Human Tendon Repair Following Injection of Autologous, Unmodified Stem Cells: A Comprehensive Immunohistochemical Evaluation

Current clinical treatment options for symptomatic rotator cuff tear offer only limited potential for true tissue healing and improvement of clinical results. In animal models, injections of adult stem cells isolated from adipose tissue into tendon injuries evidenced histological regeneration of tendon tissue. However, it is unclear whether such beneficial effects could also be observed in a human tendon treated with autologous, adipose derived regenerative cells. Here we demonstrate, for the first time, a comprehensive histological and immunohistochemical analysis of the biopsy of a supraspinatus tendon of a 66-year-old subject with traumatic rotator cuff injury, taken ten weeks after local injection of fresh, uncultured, autologous, adipose derived regenerative cells (UA-ADRCs), prepared at the point of care. Our analysis demonstrated clear evidence towards regenerative healing of the injured supraspinatus tendon. Of note, no formation of adipocytes was observed. These findings indicate that injected autologous, unmodified stem cells can indeed form new tendon tissue and regenerate an injured human tendon.