Human Chondrocyte Cell Research Articles

The diagnostic value and pathogenetic role of lncRNA-ATB in patients with osteoarthritis

BackgroundIn view of the roles of long non-coding RNAs (lncRNAs) in human diseases and the high incidence of osteoarthritis, we investigated the role of long non-coding RNA activated by transforming growth factor-β (lncRNA-ATB) in osteoarthritis and explored its diagnostic value for this disease.MethodsThe study involved 98 patients with osteoarthritis and 76 healthy subjects. Blood was extracted from each participant and the expression of lncRNA-ATB in the serum was detected using quantitative Real Time -PCR. ROC curve analysis was performed to evaluate the diagnostic value of lncRNA-ATB for osteoarthritis. Based on the median serum level of lncRNA-ATB, patients were divided into a high-level group and a low-level group. Correlations between the serum levels of lncRNA-ATB and basic information about the patients were analyzed using the chi-square test. LncRNA-ATB overexpression in human chondrocyte cell line CHON-001 (ATCC CRL-2846) was established to study the effects on chondrocyte proliferation (using the CCK-8 assay) and viability.ResultsLncRNA-ATB expression was significantly downregulated in the serum of osteoarthritis patients compared with the healthy controls, meaning this downregulation effectively distinguished osteoarthritis patients from healthy subjects. LncRNA-ATB expression in the serum was not significantly affected by the patients’ gender, age or habits, including smoking and alcohol consumption. LncRNA-ATB overexpression activated Akt signaling, promoted proliferation and increased the viability of the chondrocytes.ConclusionWe conclude that downregulation of lncRNA-ATB in serum is a reliable diagnostic marker for osteoarthritis and that this lncRNA participates in the pathogenesis of osteoarthritis by regulating the proliferation and viability of chondrocytes through the activation of Akt signaling.

The chondrocyte cell proliferation of a chitosan/silk fibroin/egg shell membrane hydrogels

Articular cartilage is a poorly cellularized, non-vascularized connective tissue that undergoes alterations due to trauma and osteoarthritis. Tissue engineering strategies involving the combination of cells, biomaterials and bioactive agents have been of interest notably for the repair of damaged articular cartilage. The aim of this study was to design Chitosan/Silk Fibroin/Egg Shell Membrane (CHI/SF/ESM) hydrogels and analyse the cell proliferation activity of human chondrocyte cells. The FTIR spectrophotometer, XRD analysis, ICP-MS, SEM analysis, swelling kinetics and biodegradation tests with protease enzyme, and antibacterial activity test with Escherichia coli, Candida albicans have been used for characterization of hydrogels. CHI/SF/ESM hydrogel structures, and chemical homogeneity of the ECM was well-reproduced. Human articular chondrocytes were seeded on hydrogels and cultured up to 2 weeks under the standard culture conditions. The attachment and cell growth of chondrocytes were examined by phase contrast microscopy and by MTT assay at 24 h, 72 h and 7 days. The hydrogel supported better adhesion, growth and differentiation of chondrocyte cells under standard culture conditions. The results obtained have suggested that, CHI/SF/ESM hydrogels can potentially function as a promising cartilage substitute for tissue engineering application.

Effect of Polydeoxyribonucleotide on Angiogenesis and Wound Healing in an In Vitro Model of Osteoarthritis

Osteoarthritis (OA) is degenerative disease, leading to pain and functional disability. It is reported that polydeoxyribonucleotide (PDRN) is a suitable therapy for OA. However, the therapeutic mechanisms of PDRN in OA are not fully understood. To investigate the effect of PDRN in an in vitro model of OA, interleukin (IL)-1β or phosphate-buffered saline (PBS) was used to treat a human chondrocytic cell line in hypoxic conditions for 24 h (IL-1β group or control group). PDRN was then used to treat IL-1β group cells for 24 h (PDRN group). By Label-Based Human Antibody Array 1000, angiopoietin-2 (ANG-2), platelet-derived growth factor (PDGF), angiostatin, and endostatin, which were related to angiogenesis, were chosen for further validation studies. Quantitative real-time reverse transcription polymerase chain reaction and western blot analysis validated that the levels of PDGF and ANG-2, which were related to pro-angiogenesis, were significantly increased in the PDRN group compared with those in the control group or the IL-1β group. However, the levels of endostatin and angiostatin, which were related in anti-angiogenesis, were significantly decreased in the PDRN group compared with those in the control group or the IL-1β group. In the same manner, vascular endothelial growth factor, which was a mediator of angiogenesis, was significantly increased in the PDRN group compared with those in the control group or the IL-1β group. Furthermore, wound closure was significantly increased in the PDRN group compared with the control group or the IL-1β group by in vitro scratch assay. Moreover, PDRN decreased expression of metalloproteinase 13, as a catabolic factor for OA, but increased expression of aggrecan, which was an anabolic factor for OA. These data suggest that PDRN may promote angiogenesis and wound healing via down-regulation of catabolism and up-regulation of anabolism in an in vitro model of OA.

High molecular weight hyaluronan protects cartilage from degradation by inhibiting aggrecanase expression.

ABSTRACTHyaluronan (HA) is an extracellular matrix (ECM) component of articular cartilage and has been used to treat patients with osteoarthritis (OA). A disintegrin and metalloproteinases with thrombospondin motifs (ADAMTSs) play an important role in cartilage degradation in OA. We have previously reported that ADAMTS4 and ADAMTS9 were induced by cytokine stimulation. However, the effect of HA on the cytokine‐inducible ADAMTS9 has never been investigated. Moreover, it is unclear whether HA protects cartilage by suppressing aggrecan degradation. Here, we examined the effects of HA on ADAMTS expression in vitro and on cartilage degradation in vivo. ADAMTS9 expression was higher than that of the other aggrecanases (ADAMTS4 and 5) in human chondrocytes, chondrocytic cells, and rat cartilage. ADAMTS4 and 9 mRNA levels were upregulated in cytokine‐stimulated chondrocytes and chondrocytic cells. Pre‐incubation with HA significantly inhibited ADAMTS9 mRNA expression in cytokine‐stimulated cells. In a rat OA model, Adamts5 and 9 mRNA levels were transiently increased after surgery; intra‐articular HA injections attenuated the induction of Adamts5 and 9 mRNA. HA also blocked aggrecan cleavage by aggrecanase in OA rats in a molecular size‐dependent manner. These results demonstrate that HA attenuates induced aggrecanases expression in OA and thereby protects articular cartilage degradation by this enzyme. Our findings provide insight into the molecular basis for the beneficial effects of HA in OA. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 36:3247–3255, 2018.

Membrane-lytic actions of sulphonated methyl ester surfactants and implications to bactericidal effect and cytotoxicity

Surfactants are multifunctional molecules widely used in personal care and healthcare formulations to cleanse, help disperse active ingredients (e.g., forming emulsions) and stabilise products. With increasing demands on improving biosafety, there is now mounting pressure to understand how different surfactants elicit toxicities at molecular and cellular levels. This work reports the membrane-lytic behaviour of a group of sulphonated methyl ester (SME) surfactants together with representative conventional surfactants. All surfactants displayed the clear rise of lysis of the model lipid bilayer membranes around their CMCs, but the two ionic surfactants SDS and C12TAB even caused measurable lysis below their CMCs, with membrane-lytic actions increasing with monomer concentration. Furthermore, whilst ionic and nonionic surfactants could achieve full membrane lysis once above their CMCs, this ability was weak from the SME surfactants and decreased with increasing the acyl chain length. In contrast to the conventional anionic surfactants such as SDS and SLES, the protein solubilizing capability of the SME surfactants was also low. On the other hand, MTT assays against 3T3 fibroblast cells and human chondrocyte cells revealed high toxicity from SDS and C12TAB against the other surfactants studied, but the difference between SME and the rest of conventional surfactants was small. Similar behaviour was also observed in their bactericidal effect against E. coli and S. aureus. The trend is broadly consistent with their membrane-lytic behaviour, indicating little selectivity in their cytotoxicity and bactericidal action. These results thus reveal different toxicities implicated from different surfactant head groups. Increase in acyl chain length as observed from SME surfactants could help improve surfactant biocompatibility.

Suppressor of cytokine signaling 3 modulates transforming growth factor-β signaling in human chondrocytes through the inhibition of the JAK/STAT3 pathway

Purpose: Osteoarthritis (OA) is a progressive joint disease which is characterized by destruction of articular cartilage. Transforming growth factor-β (TGF-β) is an important cartilage protective factor and helps maintain cartilage homeostasis. In osteoarthritis, inflammatory mediators can enhance levels of suppressor of cytokine signaling (SOCS) 3. SOCS proteins are negative regulators of cytokine and growth factor signaling via the JAK/STAT pathway. However, the exact role of SOCS3 in cartilage is unclear. We investigated if SOCS3 can inhibit TGF-β signaling in chondrocytes, which ultimately can contribute to disrupted cartilage homeostasis in OA. Methods: The effect of SOCS3 on TGF-β signaling was investigated in the G6 human chondrocyte cell line using a SOCS3 encoding adenovirus and a luciferase control virus. After SOCS3 overexpression and stimulation with rhTGF-β1 (1.0 ng/ml), pSmad3 levels were determined using western blot and gene expression of Smad3 target genes was analyzed with qPCR. To study effects of SOCS3 on TGF-β- induced JAK/STAT signaling, pSTAT3 levels were investigated after TGF-β stimulation in both G6 and primary chondrocytes using western blot. Primary chondrocytes were obtained from OA patients undergoing total knee or hip arthroplasty. Results: Overexpression of SOCS3 in the G6 chondrocyte cell line did not affect the TGF-β-induced gene expression of the TGF-β/Smad3 target genes jun-B, PAI-1, ID-1 and Smad7, although the baseline expression of jun-B was decreased by SOCS3. In addition, we did not observe an effect of SOCS3 overexpression on levels of Smad3 phosphorylation after stimulation with TGF-β for several timepoints (5, 15, and 30min, 1, 2, and 4h). Surprisingly, we found that STAT3 was phosphorylated upon TGF-β stimulation, which was completely inhibited by SOCS3 overexpression. To confirm that TGF-β indeed resulted in STAT3 activation, we repeated the stimulation with TGF-β in both G6- and human primary chondrocytes and observed an early peak (5-15 min) and a robust late peak (4h) of pSTAT3. By using small molecule inhibitors (SB-505124 and tofacitinib), we discovered that TGF-β-induced STAT3 phosphorylation was dependent on activity of the TGF-β type I receptor (ALK5) kinase and JAK kinase respectively in both G6- and primary chondrocytes. Conclusions: These results show that TGF-β can induce STAT3 phosphorylation, and that SOCS3 modulates TGF-β signaling in chondrocytes via the inhibition of TGF-β-induced STAT3 activation. STAT3 is a potent transcription factor known to regulate gene expression of multiple target genes that are involved in OA pathogenesis, such as proteases (e.g., MMP3, MMP13), cytokines and chemokines (e.g., IL-6, MCP-1), and important regulators of chondrocyte proliferation, differentiation and apoptosis (e.g., Sox9, cyclin D1, Bcl3). By blocking TGF-β-induced STAT3 activation, SOCS3 might be an important regulator of chondrocyte function and this may have major implications for OA-related cartilage damage.

Chondrocytes Contribute to Alphaviral Disease Pathogenesis as a Source of Virus Replication and Soluble Factor Production.

Arthritogenic alphavirus infections often result in debilitating musculoskeletal disorders that affect the joints, muscle, and bone. In order to evaluate the infection profile of primary human skeletal muscle and chondrocyte cells to Ross River virus (RRV) in vitro, cells were infected at a multiplicity of infection (MOI) of 1 over a period of two days. Viral titers were determined by plaque assay and cytokine expression by Bio-Plex® assays using the supernatants harvested. Gene expression studies were conducted using total RNA isolated from cells. Firstly, we show that RRV RNA is detected in chondrocytes from infected mice in vivo. Both human primary skeletal muscle and chondrocyte cells are able to support productive RRV infection in vitro. We also report the production of soluble host factors including the upregulation of heparanase (HPSE) and inflammatory host factors such as interleukin-6 (IL-6), monocyte chemoattractant protein 1 (MCP-1), RANTES (regulated on activation, normal T cell expressed and secreted), interferon gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α), which are also present during clinical disease in humans. Our study is the first to demonstrate that human chondrocyte cells are permissive to RRV infection, support the production of infectious virus, and produce soluble factors including HPSE, which may contribute to joint degradation and the pathogenesis of disease.

Physiological role of urothelial cancer-associated one long noncoding RNA in human skeletogenic cell differentiation.

A vast number of long-noncoding RNAs (lncRNA) are found expressed in human cells, which RNAs have been developed along with human evolution. However, the physiological functions of these lncRNAs remain mostly unknown. In the present study, we for the first time uncovered the fact that one of such lncRNAs plays a significant role in the differentiation of chondrocytes and, possibly, of osteoblasts differentiated from mesenchymal stem cells, which cells eventually construct the human skeleton. The urothelial cancer-associated 1 (UCA1) lncRNA is known to be associated with several human malignancies. Firstly, we confirmed that UCA1 was expressed in normal human chondrocytes, as well as in a human chondrocytic cell line; whereas it was not detected in human bone marrow mesenchymal stem cells (hBMSCs). Of note, although UCA1 expression was undetectable in hBMSCs, it was markedly induced along with the differentiation toward chondrocytes, suggesting its critical role in chondrogenesis. Consistent with this finding, silencing of the UCA1 gene significantly repressed the expression of chondrogenic genes in human chondrocytic cells. UCA1 gene silencing and hyper-expression also had a significant impact on the osteoblastic phenotype in a human cell line. Finally, forced expression of UCA1 in a murine chondrocyte precursor, which did not possess a UCA1 gene, overdrove its differentiation into chondrocytes. These results indicate a physiological and important role of this lncRNA in the skeletal development of humans, who require more sustained endochondral ossification and osteogenesis than do smaller vertebrates.

Regulatory mechanism of CCN2 production by serotonin (5-HT) via 5-HT2A and 5-HT2B receptors in chondrocytes.

Serotonin (5-hydroxytryptamine: 5-HT) is recognized as a neurotransmitter in the central nerve system and as a regulator of systemic blood pressure in the peripheral tissues. Recently, it was reported that 5-HT2 receptors (5-HT2Rs) were expressed in cartilage tissues lacking both vessels and neurons, suggesting possible novel functions of 5-HT during cartilage development and regeneration. Our previous data indicated that CCN family protein 2/connective tissue growth factor (CCN2/CTGF) plays a central role in cartilage development and regeneration. Therefore, the aim of this study was to investigate the effect of 5-HT on the production of CCN2 in chondrocytes. Firstly, we showed that the mRNAs of 5-HT2R subtypes 5-HT2AR and 5-HT2BR, were expressed in a human chondrocytic cell line, HCS-2/8; however, 5-HT2CR mRNA was not detected. In addition, exogenously added 5-HT did not affect the 5-HT2AR and 5-HT2BR expressions. Next, we demonstrated that CCN2 production was increased by treatment with a 5-HT2AR agonist and the combination of 5-HT and 5-HT2BR antagonist. In contrast, treatment with a 5-HT2BR agonist and the combination of 5-HT and 5-HT2AR antagonist decreased CCN2 production. Furthermore, we showed that phosphorylation of Akt and p38 MAPK were increased by treatment with 5-HT2AR agonist, and that phosphorylation of PKCε, PKCζ, ERK1/2 and JNK were increased by treatment with 5-HT2BR agonist. Finally, we found that 5-HT2AR was localized in the growth plate, whereas 5-HT2BR was localized in the articular cartilage. These findings suggest that 5-HT promotes CCN2 production through the 5-HT2AR in growth plates, and that it represses CCN2 production through the 5-HT2BR in articular cartilage for harmonized development of long bones.

Phosphorylation of STAT proteins by recombinant human IL-6 in immortalized human chondrocyte cell lines, T/C28a2 and C28/I2.

Two immortalized human juvenile chondrocyte cell lines, T/C28a2 and C28/I2, were employed to determine the extent to which recombinant human (rh) IL-6, a known cytokine activator of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway in many cell types, caused STAT proteins to be phosphorylated. The results showed that STAT3 was constitutively phosphorylated in the absence of rhIL-6 in T/C28a2 chondrocytes. However, C28/I2 chondrocytes treated with rhIL-6 caused STAT1, STAT3, and STAT5 to be phosphorylated without altering total unphosphorylated STAT proteins. STAT3 phosphorylation in response to rhIL-6 in T/C28a and C28/I2 chondrocytes was efficiently blocked by the JAK3-selective inhibitor WHI-P131 (Janex-1) and by soluble IL-6 receptor-α (sIL-6R). However, the combination of rhIL-6 and ruxolitinib, a JAK1/JAK2-selective inhibitor, was a less effective inhibitor of STAT protein activation. These findings showed that rhIL-6 activated STAT proteins in the C28/I2 chondrocyte cell line. STAT protein phosphorylation could be blocked by a JAK3-selective inhibitor or by the combination of rhIL-6 and sIL-6R.

Impressic acid from Acanthopanax koreanum, possesses matrix metalloproteinase-13 down-regulating capacity and protects cartilage destruction

Ethnopharmacological relevanceAcanthopanax koreanum (Araliaceae) has been used in traditional medicine for enhancing vitality, rheumatism, and bone-related pains. But its activity on cartilage protection has not been known yet. Aim of the studyMatrix metalloproteinase (MMP)−13 has an important role in degrading cartilage materials under pathologic conditions such as arthritis. The present study was designed to find the inhibitory activity of impressic acid on MMP-13 expression and cartilage protective action. Materials and methods70% ethanol extract of Acanthopanax koreanum leaves and impressic acid, a major constituent isolated from the same plant materials, were examined on MMP-13 down-regulating capacity in IL-1β-treated human chondrocyte cell line (SW1353) and rabbit cartilage explants. ResultsIn IL-1β-treated SW1353 cells, impressic acid significantly and concentration-dependently inhibited MMP-13 expression at 0.5–10μM. Impressic acid was found to be able to inhibit MMP-13 expression by blocking the phosphorylation of signal transducer and activator of transcription-1/−2 (STAT-1/−2) and activation of c-Jun and c-Fos among the cellular signaling pathways involved. Further, impressic acid was found to inhibit the expression of MMP-13 mRNA (47.7% inhibition at 10μM), glycosaminoglycan release (42.2% reduction at 10μM) and proteoglycan loss in IL-1-treated rabbit cartilage explants culture. In addition, a total of 21 lupane-type triterpenoids structurally-related to impressic acid were isolated from the same plant materials and their suppressive activities against MMP-13 expression were also examined. Among these derivatives, compounds 2, 3, 16, and 18 clearly down-regulated MMP-13 expression. However, impressic acid was more potent than these derivatives in down-regulating MMP-13 expression. ConclusionsImpressic acid, its related triterpenoids, and A. koreanum extract have potential as therapeutic agents to prevent cartilage degradation by inhibiting matrix protein degradation.

Iopromide- and gadopentetic acid-derived preparates used in MR arthrography may be harmful to chondrocytes

BackgroundMagnetic resonance arthrography, a procedure through which contrast agents containing gadolinium and/or iopromide are administered intra-articularly, has become a useful tool in musculoskeletal diagnosis. Nevertheless, despite being considered safe for systemic use, certain tissue toxicities have been identified for both drugs. In this study, the effects of short-term exposure of human primary chondrocyte cell cultures to gadolinium and/or iopromide contrast agents were examined by assaying for stage-specific embryonic antigen-1 (SSEA-1) protein expression (a chondrogenic differentiation marker), cell viability, toxicity, and proliferation.MethodsHuman articular chondrocytes were grown in monolayer culture and were exposed to iopromide and/or gadolinium diethylenetriamine-pentaacetate (Gd-DPT) for 2 and 6 h. Cell cultures with no drug exposure were used as the control group. Cell differentiation status was assessed according to SSEA-1 protein expression. Contrast agent effects on cell viability and proliferation were analyzed using MTT analysis. Further, changes in cell morphology in relation to the control group were evaluated using inverted light microscopy, environmental scanning electron microscopy (ESEM), and 3-tesla magnetic resonance imaging. The obtained data were statistically compared.ResultsWhen compared with the control group, both SSEA-1 protein expression and cell proliferation were lowest in the Gd-DPT group (P = 0.000). There was a statistically significant correlation between SSEA-1 expression and MTT results (rho = 0.351; P = 0.003).ConclusionsNevertheless, the data obtained from in vitro experiments may not directly correspond to clinical applications. However, the mere fact that a drug used solely for diagnostic purposes may repress chondrocyte cell proliferation should be carefully considered by clinicians.

Cellular automata model for human articular chondrocytes migration, proliferation and cell death: An in vitro validation.

Articular cartilage is characterized by low cell density of only one cell type, chondrocytes, and has limited self-healing properties. When articular cartilage is affected by traumatic injuries, a therapeutic strategy such as autologous chondrocyte implantation is usually proposed for its treatment. This approach requires in vitro chondrocyte expansion to yield high cell number for cell transplantation. To improve the efficiency of this procedure, it is necessary to assess cell dynamics such as migration, proliferation and cell death during culture. Computational models such as cellular automata can be used to simulate cell dynamics in order to enhance the result of cell culture procedures. This methodology has been implemented for several cell types; however, an experimental validation is required for each one. For this reason, in this research a cellular automata model, based on random-walk theory, was devised in order to predict articular chondrocyte behavior in monolayer culture during cell expansion. Results demonstrated that the cellular automata model corresponded to cell dynamics and computed-accurate quantitative results. Moreover, it was possible to observe that cell dynamics depend on weighted probabilities derived from experimental data and cell behavior varies according to the cell culture period. Thus, depending on whether cells were just seeded or proliferated exponentially, culture time probabilities differed in percentages in the CA model. Furthermore, in the experimental assessment a decreased chondrocyte proliferation was observed along with increased passage number. This approach is expected to having other uses as in enhancing articular cartilage therapies based on tissue engineering and regenerative medicine.

Hyperglycemia and Hyperinsulinemia-Like Conditions Independently Induce Inflammatory Responses in Human Chondrocytes

To elucidate the mechanisms by which type 2 Diabetes Mellitus (DM2) constitutes a risk factor for the development and progression of osteoarthritis (OA), this work determined whether high glucose and/or high insulin, the hallmarks of DM2, are capable of activating the transcription factor, Nuclear Factor-κB (NF-κB), which plays a critical role in OA by inducing the expression of pro-inflammatory and catabolic genes. For this, we analyzed NF-κB activation by measuring the nuclear levels of p65 by western blot. As readouts of NF-κB activity, Interleukin-1β, Tumor Necrosis Factor-α, and inducible nitric oxide synthase (iNOS) expression were analyzed by real time RT-PCR and western blot. Culture of the human chondrocytic cell line, C28-I2, in high glucose (30 mM) increased nuclear NF-κB p65 levels in a time-dependent manner, relative to cells cultured in medium containing 10 mM glucose (regular culture medium). High glucose-induced NF-κB activation was inhibited by co-treatment with its specific inhibitor, Bay 11-7082, 5 µM. Culture of primary human chondrocytes under high glucose for 24 h increased IL-1β and TNF-α mRNA levels by 97% (p = 0.0066) and 85% (p = 0.0045), respectively, while iNOS mRNA and protein levels and NO production increased by 61% (p = 0.0017), 148% (p = 0.0089), and 70% (p = 0.049), respectively, relative to chondrocytes maintained in 10 mM glucose. Treatment of chondrocytic cells with 100 nM insulin was also sufficient to increase nuclear NF-κB p65 levels, independently of the glucose concentration in the culture medium. This study shows that hyperglycemia and hyperinsulinemia are independently sufficient to induce inflammatory responses in human chondrocytes, namely by activating NF-κB. This can be a relevant mechanism by which DM type 2 and other conditions associated with impaired glucose and insulin homeostasis, like obesity and the metabolic syndrome, contribute to the development and progression of OA.

RhoA inhibits the hypoxia-induced apoptosis and mitochondrial dysfunction in chondrocytes via positively regulating the CREB phosphorylation.

Chondrocytes that are embedded within the growth plate or the intervertebral disc are sensitive to environmental stresses, such as inflammation and hypoxia. However, little is known about the molecular signalling pathways underlining the hypoxia-induced mitochondrial dysfunction and apoptosis in chondrocytes. In the present study, we firstly examined the hypoxia-induced apoptosis, mitochondrial dysfunction and the activation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) signalling in human chondrocyte cell line, C28/I2 and then investigated the regulatory role of RhoA, a well-recognized apoptosis suppressor, in such process, with gain-of-function strategy. Our results indicated that hypoxia induced apoptosis and inhibited CREB phosphprylation in chondrocytes, meanwhile, the dysfunctional mitochondria with up-regulated mitochondrial superoxide and reactive oxygen species (ROS) levels, whereas with a reduced mitochondrial membrane potential (MMP) and Complex IV activity were observed in the hypoxia-treated C28/I2 cells. However, the overexpressed RhoA blocked the hypoxia-mediated reduction in CREB phosphprylation and inhibited the apoptosis induction, along with an ameliorated mitochondrial function in the hypoxia-treated C28/I2 cells. In conclusion, the present study confirmed the reduced CREB phosphorylation, along with the apoptosis induction and mitochondrial dysfunction in the hypoxia-treated chondrocyte cells. And the overexpression of RhoA ameliorated the hypoxia-induced mitochondrial dysfunction and apoptosis via blocking the hypoxia-mediated reduction in CREB phosphorylation.

New chimeric peptide regulating insulin-like growth factor 1 regenerative effect for therapy in early stage osteoarthritis

Purpose: Osteoarthritis (OA) is the most frequent chronic musculoskeletal disease and knee OA is becoming the 4th most important global cause of disability in women and 8th in men. Early OA is estimated to affect nowadays more than 8.5 million of persons worldwide, this figure being estimated to reach 13.5 million in 2023. The 1st phase of osteoarthritis is the loss of cartilage. Due to his avascularity and his low number of stem cells, cartilage has a low mitotic activity and, consequently, cartilage has low ability to self-repair. Insulin-like growth factors-1 (IGF-I) is one of the most important growth factor and it’s involved in the regulation of chondrocyte metabolic function, as both a proliferative and differentiative factor. IGF-I is able to increase cell migration and also has an important function in an endocrine/paracrine and autocrine stimulating of matrix synthesis (proteoglycan and collagen type II). A new innovative chimeric peptide was developed to act on the balance of synthesis of IGF-I. This peptide combines a short amino acid sequence derived from growth hormone (GH) and an analog of somatostatin (SST). This two sequences, having an opposite effect on IGF-I releasing, induce a balanced regulation of IGF-I synthesis and its receptor expression (IGF-IR). We wanted to explore in vitro, on human chondrocytes cells culture, the effect of our chimeric peptide on stimulation of IGF-IR production as well as chondrocytes proliferation and differentiation. In addition, we evaluated his activity in in vivo spontaneous knee OA model. Methods: Human normal chondrocyte cell line was cultivated in cell growth medium with or without peptide. Cells were collected after 2, 4 and 8 days of culture. The total IGF-IR concentration was quantified using ELISA kit. The chondrogenic effect was observed by microscopy after staining with alcian blue to visualise proteoglycans. Five months old Duncan-Hartley guinea pigs (early OA) received one peptide or sham intraarticular injection per week for three weeks. Seven animals per group were used. Guinea pigs were sacrificed at 10 month old and both knees were collected for histology according OARSI-HISTOgp recommendations. Results: This GH-SST peptide increased the production of IGF-IR in human chondrocytes. The alcian blue staining revealed an increasing of cell clusters indicating a stimulation of chondrogenesis. In vivo test confirm the effect of this GH-SST peptide. Five months after injection, the quantitative histologic evaluation of knee guinea pig revealed that the GH-SST peptide injected group had a cartilage thickness significantly superior to the control group. Moreover, semiquantitative histologic scoring evaluation revealed a decrease of osteophytes development. Conclusions: This GH-SST peptide, by acting on IGF-I axis, improved the stimulation of chondrocyte cell growth and may be involved in the synthesis and maintenance of cartilage tissue. Indeed, this GH-SST peptide showed a long term effect to slow down tissues degeneration in knee OA model and preserved a better cartilage thickness. These results suggest that the GH-SST peptide may be an effective treatment of early articular cartilage defects.

Catabolic effects of FGF-1 on chondrocytes and its possible role in osteoarthritis.

Fibroblast growth factor 1 (FGF-1) is a classical member of the FGF family and is produced by chondrocytes cultured from osteoarthritic patients. Also, this growth factor was shown to bind to CCN family protein 2 (CCN2), which regenerates damaged articular cartilage and counteracts osteoarthritis (OA) in an animal model. However, the pathophysiological role of FGF-1 in cartilage has not been well investigated. In this study, we evaluated the effects of FGF-1 in vitro and its production in vivo by use of an OA model. Treatment of human chondrocytic cells with FGF-1 resulted in marked repression of genes for cartilaginous extracellular matrix components, whereas it strongly induced matrix metalloproteinase 13 (MMP-13), representing its catabolic effects on cartilage. Interestingly, expression of the CCN2 gene was dramatically repressed by FGF-1, which repression eventually caused the reduced production of CCN2 protein from the chondrocytic cells. The results of a reporter gene assay revealed that this repression could be ascribed, at least in part, to transcriptional regulation. In contrast, the gene expression of FGF-1 was enhanced by exogenous FGF-1, indicating a positive feedback system in these cells. Of note, induction of FGF-1 was observed in the articular cartilage of a rat OA model. These results collectively indicate a pathological role of FGF-1 in OA development, which includes an insufficient cartilage regeneration response caused by CCN2 down regulation.

A Comparative Study on the Effects of Methylprednisolone Concentration on Human Chondrocyte Cell Metabolism in vitro

A Comparative Study on the Effects of Methylprednisolone Concentration on Human Chondrocyte Cell Metabolism in vitro

Phytoestrogen (Daidzein) Promotes Chondrogenic Phenotype of Human Chondrocytes in 2D and 3D Culture Systems.

Clinical investigations have shown a significant relationship between osteoarthritis (OA) and estrogens levels in menopausal women. Therefore, treatment with exogenous estrogens has been shown to decrease the risk of OA. However, the effect estrogen has not been clearly demonstrated in the chondrocytes using phytoestrogens, which lack the specific side-effects of estrogens, may provide an alternative therapy. This study was designed to examine the possible effects of phytoestrogen (daidzein) on human chondrocyte phenotype and extracellular matrix formation. Phytoestrogens which lack the specific side-effects of estrogens may provide beneficial effect without causing hormone based side effect. Human chondrocytes cells were cultured in 2D (flask) and 3D (PCL-CA scaffold) systems. Daidzein cytotoxic effect was determined by MTT assay. Chondrocyte cellular content of glycosaminoglycans (GAGs), total collagen and chondrogenic gene expression were determined in both culture systems after treatment with daidzein. Daidzein showed time-dependent and dose-independent effects on chondrocyte bioactivity. The compound at low doses showed significant (p<0.05) increase in total collagen and GAGs production at similar levels in 2D and 3D culture environment. The mRNA levels of Collagen II and Sox9 were increased significantly (p<0.01) after the treatment while the upregulation in COMP expression was statistically insignificant (p>0.05). The expression levels of Fibronectin, Laminin and Integrin β1 were significantly increased especially in 3D culture system. This study was illustrated the potential positive effects of daidzein on maintenance of human chondrocyte phenotype and extracellular matrix formation suggesting an attractive and viable alternative therapy for OA.

Effect of glucosamine on expression of type II collagen, matrix metalloproteinase and sirtuin genes in a human chondrocyte cell line.

Glucosamine(GlcN) has been widely used to treat osteoarthritis(OA) in humans. However, the effects of GlcN on genes related to cartilage metabolism are still unknown. In the present study, to elucidate the chondroprotective action of GlcN on OA, we examined the effects of GlcN(0.1-10mM) on the expression of the sirtuin(SIRT) genes as well as typeII collagen and matrix metalloproteinases(MMPs) using a human chondrocyte cell lineSW1353. SW1353cells were incubated in the absence or presence of GlcN. RT-PCR analyses revealed that GlcN markedly increased the mRNA expression of typeII collagen(COL2A1). By contrast, the levels of MMP-1 andMMP-9 mRNA were only slightly increased by GlcN. Furthermore, western blot analyses revealed that GlcN significantly increased the protein level of COL2A1. Importantly, GlcN enhanced the mRNA expression and protein level of SIRT1, an upstream-regulating gene of COL2A1. Moreover, a SIRT1 inhibitor suppressed GlcN-induced COL2A1gene expression. Together these observations suggest that GlcN enhances the mRNA expression and protein level of SIRT1 and its downstream gene COL2A1 in chondrocytes, thereby possibly exhibiting chondroprotective action on OA.