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.
Highlights
Osteoarthritis (OA) represents a prevalent, chronic, and deteriorating joint affliction that is the leading cause of impaired function and disability [1]
Treatment with IL-1β did not alter the levels of sex-determining region Y-type high mobility box 9 (SOX9) expression early on (p = 0.450 compared with the negative control in the absence of cytokines on day 1) (Figure 1A,B versus Figure 1C,D) while a reduction was noted after 10 days (Figure 1A,B versus Figure 1C,D)
The treatment with recombinant adeno-associated viral (rAAV)-FLAG-hsox9 promoted a significant enhancement in SOX9 expression levels following IL-1β treatment, especially upon vector delivery via micellar systems (Figure 1C,D)
Summary
Osteoarthritis (OA) represents a prevalent, chronic, and deteriorating joint affliction that is the leading cause of impaired function and disability [1]. Pro-inflammatory cytokines such as interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α), produced by mononuclear cells, activated synoviocytes or by the cartilage itself, upregulate metalloproteinases gene expression, impairing chondrocyte counteracting synthetic pathways necessary to reinstate the integrity of the degenerated extracellular matrix (ECM) [6]. In this context, previous studies have shown an abolishment of type-II collagen expression from primary human articular chondrocytes via suppression of the expression of the cartilage-associated sex-determining region Y-type high mobility box 9 (SOX9) transcription factor upon treatment with IL-1β [7]. Recombinant adeno-associated viral (rAAV) vectors mainly remain episomal in the nucleus of their targets, showing potential integration events at very low frequency (0.1–1% vide infra) [10], while allowing for highly effective gene transfer efficiencies even in nondividing cells like articular chondrocytes (more than 70%) [11]. rAAV vectors have emerged as the preferred gene carriers in several regenerative medicine applications including for cartilage repair [12,13,14,15,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
