Rotator cuff (RC) tears are an extremely common cause of shoulder pain and
disability. Up to 50% of patients greater than the age of 65 years of age have evidence
of a RC tear. In addition, patients with small asymptomatic cuff tears tend to progress to
larger, symptomatic tears. The outcomes of surgical repair of small RC tears are good,
but there has been limited success in the surgical treatment of massive RC tears.
Massive RC tears have been linked with fatty infiltration of the rotator cuff muscles.
Patients with large RC tears who develop fatty infiltration have poorer clinical outcomes
and higher rates of failure after attempted repair. We have previously found that a newly
discovered stem cell population-fibro/adipocyte progenitor (FAP) cells-is critical in the
development of fatty infiltration after RC injury. Further, these cells share similar
expression patterns with the beige adipocyte lineage, a distinct cell population that has
unique thermogenic and metabolic capabilities that could improve muscle function.
The study will leverage our well-studied animal model and a novel repair model to
evaluate the mechanism by which FAP cells can improve muscle function through
differentiation into a beige fat phenotype in mouse and human tissue. Understanding the
relationship between FAP cells and beige adipocytes and utilizing these cells in
endogenous and exogenous treatment strategies could help improve muscle quality in
RC repair as well as other muscle injury states.