Human Osteochondral Explants as an Ex Vivo Model of Osteoarthritis for the Assessment of a Novel Class of Orthobiologics

Abstract

Osteoarthritis (OA) is a highly prevalent joint disease still lacking effective treatments. Its multifactorial etiology hampers the development of relevant preclinical models to evaluate innovative therapeutic solutions. In the last decade, the potential of Mesenchymal Stem Cell (MSC) secretome, or conditioned medium (CM), has emerged as an alternative to cell therapy. Here, we investigated the effects of the CM from adipose MSCs (ASCs), accounting for both soluble factors and extracellular vesicles, on human osteochondral explants. Biopsies, isolated from total knee replacement surgery, were cultured without additional treatment or with the CM from 106 ASCs, both in the absence and in the presence of 10 ng/mL TNFα. Tissue viability and several OA-related hallmarks were monitored at 1, 3 and 6 days. Specimen viability was maintained over culture. After 3 days, TNFα induced the enhancement of matrix metalloproteinase activity and glycosaminoglycan release, both efficiently counteracted by CM. The screening of inflammatory lipids, proteases and cytokines outlined interesting modulations, driving the attention to new players in the OA process. Here, we confirmed the promising beneficial action of ASC secretome in the OA context and profiled several bioactive factors involved in its progression, in the perspective of accelerating an answer to its unmet clinical needs.

Cartilage responses to inflammatory stimuli and adipose stem/stromal cell-derived conditioned medium: Results from an ex vivo model

“…In OA pathophysiology, TNFα and IL-1 stimulate an upregulation in inducible NO synthase (iNOS) activity, that raises NO production, ultimately resulting in NF-κB activation, release of catabolic and inflammatory mediators, and cartilage degeneration [ 33 ]. Consistently with previous findings [ 27 ], we observed an increased NO concentration in the culture supernatants after cytokine stimulation, with no effect induced by CM. This result seems in contrast with what was seen by Simental-Mendía et al.…”

“…Notably, CM did not exert any discernible effect on cytokine-induced GAG loss. This outcome partly contradicts the evidence from our ex vivo osteochondral model, where the reduction in MMP activity following CM treatment corresponded to a concurrent decrease in GAG loss [ 27 ]. This aspect warrants further investigation, including extended time points and continuous supernatant withdrawal and testing.…”

“…CM effectively hinders the activity of MMPs, as previously observed in other OA models, i.e. 2D chondrocyte cultures and an ex vivo osteochondral explants exposed to 10ng/ml TNFα and treated with different doses of CM over a 3-day period [ 26 , 27 ]. In this study, the influence of CM on extracellular MMPs is observed alongside a trend of downregulation at gene expression level, with no discernible effect on MMP3 protein level.…”

Understanding molecular characteristics of extracellular vesicles derived from different types of mesenchymal stem cells for therapeutic translation

“… 209 Therapeutic effects of AT-MSC derived EV are broadly studied in joint related degenerative diseases, especially osteoarthritis via production of type I and III collagen, 210 , 211 regeneration of extracellular matrix (ECM), 212 and immunomodulation. 213 , 214 However, a comparative study between BM and AT-MSC-EVs in an osteoarthritis mouse model indicate that BM-MSC-EVs can better induce type II collagen expression in the knee. 215 In addition, AT-MSC-EVs can improve metabolic syndrome associated with vascular disease by angiogenesis 216 and inflammatory regulation.…”