Amniotic Fluid-derived MSC Secretome Halts Action of IL-1β and TNF-α Through ERK/MAPK and Returns Cartilage Repair Under OA Inflammatory Stimuli

Abstract Background: Osteoarthritis (OA) is a degenerative cartilage disease. OA cartilage has a limited repair capacity due to the effect of IL-1β and TNF-α on the chondrocyte progenitor cells (CPC) in an OA joint. Mesenchymal stem cells (MSC) therapy is a therapeutic option for osteoarthritis that initiated by the ability of secretory growth factors and mediator molecules to heal OA. Amniotic fluid MSC (AF-MSC), an interesting MSC source, has been shown to secrete various growth factors and anti-inflammatory molecules promoting tissue repair and regeneration. However, the effect of AF-MSC secretory factors to inflammation and cartilage repair is still limited. The current study aims to explore the action of AF-MSC secretome to IL-1β and TNF-α, and the CPC function that encourages cartilage repair.Methods: The effect of AF-MSC secretome to OA inflammatory cytokines was observed via the CPC migration using scratch assay. Inhibitory action of AF-MSC secretome to IL-1β and TNF-α was determined through NF-κB and MAPK signaling pathways by western blot. The repaired function of OA cartilage was analyzed via the cartilage outgrowth study and the expression of chondrogenic and anabolic genes using qRT-PCR.Results: AF-MSC secretome can arrest inflammatory action of IL-1β and TNF-α and reduces production of NF-κB, pNF-κB, p38, pp38, ERK, COX-2, and iNOS signaling proteins. It significantly reduced the production of pERK (P = 0.0434). For cartilage repair, AF-MSC secretome promotes CPC outgrowth and migration in human OA cartilage, even under inflammatory stimuli. By the action of AF-MSC secretome, the inflamed CPC can restore Col II and anabolic genes; IGF1 expression, indicating reactivation of cartilage regeneration.Conclusion: AF-MSC secretory factors have the ability to halt inflammatory actions of IL-1β and TNF-α via the ERK/MAPK pathway and motivate CPC function and anabolic property.