A 3D hydrogel loaded with exosomes derived from bone marrow stem cells promotes cartilage repair in rats by modulating immunological microenvironment / 南方医科大学学报

OBJECTIVE@#To assess the efficacy of GelMA hydrogel loaded with bone marrow stem cell-derived exosomes for repairing injured rat knee articular cartilage.@*METHODS@#The supernatant of cultured bone marrow stem cells was subjected to ultracentrifugation separate and extract the exosomes, which were characterized by transmission electron microscopy, particle size analysis and Western blotting of the surface markers. The changes in rheology and electron microscopic features of GelMA hydrogel were examined after loading the exosomes. We assessed exosome release from the hydrogel was detected by BCA protein detection method, and labeled the exosomes with PKH26 red fluorescent dye to observe their phagocytosis by RAW264.7 cells. The effects of the exosomes alone, unloaded hydrogel, and exosome-loaded hydrogel on the polarization of RAW264.7 cells were detected by q-PCR and immunofluorescence assay. We further tested the effect of the exosome-loaded hydrogel on cartilage repair in a Transwell co-culture cell model of RAW264.7 cells and chondrocytes in a rat model of knee cartilage injury using q-PCR and immunofluorescence assay and HE and Masson staining.@*RESULTS@#GelMA hydrogel loaded with exosomes significantly promoted M2-type polarization of RAW264.7 cells (P < 0.05). In the Transwell co-culture model, the exosome-loaded GelMA hydrogel significantly promoted the repair of injured chondrocytes by regulating RAW264.7 cell transformation from M1 to M2 (P < 0.05). HE and Masson staining showed that the exosome-loaded hydrogel obviously promoted cartilage repair in the rat models damage.@*CONCLUSION@#GelMA hydrogel loaded with bone marrow stem cell-derived exosomes can significantly promote the repair of cartilage damage in rats by improving the immune microenvironment.

IRE1α deficiency impairs autophagy in chondrocytes by upregulating calcium homeostasis endoplasmic reticulum protein / 南方医科大学学报

OBJECTIVE@#To explore the mechanism by which inositol-requiring enzyme-1α (IRE1α) regulates autophagy function of chondrocytes through calcium homeostasis endoplasmic reticulum protein (CHERP).@*METHODS@#Cultured human chondrocytes (C28/I2 cells) were treated with tunicamycin, 4μ8c, rapamycin, or both 4μ8c and rapamycin, and the expressions of endoplasmic reticulum (ER) stress- and autophagy-related proteins were detected with Western blotting. Primary chondrocytes from ERN1 knockout (ERN1 CKO) mice and wild-type mice were examined for ATG5 and ATG7 mRNA expressions, IRE1α and p-IRE1α protein expressions, and intracellular calcium ion content using qPCR, Western blotting and flow cytometry. The effect of bafilomycin A1 treatment on LC3 Ⅱ/LC3 Ⅰ ratio in the isolated chondrocytes was assessed with Western blotting. Changes in autophagic flux of the chondrocytes in response to rapamycin treatment were detected using autophagy dual fluorescent virus. The changes in autophagy level in C28/I2 cells overexpressing CHERP and IRE1α were detected using immunofluorescence assay.@*RESULTS@#Tunicamycin treatment significantly up-regulated ER stress-related proteins and LC3 Ⅱ/LC3 Ⅰ ratio and down-regulated the expression of p62 in C28/I2 cells (P < 0.05). Rapamycin obviously up-regulated LC3 Ⅱ/LC3 Ⅰ ratio (P < 0.001) in C28/I2 cells, but this effect was significantly attenuated by co-treatment with 4μ8c (P < 0.05). Compared with the cells from the wild-type mice, the primary chondrocytes from ERN1 knockout mice showed significantly down-regulated mRNA levels of ERN1 (P < 0.01), ATG5 (P < 0.001) and ATG7 (P < 0.001), lowered or even lost expressions of IRE1α and p-IRE1α proteins (PP < 0.01), and increased expression of CHERP (P < 0.05) and intracellular calcium ion content (P < 0.001). Bafilomycin A1 treatment obviously increased LC3 Ⅱ/ LC3 Ⅰ ratio in the chondrocytes from both wild-type and ERN1 knockout mice (P < 0.01 or 0.05), but the increment was more obvious in the wild-type chondrocytes (P < 0.05). Treatment with autophagy dual-fluorescence virus resulted in a significantly greater fluorescence intensity of LC3-GFP in rapamycin-treated ERN1 CKO chondrocytes than in wild-type chondrocytes (P < 0.05). In C28/I2 cells, overexpression of CHERP obviously decreased the fluorescence intensity of LC3, and overexpression of IRE1α enhanced the fluorescence intensity and partially rescued the fluorescence reduction of LC3 caused by CHERP.@*CONCLUSION@#IRE1α deficiency impairs autophagy in chondrocytes by upregulating CHERP and increasing intracellular calcium ion content.

Histone demethylase JMJD3 downregulation protects against aberrant force-induced osteoarthritis through epigenetic control of NR4A1 / 国际口腔科学杂志·英文版

Osteoarthritis (OA) is a prevalent joint disease with no effective treatment strategies. Aberrant mechanical stimuli was demonstrated to be an essential factor for OA pathogenesis. Although multiple studies have detected potential regulatory mechanisms underlying OA and have concentrated on developing novel treatment strategies, the epigenetic control of OA remains unclear. Histone demethylase JMJD3 has been reported to mediate multiple physiological and pathological processes, including cell differentiation, proliferation, autophagy, and apoptosis. However, the regulation of JMJD3 in aberrant force-related OA and its mediatory effect on disease progression are still unknown. In this work, we confirmed the upregulation of JMJD3 in aberrant force-induced cartilage injury in vitro and in vivo. Functionally, inhibition of JMJD3 by its inhibitor, GSK-J4, or downregulation of JMJD3 by adenovirus infection of sh-JMJD3 could alleviate the aberrant force-induced chondrocyte injury. Mechanistic investigation illustrated that aberrant force induces JMJD3 expression and then demethylates H3K27me3 at the NR4A1 promoter to promote its expression. Further experiments indicated that NR4A1 can regulate chondrocyte apoptosis, cartilage degeneration, extracellular matrix degradation, and inflammatory responses. In vivo, anterior cruciate ligament transection (ACLT) was performed to construct an OA model, and the therapeutic effect of GSK-J4 was validated. More importantly, we adopted a peptide-siRNA nanoplatform to deliver si-JMJD3 into articular cartilage, and the severity of joint degeneration was remarkably mitigated. Taken together, our findings demonstrated that JMJD3 is flow-responsive and epigenetically regulates OA progression. Our work provides evidences for JMJD3 inhibition as an innovative epigenetic therapy approach for joint diseases by utilizing p5RHH-siRNA nanocomplexes.

Kindlin-2 loss in condylar chondrocytes causes spontaneous osteoarthritic lesions in the temporomandibular joint in mice / 国际口腔科学杂志·英文版

The progressive destruction of condylar cartilage is a hallmark of the temporomandibular joint (TMJ) osteoarthritis (OA); however, its mechanism is incompletely understood. Here, we show that Kindlin-2, a key focal adhesion protein, is strongly detected in cells of mandibular condylar cartilage in mice. We find that genetic ablation of Kindlin-2 in aggrecan-expressing condylar chondrocytes induces multiple spontaneous osteoarthritic lesions, including progressive cartilage loss and deformation, surface fissures, and ectopic cartilage and bone formation in TMJ. Kindlin-2 loss significantly downregulates the expression of aggrecan, Col2a1 and Proteoglycan 4 (Prg4), all anabolic extracellular matrix proteins, and promotes catabolic metabolism in TMJ cartilage by inducing expression of Runx2 and Mmp13 in condylar chondrocytes. Kindlin-2 loss decreases TMJ chondrocyte proliferation in condylar cartilages. Furthermore, Kindlin-2 loss promotes the release of cytochrome c as well as caspase 3 activation, and accelerates chondrocyte apoptosis in vitro and TMJ. Collectively, these findings reveal a crucial role of Kindlin-2 in condylar chondrocytes to maintain TMJ homeostasis.

Microenvironmental stiffness mediates cytoskeleton re-organization in chondrocytes through laminin-FAK mechanotransduction / 国际口腔科学杂志·英文版

Microenvironmental biophysical factors play a fundamental role in controlling cell behaviors including cell morphology, proliferation, adhesion and differentiation, and even determining the cell fate. Cells are able to actively sense the surrounding mechanical microenvironment and change their cellular morphology to adapt to it. Although cell morphological changes have been considered to be the first and most important step in the interaction between cells and their mechanical microenvironment, their regulatory network is not completely clear. In the current study, we generated silicon-based elastomer polydimethylsiloxane (PDMS) substrates with stiff (15:1, PDMS elastomer vs. curing agent) and soft (45:1) stiffnesses, which showed the Young's moduli of ~450 kPa and 46 kPa, respectively, and elucidated a new path in cytoskeleton re-organization in chondrocytes in response to changed substrate stiffnesses by characterizing the axis shift from the secreted extracellular protein laminin β1, focal adhesion complex protein FAK to microfilament bundling. We first showed the cellular cytoskeleton changes in chondrocytes by characterizing the cell spreading area and cellular synapses. We then found the changes of secreted extracellular linkage protein, laminin β1, and focal adhesion complex protein, FAK, in chondrocytes in response to different substrate stiffnesses. These two proteins were shown to be directly interacted by Co-IP and colocalization. We next showed that impact of FAK on the cytoskeleton organization by showing the changes of microfilament bundles and found the potential intermediate regulators. Taking together, this modulation axis of laminin β1-FAK-microfilament could enlarge our understanding about the interdependence among mechanosensing, mechanotransduction, and cytoskeleton re-organization.

Identification of new human mesenchymal stem cell biomarker by aptamers / Identificação de novos biomarcadores de células tronco mesenquimais de origem humana por meio de aptâmeros

Stem cells are undifferentiated cells that can be distinguished from others by their ability to self-renew and to differentiate into new specific cell types. Mesenchymal stem cells (MSC) are adult stem cells that can be obtained from different sources, such as adipose tissue, bone marrow, dental pulp, and umbilical cord. They can either replicate, originating new identical cells, or differentiate into cells of mesodermal origin and from other germ layers. MSC have been studied as new tools for regenerative therapy. Although encouraging results have been demonstrated, MSC-based therapies still face a great barrier: the difficulty of isolating these cells from heterogeneous environments. MSC are currently characterized by immunolabelling through a set of multiple surface membrane markers, including CD29, CD73, CD90 and CD105, which are also expressed by other cell types. Hence, the present work aimed to identify new specific biomarkers for the characterization of human MSC using DNA aptamers produced by the SELEX (Systematic Evolution of Ligands by EXponential Enrichment) technique. Our results showed that MSC from different origins bound to DNA candidate aptamers, that is, DNA or RNA oligonucleotides selected from random libraries that bind specifically to biological targets. Aptamer-bound MSC could be isolated by fluorescenceactivated cell sorting (FACS) procedures, enhancing the induction of differentiation into specific phenotypes (chondrocytes, osteocytes and adipocytes) when compared to the whole MSC population. Flow cytometry analyses revealed that candidate aptamers bound to 50% of the MSC population from dental pulp and did not present significant binding rates to human fibroblasts or lymphocytes, both used as negative control. Moreover, immunofluorescence images and confocal analyses revealed staining of MSC by aptamers localized in the surfacemembrane of these cells. The results also showed internal staining of human monocytes by our investigated aptamers. A non-specific control aptamer (CNTR APT) obtained from the random pool was then utilized to compare the specificity of the aptamers bound to the analyzed non-apoptotic cells, showing no staining for MSC. However, 40% of the monocytes bound to the CNTR APT. Normalized data based on the cells bound to candidate aptamers compared to those bound to the CNTR APT, revealed a 10 to 16-fold higher binding rate for MSC against 2-fold for monocytes. Despite its low specificity, monocyte-aptamer binding occurs probably due to the expression of shared markers with MSC, since monocytes are derived from hematopoietic stem cells and are important for the immune system ability to internalize/phagocyte external molecules. Given that, we performed a pull-down assay followed by mass spectrometry analysis to detect which MSC-specific protein or other target epitope not coexpressed by monocytes or the CNTR APT would bind to the candidate aptamer. Distinguishing between MSC and monocyte epitopes is important, as both cells are involved in immunomodulatory effects after MSC transplantations. ADAM17 was found to be a target of the APT10, emerging as a possible biomarker of MSC, since its involvement in the inhibition of the TGF signaling cascade, which is responsible for the differentiation of MSC. Thus, MSC with a higher stemness profile should overexpress the protein ADAM17, which presents a catalytic site with affinity to APT10. Another target of Apt 10 is VAMP3, belonging to a transmembrane protein complex that is involved in endocytosis and exocytosis processes during immune and inflammatory responses. Overall, proteins identified as targets of APT10 may be cell surface MSC biomarkers, with importance for MSC-based cell and immune therapies

Células tronco são células indiferenciadas que podem ser distinguidas de outros tipos celulares por meio da habilidade de se auto renovarem e de se diferenciarem em novos tipos celulares. Células tronco mesenquimais (MSC) são células tronco adultas encontradas em diferentes tecidos como tecido adiposo, polpa de dente e cordão umbilical. Estas células podem se autodividir em células idênticas ou se diferenciarem em células de origem mesodermal. Estas células têm sido estudadas em novas aplicações que envolvem terapia regenerativas. Embora resultados encorajadores tenham sido demonstrados, terapias que utilizam MSC ainda encontram uma grande barreira: a dificuldade no isolamento destas células a partir de um ambiente heterogêneo. MSC são caracterizadas por populações positivas em ensaios de imunomarcação para os epítopos membranares CD29, CD73, CD90 e CD105, presentes também em outros tipos celulares. Assim, o presente trabalho tem o objetivo de identificar novos biomarcadores de MSC de origem humana, utilizando aptâmeros de DNA produzidos pela técnica SELEX (Systematic Evolution of Ligands by EXponential Enrichment) como ferramenta. Nossos resultados mostraram que MSC de diferentes origens ligam-se a aptâmeros (oligonucleotídeos de DNA ou RNA que atuam como ligantes específicos de alvos moleculares) de DNA candidatos que atuam no isolamento de MSC por meio da técnica FACS de separação celular, promovendo uma maior indução de diferenciação em células específicas (condrócitos, osteócitos e adipócitos) comparada com a população total de MSC. Análises de citometria de fluxo mostraram que os aptâmeros candidatos se ligam a 50% das MSC de polpa de dente e não apresentam taxa de ligação significante para fibroblastos e linfócitos de origem humana - utilizados como controles negativo. Além domais, imagens de imunofluorescência e confocal mostraram ligação na superfície da membrana de MSC e a marcação interna de monócitos a estes aptâmeros. Portanto, um aptâmero controle (CNTR APT) foi utilizado para comparar a especificidade dos aptâmeros ligados a células viáveis, mostrando a não ligação deste aptâmero a MSC. Porém, 40% da população de monócitos ligou-se ao CNTR APT. Uma normalização baseada na comparação entre as taxas de ligação entre células ligadas com aptâmeros candidatos e o aptâmero controle gerou uma taxa de especificidade entre 10-16 vezes maior para MSC contra 2,5 vezes para os monócitos. Deste modo, embora os resultados tenham mostrado uma taxa de ligação entre monócitos e aptâmeros, as MSC ligadas aos aptâmeros candidatos possuem uma maior taxa de especificidade devido a uma maior presença de antígenos que são expressos em ambas as células. Um ensaio de Pull Down seguido de espectrometria de massas foi utilizado para a identificação de biomarcadores que se ligariam aos aptâmeros candidatos, e que não seriam co-expressos por monócitos e por antígenos ligados ao aptâmero controle. Deste modo, a proteína ADAM17 foi identificada nas amostras de APT10 ligadas às MSC. Tal proteína está relacionada à inibição de uma cascata de sinalização da família de proteínas TGF, responsável pela diferenciação de MSC. Assim, MSC com maior potencial tronco deveriam expressar ADAM17 em maior quantidade. Tal proteína apresenta um sítio catalítico que demonstra interagir com o APT10, de acordo com predição Docking entre proteína e DNA. Foi identificada também, a proteína VAMP3, que pertence a um complexo proteico transmembranar responsável pelos processos de endocitose e exocitose, e que podem ter um papel importante na liberação de citocinas e outras moléculas relacionadas às respostas imune e inflamatórias. Deste modo, o APT10 identificou proteínas importantes que devem estar relacionas com a melhora de imunoterapias que utilizam MSC

Effect of needle knife on mTOR/Atg/ULK1/Beclin-1 axis and chondrocyte autophagy in rats with knee osteoarthritis / 中国针灸

OBJECTIVE@#To observe the effect of needle knife on chondrocyte autophagy and expressions of autophagy-related protein and mammalian target of rapamycin (mTOR) in rats with knee osteoarthritis (KOA), and to explore the possible mechanism of needle knife for KOA.@*METHODS@#A total of 42 SD rats were randomly divided into a normal group, a model group and a needle knife group, 14 rats in each group. Except for the normal group, the other two groups were injected with the mixture of papain and L-cysteine into the left hind knee joint to establish the KOA model. After modeling, the rats in the needle knife group were treated with needle knife at strip or nodule around the quadriceps femoris and medial and lateral collateral ligament on the affected side, once a week for 3 times (3 weeks). The changes of left knee circumference in each group were observed; the chondrocytes and ultrastructure of left knee joint were observed by HE staining and electron microscope; the mRNA and protein expressions of autophagy-related genes (Atg5, Atg12, Atg4a), Unc-51 like autophagy activated kinase 1 (ULK1), autophagy gene Beclin-1 and mTOR in left knee cartilage were detected by real-time fluorescence quantitative PCR and Western blot.@*RESULTS@#After modeling, the left knee circumferences in the model group and the needle knife group were increased compared with those before modeling and in the normal group (P<0.05); after intervention, the left knee circumference in the needle knife group was smaller than that in the model group and after modeling (P<0.05). Compared with the normal group, the number of chondrocytes was decreased, and a few cells swelled, nuclei shrank, mitochondria swelled and autophagosomes decreased in the model group; compared with the model group, the number of chondrocytes was increased , and most cell structures returned to normal, and autophagosomes was increased. Compared with the normal group, the mRNA and protein expressions of Atg5, Atg12, Atg4a, Beclin-1 and ULK1 in the knee cartilage in the model group were decreased (P<0.05); compared with the model group, the expressions of the above indexes in the needle knife group were increased (P<0.05). Compared with the normal group, the mRNA and protein expressions of mTOR in the knee cartilage in the model group were increased (P<0.05); compared with the model group, the expressions of the above indexes in the needle knife group were decreased (P<0.05).@*CONCLUSION@#The needle knife intervention could improve knee cartilage injury in rats with KOA, and its mechanism may be related to reducing the expression of mTOR and up-regulating the expressions of Atg5, Atg12, Atg4a, ULK1 and Beclin-1, so as to promote chondrocyte autophagy and delay the aging and degeneration of chondrocytes.

Treatment of Chondral Knee Lesions with Autologous Chondrocytes Embedded in a Fibrin Scaffold. Clinical and Functional Assessment / Tratamento de lesões condrais no joelho com condrócitos autólogos embebidos em arcabouço de fibrina. Avaliação clínica e funcional

Abstract Objective The aim of our study is to analyze the clinical and functional results obtained using autologous chondrocytes embedded in a fibrin scaffold in knee joint injuries. Methods We included 56 patients, 36 men and 20 women, with a mean age 36 years. Six of the patients were professional athletes, with single knee injuries that were either chondral or osteochondral (43 chondral, 9 osteochondral, 2 cases of osteochondritis dissecans and 2 osteochondral fractures), 2 to 10 cm2 in size and ≤ 10 mm deep, with no signs of osteoarthritis. The location of the injury was in the patella (8), the medial femoral condyle (40) and lateral femoral condyle (7) and one in the trochlea. The mean follow-up was 3 (range: 1-6) years. The clinical course was assessed using the Cincinnati and Knee Injury and Osteoarthritis Outcome (KOOS) scores, 6 and 12 months after surgery. The paired Student t-test was used to compare pre-and postoperative results. Results Six months after the implant, patients resumed their everyday activities. On the assessment scores, their condition was improving in comparison with their presurgical state (p < 0.05). They were also able to carry out their sporting activities more easily than prior to surgery (p < 0.05). Conclusion The seeding of chondrocytes in fibrin may provide a favorable microenvironment for the synthesis of extracellular matrix and improved the clinical condition and activity of the patients 1 year after surgery.

Resumo Objetivo O objetivo do nosso estudo é analisar os resultados clínicos e funcionais do tratamento de lesões nas articulações do joelho com condrócitos autólogos embebidos em arcabouço de fibrina. Métodos O estudo foi realizado com 56 pacientes (36 homens e 20 mulheres) com idade média de 36 anos; 6 indivíduos eram atletas profissionais. Os pacientes apresentavam lesões únicas, condrais ou osteocondrais (43 condrais, nove osteocondrais, 2 casos de osteocondrite dissecante e duas fraturas osteocondrais) no joelho, com 2 a 10 cm2 de tamanho e ≤ 10 mm de profundidade, sem sinais de osteoartrite. As lesões estavam localizadas na patela (8), no côndilo femoral medial (40), no côndilo femoral lateral (7) e na tróclea (1). O período médio de acompanhamento foi de 3 anos (faixa de 1-6 anos). A evolução clínica foi avaliada pelos escores de Cincinnati e Knee Injury and Osteoarthritis Outcome (KOOS), 6 e 12 meses após a cirurgia. O teste t de Student pareado foi utilizado para comparação dos achados pré e pós-operatórios. Resultados Os pacientes retomaram suas atividades diárias 6 meses após o implante. Os escores avaliados demonstraram a melhora em comparação ao estado pré-cirúrgico (p < 0,05). Além disso, os pacientes conseguiram realizar suas atividades esportivas com mais facilidade do que antes da cirurgia (p < 0,05). Conclusão A cultura de condrócitos em fibrina pode proporcionar um microambiente favorável para a síntese de matriz extracelular e melhorar a condição clínica e a atividade dos pacientes 1 ano após a cirurgia

Mangiferin attenuates IL / 中南大学学报(医学版)

OBJECTIVES@#Chondrocyte apoptosis is an important process in the pathogenesis of osteoarthritis. Mangiferin exerts multiple pharmacological effects such as anti-inflammatory and anti-apoptosis. However, the role of mangiferin in chondrocyte apoptosis is not clear. In this study, we aimed to explore the role of mangiferin in IL-1β-induced chondrocyte apoptosis.@*METHODS@#ATDC5 cells were randomly divided into a control group, a IL-1β group, a MFN-L group, a MFN-M group, a MFN-H group and a MFN+LY294002 group. Cells in the control group were treated with IL-1β (10 ng/mL) for 24 h; cells in the MFN-L group, the MFN-M group and the MFN-H group were pretreated with 5, 10 and 20 μmol/L mangiferin for 1 h respectively, and then they were treated with IL-1β (10 ng/mL) for 24 h; cells in the MFN+LY294002 group were treated with LY294002 (25 μmol/L) for 1 h, then mangiferin (20 μmol/L) and IL-1β (10 ng/mL) for 1 h and 24 h, respectively. Cell viability was detected by CCK-8 assay and cell apoptosis was measured by flow cytometry. Colorimetric assay was conducted to measure the caspase-3 activity. The protein levels of Bcl-2, Bax, and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway related proteins were detected by Western blotting.@*RESULTS@#Compared to the control group, cell viability was significantly decreased; cell apoptosis, caspase-3 activity and Bax protein expression were significantly increased; the protein levels of Bcl-2, p-PI3K, and p-Akt were significantly decreased in the IL-1β group (all @*CONCLUSIONS@#Mangiferin could attenuate IL-1β-induced apoptosis of the mice chondrocytes, which is mediated by the activation of PI3K/Akt signaling pathway.

Repair of osteoarthritis in animal model with exosomes derived from BMSCs transfected by the siRNA -Piezo1 through CT navigation / 中国骨伤

OBJECTIVE@#To investigate the effect of the exosomes from bone marrow mesenchymal stem cells (BMSCs) transfected with silence plasmid of Piezol small interference RNA (siRNA)on osteoarthritis (OA) animal model.@*METHODS@#Twenty male SD rats with specific pathogen free (SPF) were selected, ranging in age from 5.46 to 6.96 months, with a mean of (6.21± 0.75) months;and ranging in weight from 385.76 g to 428.66 g, with a mean of (407.21±21.45) g. BMSCs were extracted. The siRNA silencing plasmid of piezo1 was constructed by siRNA technology. After lentivirus was transfected into BMSCs, the exosomes were extracted. At the cellular level, BMSCs were divided into blank plasmid group and siRNA silencing plasmid group according to whether siRNA-Piezo1 was transfected or not. The osteogenic induction ability of siRNA-Piezo1 on BMSCs was detected by RT-PCR and Western blot. At the animal model level, the OA model was established by surgical resection of cruciate ligament of knee joint.According to different treatment schemes, SD rats were divided into 4 groups:blank control group, model group, BMSCs group and exosome group. SD rats in the blank control group were not treated. In the model group, the cruciate ligaments of rats were excised and OA animal model was established. In BMSCs group, BMSCs were injected into knee joint under CT guidance after OA model establishment, and the cell volume was 5×10@*RESULTS@#The lentivirus transfection efficiency was(92.11±4.22)%. RT-PCR showed that the relative expression of Piezo1 mRNA in blank plasmid group was 1.07±0.06, which was significantly different from that of 0.31±0.01 in siRNA silencing plasmid group (@*CONCLUSION@#Piezo1 siRNA silencing vector can promote the differentiation of BMSCs into chondrocytes and effectively inhibit the progression of OA, so as to delay the disease of OA.

Research progression in the pathogenesis of osteoarthritis / 中国骨伤

Osteoarthritis(OA) is one of the most common joint diseases. As Chinese society enters the age of aging, the incidence of OA has been soar year by year, and research on its pathogenesis has been continuously valued by researchers. Studies have found that inflammatory cytokines, mainly interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), were responsible for the construction of OA inflammatory networks. It was also found that the overexpression of proteases, mainly matrix metalloproteinases(MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), was the direct cause of OA cartilage deficiency. What's more, signaling pathways such as stromal cell derived factor-1 (SDF-1) and Wnt, chondrocytic senescence and the senescence-associated secretory phenotype (SASP), chondrocyte apoptosis and autophagy, and estrogen all play significant roles in OA pathogenesis. This paper extensively reviews the research literature relevant to the pathogenesis of OA in recent years, and systematically expounds the pathogenesis of OA from two aspects:molecular level and cell level. At the end of the paper, we discussed and predicted some potential directions in the future clinical diagnosis and treatment of OA.

Effect of 17β-estradiol on the proliferation of condylar chondrocytes / 华西口腔医学杂志

OBJECTIVES@#To study the effects of 17β-estradiol (E2) on the regulation of the proliferation of condylar chondrocytes and provide a preliminary discussion on the role of phosphorylate-mammalian target of rapamycin (p-mTOR) in this regulatory process.@*METHODS@#Condylar chondrocytes were isolated from 6-week-old female rats for primary culture. Drug treatment with different concentrations of E2 and/or rapamycin (RAPA) was carried out on second-generation cells. Cell Counting Kit 8 was used to measure the cell viability of condylar chondrocytes after culture for 24, 48, or 72 h, and reverse transcription-polymerase chain reaction (RT-PCR) was applied to detect the relative gene expression of estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), collagen type Ⅱ (COLⅡ), autophagy-related gene 6 (Beclin-1), and autophagy-related gene 5 (ATG-5). Western blot was employed to determine the relative protein expression of ERα, ERβ, Beclin-1, lipid-modified light chain 3B (LC3-Ⅱ), and p-mTOR.@*RESULTS@#E2 could significantly promote the proliferation of chondrocytes cultured @*CONCLUSIONS@#At a concentration of 10

Research advances in cartilage stem cells markers and induced differentiation / 华西口腔医学杂志

Cartilage stem cells (CSCs) are cells that self-proliferate, have surface antigen expression, and have multidirectional differentiation potential in the articular cartilage. CSCs, as an ideal source of stem cells, has a good application prospect in stem cell therapy. This article reviews the CSCs markers, cartilage differentiation signaling pathway, and clinical treatment of osteoarthritis.

Effects of HDAC4 on IL-1β-induced matrix metalloproteinase expression regulated partially through the WNT3A/β-catenin pathway / 中华医学杂志(英文版)

BACKGROUND@#Histone deacetylase 4 (HDAC4) regulates chondrocyte hypertrophy and bone formation. The aim of the present study was to explore the effects of HDAC4 on Interleukin 1 beta (IL-1β)-induced chondrocyte extracellular matrix degradation and whether it is regulated through the WNT family member 3A (WNT3A)/β-catenin signaling pathway.@*METHODS@#Primary chondrocytes (CC) and human chondrosarcoma cells (SW1353 cells) were treated with IL-1β and the level of HDAC4 was assayed using Western blotting. Then, HDAC4 expression in the SW1353 cells was silenced using small interfering RNA to detect the effect of HDAC4 knockdown on the levels of matrix metalloproteinase 3 (MMP3) and MMP13 induced by IL-1β. After transfection with HDAC4 plasmids, the overexpression efficiency was examined using Real-time quantitative polymerase chain reaction (qRT-PCR) and the levels of MMP3 and MMP13 were assayed using Western blotting. After incubation with IL-1β, the translocation of β-catenin into the nucleus was observed using immunofluorescence staining in SW1353 cells to investigate the activation of the WNT3A/β-catenin signaling pathway. Finally, treatment with WNT3A and transfection with glycogen synthase kinase 3 beta (GSK3β) plasmids were assessed for their effects on HDAC4 levels using Western blotting.@*RESULTS@#IL-1β downregulated HDAC4 levels in chondrocytes and SW1353 cells. Furthermore, HDAC4 knockdown increased the levels of MMP3 and MMP13, which contributed to the degradation of the extracellular matrix. Overexpression of HDAC4 inhibited IL-1β-induced increases in MMP3 and MMP13. IL-1β upregulated the levels of WNT3A, and WNT3A reduced HDAC4 levels in SW1353 cells. GSK-3β rescued IL-1β-induced downregulation of HDAC4 in SW1353 cells.@*CONCLUSION@#HDAC4 exerted an inhibitory effect on IL-1β-induced extracellular matrix degradation and was regulated partially by the WNT3A/β-catenin signaling pathway.

Histological analysis of elastic cartilages treated with alkaline solution / Análise histológica de cartilagens elásticas tratadas com solução alcalina

The elastic cartilage is composed by chondroblasts and chondrocytes, extracellular matrix and surrounded by perichondrium. It has a low regeneration capacity and is a challenge in surgical repair. One of obstacles in engineering a structurally sound and long-lasting tissue is selecting the most appropriate scaffold material. One of the techniques for obtaining biomaterials from animal tissues is the decellularization that decreases antigenicity. In this work, alkaline solution was used in bovine ear elastic cartilages to evaluate the decellularization and the architecture of the extracellular matrix. The cartilages were treated in alkaline solution (pH13) for 72 hours and lyophilized to be compared with untreated cartilages by histological analysis (hematoxylin-eosin, Masson's trichrome and Verhoeff slides). Areas of interest for cell counting and elastic fiber quantification were delineated, and the distribution of collagen and elastic fibers and the presence of non-fibrous proteins were observed. The results demonstrated that the alkaline solution caused 90% decellularization in the middle and 13% in the peripheral region, and maintenance of the histological characteristics of the collagen and elastic fibers and non-fibrous protein removal. It was concluded that the alkaline solution was efficient in the decellularization and removal of non-fibrous proteins from the elastic cartilages of the bovine ear.(AU)

A cartilagem elástica é composta por condroblastos e condrócitos, matriz extracelular e envolta por pericôndrio. Possui uma baixa capacidade de regeneração e é um desafio em reparos cirúrgicos. Um dos obstáculos na engenharia de tecido estruturalmente sólido e de longa duração é a seleção do material de arcabouço mais adequado. Uma das técnicas para obtenção de biomateriais oriundos de tecidos animais é a descelularização, que diminui a antigenicidade. Neste trabalho, foi utilizada solução alcalina em cartilagem elástica auricular bovina para avaliar a descelularização e a arquitetura da matriz extracelular. As cartilagens foram tratadas em solução alcalina (pH13) durante 72 horas e liofilizadas, e comparadas com cartilagens não tratadas por análise histológica (hematoxilina-eosina, tricrômio de Masson e Verhoeff). Foram determinadas as áreas de interesse para contagem celular e quantificação de fibras elásticas, observada a distribuição de colágeno e fibras elásticas e a presença de proteínas não fibrosas. Os resultados demonstraram que a solução alcalina causou 90% de descelularização na região central e 13% na região periférica, manutenção das características histológicas do colágeno e fibras elásticas e remoção das proteínas não fibrosas. Concluiu-se que a solução alcalina foi eficiente na descelularização e retirada de proteínas não fibrosas de cartilagens elásticas da orelha de bovinos.(AU)

Research of inflammatory factors and signaling pathways in knee osteoarthritis / 中国骨伤

Knee osteoarthritis is the most common type of arthritis, which is manifested by the deformation and degeneration of articular cartilage and the discomfort of patients with joint pain, which affects the quality of life of patients and aggravates the medical burden of society. The pathogenesis of knee osteoarthritis is very complex. This paper reviews the inflammatory factors and signal pathways involved in knee osteoarthritis. It is found that most of the inflammatory factors involved are interleukin, such as IL-1 β, IL-6, IL-15, IL-17, IL-18, and tumor necrosis factors, such as TNF-α. These inflammatory factors aggravate knee osteoarthritisby activating corresponding pathways and promoting the release of inflammatory mediators. The inflammatory signaling pathways involved in knee osteoarthritis are complex. Notch pathway, Wnt pathway, SDF-1 / CXCR4 pathway, TLRs pathway, MAPKs pathway, hippo Yap pathway, OPG-RANK-RANKL pathway and TGF-β pathway are all involved in the regulation of knee osteoarthritis, and the pathways related to inflammatory mechanism are mainly MAPKs pathway and TLRs pathway. Different signaling pathways can cause the destruction of articular cartilage, promote the apoptosis of chondrocytes, and finally lead to the further imbalance of homeostasis in the knee joint. At the same time, the activation of signal pathway can promote the release of inflammatory factors, so under the cascade reaction of inflammatory factors and signal pathway, knee osteoarthritis is aggravating.

Chondrocyte cocultures with stromal vascular fraction of adipose tissue promote cartilage regeneration in vivo / 华西口腔医学杂志

OBJECTIVE@#This study aimed to compare the cartilage regeneration of the stromal vascular fraction (SVF) cells and adipose-derived mesenchymal stem cells (ASCs) cocultured with chondrocytes seeded on the scaffolds.@*METHODS@#The cellular morphologies and proliferation capabilities on the scaffolds were evaluated. The scaffolds with the cocul-ture of ASCs/SVF and chondrocytes were implanted into the full thickness cartilage defective rabbit joints for 10 weeks.@*RESULTS@#The cells seeded into the scaffolds showed good adhesion and proliferation. Implantation with SVF and chondrocytes revealed desirable in vitro healing outcomes.@*CONCLUSIONS@#The SVF cells were better than ASCs in terms of the formation of cartilage matrix in a coimplantation model. Without in vitro expansion, the SVF cells are good cell sources for cartilage repair.

Effect of quercetin on chondrocyte phenotype and extracellular matrix expression / 中国天然药物

Due to the poor repair ability of cartilage tissue, regenerative medicine still faces great challenges in the repair of large articular cartilage defects. Quercetin is widely applied as a traditional Chinese medicine in tissue regeneration including liver, bone and skin tissues. However, the evidence for its effects and internal mechanisms for cartilage regeneration are limited. In the present study, the effects of quercetin on chondrocyte function were systematically evaluated by CCK8 assay, PCR assay, cartilaginous matrix staining assays, immunofluorescence assay, and western blotting. The results showed that quercetin significantly up-regulated the expression of chondrogenesis genes and stimulated the secretion of GAG (glycosaminoglycan) through activating the ERK, P38 and AKT signalling pathways in a dose-dependent manner. Furthermore, in vivo experiments revealed that quercetin-loaded silk protein scaffolds dramatically stimulated the formation of new cartilage-like tissue with higher histological scores in rat femoral cartilage defects. These data suggest that quercetin can effectively stimulate chondrogenesis in vitro and in vivo, demonstrating the potential application of quercetin in the regeneration of cartilage defects.

Research progress on long non-coding RNA (lncRNA) in osteoarthritis / 中国骨伤

Osteoarthritis(OA) is a common clinical disease. The incidence of OA increases significantly with age, and the quality of life of patients is seriously affected. In the pathogenesis of OA, cartilage degeneration is the main cause. There are many long non-coding RNA (lncRNA) specifically expressed in osteoarthritis, which is closely related to the occurrence and development of osteoarthritis. Based on the latest research from 2014 to 2019, this paper summarizes the differential expression of lncRNA in osteoarthritis, the mechanism of lncRNA regulating chondrocyte function, and the mechanism of lncRNA regulating cartilage matrix metabolism. The fact that the expression of lncRNA is altered at different stages of OA development indicates that lncRNA can be developed forlife. The biomarkers and therapeutic targets can provide reference for the prevention, treatment and research of osteoarthritis.

Research progress of different mechanical stimulation regulating chondrocytes metabolism / 生物医学工程学杂志

As a kind of mechanical effector cells, chondrocytes can produce a variety of physical and chemical signals under the stimulation of multiaxial load