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- Pulkkinen, Hertta, et al.
(författare)
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Recombinant human type II collagen as a material for cartilage tissue engineering.
- 2008
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Ingår i: International Journal of Artificial Organs. - : Wichtig Editore Srl. - 0391-3988 .- 1724-6040. ; 31:11, s. 960-969
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Collagen type II is the major component of cartilage and would be an optimal scaffold material for reconstruction of injured cartilage tissue. In this study, the feasibility of recombinant human type II collagen gel as a 3-dimensional culture system for bovine chondrocytes was evaluated in vitro.METHODS: Bovine chondrocytes (4x106 cells) were seeded within collagen gels and cultivated for up to 4 weeks. The gels were investigated with confocal microscopy, histology, and biochemical assays.RESULTS: Confocal microscopy revealed that the cells maintained their viability during the entire cultivation period. The chondrocytes were evenly distributed inside the gels, and the number of cells and the amount of the extracellular matrix increased during cultivation. The chondrocytes maintained their round phenotype during the 4-week cultivation period. The glycosaminoglycan levels of the tissue increased during the experiment. The relative levels of aggrecan and type II collagen mRNA measured with realtime polymerase chain reaction (PCR) showed an increase at 1 week.CONCLUSION: Our results imply that recombinant human type II collagen is a promising biomaterial for cartilage tissue engineering, allowing homogeneous distribution in the gel and biosynthesis of extracellular matrix components.
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| 5. |
- Nyberg, Tobias, et al.
(författare)
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Ion conducting polymer microelectrodes for interfacing with neural networks
- 2007
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Ingår i: Journal of Neuroscience Methods. - : Elsevier BV. - 0165-0270 .- 1872-678X. ; 160:1, s. 16-25
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the stimulation and recording properties of conjugated polymer microelectrode arrays as interfaces with neural networks of dissociated cortical cells. In particular the stimulation properties were investigated as a means of supplying a neural network with information. The stimulation efficiency at low stimulation voltages was evaluated and referenced to bare indium tin oxide (ITO) electrodes. The polymer electrodes were electrochemically polymerized from a blend of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) and ethylenedioxythiophene (EDOT) onto ITO microelectrodes. Dissociated cortical cells were then plated on the electrodes and cultivated to form neural networks. Polymer electrode stimulation evoked a much greater response from the network than stimulation from ITO electrodes. Neural interfaces using polymer electrodes could be maintained for several months.
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| 6. |
- Myllymaa, Katja, et al.
(författare)
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Improved adherence and spreading of Saos-2 cells on polypropylene surfaces achieved by surface texturing and carbon nitride coating.
- 2009
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Ingår i: Journal of materials science. Materials in medicine. - : Springer. - 0957-4530 .- 1573-4838. ; 20:11, s. 2337-2347
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Tidskriftsartikel (refereegranskat)abstract
- The adhesion and contact guidance of human primary osteogenic sarcoma cells (Saos-2) were characterized on smooth, microstructured (MST) and micro- and nano-structured (MNST) polypropylene (PP) and on the same samples with a silicon-doped carbon nitride (C(3)N(4)-Si) coating. Injection molding was used to pattern the PP surfaces and the coating was obtained by using ultra-short pulsed laser deposition (USPLD). Surfaces were characterized using atomic force microscopy and surface energy components were calculated according to the Owens-Wendt model. The results showed C(3)N(4)-Si coated surfaces to be significantly more hydrophilic than uncoated ones. In addition, there were 86% more cells in the smooth C(3)N(4)-Si coated PP compared to smooth uncoated PP and 551%/476% more cells with MST/MNST C(3)N(4)-Si coated PP than could be obtained with MST/MNST uncoated PP. Thus the adhesion, spreading and contact guidance of osteoblast-like cells was effectively improved by combining surface texturing and deposition of osteocompatible C(3)N(4)-Si coating.
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| 7. |
- Jarmar, T., et al.
(författare)
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Characterization of the surface properties of commercially available dental implants using scanning electron microscopy, focused ion beam, and high-resolution transmission electron microscopy
- 2008
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 10:1, s. 11-22
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Since osseointegration of the respective implant is claimed by all manufacturing companies, it is obvious that not just one specific surface profile including the chemistry controls bone apposition. PURPOSE: The purpose was to identify and separate out a particular set of surface features of the implant surfaces that can contribute as factors in the osseointegration process. MATERIAL AND METHODS: The surface properties of several commercially available dental implants were extensively studied using profilometry, scanning electron microscopy, and transmission electron microscopy. Ultrathin sections prepared with focused ion beam microscopy (FIB) provided microstructural and chemical data which have not previously been communicated. The implants were the Nobel Biocare TiUnite (Nobel Biocare AB, Goteborg, Sweden), Nobel Biocare Steri-Oss HA-coated (Nobel Biocare AB, Yorba Linda, CA, USA), Astra-Tech OsseoSpeed (Astra Tech AB, Molndal, Sweden), Straumann SLA (Straumann AG, Waldenburg, Switzerland), and the Branemark Integration Original Fixture implant (Branemark Integration, Goteborg, Sweden). RESULTS: It was found that their surface properties had differences. The surfaces were covered with crystalline TiO(2) (both anatase and rutile), amorphous titanium oxide, phosphorus doped amorphous titanium oxide, fluorine, titanium hydride, and hydroxyapatite, respectively. CONCLUSION: This indicates that the provision of osseointegration is not exclusively linked to a particular set of surface features if the implant surface character is a major factor in that process. The studied methodology provides an effective tool to also analyze the interface between implant and surrounding bone. This would be a natural next step in understanding the ultrastructure of the interface between bone and implants.
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| 8. |
- Jarmar, T., et al.
(författare)
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Technique for preparation and characterization in cross-section of oral titanium implant surfaces using focused ion beam and transmission electron microscopy
- 2008
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 87:4, s. 1003-9
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Tidskriftsartikel (refereegranskat)abstract
- The surface properties of materials are believed to control most of the biological reactions toward implanted materials. To study the surface structure, elemental distribution, and morphology, using transmission electron microscopy (TEM) techniques, thin foils of the surface (in cross-section) are needed. These have been cumbersome to produce, in particular, from the normally irregular screw-shaped metal implants. Focused ion beam (FIB) microscopy has been developed partly for TEM sample preparation, mainly within the microelectronics industry. Our study describes a method based on FIB for producing electron transparent foils/sections from a metal implant for TEM analysis. Using a screw-shaped titanium dental implant, it was demonstrated that thin foils can be prepared with submicron specificity and from almost any surface geometry. A comparison of different lift-out techniques showed that the in situ lift-out preparation technique allowed plasma cleaning and produced particularly good samples with excellent yield. The titanium oxide on the implant surface was analyzed using energy-filtered TEM (EFTEM) and high-resolution TEM (HRTEM) and the TiO(2) rutile phase being determined via the lattice parameters. This study provides the first set of data for the optimization of a new route for preparation and analysis of biomaterial surfaces and interfaces.
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| 9. |
- Malmström, Johan, 1975, et al.
(författare)
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Bone response to free form-fabricated hydroxyapatite and zirconia scaffolds : A histological study in the human maxilla
- 2009
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Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 20:4, s. 379-385
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Synthetic and biological materials are increasingly used to provide temporary or permanent scaffolds for bone regeneration. This study evaluated the effect of material chemistry and microporosity on bone ingrowth and osseointegration of zirconia (ZrO2) and hydroxyapatite (HA) scaffolds in the human maxilla.Material and methods: Twelve patients subjected to dental implant placement were enrolled in the study. Scaffolds of ZrO 2 and HA were placed in the maxilla of each subject, using a randomization protocol. After 3 months of healing, biopsies were harvested comprising the scaffolds and surrounding bone tissue. The biopsies were processed for histological evaluation and morphometric analysis (bone ingrowth and bone-to-scaffold contact).Results: Healing was uneventful in all cases. All scaffolds demonstrated a measurable bone response using light microscopy and scanning electron microscopy. Microporous HA scaffolds revealed four times larger bone ingrowth and seven times larger bone contact as compared with ZrO2 scaffolds.Conclusion: The results show that chemistry and microporosity of HA promote bone ingrowth and bone contact of ceramic scaffolds in human maxilla.
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| 10. |
- Wermelin, Karin, 1977-, et al.
(författare)
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Stainless steel screws coated with bisphosphonates gave stronger fixation and more surrounding bone. Histomorphometry in rats.
- 2008
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 42:2, s. 365-71
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Tidskriftsartikel (refereegranskat)abstract
- Coating of stainless steel screws with bisphosphonate in a fibrinogen matrix leads to an enhancement of the pullout strength 2 weeks after insertion in rat tibiae. This effect then increases over time until at least 8 weeks. The pullout force reflects the mechanical properties of the bone within the threads, which acts as a screw nut. The aim of the present study was to find descriptive and morphometric histological correlates to the increased pullout strength. Because the bisphosphonates are applied via the implant surface, we also measured bone to implant contact and how far away from the surface any effects could be seen. Stainless steel screws underwent one of three treatments: uncoated control, controls coated with a layer of cross-linked fibrinogen, or screws further modified with bisphosphonates covalently linked and physically adsorbed to the fibrinogen layer. At 1 (n=33) and 8 (n=27) weeks, bone to implant contact and bone area density in the threads were measured, as well as bone area density at 250 and 500 microm from the outer edge of the threads. Additionally, removal torque for each screw treatment was measured at 2 weeks (n=28). At 8 weeks, the part of the bisphosphonate screw that was located in the marrow cavity had become surrounded with bone, whereas there was almost no bone surrounding the controls. The bone area density in the threads along the entire bisphosphonate screw was increased by 40% compared with uncoated controls, and at 250 microm distance it was more than doubled. At 1 week, coated screws had less implant-bone contact, but at 8 weeks there was no difference between uncoated and bisphosphonate-coated screws. The bisphosphonate screws had 50% increased removal torque at 2 weeks compared to uncoated screws. Howship's lacunae and osteoclasts were found near the screws with bisphosphonates at 8 weeks, suggesting that some bone remodeling took place near the implant, in spite of the presence of bisphosphonates.
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