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  • electrical stimulation  (1)
  • hydroxyapatite  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Scanning electron microscopy of the bone-bioactive implant interface (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 429-440 
    Details
    ISSN: 0021-9304
    Keywords: bone ; interface ; cement line ; bioactive glass ; AW glass ceramic ; hydroxyapatite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Rods of three bioactive materials, apatite/wollastonite glass ceramic (AW-GC), bioactive glass (BG), and dense slip-cast hydroxyapatite (HA), were implanted in the femora of 23 Wistar rats for periods of 1-4 weeks. The samples were harvested following vascular perfusion fixation and the femora freeze-fractured for scanning electron microscopy to expose the bone/implant interface. The focus of our observations was when new bone was forming on the implant surfaces irrespective of the implantation period. Scanning microscopy of the hydroxyapatite rods demonstrated that in areas where bone bonding had occurred, the implant surface was composed of globular accretions which fused to form a cement-like matrix to which collagen fibers were attached. Dissolution of individual grains of the implant surface created a roughened surface topography. Such features were not found in the transcortical portions of these implants. Similar globular accretions were also found on the surfaces of bulk AW-GC, although bone apposition was not disrupted by the critical point-drying procedure, and thus the interface was more difficult to image. Nevertheless, the collagen of the bony compartment interdigitated with an interfacial layer which was morphologically similar to that found on HA. The most surface reactive material, BG, demonstrated an interfacial structure where the surface reactive calcium phosphate layer was clearly distinguished from the underlying bulk implant material. However, this layer was separated from the overlying collagen-containing bony compartment by a second, thinner, calcified layer which corresponded to the cement line matrix into which the collagen fibers were inserted. Our results show that the new bone interface formed with these three bioactive materials is morphologically comparable to that of cement lines found naturally in bone-remodeling sites, and that this interfacial layer is formed on the chemically active surface of the biomaterial. The degree to which the cement line matrix interdigitated with the implant was a product of the reactivity of the implant surface. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 429-440, 1997.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Attachment, morphology, and protein expression of rat marrow stromal cells cultured on charged substrate surfaces (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 42 (1998), S. 117-127 
    Details
    ISSN: 0021-9304
    Keywords: electrical stimulation ; cell attachment ; alkaline phosphatase ; osteopontin ; protein adsorption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Although surface charge has been shown to affect the adhesion and morphology of a variety of cell types, the interactions of bone marrow stromal cells with charged surfaces still remain unclear. A novel electrical stimulation system was used to investigate the interactions between rat bone marrow stromal cells and charged substrates in this study. A conductive and transparent indium tin oxide (ITO) coating was used as an electret substrate. Rat marrow stromal cells were cultured on positive, negative, and uncharged ITO surfaces. Cell attachment, morphology, alkaline phosphatase activity, and expression of osteopontin and collagen type III were assessed using histochemical staining, immunolabeling, and fluorescence microscopy. Voltages of 0.7, 0.8, 0.9, and 1.0 V applied to the substrates created surface potentials but were insufficient to decompose the media. On positively charged ITO, cell attachment was enhanced in serum-supplemented and serum-free media. Furthermore, decreases in cell spreading, alkaline phosphatase activity, and osteopontin were observed in cells grown on the positively charged ITO. These data indicate that positively charged surfaces enhance cell attachment but suppress cell spreading and differentiation of rat marrow stromal cells. © 1998 John Wiley & Sons, Inc. J. Biomed Mater Res, 42, 117-127, 1998.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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