Innovative regenerative medicine in the management of knee OA: The role of Autologous Protein Solution

Osteoarthritis (OA) is one of the most common causes of chronic disability in adults due to pain and altered joint function. Although most patients report pain and functional limitation, symptoms, age of onset and disease progression are extremely variable. While inflammation could play a central role in the OA pathogenesis and progression, many underpinning mechanisms are still unclear. A number of proinflammatory mediators have been found in OA joints and could play a role, such as IL-1, IL-6, IL-7, IL-8, IL-15, IL-17, IL-18, TNF-alpha, macrophage chemotactic protein (MCP)-1, interferon-induced protein (IP)-10, monokine induced by interferon (MIG), oncostatin M (OSM), growth-related oncogene (GRO)-alpha, chemokine (C-C-motif) ligand 19 (CCL19), macrophage inflammatory protein (MIP)-1beta, and TGF-alpha. Biological approaches have recently got increasing interest due to their anti-inflammatory and immunomodulatory properties, regenerative potential, and high tolerability. The primary aim of this paper is to report the current concepts on regenerative medicine for knee OA with a particular focus on Autologous Protein solution (APS). APS is a blood derived product obtained by using a proprietary device, made of APS Separator, which isolates WBCs and platelets in a small volume of plasma, and APS Concentrator, which further concentrates platelets, WBCs and plasma proteins. The result is a peculiar formulation differing from other biologic products as it contains high levels of growth factors (EGF, IGF-1, PDGF-AB, PDGF-BB, VEGF, TGF-β1) along with high concentrations of anti-inflammatory mediators (IL-1ra, sIL-1RII, sTNF-RI, sTNF-RII) and low levels of pro-inflammatory cytokines (Il-1β and TNF-α). While emerging evidence supports the use of APS, as confirmed by in vitro studies and preliminary clinical results, the real clinical potential of APS and its benefits are still under investigation.