Therapeutic Delivery of rAAV sox9 via Polymeric Micelles Counteracts the Effects of Osteoarthritis-Associated Inflammatory Cytokines in Human Articular Chondrocytes

Abstract

Osteoarthritis (OA) is a prevalent joint disease linked to the irreversible degradation of key extracellular cartilage matrix (ECM) components (proteoglycans, type-II collagen) by proteolytic enzymes due to an impaired tissue homeostasis, with the critical involvement of OA-associated pro-inflammatory cytokines (interleukin 1 beta, i.e., IL-1β, and tumor necrosis factor alpha, i.e., TNF-α). Gene therapy provides effective means to re-establish such degraded ECM compounds by rejuvenating the altered OA phenotype of the articular chondrocytes, the unique cell population ubiquitous in the articular cartilage. In particular, overexpression of the highly specialized SOX9 transcription factor via recombinant adeno-associated viral (rAAV) vectors has been reported for its ability to readjust the metabolic balance in OA, in particular via controlled rAAV delivery using polymeric micelles as carriers to prevent a possible vector neutralization by antibodies present in the joints of patients. As little is known on the challenging effects of such naturally occurring OA-associated pro-inflammatory cytokines on such rAAV/polymeric gene transfer, we explored the capacity of polyethylene oxide (PEO) and polypropylene oxide (PPO)-based polymeric micelles to deliver a candidate rAAV-FLAG-hsox9 construct in human OA chondrocytes in the presence of IL-1β and TNF-α. We report that effective, micelle-guided rAAV sox9 overexpression enhanced the deposition of ECM components and the levels of cell survival, while advantageously reversing the deleterious effects afforded by the OA cytokines on these processes. These findings highlight the potentiality of polymeric micelles as effective rAAV controlled delivery systems to counterbalance the specific contribution of major OA-associated inflammatory cytokines, supporting the concept of using such systems for the treatment for chronic inflammatory diseases like OA.

Interleukins, growth factors, and transcription factors are key targets for gene therapy in osteoarthritis: A scoping review

“…The same effects were observed by Daniels et al when transforming human articular OA chondrocytes in a 3D aggregate culture model after rAAV-mediated SOX9 overexpression (67). The combinatorial overexpression of SOX9 and TGF-β1 after rAAV-mediated gene delivery to human OA chondrocytes or OA cartilage explants as evaluated by Tao et al showed the same effects, along with increased proliferation and cell density and enhanced levels of chondrogenic aggrecan (ACAN) and collagen type II alpha 1 chain (COL2A1) expression (68). The downside of rAAVmediated gene delivery is however the widespread presence of neutralizing antibodies against the viral proteins in the host.…”

Therapeutic potential of nanotechnology-based approaches in osteoarthritis

“…The high efficiency of this targeted and precise therapy has been confirmed by experiments in vitro and in vivo ( Lan et al, 2020 ). In the presence of IL-1β and tumor necrosis factor-α, polymer micelle (Copolymer PF68/T908) based on polyethylene oxide and polypropylene oxide can induce gene overexpression in human chondrocytes, enhance the deposition of extracellular matrix components and cell survival level by counteract the specific contribution of major OA-associated inflammatory cytokines in chondrocyte cultures, and effectively reverse the harmful effects of OA cytokines on these processes ( Urich et al, 2020 ).…”

Potential Methods of Targeting Cellular Aging Hallmarks to Reverse Osteoarthritic Phenotype of Chondrocytes

“…Recent studies showed that hydrogel-guided rAAV-mediated IGF-I overexpression provided long-term cartilage repair and protection against perifocal osteoarthritis in a minipig full-thickness chondral defect model [ 191 ]. The rAAV-mediated overexpression of SOX9 gene enhanced osteochondral repair in sheep [ 192 ] and protected human articular chondrocytes against deleterious effects caused by osteoarthritis-associated inflammatory cytokines [ 193 ]. Polymeric micelles are effective rAAV controlled delivery systems.…”