Investigation of the limits of nanoscale filopodial interactions

Mesenchymal stem cells are sensitive to changes in feature height, order and spacing. We had previously noted that there was an inverse relationship between osteoinductive potential and feature height on 15-, 55- and 90 nm-high titania nanopillars, with 15 nm-high pillars being the most effective substrate at inducing osteogenesis of human mesenchymal stem cells. The osteoinductive effect was somewhat diminished by decreasing the feature height to 8 nm, however, which suggested that there was a cut-off point, potentially associated with a change in cell–nanofeature interactions. To investigate this further, in this study, a scanning electron microscopy/three-dimensional scanning electron microscopy approach was used to examine the interactions between mesenchymal stem cells and the 8 and 15 nm nanopillared surfaces. As expected, the cells adopted a predominantly filopodial mode of interaction with the 15 nm-high pillars. Interestingly, fine nanoscale membrane projections, which we have termed ‘nanopodia,’ were also employed by the cells on the 8 nm pillars, and it seems that this is analogous to the cells ‘clinging on with their fingertips’ to this scale of features

Osteogenic and bactericidal surfaces from hydrothermal titania nanowires on titanium substrates

Nanotopographical cues on Ti have been shown to elicit different cell responses such as cell differentiation and selective growth. Bone remodelling is a constant process requiring specific cues for optimal bone growth and implant fixation. Moreover, biofilm formation and the resulting infection on surgical implants is a major issue. Our aim is to identify nanopatterns on Ti surfaces that would be optimal for both bone remodelling and for reducing risk of bacterial infection. Primary human osteoblast/osteoclast co-cultures were seeded onto Ti substrates with TiO2 nanowires grown under alkaline conditions at 240 °C for different times (2, 2.5 or 3 h). Cell growth and behaviour was assessed by scanning electron microscopy (SEM), immunofluorescence microscopy, histochemistry and quantitative RT-PCR methods. Bacterial colonisation of the nanowire surfaces was also assessed by confocal microscopy and SEM. From the three surfaces tested the 2 h nanowire surface supported osteoblast and to a lesser extent osteoclast growth and differentiation. At the same time bacterial viability was reduced. Hence the 2 h surface provided optimal bone remodeling in vitro conditions while reducing infection risk, making it a favourable candidate for future implant surfaces

Nanopatterning of titanium surfaces for improved implant osseointegration

With increasingly higher performance requirements and health care costs associated with dental and orthopaedic bone-anchored implants there is a need to improve the osseointegration of Ti implants. Small alterations in nanotopography feature dimensions and arrangement has recently been shown able to differentiate human mesenchymal stem cells into an osteoblastic lineage, thus showing potential for using nanotopography to improve osseointegration of Ti implants.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Adhesion of Streptococcus mitis and Fusobacterium nucleatum on Nanopatterned Titanium Surfaces

Titania nanopillars with different heights and diameters (&lt;100 nm) were patterned on titanium surfaces using a through-mask anodization technique. Two oral bacteria, that is, Streptococcus mitis (NCTC 10712) and Fusobacterium nucleatum (ATCC 25586), were used to study the bacterial attachment to nanopatterned titanium surfaces with and without saliva coating at different time points up to 4 h. The adhesion of both bacteria was decreased on 90-nm high nanopillars compared with both 15-nm high nanopillars and polished titanium surfaces, although this effect was significantly reduced with saliva coating, indicating a strong 'masking' effect of saliva on nanotopography-mediated bacterial adhesion. The results demonstrate that nanopatterning may be used to control bacterial attachment to titanium implant surfaces, but it is evident that for oral implant applications, saliva coating may reduce the desired topographical cues. </jats:p

Fabrication of pillar-like titania nanostructures on titanium and their interactions with human skeletal stem cells

Surface nanotopography is known to influence the interaction of human skeletal (mesenchymal) stem cells (hMSC) with a material surface. While most surface nanopatterning has been performed on polymer-based surfaces there is a need for techniques to produce well-defined topography features with tuneable sizes on relevant load-bearing implant materials such as titanium (Ti). In this study titania nanopillar structures with heights of either 15, 55 or 100 nm were produced on Ti surfaces using anodization through a porous alumina mask. The influence of the surface structure heights on hMSC adhesion, spreading, cytoskeletal formation and differentiation was examined. The 15 nm high topography features resulted in the greatest cell response with bone matrix nodule forming on the Ti surface after 21 days

Harnessing nanotopography to enhance osseointegration of clinical orthopedic titanium implants-an in vitro and in vivo analysis

Despite technological advancements, further innovations in the field of orthopedics and bone regeneration are essential to meet the rising demands of an increasing aging population and associated issues of disease, injury and trauma. Nanotopography provides new opportunities for novel implant surface modifications and promises to deliver further improvements in implant performance. However, the technical complexities of nanotopography fabrication and surface analysis have precluded identification of the optimal surface features to trigger osteogenesis. We herein detail the osteoinductive potential of discrete nanodot and nanowire nanotopographies. We have examined the ability of modified titanium and titanium alloy (Ti64) surfaces to induce bone-specific gene activation and extracellular matrix protein expression in human skeletal stem cells (SSCs) in vitro, and de novo osteogenic response within a murine calvarial model in vivo. This study provides evidence of enhanced osteogenic response to nanowires 300 surface modifications, with important implications for clinical orthopedic application.</p

The synergistic effects of lysophosphatidic acid receptor agonists and calcitriol on MG63 osteoblast maturation at titanium and hydroxyapatite surfaces

Successful osseointegration stems from the provision of a mechanically competent mineralised matrix at the implant site. Mature osteoblasts are the cells responsible for achieving this and a key factor for ensuring healthy bone tissue is associated with prosthetic materials will be 1α,25 dihydroxy vitamin D3 (calcitriol). However it is known that calcitriol per se does not promote osteoblast maturation, rather the osteoblasts need to be in receipt of calcitriol in combination with selected growth factors in order to undergo a robust maturation response. Herein we report how agonists of the lysophosphatidic acid (LPA) receptor, LPA and (2S)-OMPT, synergistically co-operate with calcitriol to secure osteoblast maturation for cells grown upon two widely used bone biomaterials, titanium and hydroxyapatite. Efforts could now be focussed on functionalising these materials with LPA receptor agonists to support in vivo calcitriol-induced osseointegration via heightened osteoblast maturation responses. © 2009 Elsevier Ltd. All rights reserved

Valuation in the public and private sectors Tax, risk and the cost of capital

Available from British Library Document Supply Centre-DSC:4363.2643(270-1998) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo