Effects of calcium ion‐implantation of titanium on bone cell function in vitro

Abstract

The modification of titanium (Ti) surfaces by ion-implantation has previously been reported to enhance osseointegration in vivo. However, the mechanisms underlying the apparently improved biocompatibility of these novel implant materials are unknown. The aim of this study is, therefore, to determine the precise effects of calcium ion-implanted Ti on the functional activity of bone cells in vitro. Flow cytometry (FCM) and the reverse transcriptase polymerase chain reaction (RT-PCR) were used to measure the response of bone-derived cells to key bone-associated components, including alkaline phosphatase (ALP), bone morphogenetic protein receptor-1B (BMPR-1B), bone sialoprotein (BSP), osteonectin (ON), and osteopontin (OPN). FCM analysis showed that BMPR-1B, BSP and particularly OPN were significantly up-regulated in MG-63 cells cultured on Ca-implanted Ti compared with control nonimplanted Ti. Moreover, the effects of this novel Ca-Ti surface were found to be mediated, at least partly, via gene activation, since RT-PCR demonstrated the presence of notably elevated levels of OPN mRNA transcripts in the MG-63 cells. These findings thus show that Ti surfaces implanted with Ca ions can enhance the expression of certain bone-associated components in vitro, and suggest that this effect could be the cause of the potential benefit of this material on bone in vivo.

Ion implantation of titanium based biomaterials

“…The implanted surface enhanced the expression of certain bone-associated components in vitro and increased the number of mitotic cells [149]. Ca ion implantation markedly enhanced the proportion of cells compared with those grown on the non-implanted Ti (control) surface.…”

“…An improved in vivo response to Ca ion implantation has been attributed to the following factors: thickening of the oxide layer, formation of the Ca-P rich apatite layer, and/or release of the implanted ion from the modified Ca-Ti surface [59,146,147,149]. All these factors play major role in promoting bone cell adhesion, extra-cellular matrix communication and augmentation of tissue mineralization, leading to improved bone remodeling on the Ca-implanted titanium.…”

In vitro osteoinduction of human mesenchymal stem cells in biomimetic surface modified titanium alloy implants

“…A stable and sufficiently stiff and resistant interface between the biomaterial surface and the surrounding tissue is a vital prerequisite both for immediate implant loading and for the long-term success of such implants. This phenomenon has been extensively analyzed in the literature [3][4][5][6] . The interface is usually achieved by the biological process (partially regulated by mechanical and material properties) known as osseointegration of the implant, which is obtaining an intimate connection of the implant within the bone by means of an appropriate and sufficient growth of new bone on the surface of the implant 7) .…”

Surface engineered titanium alloys for biomedical devices

“…The breakdown potentials measured are high (2.5 to 3 V). Good biocompatibility of all the investigated materials was confirmed under the specific examination conditions; however, they pointed out that the calcium implanted titanium was inferior to the unimplanted titanium, a result that is different from the result of Hanawa et al (1997) and Nayab et al (2005Nayab et al ( , 2007. Braceras et al (2007) implanted CO + ions with an energy of 30 KV and doses from 3 to 6.5 ¥ 10 17 ions/cm 2 into Ti6Al4V disks.…”