Papers by Author: Hala Zreiqat

Abstract: Hydroxyapatite (HA) ceramics is one of the most widely used bone substitute in clinics. Limited information is available concerning how HA ceramics may affect osteoprotegerin (OPG) and RANKL expression. In this study, osteoblastic-like SaOS-2 cells were grown on HA ceramics sintered at different temperature for 3 and 6 days, RANKL and OPG mRNA expression were analyzed with quantitative in situ hybridization (QISH) technique. Result showed that SaOS-2 grown on HA ceramics sintered at 800°C expressed higher RANKL mRNA than on other two HA ceramics after 3 days’ culture. No significant difference in OPG expression on different surfaces was detected after 3 days and 6 days culture. This result suggests that HA sintered at low temperature tend to induce more bone remodeling after implantation.

Abstract: Strontium(Sr) containing CaSiO3 powders were synthesized using chemical precipitation. X-Ray Fluorescence (XRF) analysis confirmed the incorporation of Sr in CaSiO3. X-Ray diffraction (XRD) analysis revealed that the incorporation of Sr into the lattice structure of β-CaSiO3 powders, does not change its β-phase composition. The lattice dimension of β-CaSiO3 powders increased with the increase of Sr contents (0-10% Sr). Sr-CaSiO3 ceramic disk were prepared from the Sr-CaSiO3 poweders by uniaxial pressing at 150 MPa and sintering at 1100°C for 3h. XRD and Differential Thermal Anaysis (DTA) analysis indicated that there is a correlation betweem Sr concentration (0-10% Sr) and the phase transition from β-CaSiO3 to α-CaSiO3 with the increase of Sr contents. This transition was promoted by the decrease in temperature.

Abstract: Titanium alloy has been used as a material for orthopaedic implants, however drawbacks still exist. Considerable efforts have been taken to modify the surface structure of the implant material and improve the biological performance. Previously we have demonstrated that biomaterials surface modification has a significant effect on the regulation of osteogenesis. We have investigated the behaviour of human osteoclasts on sol-gel coated carbonated hydroxyapatite on anodized titanium alloy. Osteoclasts cultured on the modified surface were able to attach and spread, exhibiting the characteristic peripheral brush border. Successful differentiation of the monocytes into osteoclasts and their attachment to the coated surface and the formation of resorption-like imprints indicated that carbonate hydroxyapatite (CHAP) coated titanium alloy play a significant role in regulating the functional activity of osteoclasts.

Abstract: Poor cell adhesion to orthopaedic and dental implants results in implant failure. Establishing and maintaining mature bone at the bone/device interface is critical to the long-term success of the prostheses. Considerable effort has been devoted to alter the surface characteristics of these biomaterials in order to improve the initial interlocking of device and skeleton in the noncemented joint prosthesis. Previously we demonstrated that surface chemistry modification of bioceramics induced osteogenesis. In the present work, we investigate the effect of surface chemistry modification of titanium alloy (Ti-6Al-4V) with alkoxide-derived carbonate hydroxyapatite (CHAp) using sol-gel coating methods on human bone derived cell (HBDC)behaviour. Western blotting demonstrated that sol gel coating of Ti-6Al-4V with CHAp upregulated the expression of key signalling protein Shc isoforms (p46, p52, p66) and phosphorylated Erk1/2. CHAp-modification of Ti-6Al-4V is associated with signal transduction pathways involving the key signalling protein Shc and ERK1/2 which may lead to enhanced gene expression of extracellular matrix proteins at the skeletal tissue/device interface.