FGF signaling antagonizes cytokine-mediated repression of Sox9 in SW1353 chondrosarcoma cells

Indirubin protects chondrocytes and alleviates OA by inhibiting the MAPK and NF-κB pathways

PHARMACOLOGICAL RELEVANCE

Indirubin (IR) is a key active ingredient in the traditional Chinese medication QingDai, also called indigo naturalis, which are extensively used in China to treat chronic diseases, such as inflammation and cancer. However, the function of IR in reducing chondrocyte inflammation in osteoarthritis (OA) is still unclear.

AIM OF THE STUDY

The aim of this research was to examine how IR inhibits arthritis and to highlight some of its cellular-level processes.

MATERIALS AND METHODS

Chondrocytes from the knee joint of C57 mice were gathered and grown for in vitro tests and used to determine the toxicity of IR toward chondrocytes using a CCK8 kit. Chondrocytes were treated with IL-1β and IR or with IL-1β alone, and western blotting was used to determine the expression levels of inflammatory mediators. Meanwhile, through the identification and examination of pertinent markers via quantitative PCR. By using PCR assays, western blotting, toluidine blue staining and safranin O staining, the expression of proteoglycan (AGG) and type II collagen (collagen II) was investigated. Furthermore, western blotting was used to detect activation of the NF-κB and MAPK signaling pathways, and immunofluorescence was used to detect p65 nuclear translocation. In an in vivo experiment, C57BL/6 mice were subjected to destabilization of the medial meniscus (DMM) surgery to produce an OA model, and IR was injected into the articular cavity for 8 weeks. Eventually, the mice were killed, and samples of the knee joints were obtained for histological examination and analysis.

RESULTS

IR significantly reduced the expression of inflammatory regulators in chondrocytes treated with IL-1β, including iNOS and COX-2. Inhibition of IL-1β induced production of the key catabolic enzymes MMP3, MMP13 and A5. Additionally, an improvement in the downregulation of collagen II and AGG expression was observed. Moreover, IR prevented the aberrant IL-1β-induced activation of the NF-κB and MAPK signaling pathways, which resulted in downregulation of p65 and p38 expression. Compared to the DMM group, the severity of cartilage injury in animals was dramatically lessened and OARSI scores were lower in the treated groups.

CONCLUSION

According to the above findings, IR is quite effective in preventing arthritis both in vivo and in vitro, suggesting that IR may be employed as a possible anti-arthritis drug.

Chondro-Protective Effects of Shikimic Acid on Osteoarthritis via Restoring Impaired Autophagy and Suppressing the MAPK/NF-κB Signaling Pathway

Osteoarthritis (OA) is a major cause of cartilage pain and limited mobility in middle-aged and elderly individuals. The degeneration of cartilage induced by inflammation and cartilage anabolic and catabolic disorder plays a key role in OA. Shikimic acid (SA), a natural ingredient extracted from Illicium verum, has been shown to exert notable anti-inflammatory effects in previous studies, suggesting its potential effects in the treatment of OA. In this study, we revealed that the pretreatment of SW1353 human chondrocytes with SA before interleukin 1β (IL-1β) stimulation effectively decreased the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (Cox)-2, matrix metalloproteinases (MMPs; MMP3 and MMP13), a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5, type X collagen, and p62; increased the expression of type II collagen, ATG7, Beclin-1, and LC3; and increased the autophagic flux. Mechanistically, we found that SA suppressed the IL-1β-induced activation of the mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-κB) pathways. Furthermore, the results of safranin O staining and toluidine blue staining of primary rat cartilage chondrocytes and a trauma-induced rat model of OA showed that SA alleviated progression of OA in vivo. Collectively, our research enhances understanding of the mechanism of protective effect of SA against the progression of OA, which involves amelioration of cartilage degeneration, thereby providing new evidence for the use of SA as a therapy to prevent the development of OA.

MicroRNA-486 promotes a more catabolic phenotype in chondrocyte-like cells by targeting SIRT6 : possible involvement in cartilage degradation in osteoarthritis

AIMS

Osteoarthritis (OA) is characterized by persistent destruction of articular cartilage. It has been found that microRNAs (miRNAs) are closely related to the occurrence and development of OA. The purpose of the present study was to investigate the mechanism of miR-486 in the development and progression of OA.

METHODS

The expression levels of miR-486 in cartilage were determined by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of collagen, type II, alpha 1 (COL2A1), aggrecan (ACAN), matrix metalloproteinase (MMP)-13, and a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4) in SW1353 cells at both messenger RNA (mRNA) and protein levels was determined by qRT-PCR, western blot, and enzyme-linked immunosorbent assay (ELISA). Double luciferase reporter gene assay, qRT-PCR, and western blot assay were used to determine whether silencing information regulator 6 (SIRT6) was involved in miR-486 induction of chondrocyte-like cells to a more catabolic phenotype.

RESULTS

Compared with osteonecrosis, the expression of miR-486 was significantly upregulated in cartilage from subjects with severe OA. In addition, overexpressed miR-486 promoted a catabolic phenotype in SW1353 cells by upregulating the expressions of ADAMTS4 and MMP-13 and down-regulating the expressions of COL2A1 and ACAN. Conversely, inhibition of miR-486 had the opposite effect. Furthermore, overexpression of miR-486 significantly inhibited the expression of SIRT6, confirming that SIRT6 is a direct target of miR-486. Moreover, SW1353 cells were transfected with small interfering RNA (si)-SIRT6 and it was found that SIRT6 was involved in and inhibited miR-486-induced changes to SW1353 gene expression.

CONCLUSION

Our results indicate that miR-486 promotes a catabolic phenotype in SW1353 cells in OA by targeting SIRT6. Our findings might provide a potential therapeutic target and theoretical basis for OA. Cite this article: Bone Joint Res 2021;10(7):459-466.

Establishing SW1353 Chondrocytes as a Cellular Model of Chondrolysis

Osteoarthritis (OA) is the most common degenerative joint disease characterised by chondrocyte cell death. An in vitro model of chondrocyte cell death may facilitate drug discovery in OA management. In this study, the cytotoxicity and mode of cell death of SW1353 chondrocytes treated with 24 h of OA inducers, including interleukin-1β (IL-1β), hydrogen peroxide (H2O2) and monosodium iodoacetate (MIA), were investigated. The microscopic features, oxidative (isoprostane) and inflammatory markers (tumour necrosis factor-alpha; TNF-α) for control and treated cells were compared. Our results showed that 24 h of H2O2 and MIA caused oxidative stress and a concentration-dependent reduction of SW1353 cell viability without TNF-α level upregulation. H2O2 primarily induced chondrocyte apoptosis with the detection of blebbing formation, cell shrinkage and cellular debris. MIA induced S-phase arrest on chondrocytes with a reduced number of attached cells but without significant cell death. On the other hand, 24 h of IL-1β did not affect the cell morphology and viability of SW1353 cells, with a significant increase in intracellular TNF-α levels without inducing oxidative stress. In conclusion, each OA inducer exerts differential effects on SW1353 chondrocyte cell fate. IL-1β is suitable in the inflammatory study but not for chondrocyte cell death. H2O2 and MIA are suitable for inducing chondrocyte cell death and growth arrest, respectively.

Esculentoside A protects against osteoarthritis by ameliorating inflammation and repressing osteoclastogenesis

Osteoarthritis is a relatively common disorder of articular deterioration related to cartilage damage, subchondral bone remodelling, inflammation and metabolism. Agents that can inhibit cartilage degradation and osteoclastogenesis are required for the prevention and treatment of osteoarthritis. Esculentoside A, the highest concentration triterpene saponin isolated from the root of Phytolacca esculenta, has commonly been used for the treatment of chronic bronchitis. However, the role esculentoside A plays in ameliorating osteoarthritis has not been reported. We found that esculentoside A suppresses the expression of IL-1β-induced inflammatory and metabolic factors (IL-6, IL-8, TNF-α, MMP2, MMP3 and MMP13). In addition, esculentoside A restrains osteoclast formation by inhibiting the marker gene expression of NFATc1 and c-Fos. Our results indicate that esculentoside A markedly suppresses IL-1β-induced NF-κB and MAPK signalling pathway activation in chondrocytes, and inhibits RANKL-induced osteoclast precursor generation. Finally, treatment with esculentoside A inhibits the progressive cartilage degeneration and osteoclastogenesis in osteoarthritis mouse models. In summary, these results demonstrate that esculentoside A could be a latent therapeutic reagent for the treatment of osteoarthritis.

Recombinant human irisin regulated collagen II, matrix metalloproteinase-13 and the Wnt/β-catenin and NF-κB signaling pathways in interleukin-1β-induced human SW1353 cells

Osteoarthritis (OA) is a degenerative joint disease that seriously affects the quality of life of patients. Irisin has been reported to regulate bone metabolism via the cellular autocrine mechanism and play a protective role in rat OA. In the present study, a SW1353 chondrosarcoma cell line was treated with interleukin (IL)-1β and irisin. The present study evaluated cell viability, expression levels of collagen II (Col II) and matrix metalloproteinase-13 (MMP-13), and activity of the Wnt/β-catenin and NF-κB signaling pathways in treated SW1353 cells. The present results suggested that IL-1β could decrease Col II expression and increase MMP-13 expression at both the mRNA and protein levels, and also activate the Wnt/β-catenin and NF-κB signaling pathways in SW1353 cells. By contrast, irisin was identified to reverse the effects of IL-1β in IL-1β-induced SW1353 cells. The present results suggested that irisin treatment may have a cartilage-protective role in an IL-1β-induced SW1353 cell model.

Synthesis of photo-reactive poly (vinyl alcohol) and construction of scaffold-free cartilage like pellets in vitro

Photo-reactive poly(vinyl alcohol) (PRPVA) was synthesized by introduction of phenyl azido groups into poly(vinyl alcohol) (PVA) and applied for surface modification. PRPVA was grafted onto cell culture plate surface homogeneously or in a micropattern. Human mesenchymal stem cells (hMSCs) cultured on cell culture plate surface and PVA-modified surface showed different behaviors. Cells adhered and spread well on cell culture plate surface, while they did not adhere on PVA-grafted surface at all. When hMSCs were cultured on PVA-micropatterned surface, they formed a cell micropattern. Cells formed pellets after cultured on PVA homogeneously modified surface in chondrogenic induction medium for 2 weeks. The pellets were positively stained by hematoxylin/eosin, safranin-O/fast green and toluidin blue, and they were also stained brown by Type II collagen and proteoglycan immunohistological staining. Real-time PCR analysis was conducted to investigate the expression of colI, colII, colX, aggrecan and sox9 mRNA. Results of gene expression were in agreement with those of histological and immunohistological observations. These results indicated that hMSCs cultured on PVA-modified surface performed chondrogenic differentiation, and it was possible to construct scaffold-free cartilage like pellets with PVA-modified surface in vitro.

miR-30b regulates chondrogenic differentiation of mouse embryo-derived stem cells by targeting SOX9

The present study aimed to investigate the mechanisms underlying microRNA (miRNA)-mediated regulation of chondrogenic differentiation. Mouse embryo-derived stem cells C3H10T1/2 were cultured and chondrogenic differentiation was induced using transforming growth factor-β3 (TGF-β3). In addition, miRNA expression profiles were detected via miRNA array analysis, and quantitative polymerase chain reaction was performed to verify the differentially expressed miRNAs. Furthermore, bioinformatics software was used to predict the putative targets and the prediction was validated by dual-luciferase reporter assays and western blot analysis. In addition, cell proliferation and glycosaminoglycans were measured by a direct cell count method and alcian blue staining, respectively. Compared with the control group, 86 miRNAs were identified as differentially expressed in TGF-β3-induced cells and the expression levels of 28 miRNAs were increased while the remaining 58 miRNAs exhibited a decline in expression. Amongst the differentially expressed miRNAs, miR-30b expression was observed to have significantly decreased during chondrogenic differentiation. SOX9 is a target gene of miR-30b, and miR-30b inhibits SOX9 expression during chondrogenic differentiation. Furthermore, the alcian blue staining results demonstrated that miR-30b inhibited early chondrogenic differentiation. However, the data of the present study indicated that miR-30b had no influence on C3H10T1/2 cell line proliferation. In conclusion, miR-30b is a key negative regulator of TGF-β3-induced C3H10T1/2 cell chondrogenic differentiation, which functions by directly targeting SOX9.

Fibroblast growth factor 22 is a novel modulator of depression through interleukin-1β

BACKGROUND AND AIMS

Emerging evidence shows that fibroblast growth factor 22 (FGF22) plays a critical role in the etiology of depression. However, the molecular mechanisms of FGF22 are not fully comprehended. Here, the effect of FGF22 in depression and its relationship with interleukin-1β (IL-1β) were investigated in clinical, animal, and cell experiments.

METHODS

Serum from depressive patients was collected, and the levels of FGF22 and IL-1β were analyzed by ELISA. The chronic unpredictable mild stress (CUMS) model was established, and primary hippocampal neuronal cells were cultured to examine changes in FGF22 and IL-1β levels in rat hippocampus.

RESULTS

The results revealed a negative correlation between serum FGF22 levels and serum IL-1β levels. The expression of IL-1β in the CUMS rat hippocampus decreased, and the apoptosis of hippocampal cells improved after the injection of lentiviral vector-mediated FGF22 (LV-FGF22). Further tests in primary hippocampal neuronal cells also showed a reduction in IL-1β and the cell apoptosis rate after treatment with FGF22.

CONCLUSION

In conclusion, the results revealed that FGF22 plays a role in alleviating depression, which may be mediated by reduced expression of IL-1β.

Role of autophagy in the progression of osteoarthritis: The autophagy inhibitor, 3-methyladenine, aggravates the severity of experimental osteoarthritis

Accumulating evidence suggests that autophagy is closely related to the pathogenesis of osteoarthritis (OA). The aim of this study was to determine the changes in autophagy during the progression of OA and to elucidate the specific role of autophagy in OA. For this purpose, a cellular model of OA was generated by stimulating SW1353 cells with interleukin (IL)-1β and a rabbit model of OA was also established by an intra-articular injection of collagenase, followed by treatment with the autophagy specific inhibitor, 3-methyladenine (3-MA). Cell viability was analyzed by MTS assay, and the mRNA expression levels of matrix metalloproteinases (MMP)-13 and tissue inhibitor of metalloproteinase (TIMP)-1 were determined by RT-qPCR. Cartilage degeneration was examined under a light microscope, and autophagosome and chondrocyte degeneration was observed by transmission electron microscopy. The protein expression of Beclin-1 and light chain 3 (LC3)B was evaluated by western blot analysis and immunofluorescence staining. We found that the autophagy was enhanced during the early stages and was weakened during the late stages of experimental OA. The inhibition of autophagy by 3-MA significantly aggravated the degeneration of chondrocytes and cartilage in experimental OA. Our results thus determine the changes in autophagy during different stages of OA, as well as the role of impaired autophagy in the development of OA. Our data suggest that the regulation of autophagy may be a potential therapeutic strategy with which to attenuate OA.

Therapeutic effect of human clonal bone marrow-derived mesenchymal stem cells in severe acute pancreatitis

Severe acute pancreatitis (SAP), a common necroinflammatory disease initiated by the premature activation of digestive enzymes within the pancreatic acinar cells, is associated with significant morbidity and mortality. In this study, we investigated whether human bone marrow-derived clonal mesenchymal stem cells (hcMSCs), isolated from human bone marrow aspirate according to our newly established isolation protocol, have potential therapeutic effects in SAP. SAP was induced by three intraperitoneal (i.p.) injections of cerulein (100 μg/kg) and sequential LPS (10 mg/kg) in Sprague-Dawley (SD) rats. hcMSCs (1 × 10(6)/head) were infused on 24 h after LPS injection via the tail vein. The rats were sacrificed 3 days after infusion of hcMSCs. We observed that infused hcMSCs reduced the levels of serum amylase and lipase. Infused hcMSCs ameliorated acinar cell necrosis, pancreatic edema, and inflammatory infiltration. Also, infused hcMSCs decreased the level of malondialdehyde, and increased the levels of glutathione peroxidase and superoxide dismutase. The number of TUNEL positive acinar cells was reduced after hcMSCs infusion. In addition, hcMSCs reduced the expression levels of pro-inflammation mediators and cytokines, and increased the expression of SOX9 in SAP. Taken together, hcMSCs could effectively relieve injury of pancreatitis as a promising therapeutics for SAP.

Stimulatory effects of the ionic products from Ca-Mg-Si bioceramics on both osteogenesis and angiogenesis in vitro

Ideal biomaterials for bone tissue engineering should have the capability to guide the osteogenic differentiation of mesenchymal stem cells and, at the same time, to stimulate angiogenesis of endothelia cells. In this study it was found that three Ca-Mg-Si-containing bioceramics (bredigite Ca7MgSi4O16, akermanite Ca2MgSi2O7 and diopside CaMgSi2O6) had osteogenic and angiogenic potential. The effects of three silicate ceramics on the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) and the angiogenesis of human aortic endothelial cells (HAECs) were explored in comparison with β-tricalcium phosphate (β-TCP) bioceramics. The proliferation, alkaline phosphatase (ALPase) activity and bone-related gene expression (COL1, ALPase, OP, BSP and OC) of hBMSCs were significantly enhanced upon stimulation with ionic extracts of these silicate bioceramics. In addition, the results showed that extracts from the three silicate bioceramics also stimulated HAEC proliferation and in vitro angiogenesis with improved NO synthesis and angiogenic gene expression (KDR, FGFR1, ACVRL1 and NOS3). Among the three silicate ceramics bredigite showed the highest osteogenic and angiogenic potential and with the highest extract Si (possibly Si(OH)3O(-)) concentration, while diopside had the lowest osteogenic and angiogenic potential with the lowest extract Si concentration. Furthermore, it was found that the concentration of Si ions in extracts of the three silicate bioceramics was obviously higher than that of β-TCP ceramics, indicating an important role of Si ions in stimulating cell proliferation, osteogenic differentiation and angiogenesis. The results suggest that the silicate-based akermanite and bredigite ceramics might be good scaffold biomaterials for bone tissue engineering applications due to their distinctive dual functions of osteogenesis/angiogenesis stimulation.

Spatial immobilization of bone morphogenetic protein-4 in a collagen-PLGA hybrid scaffold for enhanced osteoinductivity

The introduction of bioactive molecules into three-dimensional porous scaffolds to mimic the in vivo microenvironment is a promising strategy for tissue engineering and stem cell research. In this study, bone morphogenetic protein-4 (BMP4) was spatially immobilized in a collagen-PLGA hybrid scaffold with a fusion BMP4 composed of an additional collagen-binding domain derived from fibronectin (CBD-BMP4). CBD-BMP4 bound to the collagen-PLGA hybrid scaffold and the BMP4-immobilized hybrid scaffold supported cell adhesion and proliferation. The osteogenic induction effect of the immobilized CBD-BMP4 was investigated with three-dimensional culture of human bone marrow-derived mesenchymal stem cells in the BMP4-immobilized collagen-PLGA hybrid scaffold. The in vivo implantation experiment demonstrated that the immobilized CBD-BMP4 maintained its osteoinductive activity, being capable of up-regulating osteogenic gene expression and biomineralization. The strong osteoinductivity of the BMP4-immobilized scaffold suggests it should be useful for bone tissue engineering, stem cell function manipulation and bone substitutes.

Silicate bioceramics induce angiogenesis during bone regeneration

The capacity to induce rapid vascular ingrowth during new bone formation is an important feature of biomaterials that are to be used for bone regeneration. Akermanite, a Ca-, Mg- and Si-containing bioceramic, has been demonstrated to be osteoinductive and to promote bone repair. This study further demonstrates the ability of akermanite to promote angiogenesis and investigates the mechanism of this behavior. The akermanite ion extract predominantly caused Si-ion-stimulated proliferation of human aortic endothelial cells. The Si ion in the extract was the most important component for the effect and the most effective concentration was found to be 0.6-2 μg ml(-1). In this range of Si ion concentration, the stimulating effect of the ceramic ion extract was demonstrated by the morphology of cells at the primary, interim and late stages during in vitro angiogenesis using ECMatrix™. The akermanite ion extract up-regulated the expression of genes encoding the receptors of proangiogenic cytokines and also increased the expression level of genes encoding the proangiogenic downstream cytokines, such as nitric oxide synthase and nitric oxide synthesis. Akermanite implanted in rabbit femoral condyle model promoted neovascularization after 8 and 16 weeks of implantation, which further confirmed its stimulation effect on angiogenesis in vivo. These results indicate that akermanite ceramic, an appropriate Si ion concentration source, could induce angiogenesis through increasing gene expression of proangiogenic cytokine receptors and up-regulated downstream signaling. To our knowledge, akermanite ceramic is the first Si-containing ceramic demonstrated to be capable of inducing angiogenesis during bone regeneration.

Cultured cell-derived extracellular matrix scaffolds for tissue engineering

Cell-derived extracellular matrix (ECM) scaffolds have received considerable interest for tissue engineering applications. In this study, ECM scaffolds derived from mesenchymal stem cell (MSC), chondrocyte, and fibroblast were prepared by culturing cells in a selectively removable poly(lactic-co-glycolic acid) (PLGA) template. These three types of ECM scaffolds were used for in vitro cultures of MSC and fibroblasts to examine their potential as scaffolds for cartilage and skin tissue engineering. The MSC were cultured in MSC- and chondrocyte-derived ECM scaffolds. The ECM scaffolds supported cell adhesion, promoted both cell proliferation and the production of ECM and demonstrated a stronger stimulatory effect on the chondrogenesis of MSC compared with a conventional pellet culture method. Histological and immunohistochemical staining indicated that cartilage-like tissues were regenerated after the MSC were cultured in ECM scaffolds. Fibroblasts were cultured in the fibroblast-derived ECM scaffolds. Fibroblasts proliferated and produced ECM to fill the pores and spaces in the scaffold. After 2 weeks of culture, a uniform multilayered tissue was generated with homogenously distributed fibroblasts. Cell-derived ECM scaffolds have been demonstrated to facilitate tissue regeneration and will be a useful tool for tissue engineering.

Gradient patterning and differentiation of mesenchymal stem cells on micropatterned polymer surface

A micropatterned surface with different area ratios of cell-adhesive to nonadhesive surfaces was prepared by micropatterning poly(vinyl alcohol) on a polystyrene plate using photolithography. A gradient pattern of mesenchymal stem cells of different cell densities was generated by culturing the cells on a micropatterned surface. The effects of the cell density gradient on cell functions such as proliferation and differentiation were investigated. Cells seeded at a low density proliferated faster than cells seeded at a high density. Although mesenchymal stem cells seeded at both low and high densities showed osteogenic differentiation, the higher cell seeding density could initiate osteogenic differentiation at a faster rate than the low cell density. And high cell density was required to induce chondrogenic differentiation.

Effects of extracellular matrices derived from different cell sources on chondrocyte functions

Cell-derived extracellular matrices (ECMs) are a key factor in regulating cell functions in tissue engineering and regenerative medicine. The fact that cells are surrounded by their specific ECM in vivo elicits the need to elucidate the effects of ECM derived from different cell sources on cell functions. Here, three types of ECM were prepared by decellularizing cultured chondrocytes, fibroblasts, and mesenchymal stem cells (MSC) and used for chondrocyte culture to compare their effects on chondrocyte adhesion, proliferation, and differentiation. Chondrocyte adhesion to the chondrocyte-derived ECM was greater than those to the fibroblast- and MSC-derived ECM. Chondrocyte proliferation on the chondrocyte-derived ECM was lower than those on the fibroblast- and MSC-derived ECM. The ECM showed no evident effect on chondrocyte differentiation. The effects of ECM on cell functions depended on the cell source used to prepare the ECM.

A cell leakproof PLGA-collagen hybrid scaffold for cartilage tissue engineering

A cell leakproof porous poly(DL-lactic-co-glycolic acid) (PLGA)-collagen hybrid scaffold was prepared by wrapping the surfaces of a collagen sponge except the top surface for cell seeding with a bi-layered PLGA mesh. The PLGA-collagen hybrid scaffold had a structure consisting of a central collagen sponge formed inside a bi-layered PLGA mesh cup. The hybrid scaffold showed high mechanical strength. The cell seeding efficiency was 90.0% when human mesenchymal stem cells (MSCs) were seeded in the hybrid scaffold. The central collagen sponge provided enough space for cell loading and supported cell adhesion, while the bi-layered PLGA mesh cup protected against cell leakage and provided high mechanical strength for the collagen sponge to maintain its shape during cell culture. The MSCs in the hybrid scaffolds showed round cell morphology after 4 weeks culture in chondrogenic induction medium. Immunostaining demonstrated that type II collagen and cartilaginous proteoglycan were detected in the extracellular matrices. Gene expression analyses by real-time PCR showed that the genes encoding type II collagen, aggrecan, and SOX9 were upregulated. These results indicated that the MSCs differentiated and formed cartilage-like tissue when being cultured in the cell leakproof PLGA-collagen hybrid scaffold. The cell leakproof PLGA-collagen hybrid scaffolds should be useful for applications in cartilage tissue engineering.

Sox9 expression is not limited to chondroid neoplasms: variable occurrence in other soft tissue and bone tumors with frequent expression by synovial sarcomas

The transcription factor Sox9 is known to play a crucial role in normal chondrogenesis, and antibodies against Sox9 have been proposed as a diagnostic tool for neoplasms with chondroid differentiation. However, the pattern of Sox9 immunohistochemical expression by other bone and soft tissue neoplasms, as well as its diagnostic specificity, remain unexplored. The authors have performed immunohistochemistry with antibodies against Sox9 in 106 chondroid and nonchondroid bone and soft tissue neoplasms. Moderate to intense Sox9 nuclear staining was observed in 14/20 chondrosarcomas (70%), and in 24/81 (29.6%) cases from a multitumor tissue microarray, which included 16/18 synovial sarcomas, 4/15 osteosarcomas, 2/5 peripheral primitive neuroectodermal tumor (PNET)/Ewing sarcomas, 1/1 mesenchymal chondrosarcoma, and 1/1 chondroblastoma. The results suggest that Sox9 usefulness in the diagnosis of chondroid tumors may be limited because of low sensitivity and specificity. The finding of Sox9 expression by 88.9% of synovial sarcomas represents a novel and striking observation, which deserves further investigation.

Transcriptomic analysis identifies Foxo3A as a novel transcription factor regulating mesenchymal stem cell chrondrogenic differentiation

Multipotent mesenchymal stromal cells (MSC) are progenitor cells able to differentiate into several lineages including chondrocytes, and thus represent a suitable source of cells for cartilage engineering. However, the control of MSC differentiation to hypertrophy is a crucial step for the clinical application of MSC in cartilage repair where a stable chondrogenic phenotype without transition to terminal differentiation is the goal to achieve. This study aims at identifying new factors that may regulate this process. Using microarrays, we compared the transcriptional profiles of human MSC and MSC-derived chondrocytes obtained after culture in micropellets. After chondrogenesis induction, 676 genes were upregulated, among which five transcription factors not yet associated with chondrocyte differentiation of adult stem cells. These factors, in particular Foxo3A, are strongly expressed at day 21 and in mature chondrocytes. We investigated the role of Foxo3A using RNA interference. Our results revealed an important role of Foxo3A in the differentiation process of MSC toward chondrogenic fate, both in early and late stages. Indeed, stable Foxo3A knockdown tends to increase cell survival and decrease apoptosis, mainly in early stages of chondrogenesis. Importantly, we show that the loss of Foxo3A in MSC results in an increased expression level of markers specific for mature (aggrecan, collagen II) and hypertrophic (collagen X) chondrocytes. Therefore, our findings suggest that upregulation of Foxo3A over the course of chondrogenic differentiation plays a dual role, mainly inhibiting the differentiation process toward hypertrophy and promoting cell apoptosis.

Synergistic chondroprotective effects of curcumin and resveratrol in human articular chondrocytes: inhibition of IL-1beta-induced NF-kappaB-mediated inflammation and apoptosis

Introduction

Currently available treatments for osteoarthritis (OA) are restricted to nonsteroidal anti-inflammatory drugs, which exhibit numerous side effects and are only temporarily effective. Thus novel, safe and more efficacious anti-inflammatory agents are needed for OA. Naturally occurring polyphenolic compounds, such as curcumin and resveratrol, are potent agents for modulating inflammation. Both compounds mediate their effects by targeting the NF-κB signalling pathway.

Methods

We have recently demonstrated that in chondrocytes resveratrol modulates the NF-κB pathway by inhibiting the proteasome, while curcumin modulates the activation of NF-κB by inhibiting upstream kinases (Akt). However, the combinational effects of these compounds in chondrocytes has not been studied and/or compared with their individual effects. The aim of this study was to investigate the potential synergistic effects of curcumin and resveratrol on IL-1β-stimulated human chondrocytes in vitro using immunoblotting and electron microscopy.

Results

Treatment with curcumin and resveratrol suppressed NF-κB-regulated gene products involved in inflammation (cyclooxygenase-2, matrix metalloproteinase (MMP)-3, MMP-9, vascular endothelial growth factor), inhibited apoptosis (Bcl-2, Bcl-xL, and TNF-α receptor-associated factor 1) and prevented activation of caspase-3. IL-1β-induced NF-κB activation was suppressed directly by cocktails of curcumin and resveratrol through inhibition of Iκκ and proteasome activation, inhibition of IκBα phosphorylation and degradation, and inhibition of nuclear translocation of NF-κB. The modulatory effects of curcumin and resveratrol on IL-1β-induced expression of cartilage specific matrix and proinflammatory enzymes were mediated in part by the cartilage-specific transcription factor Sox-9.

Conclusions

We propose that combining these natural compounds may be a useful strategy in OA therapy as compared with separate treatment with each individual compound.

Development of stepwise osteogenesis-mimicking matrices for the regulation of mesenchymal stem cell functions

An extracellular microenvironment, including an extracellular matrix (ECM), is an important factor in regulating stem cell differentiation. During tissue development, the ECM is dynamically remodeled to regulate stem cell functions. Here, we developed matrices mimicking ECM remodeling during the osteogenesis of mesenchymal stem cells (MSCs). The matrices were prepared from cultured MSCs controlled at different stages of osteogenesis and referred to as "stepwise osteogenesis-mimicking matrices." The matrices supported the adhesion and proliferation of MSCs and showed different effects on the osteogenesis of MSCs. On the matrices mimicking the early stage of osteogenesis (early stage matrices), the osteogenesis occurred more rapidly than did that on the matrices mimicking undifferentiated stem cells (stem cell matrices) and the late stage of osteogenesis (late stage matrices). RUNX2 was similarly expressed when MSCs were cultured on both the early stage and late stage matrices but decreased on the stem cell matrices. PPARG expression in the MSCs cultured on the late stage matrices was higher than for those cultured on the stem cell and early stage matrices. This increase of PPARG expression was caused by the suppression of the amount of beta-catenin and downstream signal transduction. These results demonstrate that the osteogenesis-mimicking matrices had different effects on the osteogenesis of MSCs, and the early stage matrices provided a favorable microenvironment for the osteogenesis.

In vitro proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells cultured with hardystonite (Ca2ZnSi 2O7) and {beta}-TCP ceramics

The effects of hardystonite (Ca(2)ZnSi(2)O(7), CSZn) and tricalcium phosphate (beta-TCP) on the proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) were compared by directly culturing MSCs on ceramic disks (contact mode) or separately culturing cells with ceramic disks (non-contact mode). In non-contact mode, the CSZn ceramic supported MSC proliferation more strongly than did the beta-TCP ceramic. However, in contact mode, the MSCs proliferated more quickly on the beta-TCP ceramic than they did on the CSZn ceramic. Alkaline phosphatase (ALP) staining and osteogenic gene expression analysis showed that the CSZn and beta-TCP ceramics had significant effects on the promotion of the osteogenic differentiation of MSCs in both non-contact and contact mode. Furthermore, in contact mode, the CSZn disk promoted the osteogenic differentiation of MSCs more strongly than did the beta-TCP disks. Even without the induction of dexamethasone and beta-glycerophosphate, CSZn stimulated the osteogenic differentiation of MSCs. These results suggest that CSZn ceramic would be a useful candidate material for bone regeneration and hard tissue engineering.

HOXD13 binds DNA replication origins to promote origin licensing and is inhibited by geminin

HOX DNA-binding proteins control patterning during development by regulating processes such as cell aggregation and proliferation. Recently, a possible involvement of HOX proteins in replication origin activity was suggested by results showing that a number of HOX proteins interact with the DNA replication licensing regulator geminin and bind a characterized human origin of replication. The functional significance of these observations, however, remained unclear. We show that HOXD13, HOXD11, and HOXA13 bind in vivo all characterized human replication origins tested. We furthermore show that HOXD13 interacts with the CDC6 loading factor, promotes pre-replication complex (pre-RC) proteins assembly at origins, and stimulates DNA synthesis in an in vivo replication assay. HOXD13 expression in cultured cells accelerates DNA synthesis initiation in correlation with the earlier pre-RC recruitment onto origins during G(1) phase. Geminin, which interacts with HOXD13 as well, blocks HOXD13-mediated assembly of pre-RC proteins and inhibits HOXD13-induced DNA replication. Our results uncover a function for Hox proteins in the regulation of replication origin activity and reveal an unforeseen role for the inhibition of HOX protein activity by geminin in the context of replication origin licensing.

Effects of poly(L-lysine), poly(acrylic acid) and poly(ethylene glycol) on the adhesion, proliferation and chondrogenic differentiation of human mesenchymal stem cells

Microenvironments, composed of many kinds of cytokines and growth factors plus extracellular matrices with diverse electrostatic properties, play key roles in controlling cell functions in vivo. In this study, three kinds of water-soluble polymers, positively charged poly(L-lysine) (PLL), negatively charged poly(acrylic acid) (PAAc) and neutral poly(ethylene glycol) (PEG), were compared based on their effects on the adhesion, spread, proliferation and chondrogenic differentiation of human mesenchymal stem cells (MSCs). The MSCs were seeded and cultured in the presence of polymers of different concentrations applied by methods using coating, mixing or covering. The effects of the water-soluble polymers depended on their electrostatic properties and method of application. The methods were in the order of coating, mixing and covering in terms of high to low influence. A low concentration of PLL promoted MSC adhesion, spread, proliferation and chondrogenic differentiation, while a high concentration of PLL was toxic. The PEG-coated surface facilitated cell aggregation and spheroid formation by inhibiting cell adhesion. A high concentration of mixed PEG (10 microg/ml) promoted cell proliferation in serum-free medium. PAAc showed no obvious effects on MSC adhesion, spread, proliferation, or chondrogenic differentiation.

Defining the roles of inflammatory and anabolic cytokines in cartilage metabolism

In osteoarthritis (OA), adult articular chondrocytes undergo phenotypic modulation in response to alterations in the environment owing to mechanical injury and inflammation. These processes not only stimulate the production of enzymes that degrade the cartilage matrix but also inhibit repair. With the use of in vitro and in vivo models, new genes, not known previously to act in cartilage, have been identified and their roles in chondrocyte differentiation during development and in dysregulated chondrocyte function in OA have been examined. These new genes include growth arrest and DNA damage (GADD)45beta and the epithelial-specific ETS (ESE)-1 transcription factor, induced by bone morphogenetic protein (BMP)-2 and inflammatory cytokines, respectively. Both genes are induced by NF-kappaB, suppress COL2A1 and upregulate matrix meatalloproteinase-13 (MMP-13) expression. These genes have also been examined in mouse models of OA, in which discoidin domain receptor 2 is associated with MMP-13-mediated remodelling, in order to understand their roles in physiological cartilage homoeostasis and joint disease.

SOX9 transduction of a human chondrocytic cell line identifies novel genes regulated in primary human chondrocytes and in osteoarthritis

The transcription factor SOX9 is important in maintaining the chondrocyte phenotype. To identify novel genes regulated by SOX9 we investigated changes in gene expression by microarray analysis following retroviral transduction with SOX9 of a human chondrocytic cell line (SW1353). From the results the expression of a group of genes (SRPX, S100A1, APOD, RGC32, CRTL1, MYBPH, CRLF1 and SPINT1) was evaluated further in human articular chondrocytes (HACs). First, the same genes were investigated in primary cultures of HACs following SOX9 transduction, and four were found to be similarly regulated (SRPX, APOD, CRTL1 and S100A1). Second, during dedifferentiation of HACs by passage in monolayer cell culture, during which the expression of SOX9 progressively decreased, four of the genes (S100A1, RGC32, CRTL1 and SPINT1) also decreased in their expression. Third, in samples of osteoarthritic (OA) cartilage, which had decreased SOX9 expression compared with age-matched controls, there was decreased expression of SRPX, APOD, RGC32, CRTL1 and SPINT1. The results showed that a group of genes identified as being upregulated by SOX9 in the initial SW1353 screen were also regulated in expression in healthy and OA cartilage. Other genes initially identified were differently expressed in isolated OA chondrocytes and their expression was unrelated to changes in SOX9. The results thus identified some genes whose expression appeared to be linked to SOX9 expression in isolated chondrocytes and were also altered during cartilage degeneration in osteoarthritis.

Control of chondrogenesis by the transcription factor Sox9

Cell-fate determination of pluripotent cells, cell proliferation, differentiation, and maturation, as well as the maintenance of stem cells, are essential cellular events during organogenesis. Previous reports show that some distinct cell-specific transcription factors are the master genes that control cell lineage commitment and the subsequent cell proliferation and differentiation. Some of these transcription factors generate hierarchical regulation of expression and act in concert to fulfill their roles. This review discusses the molecular properties and mechanisms of Sry-related high-mobility-group box (Sox) transcription factor, Sox9, in chondrogenesis.

Hoxd13 binds in vivo and regulates the expression of genes acting in key pathways for early limb and skeletal patterning

5' HoxD genes are required for the correct formation of limb skeletal elements. Hoxd13, the most 5'-located HoxD gene, is important for patterning the most distal limb region, and its mutation causes human limb malformation syndromes. The mechanisms underlying the control of developmental processes by Hoxd13, and by Hox genes in general, are still elusive, due to the limited knowledge on their direct downstream target genes. We identified by ChIP-on-chip 248 known gene loci bound invivo by Hoxd13. Genes relevant to limb patterning and skeletogenesis were further analysed. We found that Hoxd13 binds invivo, in developing limbs, the loci of Hand2, a gene crucial to limb AP axis patterning, of Meis1 and Meis2, involved in PD patterning, of the Sfrp1, Barx1, and Fbn1 genes, involved in skeletogenesis, and of the Dach1, Bmp2, Bmp4, andEmx2 genes. We show that Hoxd13 misexpression in developing chick limbs alters the expression of the majority of these genes, supporting the conclusion that Hoxd13 directly regulates their transcription. Our results indicate that 5' Hox proteins regulate directly both key genes for early limb AP and PD axis patterning and genes involved, at later stages, in skeletal patterning.

Ectopic SOX9 mediates extracellular matrix deposition characteristic of organ fibrosis

Appropriate temporospatial expression of the transcription factor SOX9 is important for normal development of a wide range of organs. Here, we show that when SOX9 is expressed ectopically, target genes become expressed that are associated with disease. Histone deacetylase inhibitors in clinical trials for cancer therapy induced SOX9 expression via enhanced recruitment of nuclear factor Y (NF-Y) to CCAAT elements in the SOX9 proximal promoter. The effect of histone deacetylase inhibitors could be elicited in cells that normally lack SOX9, such as hepatocytes. In human fetal hepatocytes, this aberrant induction of SOX9 protein caused ectopic expression of COL2A1 and COMP1 that encode extracellular matrix (ECM) components normally associated with chondrogenesis. Previously, ectopic expression of this "chondrogenic" profile has been implicated in vascular calcification. More broadly, inappropriate ECM deposition is a hallmark of fibrosis. We demonstrated that induction of SOX9 expression also occurred during activation of fibrogenic cells from the adult liver when the transcription factor was responsible for expression of the major component of fibrotic ECM, type 1 collagen. These combined data identify new aspects in the regulation of SOX9 expression. They support a role for SOX9 beyond normal development as a transcriptional regulator in the pathology of fibrosis.

SOX9cre1, a cis-acting regulatory element located 1.1 Mb upstream of SOX9, mediates its enhancement through the SHH pathway

SOX9 is a temporal and tissue-specific transcription factor involved in male sexual development and bone formation. Haploinsufficiency of SOX9 is known to cause campomelic dysplasia (CD). CD cases without SOX9 coding region mutations have been described in association with translocations that have breakpoints mapping as far as 932 kb upstream from the gene. These rearrangements suggest that position effects acting from a great distance regulate SOX9 gene expression. Studies of one such case (900 kb upstream to SOX9) have led to the delineation of a potential 2.1 kb cis-acting regulatory element 1.1 Mb upstream of SOX9, termed SOX9cre1. We investigated the role of this putative regulator in SOX9 expression. SOX9cre1 increases the activity of a minimal SOX9 promoter in reporter constructs in a dose-dependent and tissue-specific manner, consistent with an enhancer role. In silico studies identify a putative binding site within SOX9cre1 for GLI1, a downstream mediator of sonic hedgehog (SHH). Furthermore, the stimulation of primary human chondrocyte cells in culture with SHH increases endogenous SOX9 expression 3-fold. Electrophoresis mobility shift assay (EMSA) studies that demonstrate physical interactions between the GLI1 transcription factor and a putative binding site within SOX9cre1, as well as experiments in which reporter constructs are co-transfected with GLI1, suggest a direct interaction between GLI1 and SOX9cre1. GLI1-SOX9cre1 interactions are verified in chromatin immunoprecipitation experiments. These data support a direct molecular link between the Hh signaling pathway and SOX9 regulation, wherein SHH stimulates SOX9 through its mediator GLI1, and are consistent with a mechanism of SOX9 regulation through distal chromatin interactions.

Igf-I extends the chondrogenic potential of human articular chondrocytes in vitro: Molecular association between Sox9 and Erk1/2

Expansion of articular chondrocytes in monolayer culture leads to loss of the unique chondrocyte phenotype and the cells' redifferentiation capacity. Dedifferentiation of chondrocytes in monolayer culture is a challenging problem for autologous chondrocyte transplantation (ACT). It is well established that Igf-I exerts positive anabolic effects on chondrocytes in vivo and in vitro. Accordingly, in this study, we examined whether the anabolic insulin-like growth factor-I (Igf-I) is capable of extending the chondrogenic potential of dedifferentiated chondrocytes in vitro. Chondrocyte monolayers were cultured up to 10 passages. At each passage chondrocytes were stimulated with Igf-I (10ng/ml) and introduced to high-density cultures for up to 7 days. Expression of collagen type II, cartilage-specific proteoglycans, activated caspase-3, integrin beta1, extracellular signal-regulated kinase (Erk) and Sox9 was examined by Western blotting, immunoprecipitation and immunomorphological techniques. Monolayer chondrocytes rapidly lost their differentiated phenotype. When introduced to high-density cultures, only chondrocytes from P1-P4 redifferentiated. In contrast, Igf-I treated cells from P1 up to P7 redifferentiated and formed cartilage-like tissue in high-density culture. P8-P10 cells exhibited apoptotic alterations and produced significantly less matrix. Igf-I markedly increased expression of integrin beta1, Erk and Sox9. Immunoprecipitation revealed that phosphorylated Erk1/2 physically interacts with Sox9 in chondrocyte nuclei, suggesting a previously unreported functional association which was markedly enhanced by Igf-I. Treatment of chondrocyte cultures with Igf-I stabilizes chondrogenic potential, stimulates Sox9 and promotes molecular interactions between Erk and Sox9. These effects appear to be regulated by the integrin/MAPK signaling pathways.

Comparison of the chondrosarcoma cell line SW1353 with primary human adult articular chondrocytes with regard to their gene expression profile and reactivity to IL-1beta

OBJECTIVE

In this study, the human chondrosarcoma cell line SW1353 was investigated by gene expression analysis in order to validate it as an in vitro model for primary human (adult articular) chondrocytes (PHCs).

METHODS

PHCs and SW1353 cells were cultured as high density monolayer cultures with and without 1ng/ml interleukin-1beta (IL-1beta). RNA was isolated and assayed using a custom-made oligonucleotide microarray representing 312 chondrocyte-relevant genes. The expression levels of selected genes were confirmed by real-time polymerase chain reaction and the gene expression profiles of the two cell types, both with and without IL-1beta treatment, were compared.

RESULTS

Overall, gene expression profiling showed only very limited similarities between SW1353 cells and PHCs at the transcriptional level. Similarities were predominantly seen with respect to catabolic effects after IL-1beta treatment. In both cell systems matrix metalloproteinase-1 (MMP-1), MMP-3 and MMP-13 were strongly induced by IL-1beta, without significant induction of MMP-2. IL-6 was also found to be up-regulated by IL-1beta in both cellular models. On the other hand, intercellular mediators such as leukemia inhibitory factor (LIF) and bone morphogenetic protein-2 (BMP-2) were not induced by IL-1beta in SW1353 cells, but significantly up-regulated in PHCs. Bioinformatical analysis identified nuclear factor kappa-B (NFkappaB) as a common transcriptional regulator of IL-1beta induced genes in both SW1353 cells and PHCs, whereas other transcription factors were only found to be relevant for individual cell systems.

CONCLUSION

Our data characterize SW1353 cells as a cell line with only a very limited potential to mimic PHCs, though SW1353 cells can be of value to study the induction of protease expression within cells, a phenomenon also seen in chondrocytes.

Secrets to a healthy Sox life: lessons for melanocytes

Sox proteins are transcriptional regulators with a high-mobility-group domain as sequence-specific DNA-binding domain. For function, they generally require other transcription factors as partner proteins. Sox proteins furthermore affect DNA topology and may shape the conformation of enhancer-bound multiprotein complexes as architectural proteins. Recent studies suggest that Sox proteins are tightly regulated in their expression by many signalling pathways, and that their transcriptional activity is subject to post-translational modification and sequestration mechanisms. Sox proteins are thus ideally suited to perform their many different functions as transcriptional regulators throughout mammalian development. Their unique properties also cause Sox proteins to escape detection in many standard transcription assays. In melanocytes, studies have so far focused on the Sox10 protein which functions both during melanocyte specification and at later times in the melanocyte lineage. During specification, Sox10 activates the Mitf gene as the key regulator of melanocyte development. At later stages, it ensures cell-type specific expression of melanocyte genes such as Dopachrome tautomerase. Both activities require cooperation with transcriptional partner proteins such as Pax-3, CREB and eventually Mitf. If predictions can be made from other cell lineages, further functions of Sox proteins in melanocytes may still lie ahead.

Promotion of the intrinsic damage-repair response in articular cartilage by fibroblastic growth factor-2

OBJECTIVE

To identify the effect of fibroblastic growth factor-2 (FGF-2) on the intrinsic damage-repair response in articular cartilage in vitro.

METHODS

Articular equine cartilage explants, without subchondral bone, had a single impact load of 500 g applied from a height of 2.5 cm. Explants were then cultured in 0, 12, 25, 50 or 100 ng/ml FGF-2 for up to 28 days. Unimpacted discs served as controls for each time-point. Histological and immunohistochemical techniques were used to quantify and characterise the response of putative chondrocyte progenitor cells (CPC) to damage and FGF-2 treatment.

RESULTS

FGF-2 significantly accelerated the appearance and increased the numbers of de novo repair cells identified histologically at the cartilage surface. The response was affected by the dose of FGF-2. The repair cells were shown to be chondrocytes by their expression of collagen types II, IX/XI, but not of type I collagen. In addition, these cells, and those underlying the articular surface, were shown to be immunopositive for Notch-1 and PCNA, markers for proliferating cartilage progenitor cells.

CONCLUSIONS

The results of this study indicate that, following single impact load, CPC can be stimulated in mature articular cartilage in vitro. These CPC and the cells arising from them appear to represent the cartilage's response to damage. The timing of the appearance of CPC and their overall numbers can be significantly increased by FGF-2, providing further evidence for an important role for FGF-2 in modulating cartilage repair. These results indicate that further study into the mechanisms of repair in mature cartilage using this in vitro model are vital in understanding the repair capacity of mature cartilage.

Genetics of chondrosarcoma and related tumors

PURPOSE OF REVIEW

The burgeoning body of information on the genetic changes present in and underlying the development and biology of human cancers has carried implications regarding the possible genetic events that are responsible for not only the genesis of these cancers but also the hope of the cure for these cancers. Chondrosarcomas are a group of tumors that fall into this category. The purpose of this review is to summarize the genetic findings in these tumors.

RECENT FINDINGS

The histopathologic variability of chondrosarcomas is reflected in the complexity and lack of specificity of their cytogenetic and molecular genetic findings, except for extraskeletal myxoid chondrosarcomas. These are characterized in the preponderant number of cases by a translocation, t(9;22)(q22;q12), and in a small number of cases by variant translocations t(9;17)(q22;q11) and t(9;15)(q22;q21). These translocations lead to the formation of abnormal fusion genes and gene products (proteins). In each of these translocations, the CHN gene is involved, resulting in the chimeric fusion genes EWS/CHN, RBP56/CHN, and TCF12/CHN, respectively. The specific translocations and their associated molecular genetic changes are diagnostic of extraskeletal myxoid chondrosarcomas. The abnormal proteins resulting from these fusion genes aberrantly affect gene transcription and cellular signaling pathways thought to be responsible for initiating sarcoma formation. In skeletal (central) chondrosarcomas of varying histopathologic types, the cytogenetic and molecular genetic findings are variable, complex, and apparently lacking in specificity. These changes may reflect a stepwise process (or processes) of oncogenesis involving an array of genes.

SUMMARY

Although some cartilaginous tumors are characterized by specific or recurrent chromosome alterations and molecular genetic changes, much is yet to be learned about the nature and sequence of these genetics events and about their unique role in the stepwise process involved in the development and biology of each tumor type, both malignant and nonmalignant. Until such time, some of the genetic changes, particularly the presence of specific translocations, can be of definite diagnostic value.

Growth factor combination for chondrogenic induction from human mesenchymal stem cell

During the last decade, many strategies for cartilage engineering have been emerging. Stem cell induction is one of the possible approaches for cartilage engineering. The mesenchymal stem cells (MSCs) with their pluripotency and availability have been demonstrated to be an attractive cell source. It needs the stimulation with cell growth factors to make the multipluripotent MSCs differentiate into chondrogenic lineage. We have shown particular patterns of in vitro chondrogenesis induction on human bone marrow MSCs (hBMSCs) by cycling the growth factors. The pellet cultures of hBMSCs were prepared for chondrogenic induction. Growth factors: TGF-beta3, BMP-6, and IGF-1 were used in combination for cell induction. Gene expression, histology, immunohistology, and real-time PCR methods were measured on days 21 after cell induction. As shown by histology and immunohistology, the induced cells have shown the feature of chondrocytes in their morphology and extracellular matrix in both inducing patterns of combination and cycling induction. Moreover, the real-time PCR assay has shown the expression of gene markers of chondrogenesis, collagen type II and aggrecan. This study has demonstrated that cartilage tissue can be created from bone marrow mesenchymal stem cells. Interestingly, the combined growth factors TGF-beta3 and BMP-6 or TGF-beta3 and IGF-1 were more effective for chondrogenesis induction as shown by the real-time PCR assay. The combination of these growth factors may be the important key for in vitro chondrogenesis induction.

Chondrosarcoma cell differentiation

A mixed population of lymphocytes from a healthy donor co-existed with an established culture of allogeneic chondrosarcoma cells, during which time the tumor cells changed from malignantly transformed to benign fibroblast-like morphology; from multilayered to a monolayered growth pattern; lost their potency to grow in colonies in soft agar; and showed signs of senescence. A discussion of possible molecular mechanisms for this event is offered. If there are as yet undiscovered lymphokines that can induce reversal of the malignant geno/phenotype, the cognate gene(s) should be cloned for genetic engineering and for the mass production of the corresponding molecular mediators for clinical trials.

Turning on the male – SRY, SOX9 and sex determination in mammals

The decision of the bi-potential gonad to develop into either a testis or ovary is determined by the presence or absence of the Sex-determining Region gene on the Y chromosome (SRY). Since its discovery, almost 13 years ago, the molecular role that SRY plays in initiating the male sexual development cascade has proven difficult to ascertain. While biochemical studies of clinical mutants and mouse genetic models have helped in our understanding of SRY function, no direct downstream targets of SRY have yet been identified. There are, however, a number of other genes of equal importance in determining sexual phenotype, expressed before and after expression of SRY. Of these, one has proven of central importance to mammals and vertebrates, SOX9. This review describes our current knowledge of SRY and SOX9 structure and function in the light of recent key developments.