Exosomes derived from umbilical cord mesenchymal stem cells protect cartilage and regulate the polarization of macrophages in osteoarthritis

Abstract BackgroundOsteoarthritis (OA) is one of the most common joint diseases and a major public health concern. Current therapies for OA can relieve symptoms but offer no potential for cartilage regeneration. Mesenchymal stem cells (MSCs) have been widely used for the treatment of OA owing to their paracrine secretion of trophic factors, a phenomenon in which exosomes may play a major role. Here, we investigated the potential of exosomes from human umbilical cord-derived MSCs (hUC-MSCs-Exos) at alleviating OA.MethodshUC-MSCs were isolated, cultured, and identified based on the expression of MSC markers and multipotency differentiation. hUC-MSCs-Exos were harvested from hUC-MSC conditioned medium using a sequential centrifugation method. Transmission electron microscopy, dynamic light scattering, flow cytometry, and western blotting were used to identify the exosomes. The effects of hUC-MSCs-Exos on the proliferation and migration of human chondrocytes were evaluated using the cell counting kit-8, EdU-555 cell proliferation kit, and transwell assays. Annexin V-FITC/PI staining and flow cytometry were used to evaluate the effect of exosomes on chondrocyte apoptosis. An in vitro model of human articular chondrocytes treated with interleukin 1 beta (IL-1β) was used to evaluate the effects of exosomes; analyses involved using quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence, and western blotting. The role of exosomes in macrophage polarization was examined in the monocyte cell line, THP-1. Rats with surgically induced OA (ACLT+pMMx method) were intra-articularly injected with hUC-MSCs-Exos. The efficacy of exosome injections was assessed using hematoxylin and eosin and safranin-O and fast green staining, and immunohistochemistry.ResultsWe confirmed the superior efficacy of hUC-MSCs-Exos at promoting chondrocyte proliferation and migration and inhibiting chondrocyte apoptosis. Additionally, hUC-MSCs-Exos reversed IL-1β-induced injury in vitro. hUC-MSCs-Exos could inhibit the secretion of pro-inflammatory factors, promote the expression of anti-inflammatory factors, and regulate the polarization of macrophages. hUC-MSCs-Exos attenuated the progression of OA and prevented severe damage to the knee articular cartilage in the rat OA model. ConclusionshUC-MSCs-Exos exerted immunomodulatory and therapeutic effects in a rat model of OA. These exosomes derived from hUC-MSCs can potentially serve as treatments for OA.