Correlation Analysis of SOX9, -5, and -6 as well as COL2A1 and Aggrecan Gene Expression of Collagen I Implant-Derived and Osteoarthritic Chondrocytes

Therapeutic potential of SOX family transcription factors in osteoarthritis

BACKGROUND

As the worldwide population ages, osteoarthritis has significantly increased. This musculoskeletal condition has become a pressing global health issue and thus, prevention and treatment of osteoarthritis have become the primary focus of domestic and international research. Scholarly investigations of the molecular mechanisms that are related to the occurrence and development of osteoarthritis have shed light on the pathological causes of this condition to a certain extent, providing a foundation for its prevention and treatment. However, further research is necessary to fully understand the critical role of the transcription factor SOX9 in chondrocyte differentiation and the development of osteoarthritis. As a result, there has been widespread interest in SOX transcription factors. While SOX9 has been utilized as a biomarker to indicate the occurrence and prognosis of osteoarthritis, investigations into other members of the SOX family and the development of targeted treatments around SOX9 are still required.

PURPOSE

This article considers the impact of the SOX protein on the development and inhibition of osteoarthritis and highlights the need for therapeutic approaches targeting SOX9, as supported by existing research.

RESULTS

SOX9 can contribute to the process of osteoarthritis through acetylation and ubiquitination modifications. The regulation of the WNT signalling pathway, Nrf2/ARE signalling pathway, NF-κB signalling pathway and SOX9 is implicated in the emergence of osteoarthritis. Non-coding RNA may play a role in the onset and progression of osteoarthritis by modulating various SOX family members, including SOX2, SOX4, SOX5, SOX6, SOX8, SOX9 and SOX11.

CONCLUSION

SOX9 has the capability of mitigating the onset and progression of osteoarthritis through means such as medication therapy, stem cell therapy, recombinant adeno-associated virus (rAAV) vector therapy, physical therapy and other approaches.

Recent Research on Chondrocyte Dedifferentiation and Insights for Regenerative Medicine

Chondrocytes maintain the balance of the extracellular matrix by synthesizing glycoproteins, collagen, proteoglycans and hyaluronic acid. Chondrocyte dedifferentiation refers to a process in which chondrocytes lose their mature differentiated phenotype and transform into a fibroblast-like morphology with fewer differentiated stages and inferior function under external stimulation. The important mechanism of homeostasis loss in osteoarthritis (OA) is a change in the chondrocyte phenotype. The dedifferentiation markers of chondrocytes are upregulated in OA, and the pathogenic factors related to OA have also been shown to enhance chondrocyte dedifferentiation. In this review, we compile recent studies on chondrocyte dedifferentiation, with an emphasis on potential markers and the underlying mechanisms of dedifferentiation, as well as the current research progress in inhibiting dedifferentiation or achieving redifferentiation. A deep understanding of chondrocyte dedifferentiation would not only support the pathogenesis of OA theoretically but also provide insightful ideas for regenerative medicine to manipulate the functional phenotype of cells.

The Expression Level of SOX Family Transcription Factors' mRNA as a Diagnostic Marker for Osteoarthritis

Background/Objectives:Osteoarthritis (OA) is the most common degenerative and chronic joint disease and is a leading cause of pain and disability in adults worldwide. The SRY-related HMG box (SOX) family transcription factors (TFs) play a crucial role during the pathogenesis of OA; however, their exact mechanisms remain unexplored. The aim of our study was to conduct a bioinformatics analysis of the common interactions of SOX-5, SOX-9, and SOX-11 with other proteins, as well as their role in OA pathogenesis. Methods:SOX5, SOX9, and SOX11 mRNA expression levels in articular cartilage with subchondral bone and synovium from knee OA patients were assessed using the qPCR method. The study group consisted of thirty-one patients (n = 31). Total RNA was isolated from the articular cartilage with subchondral bone and synovium from the affected and unaffected area of the knee joint. Results: Our results revealed a regulatory network between SOX-5, SOX-9, and SOX-11, and various proteins involved in the pathogenesis of knee OA and their collective interactions, which are involved in the regulation of cartilage extracellular matrix (ECM) organization, response to stimulus, regulation of gene expression, inflammatory response, cartilage condensation, and ossification in chondrocytes. Higher expression levels of SOX5, SOX9, and SOX11 mRNA were noted in OA-affected articular cartilage with subchondral bone compared to control tissue (p = 0.00015, p = 0.0024 and p > 0.05, respectively, Mann-Whitney U-test). All studied genes demonstrated elevated mRNA expression levels in the articular cartilage with subchondral bone from stage 4 patients than those with stage 3 (p > 0.05; Mann-Whitney U-test). Lower SOX5, SOX9, and SOX11 mRNA expression levels were found in OA-affected synovium compared to the control tissue (p = 0.0003, p > 0.05 and p = 0.0007, respectively, Mann-Whitney U-test). Decreased SOX9 mRNA expression levels in synovium were noted in patients with stage 4 disease than those with stage 3; however, SOX5 and SOX11 mRNA expression levels were higher in patients with stage 4 (p > 0.05; Mann-Whitney U-test). Conclusions: The results of our research show that the studied SOX TFs play a role in the development of OA, contributing to the formation of pathological changes not only in the articular cartilage, but also in the synovial membrane. The changes in the SOX5, SOX9, and SOX11 mRNA expression levels in the articular cartilage with subchondral bone and synovium may serve as potential molecular diagnostic biomarkers for detecting OA and could indicate the progression of this disease; however, our observations require further investigation.

Cell and transcriptomic diversity of infrapatellar fat pad during knee osteoarthritis

OBJECTIVES

In this study, we employ a multiomic approach to identify major cell types and subsets, and their transcriptomic profiles within the infrapatellar fat pad (IFP), and to determine differences in the IFP based on knee osteoarthritis (KOA), sex and obesity status.

METHODS

Single-nucleus RNA sequencing of 82 924 nuclei from 21 IFPs (n=6 healthy control and n=15 KOA donors), spatial transcriptomics and bioinformatic analyses were used to identify contributions of the IFP to KOA. We mapped cell subclusters from other white adipose tissues using publicly available literature. The diversity of fibroblasts within the IFP was investigated by bioinformatic analyses, comparing by KOA, sex and obesity status. Metabolomics was used to further explore differences in fibroblasts by obesity status.

RESULTS

We identified multiple subclusters of fibroblasts, macrophages, adipocytes and endothelial cells with unique transcriptomic profiles. Using spatial transcriptomics, we resolved distributions of cell types and their transcriptomic profiles and computationally identified putative cell-cell communication networks. Furthermore, we identified transcriptomic differences in fibroblasts from KOA versus healthy control donor IFPs, female versus male KOA-IFPs and obese versus normal body mass index (BMI) KOA-IFPs. Finally, using metabolomics, we defined differences in metabolite levels in supernatants of naïve, profibrotic stimuli-treated and proinflammatory stimuli-treated fibroblasts from obese compared to normal BMI KOA-IFPs.

CONCLUSIONS

Overall, by employing a multiomic approach, this study provides the first comprehensive map of the cellular and transcriptomic diversity of human IFP and identifies IFP fibroblasts as key cells contributing to transcriptomic and metabolic differences related to KOA disease, sex or obesity.

Maternal Hyperthyroidism in Rats Alters the Composition and Gene Expression of the Matrix Produced In Vitro by Chondrocytes from Offspring with Intrauterine Growth Restriction

Herein, we aimed to evaluate cultures of femoral chondrocytes from offspring of rats with intrauterine growth restriction (IUGR) induced by maternal hyperthyroidism. Fourteen adult female Wistar rats were divided into two groups, a control group and a group treated with daily L-thyroxine administration using an orogastric tube (50 µg/animal/day) during pregnancy. Three days after birth, the offspring were euthanized for chondrocyte extraction. At 7, 14, and 21 days, viability and alkaline-phosphatase (ALP) activity were assessed using the MTT assay and BCIP/NBT method, respectively, in a 2D culture. Pellets (3D cultures) were stained with periodic acid Schiff (PAS) to assess the morphology and percentage of PAS+ areas. The gene transcripts for Col2, Col10, Acan, Sox9, and Runx2 were evaluated by qRT-PCR. The MTT and ALP-assay results showed no significant differences between the groups. Maternal hyperthyroidism did not alter the chondrocyte morphology, but significantly reduced the percentage of PAS+ areas, decreased the expression of the gene transcripts of Col2 and Acan, and increased Sox9 expression. Maternal hyperthyroidism in rats alters the composition and gene expression of the matrix produced by chondrocytes from offspring with IUGR. This may be one of the mechanisms through which excess maternal thyroid hormones reduce offspring bone growth.

Human adipose and synovial mesenchymal stem cells improve osteoarthritis in rats by reducing chondrocyte reactive oxygen species and inhibiting inflammatory response

Background

We explored the therapeutic effects of Adipose‐derived mesenchymal stem cells (ADMSCs) and Synovial‐derived mesenchymal stem cells (SDMSCs) on osteoarthritis (OA).

Methods

SDMSCs and ADMSCs were co‐cultured with chondrocytes and stimulated with interleukin (IL)‐1β. An OA model was established on rats by intra‐articular injection with ADMSCs and SDMSCs. After 8 weeks, the joint diameter difference was detected, and histological staining was used to observe the pathological changes in cartilage tissue. Enzyme‐linked immunosorbent assay (ELISA) was used to detect the expressions of IL‐6, tumor necrosis factor (TNF)‐α and IL‐1β in joint fluid. The expressions of COL2A1, Aggrecan, Matrix metalloproteinase (MMP)‐13, SOX9, IL‐6, TNF‐α and IL‐1β were detected by qRT‐PCR and Western blotting in cartilage tissue. Reactive oxygen species (ROS) content in cells and cartilage tissues was detected by ROS kit.

Results

SDMSCs and ADMSCs co‐cultured with chondrocytes could reduce MMP‐13 expression, increase the expressions of COL2A1, Aggrecan and SOX9, as well as reverse the effects of IL‐1β on promoting ROS content and inflammatory factors levels. After the OA model was established, the injection of ADMSCs and SDMSCs reduced the differences in joint diameter and tissue lesions in OA rats. The OA model led to increased levels of IL‐6, TNF‐α and IL‐1β in joint fluid and cartilage tissue, while the injection of ADMSCs and SDMSCs inhibited the inflammatory factor levels in OA rats, and increased the expressions of COL2A1, Aggrecan and SOX9 in OA rats.

Conclusion

ADMSCs and SDMSCs improve osteoarthritis in rats by reducing chondrocyte ROS and inhibiting inflammatory response.

Sequential Enzymatic Digestion of Different Cartilage Tissues: A Rapid and High-Efficiency Protocol for Chondrocyte Isolation, and Its Application in Cartilage Tissue Engineering

OBJECTIVE

The classic chondrocyte isolation protocol is a 1-step enzymatic digestion protocol in which cartilage samples are digested in collagenase solution for a single, long period. However, this method usually results in incomplete cartilage dissociation and low chondrocyte quality. In this study, we aimed to develop a rapid, high-efficiency, and flexible chondrocyte isolation protocol for cartilage tissue engineering.

DESIGN

Cartilage tissues harvested from rabbit ear, rib, septum, and articulation were minced and subjected to enzymatic digestion using the classic protocol or the newly developed sequential protocol. In the classic protocol, cartilage fragments were subjected to one 12-hour digestion. In the sequential protocol, cartilage fragments were sequentially subjected to 2-hour first digestion, followed by two 3-hour digestions. The collected cells were then subjected to analyses of cell-yield efficiency, viability, proliferation, phenotype, and cartilage matrix synthesis capacity.

RESULTS

Overall, the sequential protocol exhibited higher cell-yield efficiency than the classic protocol for the 4 cartilage types. The cells harvested from the second and third digestions demonstrated higher cell viability, more proliferative activity, a better chondrocyte phenotype, and a higher cartilage-specific matrix synthesis ability than those harvested from the first digestion and after the classic 1-step protocol.

CONCLUSIONS

The sequential protocol is a rapid, flexible, high-efficiency chondrocyte isolation protocol for different cartilage tissues. We recommend using this protocol for chondrocyte isolation, and in particular, the cells obtained after the subsequent 3-hour sequential digestions should be used for chondrocyte-based therapy.

Optimization of Protocol for Isolation of Chondrocytes from Human Articular Cartilage

OBJECTIVE

Cartilage tissue engineering has evolved as one of the therapeutic strategies for cartilage defect, which relies on a large number of viable chondrocytes. Because of limited availability of cartilage and low chondrocytes yield from cartilage, the need for an improve isolation protocol for maximum yield of viable cells is a key to achieving successful clinical constructs. This study optimizes and compares different protocols for isolation of chondrocytes from cartilage.

DESIGN

We employed enzymatic digestion of cartilage using collagenase II and trypsin. The chondrocytes yield, growth kinetics, aggrecan, and collagen type 2 (COL2) expression were evaluated. Collagen type 1 (COL1) mRNA expression was assessed to monitor the possibility of chondrocytes dedifferentiation.

RESULTS

Chondrocyte yield per gram of cartilage was significantly higher (P < 0.05) using collagenase II in Hank's balanced salt solution (HBSS) compared with 0.25% trypsin. The number of chondrocyte yield per gram was higher in cartilage digested with collagenase in HBSS compared with Dulbecco's modified Eagle medium/F12; however, the difference was not statistically significant. Chondrocytes seeded at lower densities had shorter population doubling time compared to those seeded at higher density. Protein and gene expression of chondrocyte phenotype indicates the expression of aggrecan and COL2. The expression of COL1 was significantly increased (P < 0.05) in passage 3 compared with primary chondrocytes. The mRNA expression of chondrocyte phenotype was similar in primary and passaged one cells.

CONCLUSIONS

Collagenase in HBSS yield the highest number of viable chondrocytes and the isolated cells expressed chondrocyte phenotype. This protocol can be employed to generate large number of viable chondrocytes, particularly with limited cartilage biopsies.

BMSC-Derived Exosomes Ameliorate Osteoarthritis by Inhibiting Pyroptosis of Cartilage via Delivering miR-326 Targeting HDAC3 and STAT1//NF-κB p65 to Chondrocytes

Background

In the past decade, mesenchymal stem cells (MSCs) have been widely used for the treatment of osteoarthritis (OA), and noncoding RNAs in exosomes may play a major role.

Aim

The present study is aimed at exploring the effect and mechanism of miR-326 in exosomes secreted by bone marrow mesenchymal stem cells (BMSCs) on pyroptosis of cartilage and OA improvement.

Methods

Exosomes from BMSCs (BMSC-Exos) were isolated and identified to incubate with OA chondrocytes. Proliferation, migration, specific gene and miR-326 expression, and pyroptosis of chondrocytes were detected. BMSCs or chondrocytes were transfected with miR-326 mimics or inhibitors to investigate the effect of miR-326 in BMSC-Exos on pyroptosis of chondrocytes and the potential mechanism. Finally, a rat OA model was established to verify the effect and mechanism of miR-326 in BMSC-Exos on cartilage of pyroptosis.

Results

Incubation with BMSC-Exos could significantly improve the survival rate, migration ability, and chondrocyte-specific genes (COL2A1, SOX9, Agg, and Prg4) and miR-326 expression of OA chondrocytes and significantly inhibit pyroptosis of chondrocytes by downregulation of the levels of inflammatory cytokines, Caspase-1 activity, and pyroptosis-related proteins such as GSDMD, NLRP3, ASC, IL-1β, and IL-18 (P < 0.01). PKH26 labeling confirmed the uptake of BMSC-Exos by chondrocytes. Incubation with exosomes extracted from BMSCs overexpressing miR-326 can significantly repress the pyroptosis of chondrocytes, while knockdown of miR-326 had the opposite effect (P < 0.01). The same result was also demonstrated by direct interference with the expression level of miR-326 in chondrocytes (P < 0.01). In addition, we found that the overexpression of miR-326 significantly inhibited the expression of HDAC3 and NF-κB p65 and significantly promoted the expression of STAT1, acetylated STAT1, and acetylated NF-κB p65 in chondrocytes (P < 0.01). The targeted relationship between miR-326 and HDAC3 was verified by dual-luciferase reporter assay. Animal experiments confirmed the mechanism by which miR-326 delivered by BMSC-Exos inhibits pyroptosis of cartilage by targeting HDAC3 and STAT1/NF-κB p65 signaling pathway.

Conclusion

BMSC-Exos can deliver miR-326 to chondrocytes and cartilage and improve OA by targeting HDAC3 and STAT1//NF-κB p65 to inhibit pyroptosis of chondrocytes and cartilage. Our findings provide a new mechanism for BMSC-Exos to treat OA.

BMSC-derived exosomes from congenital polydactyly tissue alleviate osteoarthritis by promoting chondrocyte proliferation

In the past decade, mesenchymal stem cells (MSCs) have been widely used for the treatment of osteoarthritis (OA), and exosomes may play a major role. Here, we acquired a special kind of MSCs from the bone marrow of surgically resected tissue from the hand of a patient with polydactyly. Experiments were focused on the role of polydactyly bone marrow-derived MSCs (pBMSCs) in osteoarthritis. The results showed that the pBMSCs had a greater ability than the BMSCs to differentiate into chondrocytes. Mechanistically, the expression of BMP4 was significantly higher in the pBMSCs than it was in the BMSCs. Furthermore, we showed that the migration and proliferation of chondrocytes were stimulated by exosomes secreted by pBMSC (pBMSC-EXOs). Notably, the downregulation of BMP4 in pBMSCs by siRNA inhibited both the chondrogenic differentiation potential of the MSCs and the function of the chondrocytes. In addition, the injection of pBMSC-EXOs and BMSC-EXOs attenuated OA in an OA mouse model, but the pBMSC-EXOs had a superior therapeutic effect compared with that of the BMSC-EXOs. Taken together, the data indicate that pBMSCs have greater ability to differentiate into chondrocytes and regulate chondrocyte formation through BMP4 signaling. Therefore, pBMSC-EXOs may represent a novel treatment for OA.

Transcription Factors in Cartilage Homeostasis and Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease, and it is characterized by articular cartilage loss. In part, OA is caused by aberrant anabolic and catabolic activities of the chondrocyte, the only cell type present in cartilage. These chondrocyte activities depend on the intra- and extracellular signals that the cell receives and integrates into gene expression. The key proteins for this integration are transcription factors. A large number of transcription factors exist, and a better understanding of the transcription factors activated by the various signaling pathways active during OA can help us to better understand the complex etiology of OA. In addition, establishing such a profile can help to stratify patients in different subtypes, which can be a very useful approach towards personalized therapy. In this review, we discuss crucial transcription factors for extracellular matrix metabolism, chondrocyte hypertrophy, chondrocyte senescence, and autophagy in chondrocytes. In addition, we discuss how insight into these factors can be used for treatment purposes.

Maturity-dependent cartilage cell plasticity and sensitivity to external perturbation

OBJECTIVE

Articular cartilage undergoes biological and morphological changes throughout maturation. The prevalence of osteoarthritis in the aged population suggests that maturation predisposes cartilage to degradation and/or impaired regeneration, but this process is not fully understood. Therefore, the objective of this study was to characterize the cellular and genetic profile of cartilage, as well as biological plasticity in response to mechanical and culture time stimuli, as a function of animal maturity.

METHODS/DESIGN

Porcine articular cartilage explants were harvested from stifle joints of immature (2-4 weeks), adolescent (5-6 months), and mature (1-5 years) animals. Half of all samples were subjected to a single compressive mechanical load. Loaded samples were paired with unloaded controls for downstream analyses. Expression of cartilage progenitor cell markers CD105, CD44, and CD29 were determined via flow cytometry. Expression of matrix synthesis genes Col1, Col2, Col10, ACAN, and SOX9 were determined via qPCR. Tissue morphology and matrix content were examined histologically. Post-loading assays were performed immediately and following 7 days in culture.

RESULTS

CD105 and CD29 expression decreased with maturity, while CD44 expression was upregulated in cartilage from mature animals. Expression of matrix synthesis genes were generally upregulated in cartilage from mature animals, and adolescent animals showed the lowest expression of several matrix synthesizing genes. Culture time and mechanical loading analyses revealed greater plasticity to mechanical loading and culture time in cartilage from younger animals. Histology confirmed distinct structural and biochemical profiles across maturity.

CONCLUSION

This study demonstrates differential, nonlinear expression of chondroprogenitor markers and matrix synthesis genes as a function of cartilage maturity, as well as loss of biological plasticity in aged tissue. These findings have likely implications for age-related loss of regeneration and osteoarthritis progression.

Cladophora glomerata methanolic extract promotes chondrogenic gene expression and cartilage phenotype differentiation in equine adipose-derived mesenchymal stromal stem cells affected by metabolic syndrome

BACKGROUND

Chondrogenesis represents a highly dynamic cellular process that leads to the establishment of various types of cartilage. However, when stress-related injuries occur, a rapid and efficient regeneration of the tissues is necessary to maintain cartilage integrity. Mesenchymal stem cells (MSCs) are known to exhibit high capacity for self-renewal and pluripotency effects, and thus play a pivotal role in the repair and regeneration of damaged cartilage. On the other hand, the influence of certain pathological conditions such as metabolic disorders on MSCs can seriously impair their regenerative properties and thus reduce their therapeutic potential.

OBJECTIVES

In this investigation, we attempted to improve and potentiate the in vitro chondrogenic ability of adipose-derived mesenchymal stromal stem cells (ASCs) isolated from horses suffering from metabolic syndrome.

METHODS

Cultured cells in chondrogenic-inductive medium supplemented with Cladophora glomerata methanolic extract were experimented for expression of the main genes and microRNAs involved in the differentiation process using RT-PCR, for their morphological changes through confocal and scanning electron microscopy and for their physiological homeostasis.

RESULTS

The different added concentrations of C. glomerata extract to the basic chondrogenic inductive culture medium promoted the proliferation of equine metabolic syndrome ASCs (ASCsEMS) and resulted in chondrogenic phenotype differentiation and higher mRNA expression of collagen type II, aggrecan, cartilage oligomeric matrix protein, and Sox9 among others. The results reveal an obvious inhibitory effect of hypertrophy and a strong repression of miR-145-5p, miR-146-3p, and miR-34a and miR-449a largely involved in cartilage degradation. Treated cells additionally exhibited significant reduced apoptosis and oxidative stress, as well as promoted viability and mitochondrial potentiation.

CONCLUSION

Chondrogenesis in EqASCsEMS was found to be prominent after chondrogenic induction in conditions containing C. glomerata extract, suggesting that the macroalgae could be considered for the enhancement of ASC cultures and their reparative properties.

Circular RNAs in nucleus pulposus cell function and intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common cause of low back pain, which inflicts more global disability than any other condition. Although IDD was deemed to be a natural process that comes with ageing, a growing body of evidence suggested that both genetic and environmental factors could modify the development of IDD. In this connection, aberrant function of nucleus pulposus cells has been implicated in IDD pathogenesis. Circular RNAs are a novel class of endogenous non-coding RNAs that play crucial regulatory roles in diverse cellular processes. Recently, deregulation of circRNAs in nucleus pulposus cells was found to functionally participate in IDD development. In this review, we summarize the current knowledge regarding the deregulation of circRNAs in IDD in relation to their actions on nucleus pulposus cell functions, including cell proliferation, apoptosis and extracellular matrix synthesis/degradation. The potential clinical utilities of circRNAs as therapeutic targets for the management of IDD are also discussed.

Proinflammatory Effects of IL-1β Combined with IL-17A Promoted Cartilage Degradation and Suppressed Genes Associated with Cartilage Matrix Synthesis In Vitro

Combinations of IL-1β and other proinflammatory cytokines reportedly promote the severity of arthritis. We aimed to investigate the effects of IL-1β combined with IL-17A on cartilage degradation and synthesis in in vitro models. Cartilage explant degradation was determined using sulfated glycosaminoglycans (S-GAGs) levels, matrix metalloproteinase (MMP13) gene expression, uronic acid, and collagen contents. Cell morphology and accumulation of proteoglycans were evaluated using hematoxylin-eosin and safranin O staining, respectively. In the pellet culture model, expressions of cartilage-specific anabolic and catabolic genes were evaluated using real-time qRT-PCR. Early induction of MMP13 gene expression was found concomitantly with significant S-GAGs release. During the prolonged period, S-GAGs release was significantly elevated, while MMP-13 enzyme levels were persistently increased together with the reduction of the cartilaginous matrix molecules. The pellet culture showed anabolic gene downregulation, while expression of the proinflammatory cytokines, mediators, and MMP13 genes were elevated. After cytokine removal, these effects were restored to nearly basal levels. This study provides evidence that IL-1β combined with IL-17A promoted chronic inflammatory arthritis by activating the catabolic processes accompanied with the suppression of cartilage anabolism. These suggest that further applications, which suppress inflammatory enhancers, especially IL-17A, should be considered as a target for arthritis research and therapy.

In Vitro Analysis of Cartilage Regeneration Using a Collagen Type I Hydrogel (CaReS) in the Bovine Cartilage Punch Model

OBJECTIVE

Limitations of matrix-assisted autologous chondrocyte implantation to regenerate functional hyaline cartilage demand a better understanding of the underlying cellular/molecular processes. Thus, the regenerative capacity of a clinically approved hydrogel collagen type I implant was tested in a standardized bovine cartilage punch model.

METHODS

Cartilage rings (outer diameter 6 mm; inner defect diameter 2 mm) were prepared from the bovine trochlear groove. Collagen implants (± bovine chondrocytes) were placed inside the cartilage rings and cultured up to 12 weeks. Cartilage-implant constructs were analyzed by histology (hematoxylin/eosin; safranin O), immunohistology (aggrecan, collagens 1 and 2), and for protein content, RNA expression, and implant push-out force.

RESULTS

Cartilage-implant constructs revealed vital morphology, preserved matrix integrity throughout culture, progressive, but slight proteoglycan loss from the "host" cartilage or its surface and decreasing proteoglycan release into the culture supernatant. In contrast, collagen 2 and 1 content of cartilage and cartilage-implant interface was approximately constant over time. Cell-free and cell-loaded implants showed (1) cell migration onto/into the implant, (2) progressive deposition of aggrecan and constant levels of collagens 1 and 2, (3) progressively increased mRNA levels for aggrecan and collagen 2, and (4) significantly augmented push-out forces over time. Cell-loaded implants displayed a significantly earlier and more long-lasting deposition of aggrecan, as well as tendentially higher push-out forces.

CONCLUSION

Preserved tissue integrity and progressively increasing cartilage differentiation and push-out forces for up to 12 weeks of cultivation suggest initial cartilage regeneration and lateral bonding of the implant in this in vitro model for cartilage replacement materials.

Expression of miR-206 in Human Knee Articular Chondrocytes and Effects of miR-206 on Proliferation and Apoptosis of Articular Chondrocytes

BACKGROUND

Increasing evidence has demonstrated that microRNAs regulate the development of cartilage and osteogenesis. Whether miR-206 participates in the development of human articular cartilage remains largely unknown. This study aimed to investigate the role of miR-206 in human chondrocytes.

METHODS

Expression of miR-206 was initially assessed in human osteoarthritis (OA) tissues and articular chondrocytes through quantitative real-time polymerase chain reaction. The effects of miR-206 on proliferation and apoptosis of human chondrocytes were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining assay. Then, the effects of miR-206 on type II collagen alpha 1 (Col2a1), aggrecan, runt-related transcription factor 2 (RUNX2) and matrix metalloproteinase13 (MMP13) were examined with quantitative real-time polymerase chain reaction and Western blot analysis.

RESULTS

MiR-206 was significantly increased in human OA tissues and chondrocytes. MiR-206 significantly inhibited the proliferation of chondrocytes, but promoted apoptosis. Expression of Col2a1 and aggrecan were dramatically decreased, and the expression of RUNX2 and MMP13 were significantly increased when miR-206 was overexpressed.

CONCLUSIONS

MiR-206 may participate in cartilage degradation in OA. Manipulation of the expression of miR-206 in human chondrocytes may be a novel therapeutic strategy for the treatment of OA.

T140 blocks the SDF-1/CXCR4 signaling pathway and prevents cartilage degeneration in an osteoarthritis disease model

Osteoarthritis (OA) is one of the most common diseases affecting older people; however, there remains no effective targeted drug to combat OA. The aims of this study were (1) to explore the effect of T140 in regulating degeneration of articular cartilage in vivo by targeted blocking of the SDF-1/CXCR4 signaling pathway, and (2) to provide experimental evidence for the development of a novel OA-targeted pharmacotherapy. Thirty-six healthy Hartley guinea pigs were randomly divided into three groups: a T140-treated group (n = 12), a phosphate buffer saline control group (n = 12) and an untreated control group (n = 12). At 2, 4, 6, 8, 10 and 12 weeks of treatment, SDF-1 in serum was quantified by enzyme-linked immunosorbent assay. At 12 weeks of treatment, the cartilage from knee tibial plateau in the knee joint was collected for H&E, Safranin-O staining and Mankin grading; measurement for mRNA levels of matrix metalloproteinases (MMP-3, MMP-9 and MMP-13), aggrecan (ACAN) and collagen II (Col II) using RT-PCR; and measurement for Col II protein levels by western blot. Results showed that SDF-1 in serum increased in the T140 group and increased in the control groups. H&E and Safranin-O staining revealed less cartilage loss in T140-treated animals compared to controls. The mRNA levels of MMP-3, MMP-9 and MMP-13 in cartilage were much lower in the T140 group than other groups, but mRNA levels of ACAN and Col II in cartilage were higher in the T140-treated group. Col II protein levels in the T140 group and control groups were different. T140 can downregulate the expression of matrix-degrading enzyme and lessen the degeneration of cartilage by blocking the SDF-1/CRCR4 signaling pathway in vivo. This mechanism may present a pharmacological target for the treatment of OA.