Hydroxylapatite binds more serum proteins, purified integrins, and osteoblast precursor cells than titanium or steel

Krista L. Kilpadi, Pi Ling Chang, Susan L. Bellis

Research output: Contribution to journalArticlepeer-review

359 Scopus citations


The implant material hydroxylapatite (HA) has been shown in numerous studies to be highly biocompatible and to osseointegrate well with existing bone; however, the molecular mechanisms at work behind this osseointegration remain largely unexplored. One possibility is that the implant, exposed to the patient's blood during surgery, adsorbs known cell adhesive proteins such as fibronectin and vitronectin from the serum. Osteoblast precursors could then adhere to these proteins through integrin-mediated mechanisms. In the present study, we have used a quantitative ELISA assay to test the hypothesis that hydroxylapatite will adsorb more fibronectin and vitronectin from serum than two commonly used hard-tissue materials, commercially pure titanium, and 316L stainless steel. We further used the ELISA, as well as a standard cell adhesion assay, to test the hypothesis that increased protein adsorption will lead to better binding of purified integrins α 5β 1 and α vβ 3 and osteoblast precursor cells to the HA than to the metals. Our results show that fibronectin, vitronectin, α 5β 1, α vβ 3, and osteoblast precursor cells do indeed bind better to HA than to the metals, suggesting that improved integrin-mediated cell binding may be one of the mechanisms leading to better clinical bone integration with HA-coated implants.

Original languageEnglish (US)
Pages (from-to)258-267
Number of pages10
JournalJournal of Biomedical Materials Research
Issue number2
StatePublished - 2001


  • Cell adhesion
  • Fibronectin/vitronectin
  • Hydroxylapatite
  • Integrins
  • Titanium

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering


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