Portal de Periódicos da CAPES

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

2009; Wiley; Volume: 93A; Issue: 3 Linguagem: Inglês

10.1002/jbm.a.32596

1552-4965

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

Titanium Alloys Microstructure and Properties

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‐D 3 [24R,25(OH) 2 D 3 ]. 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 comparableto PLD inhibition. 24R,25(OH) 2 D 3 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) 2 D 3 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. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010