title: Muscle progenitor cell regenerative capacity in the torn rotator cuff.
abstract: Chronic rotator cuff (RC) tears affect a large portion of the population and result in substantial upper extremity impairment, shoulder weakness, pain, and limited range of motion. Regardless of surgical or conservative treatment, persistent atrophic muscle changes limit functional restoration and may contribute to surgical failure. We hypothesized that deficits in the skeletal muscle progenitor (SMP) cell pool could contribute to poor muscle recovery following tendon repair. Biopsies were obtained from patients undergoing arthroscopic RC surgery. The SMP population was quantified, isolated, and assayed in culture for its ability to proliferate and fuse in vitro and in vivo. The SMP population was larger in muscles from cuffs with partial tears compared with no tears or full thickness tears. However, SMPs from muscles in the partial tear group also exhibited reduced proliferative ability. Cells from all cuff states were able to fuse robustly in culture and engraft when injected into injured mouse muscle, suggesting that when given the correct signals, SMPs are capable of contributing to muscle hypertrophy and regeneration regardless of tear severity. The fact that this does not appear to happen in vivo helps focus future therapeutic targets for promoting muscle recovery following rotator cuff repairs and may help improve clinical outcomes.
authors.affiliation: Department of Bioengineering, University of California, San Diego, La Jolla, California, 92093.
authors.forename: Gretchen A
authors.initials: GA
authors.lastname: Meyer
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Farris
authors.forename: Eugene
authors.initials: E
authors.lastname: Sato
authors.forename: Michael
authors.initials: M
authors.lastname: Gibbons
authors.forename: John G
authors.initials: JG
authors.lastname: Lane
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Ward
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Engler
mesh_terms: D000328:Adult; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000166:cytology*; D012038:Regeneration / Q000502:physiology*; D017006:Rotator Cuff / Q000503:physiopathology / Q000601:surgery; D000070636:Rotator Cuff Injuries; D013234:Stem Cells / Q000502:physiology*
keywords: muscle; progenitor; regeneration; rotator cuff; shoulder