Ultrastructure of the interface between cultured osteoblasts and surface-modified polymer substrates

Masaya Yamamoto, Koichi Kato, Yoshito Ikada

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Osteoblasts derived from rat bone marrow cells were cultured on surface- modified poly(ethylene terephthalate) films in the presence of ascorbic acid, β-glycerophosphate, and dexamethasone. The surfaces employed for cell culture included the untreated hydrophobic surface and three modified surfaces possessing immobilized phosphate polymer chains, collagen molecules, and a thin hydroxy-apatite-deposited layer. They all were produced by photo- induced graft polymerization with subsequent surface modifications of the graft chains. The ultrastructural morphology of the substrate/cell interfaces formed in in vitro osteoblast culture on these substrates was studied by transmission electron microscopy. The osteoblasts cultured for 1 week on the modified surfaces showed rough endoplasmic reticula rich in intracellular space and early matrix production in the extracellular space, irrespective of the surface chemistry. After 2 weeks of culture, osteoblasts exhibited active elaboration of extracellular matrix proteins, mostly composed of collagen, on all the surfaces. A remarkable result observed at this stage was direct deposition of an electron-dense, afibrillar layer of 180 rim thickness onto the surface having phosphate polymer chains. This layer became much more electron dense after 3 weeks of culture. Energy dispersive X-ray microanalysis revealed the presence of calcium phosphate in this layer. It was further found that the predeposited hydroxyapatite layer on the phosphate polymer-grafted surface promoted mineral deposition in the extracellular matrix that surrounded cuboid, osteocyte-like cells.

Original languageEnglish
Pages (from-to)29-36
Number of pages8
JournalJournal of Biomedical Materials Research
Issue number1
Publication statusPublished - 1997 Oct
Externally publishedYes


  • Hydroxyapatitedeposited surface
  • Material/cell interface
  • Osteoblast
  • Polymer surface
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering


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