Titanium substrata composition influences osteoblastic phenotype: In vitrostudy

In spite of observed differences at the interface between boon and either c ommercially pure titanium [Ti(cpi)] or titanium alloy (Ti-6Al-4V), the mech anism of such a response is ill understood. This prompted further investiga tion of the influence of similar metals on human bone-derived cells (HBDCs) . This study investigated the influence of Ti(cpi) and its alloy on osteobl astic proteins formed by HBDCs grown for 5, 7, 10, and 14 days on these met als and compared them to cells grown on tissue culture polystyrene plates. Messenger RNA and translated proteins that form an array of osteogenic para meters were determined: alkaline phosphatase (ALP), thrombospondin, osteopo ntin, osteocalcin (OC), osteonectin (ON/SPARC), type I collagen (Col I) and bone sialoprotein (BSP). At the four predetermined time points, cells grow n on either Ti(cpi) or Ti-6Al-4V generally expressed similar mRNA. levels, while levels of their respective proteins differed. Cells on Ti(cpi) had pe ak levels for most proteins at day 7, whereas those on Ti-6Al-4V peaked at either day 5 and/or day 7. At day 5 cells grown on Ti-6Al-4V had higher lev els of ALP, Col I, ON/SPARC, OC, and BSP than those in Ti(cpi); this differ ence was not maintained at later time points in culture. The differential r egulation of proteins occurring between cells from the same patient grown o n titanium and its alloy implies that HBDCs respond to small differences in the surface chemistry and/or microcrystallinity. (C) 1999 John Wiley & Son s, Inc.