Background: Currently, platelet-poor plasma (PPP) is a discarded waste product of platelet-rich plasma (PRP) and may contain valuable proteins. Purpose/Hypothesis: The study’s goal was to evaluate the concentration of plasma as a potential additive biotherapy for the treatment of osteoarthritis. We hypothesized that a novel polyacrylamide concentration device would efficiently concentrate insulin-like growth factor–1 (IGF-1) from PPP and be additive to PRP or autologous protein solution (APS). Study Design: Descriptive laboratory study. Methods: A laboratory study was conducted with human and equine whole blood from healthy volunteers/donors. Fresh samples of blood and plasma were processed and characterized for platelet, white blood cell, and growth factor/cytokine content and then quantified by enzyme-linked immunosorbent assays specific for IGF-1, transforming growth factor–β, interleukin-1β, and interleukin-1 receptor antagonist as representatives of cartilage anabolic and inflammatory mediators. Results: A potent cartilage anabolic protein, IGF-1, was significantly concentrated by the polyacrylamide concentration device in both human and equine PPP. The polyacrylamide device also substantially increased plasma proteins over whole blood, most dramatically key proteins relevant to the treatment of osteoarthritis, including transforming growth factor–β (29-fold over blood) and interleukin-1 receptor antagonist (70-fold over plasma). Conclusion: Concentrated PPP is a unique source for biologically relevant concentrations of IGF-1. PRP and APS can produce greater concentrations of other anabolic and anti-inflammatory proteins not found in plasma. Clinical Relevance: The polyacrylamide device efficiently concentrated PPP to create a unique source of IGF-1 that may supplement orthopaedic biologic therapies.
