c) Percent CD31-/CD45-/a7-/sca1+ cells of total cells sorted in injured muscle groups.
Fig 7.
SB431542 promotes FAP cell apoptosis in injured rotator cuff muscle.
(a-d) Representative fluorescent TUNEL assay of supraspinatus muscle from PDGFRα-GFP reporter mice, counterstained with DAPI, scale bar = 25 μm; selection in yellow box enlarged in right lower corner. (e) ImageJ quantification of TUNEL+ cells (rhodamine) that co-express PDGFRα (GFP) from 4 representative fields of view imaged at 20X magnification from PDGFRα-GFP reporter mice (N = 3/group). *p<0.05.