| 1. |
- Florea, Cristina, et al.
(författare)
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A combined experimental atomic force microscopy-based nanoindentation and computational modeling approach to unravel the key contributors to the time-dependent mechanical behavior of single cells
- 2017
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Ingår i: Biomechanics and Modeling in Mechanobiology. - : Springer Berlin/Heidelberg. - 1617-7959 .- 1617-7940. ; 16:1, s. 297-311
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Tidskriftsartikel (refereegranskat)abstract
- Cellular responses to mechanical stimuli are influenced by the mechanical properties of cells and the surrounding tissue matrix. Cells exhibit viscoelastic behavior in response to an applied stress. This has been attributed to fluid flow-dependent and flow-independent mechanisms. However, the particular mechanism that controls the local time-dependent behavior of cells is unknown. Here, a combined approach of experimental AFM nanoindentation with computational modeling is proposed, taking into account complex material behavior. Three constitutive models (porohyperelastic, viscohyperelastic, poroviscohyperelastic) in tandem with optimization algorithms were employed to capture the experimental stress relaxation data of chondrocytes at 5 % strain. The poroviscohyperelastic models with and without fluid flow allowed through the cell membrane provided excellent description of the experimental time-dependent cell responses (normalized mean squared error (NMSE) of 0.003 between the model and experiments). The viscohyperelastic model without fluid could not follow the entire experimental data that well (NMSE = 0.005), while the porohyperelastic model could not capture it at all (NMSE = 0.383). We also show by parametric analysis that the fluid flow has a small, but essential effect on the loading phase and short-term cell relaxation response, while the solid viscoelasticity controls the longer-term responses. We suggest that the local time-dependent cell mechanical response is determined by the combined effects of intrinsic viscoelasticity of the cytoskeleton and fluid flow redistribution in the cells, although the contribution of fluid flow is smaller when using a nanosized probe and moderate indentation rate. The present approach provides new insights into viscoelastic responses of chondrocytes, important for further understanding cell mechanobiological mechanisms in health and disease.
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| 2. |
- Karhula, Sakari, et al.
(författare)
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Effects of articular cartilage constituents on phosphotungstic acid enhanced micro-computed tomography
- 2017
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Contrast-enhanced micro-computed tomography (CEμCT) with phosphotungstic acid (PTA) has shown potential for detecting collagen distribution of articular cartilage. However, the selectivity of the PTA staining to articular cartilage constituents remains to be elucidated. The aim of this study was to investigate the dependence of PTA for the collagen content in bovine articular cartilage. Adjacent bovine articular cartilage samples were treated with chondroitinase ABC and collagenase to degrade the proteoglycan and the collagen constituents in articular cartilage, respectively. Enzymatically degraded samples were compared to the untreated samples using CEμCT and reference methods, such as Fourier-transform infrared imaging. Decrease in the X-ray attenuation of PTA in articular cartilage and collagen content was observed in cartilage depth of 0-13% and deeper in tissue after collagen degradation. Increase in the X-ray attenuation of PTA was observed in the cartilage depth of 13-39% after proteoglycan degradation. The X-ray attenuation of PTA-labelled articular cartilage in CEμCT is associated mainly with collagen content but the proteoglycans have a minor effect on the X-ray attenuation of the PTA-labelled articular cartilage. In conclusion, the PTA labeling provides a feasible CEμCT method for 3D characterization of articular cartilage.
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| 3. |
- Arasu, Uma Thanigai, et al.
(författare)
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Human mesenchymal stem cells secrete hyaluronan-coated extracellular vesicles
- 2017
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Ingår i: Matrix Biology. - Amsterdam : Elsevier. - 0945-053X .- 1569-1802. ; 64, s. 54-68
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular vesicles (EVs) secreted by stem cells are potential factors mediating tissue regeneration. They travel from bone marrow stem cells into damaged tissues, suggesting that they can repair tissue injuries without directly replacing parenchymal cells. We have discovered that hyaluronan (HA) synthesis is associated with the shedding of HA-coated EVs. The aim of this study was to test whether bone marrow-derived hMSCs secrete HA-coated EVs. The EVs secreted by MSCs were isolated by differential centrifugation and characterized by nanoparticle tracking analysis. Their morphology and budding mechanisms were inspected by confocal microscopy and correlative light and electron microscopy. Hyaluronan synthesis of hMSCs was induced by lipopolysaccharide and inhibited by RNA interference and 4-methylumbelliferone. It was found that the MSCs have extremely long apical and lateral HA-coated filopodia, typical for cells with an active HA secretion. Additionally, they secreted HA-coated EVs carrying mRNAs for CD44 and all HAS isoforms. The results show that stem cells have a strong intrinsic potential for HA synthesis and EV secretion, and the amount of HA carried on EVs reflects the HA content of the original cells. These results show that the secretion of HA-coated EVs by hMSCs is a general process, that may contribute to many of the mechanisms of HA-mediated tissue regeneration. Additionally, an HA coat on EVs may regulate their interactions with target cells and participate in extracellular matrix remodeling.
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| 4. |
- Chang, Yanhai, et al.
(författare)
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Inflammatory cytokine of IL-1β is involved in T-2 toxin-triggered chondrocyte injury and metabolism imbalance by the activation of Wnt/β-catenin signaling
- 2017
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Ingår i: Molecular Immunology. - : Elsevier. - 0161-5890 .- 1872-9142. ; 91, s. 195-201
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Tidskriftsartikel (refereegranskat)abstract
- Mycotoxin T-2 exerts a causative role in Kashin-Beck disease (KBD) suffering chondrocyte apoptosis and cartilage matrix homeostasis disruption. Recent research corroborated the aberrant levels of pro-inflammatory cytokine IL-1ß in KBD patients and mycotoxin environment. In the present study, we investigated the relevance of IL-1ß in T-2 toxin-evoked chondrocyte cytotoxic injury and aberrant catabolism. High levels of IL-1ß were detected in serum and cartilages from KBD patients and in T-2-stimulated chondrocytes. Moreover, knockdown of IL-1ß antagonized the adverse effects of T-2 on cytotoxic injury by enhancing cell viability and inhibiting apoptosis. However, exogenous supplementation of IL-1β further aggravated cell damage in response to T-2. Additionally, cessation of IL-1β rescued T-2-elicited tilt of matrix homeostasis toward catabolism by elevating the transcription of collagen II and aggrecan, promoting release of sulphated glycosaminoglycans (sGAG) and TIMP1, and suppressing matrix metalloproteinases production including MMP-1, MMP-3 and MMP-13. Conversely, IL-1β stimulation deteriorated T-2-induced disruption of matrix metabolism balance toward catabolism. Mechanistic analysis found the high activation of Wnt/β-catenin in KBD patients and chondrocytes upon T-2. Furthermore, this activation was mitigated after IL-1β inhibition, but further enhanced following IL-1β precondition. Importantly, blocking this pathway by transfection with β-catenin alleviated the adverse roles of IL-1β on cytotoxic injury and metabolism disorders under T-2 conditioning. Together, this study elucidates a new insight into how T-2 deteriorates the pathological progression of KBD by regulating inflammation-related pathways, indicating a promising anti-inflammation strategy for KBD therapy.
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| 5. |
- Guo, Xiong, et al.
(författare)
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Kashin-Beck Disease (KBD)
- 2017
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Ingår i: Endemic disease in China. - Beijing : People's Medical Publishing House. - 9787117247139 ; , s. 150-211
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Bokkapitel (refereegranskat)
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| 6. |
- Han, Jing, et al.
(författare)
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Altered expression of chondroitin sulfate structure modifying sulfotransferases in the articular cartilage from adult osteoarthritis and Kashin-Beck disease
- 2017
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier. - 1063-4584 .- 1522-9653. ; 25:8, s. 1372-1375
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the expression of enzymes involved in chondroitin sulfate (CS) sulfation in the articular cartilage isolated from adult patients with osteoarthritis (OA) and Kashin-Beck disease (KBD), using normal adults as controls.METHODS: Articular cartilage samples were collected from normal, OA and KBD adults aged 38-60 years old, and divided into three groups with six individual subjects in each group. The morphology and pathology grading of knee joint cartilage was examined by Safranin O staining. The localization and expression of enzymes involved in CS sulfation (CHST-3, CHST-11, CHST-12, CHST-13, CHST-15, and UST) were examined by immunohistochemical staining and semi-quantitative analysis.RESULTS: Positive staining rates for anabolic enzymes CHST-3, CHST-12, CHST-15, and UST were lower in the KBD and OA groups than those in the control group. Meanwhile, reduced levels of CHST-11, and CHST-13 in KBD group were observed, in contrast to those in OA and control groups. The expressions of all six CS sulfation enzymes were less detected in the superficial and deep zones of KBD cartilage compared with control and OA cartilage.CONCLUSION: The reduced expression of the CS structure modifying sulfotransferases in the chondrocytes of both KBD and OA adult patients may provide explanations for their cartilage damages, and therapeutic targets for their treatment.
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| 7. |
- Jin, Zhan-Kui, et al.
(författare)
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Outcomes of total knee arthroplasty in the adult Kashin-Beck disease with severe osteoarthritis.
- 2019
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Ingår i: International Orthopaedics. - : Springer. - 0341-2695 .- 1432-5195. ; 43:2, s. 323-331
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Kashin-Beck disease (KBD) is an endemic osteoarthropathy, and the severe knee pain and functional limitations were seriously affecting the quality of life in patients with end-stage KBD. We retrospectively evaluated the clinical outcomes and the quality of life in KBD patients with total knee arthroplasty (TKA).METHODS: A total of 22 subjects (25 knees) suffered KBD with severe knee pain and underwent primary TKA. Knee pain was measured by visual analogue scale (VAS), and the knee function was evaluated by Knee Society Clinical Rating System Score (KSS). KBD Quality of Life (KBDQOL) was used to evaluate the quality of life in KBD patients before and after TKA.RESULTS: There were no major complications after TKA. The levels of VAS score were obviously deceased in post-operation than that in pre-operation. The levels of KSS score were increased in one year after TKA compared with the pre-operative values, and it maintained a higher level on three years after TKA. The average KBDQOL score level of each domain in pre-operation and one and three years after TKA was increased accordingly. The average scores of physical function, activity limitation, support of society, mental health, and general health in one year after TKA were significantly higher than those in pre-operation.CONCLUSIONS: TKA can reduce knee pain, improve knee function, and improve the quality life in KBD patients. KBDQOL questionnaire may be a promising instrument for assessing the quality life in KBD patients.
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| 8. |
- Karjalainen, Hannu, et al.
(författare)
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Chondrocytic cells express the taurine transporter on their plasma membrane and regulate its expression under anisotonic conditions
- 2015
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Ingår i: Amino Acids. - Vienna, Austria : Springer. - 0939-4451 .- 1438-2199. ; 47:3, s. 561-570
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Tidskriftsartikel (refereegranskat)abstract
- Taurine is a small organic osmolyte which participates in cell volume regulation. Chondrocytes have been shown to accumulate and release taurine; in bone, taurine participates in bone metabolism. However, its role in skeletal cells is poorly understood, especially in chondrocytes. This study investigated the regulation of taurine transporter in chondrocytic cells. We examined the transcriptional regulation of the taurine transporter under anisotonia by reporter gene and real-time RT-PCR assays. The effect of providing supplementary taurine on cell viability was evaluated with the lactate dehydrogenase release assay. The localization of the taurine transporter in human chondrosarcoma cells was studied by overexpressing a taurine transporter-enhanced green fluorescent protein. We observed that the transcription of the taurine transporter gene was up-regulated in hypertonic conditions. Hyperosmolarity-related cell death could be partly abolished by taurine supplementation in the medium. As expected, the fluorescently labeled taurine transporter localized at the plasma membrane. In polarized epithelial MDCK cells, the strongest fluorescence signal was located in the lateral cell membrane area. We also observed that the taurine transporter gene was expressed in several human tissues and malignant cell lines. This is the first study to present information on the transcriptional regulation of taurine transporter gene and the localization of the taurine transporter protein in chondrocytic cells.
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| 9. |
- Lammi, Mikko, 1961-, et al.
(författare)
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Challenges in fabrication of tissue-engineered cartilage with correct cellular colonization and extracellular matrix assembly
- 2018
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 19:9
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Forskningsöversikt (refereegranskat)abstract
- A correct articular cartilage ultrastructure regarding its structural components and cellularity is important for appropriate performance of tissue-engineered articular cartilage. Various scaffold-based, as well as scaffold-free, culture models have been under development to manufacture functional cartilage tissue. Even decellularized tissues have been considered as a potential choice for cellular seeding and tissue fabrication. Pore size, interconnectivity, and functionalization of the scaffold architecture can be varied. Increased mechanical function requires a dense scaffold, which also easily restricts cellular access within the scaffold at seeding. High pore size enhances nutrient transport, while small pore size improves cellular interactions and scaffold resorption. In scaffold-free cultures, the cells assemble the tissue completely by themselves; in optimized cultures, they should be able to fabricate native-like tissue. Decellularized cartilage has a native ultrastructure, although it is a challenge to obtain proper cellular colonization during cell seeding. Bioprinting can, in principle, provide the tissue with correct cellularity and extracellular matrix content, although it is still an open question as to how the correct molecular interaction and structure of extracellular matrix could be achieved. These are challenges facing the ongoing efforts to manufacture optimal articular cartilage.
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| 10. |
- Lammi, Mikko, 1961-, et al.
(författare)
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Selenium-related transcriptional regulation of gene expression
- 2018
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 19:9
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Forskningsöversikt (refereegranskat)abstract
- The selenium content of the body is known to control the expression levels of numerous genes, both so-called selenoproteins and non-selenoproteins. Selenium is a trace element essential to human health, and its deficiency is related to, for instance, cardiovascular and myodegenerative diseases, infertility and osteochondropathy called Kashin⁻Beck disease. It is incorporated as selenocysteine to the selenoproteins, which protect against reactive oxygen and nitrogen species. They also participate in the activation of the thyroid hormone, and play a role in immune system functioning. The synthesis and incorporation of selenocysteine occurs via a special mechanism, which differs from the one used for standard amino acids. The codon for selenocysteine is a regular in-frame stop codon, which can be passed by a specific complex machinery participating in translation elongation and termination. This includes a presence of selenocysteine insertion sequence (SECIS) in the 3'-untranslated part of the selenoprotein mRNAs. Nonsense-mediated decay is involved in the regulation of the selenoprotein mRNA levels, but other mechanisms are also possible. Recent transcriptional analyses of messenger RNAs, microRNAs and long non-coding RNAs combined with proteomic data of samples from Keshan and Kashin⁻Beck disease patients have identified new possible cellular pathways related to transcriptional regulation by selenium.
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