| 1. |
- Eerola, Iiro, et al.
(author)
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Type X collagen, a natural component of mouse articular cartilage : association with growth, aging, and osteoarthritis.
- 1998
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In: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 41:7, s. 1287-1295
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To perform a systematic study on the production and deposition of type X collagen in developing, aging, and osteoarthritic (OA) mouse articular cartilage.METHODS: Immunohistochemistry was employed to define the distribution of type X collagen and Northern analyses to determine the messenger RNA levels as an indicator of the synthetic activity of the protein.RESULTS: Type X collagen was observed in the epiphyseal and articular cartilage of mouse knee joints throughout development and growth. Type X collagen deposition in the transitional zone of articular cartilage became evident toward cessation of growth, at the age of 2-3 months. The most intense staining for type X collagen was limited to the tidemark, the border between uncalcified and calcified cartilage. Northern analysis confirmed that the type X collagen gene is also transcribed by articular cartilage chondrocytes. Intense immunostaining was observed in the areas of OA lesions, specifically, at sites of osteophyte formation and surface fibrillation. Type X collagen deposition was also seen in degenerating menisci.CONCLUSION: This study demonstrates that type X collagen is a natural component of mouse articular cartilage throughout development, growth, and aging. This finding and the deposition of type X collagen at sites of OA lesions suggest that type X collagen may have a role in providing structural support for articular cartilage.
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| 2. |
- Espanha, Maria, et al.
(author)
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Extracellular matrix composition of full-thickness defect repair tissue is little influenced by exercise in rat articular cartilage.
- 2001
-
In: Connective Tissue Research. - 0300-8207 .- 1607-8438. ; 42:2, s. 97-109
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Journal article (peer-reviewed)abstract
- Full-thickness articular cartilage defects in the femoral condyles of adult rats were examined four and eight weeks after injury. Quantitative polarized light microscopic analysis showed that birefringence of the tissue in the central repair area increased more in rats exercised on a treadmill. Glycosaminoglycan content in the repair tissue was also higher than in the intermittent active motion group at four weeks after injury, but by eight weeks the levels were similar in both groups. No normal-looking articular cartilage was formed in the lesions, and only in one animal type II collagen was observed in the superficial zone of repair tissue. No 3B3(-) antigenicity of the proteoglycans was seen during repair. In conclusion, exercise minimally modified the repair of full-thickness articular cartilage defects in adult rats. The repair in the exercised group may occur slightly faster in the early stages but no difference was seen at the eight week time interval between the exercised and the intermittently active group.
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| 3. |
- Florea, Cristina, et al.
(author)
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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
-
In: Biomechanics and Modeling in Mechanobiology. - : Springer Berlin/Heidelberg. - 1617-7959 .- 1617-7940. ; 16:1, s. 297-311
-
Journal article (peer-reviewed)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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| 4. |
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| 5. |
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| 6. |
- Karhula, Sakari, et al.
(author)
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Effects of articular cartilage constituents on phosphotungstic acid enhanced micro-computed tomography
- 2017
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:1
-
Journal article (peer-reviewed)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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| 7. |
- Kääpä, Eeva, et al.
(author)
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Elevated protein content and prolyl 4-hydroxylase activity in severely degenerated human annulus fibrosus.
- 2000
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In: Connective Tissue Research. - : Informa Healthcare. - 0300-8207 .- 1607-8438. ; 41:2, s. 93-99
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Journal article (peer-reviewed)abstract
- Alterations involved with the intervertebral disc degeneration are partly well described, however, it is not so well known how collagen network is affected by the disease. We analyzed the rate of collagen biosynthesis (estimated by the enzymic activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase) and the level of hydroxylysylpyridinoline and lysylpyridinoline crosslinks both in normal (n=7) and degenerated (n=7) human annulus fibrosus. The activity of prolyl 4-hydroxylase was significantly increased in degenerated tissue. However, no significant changes in the collagen content or in the amount of hydroxylysylpyridinoline and lysylpyridinoline collagen crosslinks were observed. On the other hand, the content of soluble proteins was significantly increased. Our results suggest that collagen biosynthesis is increased in degenerated human annulus fibrosus, obviously to compensate the impairment of collagen fibers. The faster turnover of collagen in degenerated annulus fibrosus, suggested by the increased prolyl 4-hydroxylase activity and unchanged collagen content, seems not to cause any significant changes in its mature pyridinium crosslink concentrations.
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| 8. |
- Lammi, Mikko, 1961-, et al.
(author)
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Undersulfated chondroitin sulfate does not increase in osteoarthritic cartilage.
- 2004
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In: Journal of Rheumatology. - : Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 31:12, s. 2449-2453
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To test whether there is undersulfation of chondroitin sulfate in osteoarthritic bovine articular cartilage to support the hypothesis that sulfate deficiency is involved with the development of osteoarthritis.METHODS: Cartilage samples from bovine patellae (n = 32) were divided into 3 groups based on their osteoarthritic progression, as assessed by modified Mankin score. Uronic acid contents of the samples were determined. Fragmentation of the proteoglycans due to proteolytic processing was estimated with agarose gel electrophoresis. The molar ratios of chondroitin sulfate isoforms in the extracted proteoglycans were determined with fluorophore-assisted carbohydrate electrophoresis.RESULTS: Loss of proteoglycans and accumulation of tissue water was evident in groups II and III, and progressive OA increased heterogeneity of aggrecan population in groups II and III. Importantly, the molar ratio of nonsulfated disaccharide was decreased in the osteoarthritic articular cartilage.CONCLUSION: The structure of chondroitin sulfate in degenerated bovine cartilage did not support the hypothesis that sulfate depletion is present in osteoarthritic joint.
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| 9. |
- Lammi, Pirkko, et al.
(author)
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Localization of type X collagen in the intervertebral disc of mature beagle dogs.
- 1998
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In: Matrix Biology. - : Elsevier. - 0945-053X .- 1569-1802. ; 17:6, s. 449-453
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Journal article (peer-reviewed)abstract
- Type X collagen expression in intervertebral disc of young adult beagle dogs (n = 10) was studied. Type X collagen was immunostained mainly pericellularly in the central area of the vertebral endplate, but interterritorial staining there was also present. Annulus fibrosus and nucleus pulposus did not usually stain for type X collagen. However, immunostaining of nucleus pulposus for type X collagen with a simultaneous expression of collagen alpha1(X) mRNA was observed in one dog. A weak staining was observed in two other animals with a weak collagen alpha1(X) mRNA signal. In annulus fibrosus, lamellar staining was observed in two dogs. In three animals, type X collagen mRNAs were observed in the outer edge of the annulus fibrosus, but immunohistochemical staining did not always correlate with in situ hybridization signals. In conclusion, intervertebral disc type X collagen was mainly expressed in the cartilaginous endplate. In some apparently healthy animals there was type X collagen expression in the nucleus pulposus and also in the annulus fibrosus.
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| 10. |
- Lammi, Pirkko, et al.
(author)
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Site-specific immunostaining for type X collagen in noncalcified articular cartilage of canine stifle knee joint.
- 2002
-
In: Bone. - : Elsevier. - 8756-3282 .- 1873-2763. ; 31:6, s. 690-696
-
Journal article (peer-reviewed)abstract
- Type X collagen is a short-chain collagen that is strongly expressed in hypertrophic chondrocytes. In this study, we used an immunohistochemical technique exploiting a prolonged hyaluronidase unmasking of type X collagen epitopes to show that type X collagen is not restricted to calcified cartilage, but is also present in normal canine noncalcified articular cartilage. A 30 degrees valgus angulation procedure of the right tibia was performed in 15 dogs at the age of 3 months, whereas their nonoperated sister dogs served as controls. Samples were collected 7 and 18 months after the surgery and immunostained for type X collagen. The deposition of type X collagen increased during maturation from age 43 weeks to 91 weeks. In the patella, most of the noncalcified cartilage stained for type X collagen, whereas, in the patellar surface of the femur, it was present mainly in the femoral groove close to cartilage surface. In femoral condyles, the staining localized mostly in the superficial cartilage on the lateral and medial sides, but not in the central weight-bearing area. In tibial condyles, type X collagen was often observed close to the cartilage surface in medial parts of the condyles, although staining could also be seen in the deep zone of the cartilage. Staining for type X collagen appeared strongest at sites where the birefringence of polarized light was lowest, suggesting a colocalization of type X collagen with the collagen fibril arcades in the intermediate zone. No significant difference in type X collagen immunostaining was observed in lesion-free articular cartilage between controls and dogs that underwent a 30 degrees valgus osteotomy. In osteoarthritic lesions, however, there was strong immunostaining for both type X collagen and collagenase-induced collagen cleavage products. The presence of type X collagen in the transitional zone of cartilage in the patella, femoropatellar groove, and in tibial cartilage uncovered by menisci suggests that it may involve a modification of collagen fibril arrangement at the site of collagen fibril arcades, perhaps providing additional support to the collagen network.
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| 11. |
- Lammi, Pirkko, et al.
(author)
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Strong hyaluronan expression in the full-thickness rat articular cartilage repair tissue.
- 2001
-
In: Histochemistry and Cell Biology. - : Springer. - 0948-6143 .- 1432-119X. ; 115:4, s. 301-308
-
Journal article (peer-reviewed)abstract
- Articular cartilage lesions have a poor capacity to regenerate. In full-depth articular cartilage defects, the repair process involves an ingrowth of mesenchymal cells from the bone marrow to the injured area, and these cells attempt to restore the lesion with cartilage-like repair tissue. In this study, we investigated histologically the distribution of hyaluronan in the rat repair tissue in relation to other glycosaminoglycans. Full-depth lesions were drilled to the weight-bearing region of rat medical femoral condyle. The rats were divided into two groups: intermittent active motion (IAM) and running training (RT) groups. In the RT group, programmed exercise was started 1 week after surgery, while the rats in the IAM group could move freely in their cages. The lesions were investigated 4 and 8 weeks after the surgery. Semiquantitative histological grading showed no significant differences in the repair between the groups. In normal articular cartilage, hyaluronan was stained mainly around chondrocytes. During repair, strong hyaluronan staining was observed in loose mesenchymal tissue, while in the repair area undergoing endochondral ossification, hyaluronan was intensively stained mainly around the hypertrophic chondrocytes. Remarkably strong staining for hyaluronan was noticed in areas of apparent mesenchymal progenitor cell invasion, the areas being simultaneously devoid of staining for keratan sulphate. In conclusion, hyaluronan is strongly expressed in the early cartilage repair tissue, and its staining intensity and distribution shows very sensitively abnormal articular cartilage structure.
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| 12. |
- Pulkkinen, Hertta, et al.
(author)
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Cellulose sponge as a scaffold for cartilage tissue engineering.
- 2006
-
In: Bio-medical materials and engineering. - : IOS Press. - 0959-2989 .- 1878-3619. ; 16:4 Suppl, s. S29-S35
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Journal article (peer-reviewed)abstract
- One goal of functional tissue engineering is to manufacture scaffolds infiltrated with chondrocytes which are suitable for transplantation into the lesion areas of articular cartilage. Various research strategies are used to fabricate cartilage transplants which would have the correct phenotype, contain enough extracellular matrix components, and have structural and biomechanical properties equivalent to normal articular cartilage. We have investigated the suitability of viscose cellulose sponges as a scaffold for cartilage tissue engineering. The sponges were tested alone, or with recombinant human type II collagen cross-linked inside the material. Scanning electron microscopy and confocal microscopy were used to study the structure of the scaffold during four weeks of cultivation. Cellulose and cellulose/recombinant type II collagen sponges were biocompatible for at least four weeks in cultivation, and gradual filling of the scaffold was observed. However, the constructs remained soft during the observation period, and were devoid of extracellular matrix composition typical for normal articular cartilage.
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| 13. |
- Qu, Chengjuan, 1967-, et al.
(author)
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Effects of freeze-thaw cycle with and without proteolysis inhibitors and cryopreservant on the biochemical and biomechanical properties of articular cartilage
- 2014
-
In: Cartilage. - : Sage Publications. - 1947-6035 .- 1947-6043. ; 5:2, s. 97-106
-
Journal article (peer-reviewed)abstract
- Objective: We investigated the effects of freeze-thawing on the properties of articular cartilage. Design: The reproducibility of repeated biomechanical assay of the same osteochondral sample was first verified with 11 patellar plugs from 3 animals. Then, 4 osteochondral samples from 15 bovine patellae were divided into 4 groups. The reference samples were immersed in phosphate-buffered saline (PBS) containing proteolysis inhibitors and biomechanically tested before storage for further analyses. Samples of group 1 were biomechanically tested before and after freeze-thawing in PBS in the absence and those of group 2 in the presence of inhibitors. Samples of the group 3 were biomechanically tested in PBS-containing inhibitors, but frozen in 30% dimethyl sulfoxide/PBS and subsequently tested in PBS supplemented with the inhibitors. Glycosaminoglycan contents of the samples and immersion solutions were analyzed, and proteoglycan structures examined with SDS-agarose gel electrophoresis. Results: Freeze-thawing decreased slightly dynamic moduli in all 3 groups. The glycosaminoglycan contents and proteoglycan structures of the cartilage were similar in all experimental groups. Occasionally, the diffused proteoglycans were partly degraded in group 1. Digital densitometry revealed similar staining intensities for the glycosaminoglycans in all groups. Use of cryopreservant had no marked effect on the glycosaminoglycan loss during freeze-thawing. Conclusion: The freeze-thawed cartilage samples appear suitable for the biochemical and biomechanical studies.
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| 14. |
- Riekkinen, Ossi, et al.
(author)
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Acoustic properties of trabecular bone–relationships to tissue composition.
- 2007
-
In: Ultrasound in Medicine and Biology. - : Elsevier. - 0301-5629 .- 1879-291X. ; 33:9, s. 1438-1444
-
Journal article (peer-reviewed)abstract
- In osteoporosis, changes in tissue composition and structure reduce bone strength and expose it to fractures. The current primary diagnostic technique, i.e., dual energy X-ray absorptiometry, measures areal bone mineral density (BMD) but provides no direct information on trabecular structure or organic composition. Although still poorly characterized, ultrasound techniques may bring about information on bone composition and structure. In this study, relationships of 2.25-MHz ultrasound speed, attenuation, reflection and backscattering with composition of human trabecular bone (n=26) were characterized experimentally, as well as by using numerical analyses. We also determined composition of the trabecular sample (fat and water content, bone volume fraction) and that of the calcified matrix (mineral, proteoglycan and collagen content of trabeculae). In experimental analyses, bone volume fraction and mineral content of the calcified matrix were the only determinants of BMD. Further, bone volume fraction served as the strongest determinant of ultrasound parameters (r=0.51-0.87). In numerical simulations, density and mechanical properties of the calcified matrix systematically affected ultrasound speed, attenuation, reflection and backscattering. However, partial correlation coefficients revealed only low associations(|r|
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| 15. |
- Saarakkala, Simo, et al.
(author)
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Ultrasound indentation of normal and spontaneously degenerated bovine articular cartilage.
- 2003
-
In: Osteoarthritis and Cartilage. - : Saunders Elsevier. - 1063-4584 .- 1522-9653. ; 11:9, s. 697-705
-
Journal article (peer-reviewed)abstract
- OBJECTIVE: We have previously developed a handheld ultrasound indentation instrument for the diagnosis of cartilage degeneration. The instrument has been demonstrated to be capable of quantifying mechanical and acoustic properties of enzymatically degraded and normal bovine articular cartilage in vitro and in situ. The aim of this study was to investigate the sensitivity of the instrument to distinguish between normal and spontaneously degenerated (e.g., in osteoarthrosis) articular cartilage in vitro.DESIGN: Thirty articular cartilage samples were prepared from the bovine lateral patellae: 19 patellae with different degenerative stages and 11 patellae with visually normal appearance. Cartilage thickness, stiffness (dynamic modulus) and ultrasound reflection from the cartilage surface were measured with the handheld instrument. Subsequently, biomechanical, histological and biochemical reference measurements were conducted.RESULTS: Reproducibility of the measurements with the ultrasound indentation instrument was good. Standardized coefficient of variation was < or =6.1% for thickness, dynamic modulus and reflection coefficient. Linear correlation between the dynamic modulus, measured with the ultrasound indentation instrument, and the reference dynamic modulus was high (r=0.993, n=30, P<0.05). Ultrasound reflection coefficient, as determined from the cartilage surface, showed high linear correlations (typically r(2)>0.64, n=30, P<0.05) with the cartilage composition and histological or mechanical properties. The instrument was superior compared to visual evaluation in detecting tissue degeneration.CONCLUSION: This study indicates that the ultrasound indentation technique and instrument may significantly improve the early diagnosis of cartilage degeneration. The results revealed that visual evaluation is insensitive for estimating the structural and mechanical properties of articular cartilage at the initial stages of degeneration.
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| 16. |
- Sahlman, Janne, et al.
(author)
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Premature vertebral endplate ossification and mild disc degeneration in mice after inactivation of one allele belonging to the Col2a1 gene for Type II collagen.
- 2001
-
In: Spine. - : Lippincott Williams & Wilkins. - 0362-2436 .- 1528-1159. ; 26:23, s. 2558-2565
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Journal article (peer-reviewed)abstract
- STUDY DESIGN: Skeletal tissues of mice with an inactivated allele of the Col2a1 gene for Type II collagen ("heterozygous knockout") were studied.OBJECTIVE: To determine whether a heterozygous inactivation of the Col2a1 gene has a role in the etiology of spine disorders such as disc degeneration.SUMMARY OF BACKGROUND DATA: Mutations in the COL2A1, COL11A1, COL11A2, and COL9A2 genes have been linked to spine disorders. However, the mechanism by which genetic factors lead to disc degeneration still are largely unknown.METHODS: Spine tissues were studied using radiograph analyses; conventional, quantitative, and polarized light microscopy; immunohistochemistry for the major extracellular components, and in situ hybridization for procollagens alpha1(I) and alpha1(II). Voluntary running activity also was monitored in half of the mice.RESULTS: As the findings showed, 1-month-old heterozygous knockout mice had shorter limb bones, skulls, and spines, as well as thicker and more irregular vertebral endplates, which calcified earlier than in the control mice. They also had a lower concentration of glycosaminoglycans in the anulus fibrosus, in the endplates, and in the vertebral bone than the controls. These features in the heterozygous knockout mice were compensated by the age of 15 months. However, the long bones and skulls of the mature heterozygous mice remained shorter than those of the controls. Gene-deficient mice used the running wheel less. However, physical exercise did not induce any marked structural changes in the skeleton.CONCLUSION: Mice with heterozygous knockout of Col2a1 show subtle early skeletal manifestations that bear some resemblance to those of human spine disorders.
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| 17. |
- Sierpowska, Joanna, et al.
(author)
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Effect of human trabecular bone composition on its electrical properties.
- 2007
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In: Medical Engineering and Physics. - : Elsevier. - 1350-4533 .- 1873-4030. ; 29:8, s. 845-852
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Journal article (peer-reviewed)abstract
- Mechanical properties of bone are determined not only by bone mineral density (BMD), but also by tissue trabecular structure and organic composition. Impedance spectroscopy has shown potential to diagnose trabecular bone BMD and strength, however, the relationships between organic composition and electrical and dielectric properties have not been systematically investigated. To investigate these issues organic composition of 26 human trabecular bone samples harvested from the distal femur and proximal tibia was determined and compared with relative permittivity, loss factor, conductivity, phase angle, specific impedance and dissipation factor measured at wide range (50 Hz to 5 MHz) of frequencies. A strong linear correlation was found between the relative permittivity at 1.2 MHz and trabecular bone fat content (r = -0.85, p<0.01, n=26). On the other hand, relative permittivity measured at 200 Hz served as a good predictor of water content (r = 0.83). Phase angle, specific impedance and especially conductivity were strongly related to the trabecular bone dry density and water content (|r| > or = 0.69). Variation in bone tissue collagen content was strongly related to the relative permittivity measured at 1.2 MHz (r = 0.64), but only moderately to other parameters. Glycosaminoglycan content showed no significant relations with any investigated electrical parameters. The present study indicates that if the trabecular bone composition is known, the relationships presented in this study could facilitate calculation of current field distribution, e.g. during electrical stimulation of osteogenesis. On the other hand, our results suggest that permittivity measured at low (<1 kHz) or high (>100 kHz) frequencies could be used, e.g. during implant surgery, for prediction of trabecular bone water or fat contents, respectively.
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| 18. |
- Töyräs, Juha, et al.
(author)
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Speed of sound in normal and degenerated bovine articular cartilage.
- 2003
-
In: Ultrasound in Medicine and Biology. - : Elsevier. - 0301-5629 .- 1879-291X. ; 29:3, s. 447-454
-
Journal article (peer-reviewed)abstract
- The unknown and variable speed of sound may impair accuracy of the acoustic measurement of cartilage properties. In this study, relationships between the speed of sound and cartilage composition, mechanical properties and degenerative state were studied in bovine knee and ankle cartilage (n = 62). Further, the effect of speed variation on the determination of cartilage thickness and stiffness with ultrasound (US) indentation was numerically simulated. The speed of sound was significantly (n = 32, p < 0.05) dependent on the cartilage water content (r = -0.800), uronic acid content (per wet weight, r = 0.886) and hydroxyproline content (per wet weight, r = 0.887, n = 28), Young's modulus at equilibrium (r = 0.740), dynamic modulus (r = 0.905), and degenerative state (i.e., Mankin score) (r = -0.727). In addition to cartilage composition, mechanical and acoustic properties varied significantly between different anatomical locations. In US indentation, cartilage is indented with a US transducer. Deformation and thickness of tissue are calculated using a predefined speed of sound and used in determination of dynamic modulus. Based on the simulations, use of the mean speed of sound of 1627 m/s (whole material) induced a maximum error of 7.8% on cartilage thickness and of 6.2% on cartilage dynamic modulus, as determined with the US indentation technique (indenter diameter 3 mm). We believe that these errors are acceptable in clinical US indentation measurements.
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| 19. |
- Vasara, Anna I, et al.
(author)
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Subchondral bone reaction associated with chondral defect and attempted cartilage repair in goats.
- 2004
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In: Calcified tissue international. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 74:1, s. 107-14
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Journal article (peer-reviewed)abstract
- Repair of cartilage damage with autologous chondrocyte transplantation (ACT) has become popular in clinical use during the past few years. Although clinical results have mostly been successful, several unanswered questions remain regarding the biological mechanism of the repair process. The aim of this study was to develop a goat model for ACT. The repair was not successful due to the graft delamination, but we characterize the subchondral changes seen after the procedure. A chondral lesion was created in 14 goat knees, operated on 1 month later with ACT, and covered with periosteum or a bioabsorbable poly-L/D-lactide scaffold. After 3 months, only two of the five lesions repaired with ACT showed partly hyaline-like repair tissue, and all lesions (n = 4) with the scaffold failed. Even though the lesions did not extend through the calcified cartilage, the bone volume and collagen organization of bone structure were decreased when assessed by quantitative polarized light microscopy. There was a significant loss of bone matrix and distortion of the trabecular structure of subchondral bone, which extended several millimeters into the bone. The subchondral bone demonstrated strong hyaluronan staining in the bone marrow and cartilaginous areas with signs of endochondral ossification, suggesting structural remodeling of the bone. The goat model used here proved not to be an optimal model for ACT. The changes in subchondral bone may alter the biomechanical properties of the subchondral plate and thus the long-term survival of the repair tissue after ACT.
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| 20. |
- Anerillas, Luis Oliveros, et al.
(author)
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Three-dimensional osteogenic differentiation of bone marrow mesenchymal stem cells promotes matrix metallopeptidase 13 (Mmp13) expression in type i collagen hydrogels
- 2021
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In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:24
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Journal article (peer-reviewed)abstract
- Autologous bone transplantation is the principal method for reconstruction of large bone defects. This technique has limitations, such as donor site availability, amount of bone needed and morbidity. An alternative to this technique is tissue engineering with bone marrow-derived mesenchymal stem cells (BMSCs). In this study, our aim was to elucidate the benefits of culturing BMSCs in 3D compared with the traditional 2D culture. In an initial screening, we combined BMSCs with four different biogels: unmodified type I collagen (Col I), type I collagen methacrylate (ColMa), an alginate and cellulose-based bioink (CELLINK) and a gelatin-based bioink containing xanthan gum (GelXA-bone). Col I was the best for structural integrity and maintenance of cell morphology. Osteogenic, adipogenic, and chondrogenic differentiations of the BMSCs in 2D versus 3D type I collagen gels were investigated. While the traditional pellet culture for chondrogenesis was superior to our tested 3D culture, Col I hydrogels (i.e., 3D) favored adipogenic and osteogenic differentiation. Further focus of this study on osteogenesis were conducted by comparing 2D and 3D differentiated BMSCs with Osteoimage® (stains hydroxyapatite), von Kossa (stains anionic portion of phosphates, carbonates, and other salts) and Alizarin Red (stains Ca2+ deposits). Multivariate gene analysis with various covariates showed low variability among donors, successful osteogenic differentiation, and the identification of one gene (matrix metallopeptidase 13, MMP13) significantly differentially expressed in 2D vs. 3D cultures. MMP13 protein expression was confirmed with immunohistochemistry. In conclusion, this study shows evidence for the suitability of type I collagen gels for 3D osteogenic differentiation of BMSCs, which might improve the production of tissue-engineered constructs for treatment of bone defects.
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| 21. |
- Arasu, Uma Thanigai, et al.
(author)
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Human mesenchymal stem cells secrete hyaluronan-coated extracellular vesicles
- 2017
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In: Matrix Biology. - Amsterdam : Elsevier. - 0945-053X .- 1569-1802. ; 64, s. 54-68
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Journal article (peer-reviewed)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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| 22. |
- Arokoski, Jari, et al.
(author)
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Nivelrikon etiopatogeneesi [Etiopathogenesis of osteoarthritis].
- 2001
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In: Duodecim. - : Duodecim. - 0012-7183 .- 2242-3281. ; 117:16, s. 1617-1626
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Journal article (peer-reviewed)abstract
- Nivelrikon patofysiologia tunnetaan huonosti. Nykykäsityksen mukaan artroosissa ei olekyse nivelruston passiivisesta kulumisesta vaan biokemiallisesta tapahtumasarjasta, jossasoluväliaineen tuhoutuminen saa ylivallan rustoa korjaavista prosesseista. Nivelrikon alkuvaiheessarustosoluissa eli kondrosyyteissä aktivoituvat sekä ruston aineosien synteesitoimintaettä rustoa hajottavien entsyymien ilmentyminen ja niitä koodaavien geenientoiminta. Nivelrikko on koko nivelen sairaus, joka aiheuttaa muutoksia niin nivelrustossa,luussa kuin pehmytosissakin. Vallitsevan käsityksen mukaan nivelrikko käynnistyynivelruston pinnallisesta vyöhykkeestä. On myös esitetty, että nivelalueen altistuminenliialliselle kuormitukselle aiheuttaisi ensin rustonalaisen luun paksunemisen ja jäykkenemisen,mikä puolestaan altistaisi nivelruston suuremmille kuormittaville voimille. Riskitekijöistätärkeimpiä ovat ikääntyminen, liikapaino, niveleen kohdistuvat vammat ja ruumiillisentyön aiheuttama liikarasitus. Perinnöllisten tekijöiden osuus on myös merkittävä.Ruston kollageenien rakennevirheiden tiedetään altistavan nivelrikolle.
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| 23. |
- Arokoski, Jari, et al.
(author)
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Nivelrikon lääkehoito [Medical treatment of osteoarthritis]
- 2008
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In: Duodecim. - 0012-7183. ; 124, s. 1899--1907
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Research review (peer-reviewed)abstract
- teho ei riitä, siirrytään tulehduskipulääkkeisiin niiden haitat huomioiden. Ellei parasetamolilla ja tulehduskipulääkkeillä saada riittävää tehoa nivelrikkokipuun tai niitä ei haittavaikutusten vuoksi ole mahdollista käyttää, kipua voidaan hoitaa opioideilla. Niveleen annettu glukokortikoidi- tai hyaluronaattihoito näyttää lievittävän nivelkipua. Glukosamiini saattaa helpottaa nivelrikon oireita, mutta luotettava tieteellinen näyttö sen tehosta puuttuu edelleen. Kehitteillä on nykyisiin vaikutusmekanismeihin tukeutuvia oireita lievittäviä lääkeaineita, mutta merkittävämpi ja haastavampi pitkän aikavälin tavoite on kehittää rustovaurioita hidastavia lääkkeitä. Potentiaalisia tautiprosessiin vaikuttavia lääkeaineita ovat mm. rustomatriksia hajottavien entsyymien estäjät, typpioksidisynteesin estäjät, sytokiinimodulaattorit ja PPAR-agonistit.
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| 24. |
- Beier, Frank, et al.
(author)
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Localization of silencer and enhancer elements in the human type X collagen gene.
- 1997
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In: Journal of Cellular Biochemistry. - : John Wiley & Sons. - 0730-2312 .- 1097-4644. ; 66:2, s. 210-218
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Journal article (peer-reviewed)abstract
- Collagen type X is a short, network-forming collagen expressed temporally and spatially tightly controlled in hypertrophic chondrocytes during endochondral ossification. Studies on chicken chondrocytes indicate that the regulation of type X collagen gene expression is regulated at the transcriptional level. In this study, we have analyzed the regulatory elements of the human type X collagen (Col10a1) by reporter gene constructs and transient transfections in chondrogenic and nonchondrogenic cells. Four different promoter fragments covering up to 2,864 bp of 5'-flanking sequences, either including or lacking the first intron, were linked to luciferase reporter gene and transfected into 3T3 fibroblasts, HT1080 fibrosarcoma cells, prehypertrophic chondrocytes from the resting zone, hypertrophic chondrocytes, and chondrogenic cell lines. The results indicated the presence of three regulatory elements in the human Col10a1 gene besides the proximal promoter. First, a negative regulatory element located between 2.4 and 2.8 kb upstream of the transcription initiation site was active in all nonchondrogenic cells and in prehypertrophic chondrocytes. Second, a positive, but also non-tissue-specific positive regulatory element was present in the first intron. Third, a cell-type-specific enhancer element active only in hypertrophic chondrocytes was located between -2.4 and -0.9 kb confirming a previous report by Thomas et al. [(1995): Gene 160:291-296]. The enhancing effect, however, was observed only when calcium phosphate was either used for transfection or included in the culture medium after lipofection. These findings demonstrate that the rigid control of human Col10a1 gene expression is achieved by both positive and negative regulatory elements in the gene and provide the basis for the identification of factors binding to those elements.
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| 25. |
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