Purpose: This study was performed to evaluate the effects of adipose-derived mesenchymal stem cells (ADMSC) in a subacute rotator cuff tear model of a rabbit by way of comparing the expression of insulin-like growth factor 1 receptor (IGF-1R) and myosin heavy chain (MyHC) in the ADMSC injected muscle and control.
Methods: Supraspinatus tears were created in both shoulders of 11 rabbits, and rotator cuff repair was performed after 3 weeks. At the time of repair, each side of the shoulders was randomly selected, and the injection of the ADMSCs at the muscle belly near musculotendinous junction (injection side) and saline to the contralateral side (control side) was performed. After 3 weeks, we randomly assigned 5 rabbits to the immunohistochemistric analysis and 6 to Western blot analysis.
Results: Expression of both IGF-1R (95 kD) and MyHC (200 kD) at the injection side was significantly elevated compared to control side (both p = 0.028). Immunohistochemistry showed that staining areas of both IGF-1R and MyHC were overlapped with staining of ADMSCs.
Conclusion: The injection of ADMSCs resulted in high expression of IGF-1R and MyHC in subacute rotator cuff tear and repaired model in rabbit compared to control side. Therefore, the injected ADMSCs may assist in regeneration of the rotator cuff muscle by way of insulin-like growth factor 1 (IGF-1) signalling pathway. This result may suggest another solution to facilitate the recovery of rotator cuff muscle and to improve the result of rotator cuff repair by ADMSC injection via IGF-1 pathway, which is one of the potent anabolic pathways.