The role of phospholipase D in osteoblast response to titanium surface microstructure

Mimi Fang, Rene Olivares-Navarrete, Marco Wieland, David L. Cochran, Barbara D. Boyan, Zvi Schwartz

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Biomaterial surface properties such as microtopography and energy can change cellular responses at the cell-implant interface. Phospholipase D (PLD) is required for the differentiation of osteoblast-like MG63 cells on machined and grit-blasted titanium surfaces. Here, we determined if PLD is also required on microstructured/high-energy substrates and the mechanism involved. shRNAs for human PLD1 and PLD2 were used to silence MG63 cells. Wild-type and PLD1 or PLD1/2 silenced cells were cultured on smooth-pretreatment surfaces (PT); grit-blasted, acid-etched surfaces (SLA); and SLA surfaces modified to have higher surface energy (modSLA). PLD was inhibited with ethanol or activated with 24,25-dihydroxyvitamin-D3 [24R,25(OH)2D3]. As surface roughness/energy increased, PLD mRNA and activity increased, cell number decreased, osteocalcin and osteoprotegerin increased, and protein kinase C (PKC) and alkaline phosphatase specific activities increased. Ethanol inhibited PLD and reduced surface effects on these parameters. There was no effect on these parameters after knockdown of PLD1, but PLD1/2 double knockdown had effects comparable to PLD inhibition. 24R,25(OH)2D3 increased PLD activity and the production of osteocalcin and osteoprotegerin, but decreased cell number on the rough/high-energy surfaces. These results confirm that surface roughness/energy-induced PLD activity is required for osteoblast differentiation and that PLD2 is the main isoform involved in this pathway. PLD is activated by 24R,25(OH)2D3 in a surface-dependent manner and inhibition of PLD reduces the effects of surface microstructure/energy on PKC, suggesting that PLD mediates the stimulatory effect of microstructured/high-energy surfaces via PKC-dependent signaling.

Original languageEnglish (US)
Pages (from-to)897-909
Number of pages13
JournalJournal of Biomedical Materials Research - Part A
Volume93
Issue number3
DOIs
StatePublished - Jun 1 2010

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Keywords

  • Mechanism of cell surface interaction
  • Osteoblast differentiation
  • Phospholipase D
  • Titanium surface microstructure and surface energy
  • Vitamin D metabolites

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Biomedical Engineering
  • Metals and Alloys

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