The isolation and characterisation of equine bone marrow stem cell derived extracellular vesicles – evidence of an anti-inflammatory action on chondrocytes.

Abstract

Background Osteoarthritis (OA) in the horse is an economic and welfare issue and there are no current disease modifying drugs available. Stem cells have been suggested as potential therapeutics for OA, originally on the basis of their regenerative capacity. However, it is now hypothesised that MSCs exert their effects via paracrine factors including the production of extracellular vesicles, that can themselves recapitulate the MSC effects in the joint. Results In this study we have, for the first time, isolated and characterised extracellular vesicles from equine bone marrow stem cells. We have shown these vesicles can be taken up by autologous chondrocytes and have anti-inflammatory effects on gene expression following chondrocyte exposure to tissue necrosis factor α and Interleukin 1β. No effects on chonodrocyte proliferation or migration was observed. Conclusion Extracellular vesicles can be isolated from equine bone marrow mesenchymal stem cells, they are taken up by chondrocytes and have an anti-inflammatory action.

Extracellular vesicles in the treatment and prevention of osteoarthritis: can horses help us translate this therapy to humans?

“…Osteochondral defects created in the trochlear groove of rats that were treated with EVs demonstrated superior healing compared with controls (phosphate buffered saline), and by 12 weeks, there was: (i) complete restoration of cartilage and subchondral bone with hyaline cartilage; (ii) complete integration with the adjacent articular cartilage; and (iii) an extracellular matrix composition that closely resembled that of age-matched unoperated controls [17] . Other preclinical studies in rodents demonstrate consistent findings; that articular delivery of MSC-EVs into a joint with a surgically created osteochondral defect promotes superior healing compared with control-treated joints [17,128,131] . In addition to rodent models, EVs also facilitate osteochondral/chondral repair in relevant porcine and rabbit models of osteochondral damage [132,133] .…”

“…In an inflammatory in vivo OA model, EV treatment significantly upregulated COL2A1, downregulated MMP13 production, and significantly improved pain scores in rats [126] . In a study using human OA cartilage explants, administration of BMMSC-EVs dampened TNF-α upregulation of COX2 and other proinflammatory cytokines and inhibited TNF-α induced collagenase activity [128] . In a more recent study, treatment with human umbilical cord MSCs (hUMSCs) derived EVs effectively promoted the polarization of macrophages towards an M2 phenotype, and treatment with the supernatant from EV stimulated M2 macrophages upregulated anabolic gene expression and downregulated MMP-13 and TNF-α production on IL-1β stimulated chondrocytes [16] .…”

“…An overlap generally exists between in vitro studies that evaluate inflammation and regeneration of OA-affected tissues, as these usually occur concurrently. In one study, chondrocyte explants taken from naturally occurring OA-affected human knees and treated with allogeneic BMMSC-EVs demonstrated cartilage regeneration and increased production of proteoglycans and type II collagen [128] . In another study, the administration of human BMMSC-EVs to IL-1β stimulated chondrocytes, suppressed chondrocyte apoptosis, and protected against degradation [130] .…”

“…Across studies, outcome parameters consistently compare the quality and the ability of repair tissue to integrate with adjacent tissue in the treated joint relative to the control joint [18] . In most studies, EV-treated joints show increased cellular proliferation, enhanced matrix deposition, and improved histological scoring compared with controls [17,18,128,131] . Osteochondral defects created in the trochlear groove of rats that were treated with EVs demonstrated superior healing compared with controls (phosphate buffered saline), and by 12 weeks, there was: (i) complete restoration of cartilage and subchondral bone with hyaline cartilage; (ii) complete integration with the adjacent articular cartilage; and (iii) an extracellular matrix composition that closely resembled that of age-matched unoperated controls [17] .…”

“…In a more recent study, treatment with human umbilical cord MSCs (hUMSCs) derived EVs effectively promoted the polarization of macrophages towards an M2 phenotype, and treatment with the supernatant from EV stimulated M2 macrophages upregulated anabolic gene expression and downregulated MMP-13 and TNF- production on IL- stimulated chondrocytes [ 16 ] . In horses, the delivery of equine BM-MSC-derived EVs was shown to significantly reduce inflammatory markers associated with OA in chondrocytes treated with IL- [ 103 , 129 ] . Inflammation is considered a key component in the pathogenesis of OA, and these initial studies highlight that EVs have potent anti-inflammatory and immunomodulatory effects in inflamed and OA-affected tissues.…”