S Santavirta

Orton Orthopaedic Hospital, Helsinki, Southern Finland Province, Finland

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Publications (320)722.32 Total impact

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    ABSTRACT: Konttinen YT, Hukkanen M, Segerberg M, Rees R, Kemppinen P, Sorsa T, Saari H, Polak JM, Santavirta S. Relationship between Neuropeptide Immunoractive Nerves and Inflammatory Cells in Adjuvant Arthritic Rats. Scand J Rheumatol 1992; 21: 55–9. The purpose of this study was to assess the relationship of neuropeptide nerves and inflammatory leukocytes in PVG rats with adjuvant-induced arthritis. Substance P- and calcitonin gene-related peptide (CGRP)-immuno reactive nerves and inflammatory leukocytes were studied, using peroxidase (ABC) andor alkaline phosphatase (APAAP) staining. Inflamed synovial tissue proper was infiltrated with neutrophils, ED1 macrophages and focal accumulations of CD2 T lymphocytes. In such tissue, the relationship between peptide-immuno reactive nerves and inflammatory cells was such that substance P and CGRP nerves were absent in heavily infiltrated villous synovial tissue, whereas healthy synovial tissue and non-inflammatory areas in adjuvant arthritic rats were innervated by substance P and CGRP nerves close to normal synovial tissue resident cells. In order to elucidate an eventual mechanism for lost immuno reactivity, healthy synovial tissue was exposed to chymotrypsin or oxygen derived free radicals (ODFR) in vitro. The former treatment caused total loss of immuno reactivity. These findings suggest that neuropeptides and neuropeptide containing nerves may be destroyed by locally produced proteolytic enzymes and various reactive oxygen species in the vicinity of inflammatory cells.
    07/2009; 21(2):55-59.
  • 07/2009; 17(s67):22-26.
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    ABSTRACT: Twenty-six patients with rheumatoid arthritis (RA) participated either in a 21 day, community sponsored, in-patient multidisciplinary rehabilitation program (N=20) or; received traditional, out-patient physiotherapy designed by the patient's rheumatologist (N = 6). Clinical assessments were made (prior to, immediately after, and 6 months after rehabilitation) to evaluate the response to these two quite different rehabilitative measures that included: functional classification, joint score index, subjective VAS of pain, HAQ, Pain disability index, Comprehensible psychopathological rating scale, hemoglobin, and CRP measurements. Economic assessments included salary, direct and community sponsored costs, for rehabilitation and costs for sick days and production losses. No clear-cut differences between the two rehabilitation modes were detected. Both modes showed improvement in different assessment parameters; patients with higher education and, therefore, with a less joint-disturbing work profile appeared to profit more from an extensive in-patient rehabilitation program. Patients with less education and a more manually-oriented working profile, did worse and had a higher tendency to seek medical pensioning, in spite of rehabilitative measures. As the total costs for out-patient rehabilitation only add up to 15.8% of the total costs for in-patient rehabilitation, this study setting cautiously suggests that out-patient rehabilitation might be an acceptable alternative to individualized patient groups that might not compromise clinical and vocational outcome. Larger patient groups are needed, however, to confirm these findings.
    07/2009; 25(4):200-206.
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    ABSTRACT: Sixteen patients with seropositive rheumatoid arthritis were operated on for subaxial subluxations. Four of the patients had slight, but progressive, tetraparesis, and 5 had severe or total tetraparesis; they were operated on 1–4 months after the first signs. Seven patients were treated for severe neck and shoulder pain. Nine patients had subluxation at the C3–4 level, the most common site, and 3 patients also had an atlantoaxial subluxation. Patients with cord compression were treated with posterior laminectomies and fusions that relieved the tetraparesis. Two patients died during the early postoperative period: 1 of a cardiac infarction and the other of pneumonia. During 4 (1.5–9) years' follow-up, 3 patients had new subluxations at other levels.
    07/2009; 61(2):106-110.
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    ABSTRACT: Proper mechanical loading is essential for bone remodeling and maintenance of human skeletal system. Matrix metalloproteinases (MMPs) are secreted by mesenchymal stromal lining cells and osteoblasts to prepare the initiation sites for osteoclastic bone resorption at the beginning of the remodeling cycle. However, only a few studies have addressed the effect of mechanical stress on MMPs and their endogenous tissue inhibitors of matrix metalloproteinases (TIMPs) in osteoblasts. In this study, the response of human osteoblasts to uniaxial cyclic stretching was investigated to clarify this more in detail. Stretching affected the orientation of the osteoblasts, and quantitative reverse transcription-polymerase chain reaction revealed coordinated upregulation of MMP-1 and its activator MMP-3 mRNA by cyclic 5% stretching at 3 h (p < 0.01). Upregulation of cyclooxygenase-2 mRNA was also found in response to cyclic 1 and 5% stretchings at 1, 3, and 6 h (p < 0.01). No changes were found in MMP-2, TIMP-1, and -2. The mRNA expression of MMP-9 was low and MMP-13 was not detected. This study suggests that MMP-1 and -3, enhanced by uniaxial cyclic mechanical stimulation of osteoblasts, are candidate key enzymes in the processing of collagen on bone surface, which might be necessary to allow osteoclastic recruitment leading to bone resorption. The strain might also play a role in cleaning of demineralized bone surface during the reversal phase, before bone formation starts.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 02/2007; 80(2):491-8. · 2.31 Impact Factor
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    ABSTRACT: Healthy bone is a rigid yet living tissue that undergoes continuous remodeling. Osteoclasts resorb bone in the remodeling cycle. They secrete H(+)-ions and proteinases to dissolve bone mineral and degrade organic bone matrix, respectively. One of the main collagenolytic proteinase in osteoclasts is cathepsin K, a member of papain family cysteine proteinases. Recently, it has been shown that osteoblasts may contribute to organic matrix remodeling. We therefore investigated their ability to produce cathepsin K for this action. Trabecular bone samples were collected from patients operated due to a fracture of the femoral neck. Part of the bone was decalcified and the rest was used for cell isolation. Sections from the decalcified bone were immunostained with antibodies against cathepsin K. Isolated cells were characterized for their ability to form mineralized matrix and subsequently analyzed for their cathepsin K production by Western blotting and quantitative RT-PCR. Osteoblasts, bone lining cells and some osteocytes in situ showed cathepsin K immunoreactivity and osteoblast-like cells in vitro produced cathepsin K mRNA and released both 42 kDa pro- and 27 kDa processed cathepsin K to culture media. Osteoblastic cathepsin K may thus contribute to collagenous matrix maintenance and recycling of improperly processed collagen I. Whether osteoblastic cathepsin K synthesis has consequences in diseases characterized by abnormal bone matrix turnover remains to be investigated.
    Bone 07/2006; 38(6):769-77. · 4.46 Impact Factor
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    ABSTRACT: It was hypothesized that peri-implant tissue around loosening dental implants may contain cytokines with a potential to regulate osteoclasts. Peri-implant and/or gingival samples from loosened implants, chronic periodontitis (CP), and normal controls (n = 10 samples in each group) were analyzed using immunohistochemical staining to observe tumor necrosis factor alpha (TNF-alpha), interleukin 1-alpha (IL-1alpha), IL-6, platelet-derived growth factor A (PDGF-A), and transforming growth factor alpha (TGF-alpha). These cytokines were found in foreign-body giant cells, macrophages, fibroblasts, and epithelial cells. TNF-alpha, IL-1alpha, and IL-6 were increased (P < .05; unpaired t test) in peri-implantitis and CP, whereas PDGF-A and TGF-alpha were not. In conclusion, cytokines with a potential to activate osteoclasts were found in both peri-implantitis and CP, but the cytokine profiles differed in that IL-1alpha was the most prevalent cytokine in the former and TNF-alpha was the most common in the latter. These cytokines may contribute to peri-implant bone loss/loosening by stimulating formation and activity of osteoclasts and might be an amenable target for local therapies with cytokine modulators.
    The International journal of periodontics & restorative dentistry 05/2006; 26(2):135-41. · 1.08 Impact Factor
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    ABSTRACT: In this study, the potential of high-quality amorphous diamond (AD) coatings in reducing the torque and failures of bone screws was studied. Torque values were recorded for 32 stainless steel screws, 2.7 or 3.5 mm in diameter and 60 mm in length. Half of the screw sets were coated with the AD coating before installing in predrilled holes of human cadaveric femoral bone samples. The bone samples were selected from two groups of four persons with mean ages of 34 years (range 25-41 years) and 75 years (range 73-77 years), respectively. The bone mineral density (BMD) values of the samples were determined exactly at the screw insertion site by peripheral quantitative computed tomography (pQCT). In the mechanical tests, insertion and removal torques were measured. BMD had a significant effect on insertion torque; the maximum torque (adjusted with respect to the screw diameter) was significantly higher for the young bone than for the old bone (p < 0.05). By using a polished AD coating, insertion torque was decreased even up to 50% in comparison with the screws without coating. The results suggest that AD coating provides a stable, smooth surface and reduces the risk of screw failures.
    Biomaterials 11/2005; 26(28):5687-94. · 8.31 Impact Factor
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    Acta Orthopaedica 11/2005; 76(5):614-9. · 2.74 Impact Factor
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    ABSTRACT: To assess the expression and processing of a disintegrin and metalloproteinase, ADAM 12 (meltrin-alpha), in the formation of multinuclear cells. Methods. In situ hybridization, immunohistochemical staining, and Western blotting of interface membrane around loosened total hip replacement implants. Macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB ligand (RANKL) costimulation of human monocytes followed by FACS, immunofluorescence staining, Western blotting, and bone resorption assay. ADAM 12 mRNA-containing mononuclear cells were often seen in a close spatial relationship with ADAM 12-positive multinuclear cells. Morphometric analysis of ADAM 12 disclosed that 53% +/- 2% of all interface cells were ADAM 12-positive compared to 5% +/- 1% in controls (p < 0.001). M-CSF and RANKL were richly present in interface tissue around loosening implants. Upon M-CSF and RANKL costimulation of human monocytes in vitro, the ADAM 12 staining pattern changed over time, and ADAM 12-positive cells formed large mono-, bi-, and multinuclear cells at Day 7 and many multinuclear giant cells and/or osteoclasts at Day 14. Western blot disclosed 90 kDa latent ADAM 12L but also the metalloproteinase-cleaved, fusion-active 60 kDa form transiently just before the burst of fusion. ADAM 12, well recognized for participation in cell-cell fusion in myoblast formation, is upregulated and processed upon formation of multinuclear giant cells and osteoclasts. It may play a role in formation of giant cells and osteoclasts around loosened total hip replacement implants.
    The Journal of Rheumatology 10/2005; 32(10):1943-50. · 3.26 Impact Factor
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    ABSTRACT: Interface tissue between the bone and loosening total hip implant is acidic and highly osteolytic. It is characterized by the formation of cathepsin K positive foreign body giant cells. Similar structures to those found in the normal joint surround the artificial hip joint. Cells in synovial membrane of the artificial hip generate synovial fluid that is called pseudosynovial fluid. Interface tissue fibroblasts are able to produce receptor activator of NF-kappaB ligand (RANKL), which can induce osteoclastogenesis during the loosening process. Western blot analysis indicated that RANKL is present in the pseudosynovial fluid. Pseudosynovial fluid induced cultured peripheral blood mononuclear cells to form multinuclear TRAP positive giant cells. In the presence of osteoprotegerin, the soluble RANKL decoy receptor, the number of TRAP positive multinuclear cells was reduced to half (p < 0.05). The multinuclear cells induced with pseudosynovial fluid contained active cathepsin K protein and were capable of bone matrix resorption in vitro. The cells were shown to express osteoclast phenotype markers, such as mRNA for cathepsin K, TRAP, and calcitonin receptor. It is therefore apparent that pseudosynovial fluid from patients with aseptic loosening of total hip prosthesis contains a potent osteoclastogenic factor RANKL that further suggests a favorable environment for osteoclast formation in the peri-implant tissues. It is thus concluded that suppression of RANKL activity may be beneficial in terms of increasing the lifetime of total hip prostheses.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 08/2005; 74(1):582-8. · 2.31 Impact Factor
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    ABSTRACT: The highly osteolytic interface tissue between the bone and loosening total hip prosthesis is characterized by low pH, formation of foreign body giant cells, osteoclasts, and production of receptor activator of nuclear factor-kappaB (RANKL) and cathepsin K. We hypothesized that fibroblasts in the interface tissue may form a source for RANKL production. Primary interface tissue fibroblasts, fibrous joint capsule fibroblasts, and trabecular bone osteoblasts were stimulated with tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), IL-6, IL-11, or 1alpha,25-(OH)2 vitamin D3. Cellular RANKL and released cathepsin K were detected by Western blotting. RANKL in cell lysates and osteoprotegerin (OPG) in cell culture medium were measured by ELISA. RANKL, OPG, and cathepsin K mRNA were measured with quantitative reverse transcriptase polymerase chain reaction. Interface tissue fibroblasts were found to produce RANKL. 1alpha,25-(OH)2 vitamin D3 stimulation increased RANKL mRNA expression. TNF-alpha was found to be the most potent OPG inducer in interface tissue fibroblasts. Cathepsin K mRNA production in fibroblasts was upregulated roughly 3-fold (p < 0.01) after 1alpha,25-(OH)2D3 stimulation, and both pro- and active cathepsin K protein was released to fibroblast culture media. Interface tissue fibroblasts are able to produce RANKL, OPG, and cathepsin K and may contribute indirectly and directly to pathologic periprosthetic collagenolysis and bone destruction.
    The Journal of Rheumatology 04/2005; 32(4):713-20. · 3.26 Impact Factor
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    ABSTRACT: The metal stem of the totally replaced hip carries load and resists fatigue, but it is electrochemically corroded. Metallic atoms act as haptens, induce type 1 T-helper cells/Th1-type immune responses and enhance periprosthetic osteolysis. Stiff metal implants, which do not have the same elasticity as the surrounding bone, cause stress shielding. Cyclic loading and lack of ligamentous support lead to mechanical and ischemia reperfusion injury and particle formation from bone, polymethylmethacrylate, and porous implant surfaces, which accelerate third-body polyethylene wear. Surgical injury and micromotion induce the formation of a fibrous capsule interface. Type-B lining cells produce lubricin and surface-active phospholipids to promote solid-to-solid lubrication but may loosen the implant from bone. The pumping action of the cyclically loaded joint and synovial fluid pressure waves dissect the implant-host interface and transports polyethylene particles and pro-inflammatory mediators to the interface. Hyaluronan induces formation of a synovial lining like layer. Because of its localization close to bone, foreign body inflammation at the interface stimulates osteoclastogenesis and peri-implant bone loss. Metal-on-metal and ceramic-on-ceramic pairs might minimize third body wear, but can lead to high-impact load of the acetabulum. Diamond coating of a metal-on-polyethylene couple might solve both of these problems. The basic biomaterial solutions allow good mechanical performance and relatively long life in-service, but surface modifications (porous coating, hydroxyapatite, diamond, bioglass, and others) may facilitate performance of the implant and improve the biomaterial and body interfaces.
    Clinical Orthopaedics and Related Research 02/2005; · 2.79 Impact Factor
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    ABSTRACT: The most common cause for heel pain is plantar fasciitis. The diagnosis can usually be made by clinical examination, but sometimes ENMG (electroneuromyography), ultrasound, and magnetic resonance imaging examinations are helpful. Other reasons for heel pain, e.g., nerve entrapments, atherosclerosis/ischemia, and fat pad degeneration, should be excluded. Plantar fasciitis can also present a symptom of chronic seronegative spondyloarthropathies or reactive arthritis. In the case of common plantar fasciitis, three different modes of treatment can be administered, namely, (1) anti-inflammatory and analgesic treatment, (2) rest and diminution of the strain at the insertion, and (3) maintenance of the tension and flexibility of the soft tissues. A simple four-step treatment plan algorithm, based on symptoms, their duration, and response to treatment, is presented. Operative treatment is seldom needed if the algorithm is correctly followed. Operative treatment is recommended only when the pain remains resistant to conservative treatment after more than 1 year. For operative treatment, partial release of the fascia close to insertion to avoid flat foot and secondary strain on the calcaneocuboid and midtarsal (Lisfranc) joints is our preferred option.
    Modern Rheumatology 02/2005; 15(5):307-14. · 1.72 Impact Factor
  • Reijo Lappalainen, Seppo S Santavirta
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    ABSTRACT: In total hip replacements, the bulk properties of materials, such as proper elasticity and hardness, are important. However, the material interacts with the body mainly at the surfaces. Wear and corrosion are initiated at the surfaces also. Therefore, the control of surface properties using different kinds of treatments or coatings may improve total hip replacements considerably. The most studied surface treatments include ion implantation and methods to control surface topography, such as grit or sand blasting or plasma treatments. Among the large variety of coatings, hydroxyapatite, titanium oxide and nitride, zirconium oxide, pyrolytic carbon, and diamondlike carbon coatings have shown the most promising results. These coatings mainly are used to enhance bone growth; to minimize friction, wear, and corrosion; and to improve biocompatibility of total joint prostheses. The potential of novel coatings to solve some present problems in joint prostheses is discussed based on the structure and properties of different kind of coatings. It can be concluded that currently, coating methods exist to improve the tribologic performance and longevity of the total hip replacements. However, coatings must fulfill two essential requirements: no delamination in biochemical and biomechanical environments and sufficient protection of substrate from corrosion.
    Clinical Orthopaedics and Related Research 02/2005; · 2.79 Impact Factor
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    ABSTRACT: Contact pressure of UHMWPE acetabular cup has been shown to correlate with wear in total hip replacement (THR). The aim of the present study was to test the hypotheses that the cup geometry, abduction angle, thickness and clearance can modify the stresses in cemented polyethylene cups. Acetabular cups with different geometries (Link: IP and Lubinus eccentric) were tested cyclically in a simulator at 45 degrees and 60 degrees abduction angles. Finite element (FE) meshes were generated and two additional designs were reconstructed to test the effects of the cup clearance and thickness. Contact pressures at cup-head and cup-cement interfaces were calculated as a function of loading force at 45 degrees, 60 degrees and 80 degrees abduction angles. At the cup-head interface, IP experienced lower contact pressures than the Lubinus eccentric at low loading forces. However, at higher loading forces, much higher contact pressures were produced on the surface of IP cup. An increase in the abduction angle increased contact pressure in the IP model, but this did not occur to any major extent with the Lubinus eccentric model. At the cup-cement interface, IP experienced lower contact pressures. Increased clearance between cup and head increased contact pressure both at cup-head and cup-cement interfaces, whereas a decreased thickness of polyethylene layer increased contact pressure only at the cup-cement interface. FE results were consistent with experimental tests and acetabular cup deformations. FE analyses showed that geometrical design, thickness and abduction angle of the acetabular cup, as well as the clearance between the cup and head do change significantly the mechanical stresses experienced by a cemented UHMWPE acetabular cup. These factors should be taken into account in future development of THR prostheses. FE technique is a useful tool with which to address these issues.
    BioMedical Engineering OnLine 02/2005; 4(1):32. · 1.61 Impact Factor
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    ABSTRACT: Osteoarthritis (OA) is associated with destruction of type II collagen-rich hyaline articular cartilage. We hypothesized that classical interstitial collagenases cleave collagen type II, leading to the increased expression of the 3/4 native type II collagen fragment (COL2-3/4C) and the corresponding denatured type II collagen fragment (COL2-3/4M), which could correlate with different cartilage destruction grades. In addition, we assessed whether these fragments could be measured in joint fluid and serve as diagnostic markers. Cartilage specimens were obtained from the femoral heads of hip joints from total hip replacement operations. Articular gliding surfaces of the cartilage were categorized into normal (G0), fibrillated (G1), superficiallyfissured (G2) and deeplyfissured (fissures that reach to the subchondral bone) (G3). A histological scoring of the cartilage was also used. COL2-3/4C and COL2-3/4M were detected by immunohistochemical staining. Dot blotting was used to detect these fragments in joint fluid. COL2-3/4C and COL2-3/4M were found in the perichondrocyte matrix around lacunae. Such COL2-3/4C (p < 0.05) and COL2-3/4M (p < 0.05) immunoreactivity was significantly increased in G3 and G2 compared to GO and G1. A positive correlation (n = 35, Spearman rank correlation) was observed between the histological score and the percentage of COL2-3/4C positive lacunae (r = 0.43, p = 0.01) and COL2- 3/4M positive lacunae (r = 0.53, p = 0.001). All 7/7 joint fluid samples contained COL2-3/4C in dot blots whereas only 4/7 contained COL2-3/4M. Collagenase-cleaved collagen--both native and denatured--increases as the severity of OA increases, assessed using a macroscopic clinical and microscopic histological grading system. Collagen degradation was always most apparent around chondrocytes. Furthermore, the native COL2-3/4C fragment has potential as a joint fluid marker for OA.
    Clinical and experimental rheumatology 01/2005; 23(1):19-26. · 2.66 Impact Factor
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    Mika P Koivikko, Pertti Myllynen, Seppo Santavirta
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    ABSTRACT: We compared clinical outcomes following conservative treatment of subaxial fracture dislocations of the cervical spine and posterior fusion using bone grafts and interspinous Roger's wiring (Bohlman modification). We reviewed 106 patients: 51 were treated primarily surgically, and 55 treated conservatively served as historical controls. Those patients who neurologically recovered at least one Frankel grade had on average less displacement on discharge (1.3 mm vs 3.1 mm, p=0.04). Although anatomical outcomes were better in the operatively treated group (1.6 mm vs 2.9 mm displacement at end of follow-up, p=0.001), there was no difference in neurological recovery. Late neck pain correlated with residual displacement ( p=0.04) and was more common in the conservatively treated patients ( p=0.01). Time in hospital was shorter in the group with posterior fusions, and complication rates were similar to those found after conservative treatment. A significant number of the conservatively treated patients developed kyphotic deformity, and 29% needed later surgery because of chronic instability or unacceptable anatomical results.
    European Spine Journal 12/2004; 13(7):610-6. · 2.47 Impact Factor
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    ABSTRACT: Bioabsorbable fixation devices are increasingly used in trauma, orthopedic and craniomaxillofacial surgery. The devices are essentially made of polylactic acid and/or polyglycolic acid polymers. Ultra-high-strength implants are manufactured from such polymers using self-reinforcing techniques. Implants are available for stabilization of fractures, osteotomies, bone grafts and fusions, as well as for reattachment of ligaments, tendons, meniscal tears and other soft tissue structures. As these implants are completely absorbed, the need for a removal operation is overcome and long-term interference with tendons, nerves and the growing skeleton is avoided. The risk of implant-associated stress shielding, peri-implant osteoporosis and infections is reduced. Implants do not interfere with clinical imaging. Current clinical use of bioabsorbable devices is reviewed.
    Expert Review of Medical Devices 12/2004; 1(2):229-40. · 2.43 Impact Factor
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    ABSTRACT: Intra-articular administration of hyaluronate (HA) is an effective treatment for arthritis. HA injections can decrease not only joint pain but also synovial effusion, although little is known concerning the mechanism of HA action. The aim of this study was to investigate the role of HA on the expression and production of matrix metalloproteinase (MMP) in synovial cells activated by interleukin (IL)-1beta in order to achieve a better understanding of exogenous HA function in the extracellular matrix degradation in arthritic joints. Human synovial cells were incubated with HA (0.1-1000 microg/ml) and/or IL-1beta (1 ng/ml). The expression of MMP-1 and MMP-3 mRNAs was analyzed by quantitative real-time polymerase chain reaction. The protein levels of MMP-1 and MMP-3 in cultured media were measured by immunoblotting. Expression of MMP-1 and MMP-3 mRNAs was induced by IL-1beta. The IL-1beta-mediated induction of MMP-1 mRNA expression was attenuated by 10 microg/ml HA (p=0.026) and that of MMP-3 mRNA was strongly down-regulated in the presence of 10 or 1000 microg/ml HA (p<0.001). The increased protein levels of MMP-1 and MMP-3 were also reduced by 1000 microg/ml HA. These data suggest that HA inhibits the expression and production of MMP-1 and MMP-3 in IL-1beta-stimulated human synovial cells. We therefore prepose that intra-articular HA may rescue inflamed joints from bone and cartilage destruction by reducing the production of MMP-1 and MMP-3.
    The Tohoku Journal of Experimental Medicine 11/2004; 204(2):99-107. · 1.37 Impact Factor

Publication Stats

5k Citations
722.32 Total Impact Points


  • 1990–2009
    • Orton Orthopaedic Hospital
      Helsinki, Southern Finland Province, Finland
  • 1987–2009
    • ORTON Foundation, Helsinki, Finland
      Helsinki, Southern Finland Province, Finland
    • Central University of Venezuela
      Caracas, Distrito Federal, Venezuela
  • 1978–2009
    • Helsinki University Central Hospital
      • • Department of Medicine
      • • Department of Orthopaedics and Traumatology
      • • Department of Oral and Maxillofacial Surgery
      • • Surgical Hospital
      Helsinki, Province of Southern Finland, Finland
  • 1987–2006
    • University of Helsinki
      • • Institute of Biomedicine
      • • Department of Anatomy
      • • Department of Pathology
      Helsinki, Province of Southern Finland, Finland
  • 2004–2005
    • University of Kuopio
      • Department of Applied Physics
      Kuopio, Eastern Finland Province, Finland
    • Hospital District for Helsinki and Uusimaa
      Helsinki, Southern Finland Province, Finland
  • 1998–2001
    • Yamagata University
      • Department of Orthopaedic Surgery
      Yamagata-shi, Yamagata-ken, Japan
    • Imperial College London
      Londinium, England, United Kingdom
  • 1999
    • Aarhus University
      • Department of Biomedicine
      Aarhus, Central Jutland, Denmark
  • 1996
    • Satakunta Hospital District
      Björneborg, Province of Western Finland, Finland
    • Lund University
      • Department of Orthopaedics
      Lund, Skane, Sweden
    • Karolinska Institutet
      • Institutionen för medicin, Huddinge
      Solna, Stockholm, Sweden
  • 1995
    • Windsor Regional Hospital
      Windsor, Ontario, Canada
  • 1994
    • University of Oslo
      • Institute for Cancer Research (ICR)
      Oslo, Oslo, Norway
  • 1992
    • NYU Langone Medical Center
      New York City, New York, United States
    • Oulu University Hospital
      Uleoborg, Oulu, Finland