Allogenic Pure Platelet-Rich Plasma Therapy for Rotator Cuff Disease: A Bench and Bed Study

Background: Although platelet-rich plasma (PRP) is a popular option for rotator cuff disease, the underlying mechanism of PRP and its clinical indications are unclear. Further, some kinds of PRP might be detrimental to patients. Allogenic PRP prepared through a standardized process and fully characterized could eliminate variations in PRP as well as uncertainties regarding its use in each patient, which could provide clues about its mechanism of action and indications for its use. Purpose: To assess the effects of pure PRP on tenocytes with or without inflammation in an in vitro study and to evaluate the safety and efficacy of a fully characterized pure PRP injection in patients with rotator cuff disease in a clinical study. Study Design: Controlled laboratory study and cohort study; Level of evidence, 3. Methods: For the in vitro study, tenocytes were enzymatically isolated and cultured from patients with rotator cuff tear and treated with or without interleukin 1β (IL-1β) and PRP. Gene expression and protein synthesis of pro- and anti-inflammatory cytokines, enzymes and their inhibitors, matrix synthesis, and cell viability were evaluated. For the clinical study, a total of 17 patients with rotator cuff disease received ultrasonography-guided subacromial PRP injection and were followed for 6 months. Pain, range of motion, muscle strength, shoulder function, and overall satisfaction in patients were compared with the results in a propensity score–matched control group who received corticosteroid (triamcinolone acetonide 40 mg). Results: PRP induced inflammation in the absence of inflammation and ameliorated inflammation in IL-1β-induced tendinopathic conditions by regulation of cytokines such as IL-1β, cyclooxygenase 2, microsomal prostaglandin E synthase 1, vasoactive intestinal peptide, and downstream matrix metalloproteinases. No general or local adverse events were noted with regard to allogenic PRP injection. Whereas steroid injection showed earlier improvement in some kinds of pain and functional scores, PRP generally showed comparable effects with steroid injection in all clinical outcomes at 6 months. Conclusion: This study showed that allogenic pure PRP had pleiotropic effects on tenocytes depending on inflammation and that it did not cause adverse events but rather decreased pain and improved shoulder function to a degree comparable with steroid injection in patients with rotator cuff disease. Clinical Relevance: Allogenic PRP could be a treatment option for rotator cuff disease.