Expression and Role of IL-1β Signaling in Chondrocytes Associated with Retinoid Signaling during Fracture Healing

Role of AOX1 on RXR signaling regulates osteoblastogenesis in hPDLMSCs

Alveolar bone loss resulting from periodontal disease ultimately leads to tooth loss. Periodontal ligament mesenchymal stem cells (PDLMSCs) are the tissue-specific cells responsible for maintaining and repairing the periodontal ligament, cementum, and alveolar bone. In this study, we explored the role of aldehyde oxidase 1 (AOX1) in regulating the osteoinduction of human periodontal ligament stem cells (hPDLMSCs). hPDLMSCs were isolated from clinically healthy donors, and AOX1 expression was assessed by comparing inducted and non-inducted hPDLMSCs. Remarkably, we observed a significant upregulation of AOX1 expression during osteoinduction, while AOX1 silencing resulted in the enhanced osteogenic potential of hPDLMSCs. Subsequent experiments and analysis unveiled the involvement of retinoid X receptor (RXR) signaling in the inhibition of osteogenesis in hPDLMSCs. Ligands targeting the RXR receptor mirrored the effects of AOX1 on osteogenesis, as evidenced by alterations in alkaline phosphatase (ALP) activity and bone formation levels. Collectively, these findings underscore the potential regulatory role of AOX1 via RXR signaling in the osteogenesis of hPDLMSCs. This elucidation is pivotal for advancing hPDLMSC-based periodontal regeneration strategies and lays the groundwork for the development of targeted therapeutic interventions aimed at enhancing bone formation in the context of periodontal disease.

Potential therapeutic strategies for osteoarthritis via CRISPR/Cas9 mediated gene editing

Osteoarthritis (OA) is an incapacitating and one of the most common physically degenerative conditions with an assorted etiology and a highly complicated molecular mechanism that to date lacks an efficient treatment. The capacity to design biological networks and accurately modify existing genomic sites holds an apt potential for applications across medical and biotechnological sciences. One of these highly specific genomes editing technologies is the CRISPR/Cas9 mechanism, referred to as the clustered regularly interspaced short palindromic repeats, which is a defense mechanism constituted by CRISPR associated protein 9 (Cas9) directed by small non-coding RNAs (sncRNA) that bind to target DNA through Watson-Crick base pairing rules where subsequent repair of the target DNA is initiated. Up-to-date research has established the effectiveness of the CRISPR/Cas9 mechanism in targeting the genetic and epigenetic alterations in OA by suppressing or deleting gene expressions and eventually distributing distinctive anti-arthritic properties in both in vitro and in vivo osteoarthritic models. This review aims to epitomize the role of this high-throughput and multiplexed gene editing method as an analogous therapeutic strategy that could greatly facilitate the clinical development of OA-related treatments since it's reportedly an easy, minimally invasive technique, and a comparatively less painful method for osteoarthritic patients.

Current therapies for osteoarthritis and prospects of CRISPR-based genome, epigenome, and RNA editing in osteoarthritis treatment

Osteoarthritis (OA) is one of the most common degenerative joint diseases worldwide, causing pain, disability, and decreased quality of life. The balance between regeneration and inflammation-induced degradation results in multiple etiologies and complex pathogenesis of OA. Currently, there is a lack of effective therapeutic strategies for OA treatment. With the development of CRISPR-based genome, epigenome, and RNA editing tools, OA treatment has been improved by targeting genetic risk factors, activating chondrogenic elements, and modulating inflammatory regulators. Supported by cell therapy and in vivo delivery vectors, genome, epigenome, and RNA editing tools may provide a promising approach for personalized OA therapy. This review summarizes CRISPR-based genome, epigenome, and RNA editing tools that can be applied to the treatment of OA and provides insights into the development of CRISPR-based therapeutics for OA treatment. Moreover, in-depth evaluations of the efficacy and safety of these tools in human OA treatment are needed.

Cartilage Destruction by Hemophilic Arthropathy Can Be Prevented by Inhibition of the Ferroptosis Pathway in Human Chondrocytes

(1) Background: Around 50% of hemophilia patients develop severe arthropathy, with even subclinical hemorrhage in childhood potentially leading to intra-articular iron deposition, synovia proliferation, neoangiogenesis, and eventual damage to articular cartilage and subchondral bone. Treatments typically include coagulation factor substitution, radiosynoviorthesis, and joint replacement for advanced cases. This study aims to elucidate programmed cell death mechanisms in hemophilic arthropathy (HA) to identify novel treatments. (2) Methods: Human chondrocytes were exposed to lysed/non-lysed erythrocytes, ferroptosis inducer ML-162, cytokines (IL-1ß, TNFα), and ferric citrate, then assessed for metabolic activity, DNA content, and cell death using Alamar Blue, cyQUANT, and Sytox assays. Three-dimensional spheroids served as a cartilage model to study the effects of erythrocytes and ML-162. (3) Results: Erythrocytes caused significant cell death in 2D cultures (p < 0.001) and damaged 3D chondrocyte spheroids. Iron citrate and erythrocytes reduced chondrocyte DNA content (p < 0.001). The ferroptosis pathway was implicated in cell death, with no effects from apoptosis and necroptosis inhibitors. (4) Conclusions: This study offers insights into HA's cell death pathway, suggesting ferroptosis inhibitors as potential therapies. Further studies are needed to evaluate their efficacy against the chronic effects of HA.

Pelargonidin ameliorates inflammatory response and cartilage degeneration in osteoarthritis via suppressing the NF-κB pathway

Pelargonidin (PG), a derivative of anthocyanins, has anti-oxidant and anti-inflammatory properties. Herein, the protective effect and the mechanism of PG in counteract the osteoarthritis (OA) progression were needed to further evaluate. In the current study, C57BL/6 mice was induced by destabilization of medial meniscus (DMM) surgery to establish the OA model. Primary chondrocytes were acquired from the knee cartilage of newborn mice. Then, PG was administrated to OA mice and IL-1β-stimulated chondrocytes to evaluate its protective effects, respectively. Results uncovered that no conspicuous cytotoxic effects were observed when chondrocytes were treated with PG at a concentration lower than 40 μM for 24-72h. Thus, 10 μM, 20 μM, and 40 μM PG were chosen for subsequent experiments in vitro. Then, we observed that 10, 20, and 40 μM PG reduced the levels of IL-6, TNF-α, COX-2 and iNOS in chondrocytes. In line, PG inhibited the IL-1β-induced ECM catabolism in chondrocytes, as evidenced by deepening toluidine blue staining, increased expression of Collagen II, and decreased expressions of ADAMTS5 and MMP13. Moreover, PG also reduced the IL-1β-stimulated p-p65 overexpression and nuclear translocation of p65 in chondrocytes. In vivo, Safranin O/Fast green and HE staining showed that articular cartilage surface morphology was basically smooth and complete after PG treatment for 8 weeks. Similarly, OARSI scores and MMP13 expression were apparently decreased, whereas Aggrecan expression was elevated in PG-treated mice 8 weeks after DMM surgery. In conclusion, PG can effectively ameliorate inflammatory reactions and cartilage degeneration via suppressing the NF-κB pathway, thereby restraining the OA progression.

Immunohistochemical Analysis of CCN2 in Experimental Fracture Healing Models

Skeletal fractures are most common large-organ traumatic injuries that impact the functions and esthetic outcomes and quality of life. Unfortunately, infection during the fracture healing process and inadequate blood supply to the bone impede reduced ability to produce cartilage and effective bone callus formation, leading to nonunion or delayed union fracture. Therefore, studying the mechanism of fracture healing is an important task in solving the problem of fracture healing failure. Animal models of bone fracture healing are important tools to investigate the pathogenesis and develop treatment strategies. This protocol introduces researchers to a bone repair model utilizing the ribs of rats and the immunohistological expression of cellular communication network factor/connective tissue growth factor (CTGF/CCN2) during the fracture healing processes.

Retinol-Loaded Poly(vinyl alcohol)-Based Hydrogels as Suitable Biomaterials with Antimicrobial Properties for the Proliferation of Mesenchymal Stem Cells

Polyvinyl alcohol (PVA) hydrogels are well-known biomimetic 3D systems for mammalian cell cultures to mimic native tissues. Recently, several biomolecules were intended for use in PVA hydrogels to improve their biological properties. However, retinol, an important biomolecule, has not been combined with a PVA hydrogel for culturing bone marrow mesenchymal stem (BMMS) cells. Thus, for the first time, the effect of retinol on the physicochemical, antimicrobial, and cell proliferative properties of a PVA hydrogel was investigated. The ability of protein (3.15 nm) and mineral adsorption (4.8 mg/mL) of a PVA hydrogel was improved by 0.5 wt.% retinol. The antimicrobial effect of hydrogel was more significant in S. aureus (39.3 mm) than in E. coli (14.6 mm), and the effect was improved by increasing the retinol concentration. The BMMS cell proliferation was more upregulated in retinol-loaded PVA hydrogel than in the control at 7 days. We demonstrate that the respective in vitro degradation rate of retinol-loaded PVA hydrogels (RPH) (75-78% degradation) may promote both antibacterial and cellular proliferation. Interestingly, the incorporation of retinol did not affect the cell-loading capacity of PVA hydrogel. Accordingly, the fabricated PVA retinol hydrogel proved its compatibility in a stem cell culture and could be a potential biomaterial for tissue regeneration.

A network pharmacology strategy to investigate the anti-osteoarthritis mechanism of main lignans components of Schisandrae Fructus

Osteoarthritis (OA) is a chronic age-related progressive joint disorder. Degradation of the cartilage extracellular matrix (ECM) is considered a hallmark of OA and may be a target for new therapeutic methods. Schisandrae Fructus (SF) has been shown to be effective in treating OA. The major active components of SF are lignans. However, the targets of SF and the pharmacological mechanisms underlying the effects of SF lignans in the treatment of OA have not been elucidated. Therefore, based on network pharmacology, this research predicted the treatment targets of six lignans in SF, constructed a protein-protein interaction network and identified 15 hub genes in the OA-target protein-protein interaction network. Through Gene Ontology function and pathway analyses, the gene functions of lignans in the treatment of OA were determined. Finally, the anti-OA effects of lignans and underlying mechanisms identified in the network pharmacology analysis were verified by molecular docking, real-time PCR and western blotting in vitro. The biological processes of the genes and proteins targeted by lignans in the treatment of OA included the immune response, inflammatory response, cell signal transduction and phospholipid metabolism. Moreover, 20 metabolic pathways were enriched. Network pharmacology, molecular docking and in vitro and in vivo experimental results revealed that SF, schisanhenol and gamma-schisandrin inhibited EGFR and MAPK14 gene expression by inhibiting SRC gene expression and activity and then decreased MMP 13 and collagen II protein and gene expression. This research provides a basis for further study of the anti-OA effects and mechanisms of SF, schisanhenol and gamma-schisandrin.

Post-traumatic osteoarthritis development is not modified by postnatal chondrocyte deletion of Ccn2

CCN2 is a matricellular protein involved in several crucial biological processes. In particular, CCN2 is involved in cartilage development and in osteoarthritis. Ccn2 null mice exhibit a range of skeletal dysmorphisms, highlighting its importance in regulating matrix formation during development; however, its role in adult cartilage remains unclear. The aim of this study was to determine the role of CCN2 in postnatal chondrocytes in models of post-traumatic osteoarthritis (PTOA). Ccn2 deletion was induced in articular chondrocytes of male transgenic mice at 8 weeks of age. PTOA was induced in knees either surgically or non-invasively by repetitive mechanical loading at 10 weeks of age. Knee joints were harvested, scanned with micro-computed tomography and processed for histology. Sections were stained with Toluidine Blue and scored using the Osteoarthritis Research Society International (OARSI) grading system. In the non-invasive model, cartilage lesions were present in the lateral femur, but no significant differences were observed between wild-type (WT) and Ccn2 knockout (KO) mice 6 weeks post-loading. In the surgical model, severe cartilage degeneration was observed in the medial compartments, but no significant differences were observed between WT and Ccn2 KO mice at 2, 4 and 8 weeks post-surgery. We conclude that Ccn2 deletion in chondrocytes does not modify the development of PTOA in mice, suggesting that chondrocyte expression of CCN2 in adults is not a crucial factor in protecting cartilage from the degeneration associated with PTOA.This article has an associated First Person interview with the first author of the paper.