title: Investigation of the limits of nanoscale filopodial interactions.
abstract: 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.
authors.affiliation: Centre for Cell Engineering, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Laura E
authors.initials: LE
authors.lastname: McNamara
authors.affiliation: School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors.forename: Terje
authors.initials: T
authors.lastname: Sjöström
authors.affiliation: Department of Electronics & Electrical Engineering, College of Science and Engineering, University of Glasgow, Glasgow, UK.
authors.forename: Krishna
authors.initials: K
authors.lastname: Seunarine
authors.affiliation: Department of Orthopaedics and Trauma, Southern General Hospital, Glasgow, UK.
authors.forename: Rm Dominic
authors.initials: RD
authors.lastname: Meek
authors.affiliation: School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors.forename: Bo
authors.initials: B
authors.lastname: Su
authors.affiliation: Centre for Cell Engineering, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Dalby
keywords: Nanotopography; filopodia; mesenchymal stem cell; nanopodia; orthopaedics; titanium