Product Code: ICA13_N405

Mesenchymal Stem Cells Behaviour Onto Femtosecond Laser Textured Ti Alloys
Authors:
Alexandre Cunha, Instituto Superior Tecnico; Lisboa Portugal
Amelia Almeida, Instituto Superior Tecnico; Lisboa Portugal
Marie-Christine Durrieu, Université De Bordeaux; Bordeaux France
Omar Farouk Zouani, Université De Bordeaux; Bordeaux France
Rui Vilar, Instituto Superior Técnico; Lisbon Portugal
Presented at ICALEO 2013

Cells are likely to respond to nanostructured biomaterial surfaces because in vivo they live in an extracellular matrix (ECM) with characteristic dimensions at the nano scale and their own surface is structured at this scale. As a result, surface nanotexturing affects the capability of biomaterials to induce cell adhesion and differentiation, potentially favouring osseointegration. Femtosecond lasers are particularly attractive for surface texturing because they allow creating a wide range of surface textures, including bimodal textures, with both nano and microscale components. In the present work, the effect of surface textures created in biomedical Ti alloys (Grade 2 Ti and Ti-6Al-4V) by surface treatment with a femtosecond laser (λ= 1030 nm; τ= 500 fs) on human mesenchymal stem cells (hMSC) response is analysed.
The topography of the laser treated surfaces was studied by scanning electron microscopy and optical profilometry and their chemical composition determined by X-ray photoelectron spectroscopy (XPS). Adhesion, proliferation and differentiation of hMSC were assessed by immunolabeling of vinculin, F-actin fibres, nucleus and specific expressions of osteoblast markers. Three types of textures were studied, consisting of: (i) nanoscale laser-induced periodic surface structures (LIPSS); (ii) nanopillars; (iii) a bimodal roughness distribution texture formed of LIPSS overlapping microcolumns. The laser treatment, carried out in air, induces further surface oxidation, leading to the formation of TiO2 in Grade 2 Ti and TiO2 and Al2O3 in Ti-6Al-4V alloy. The cell adhesion, shape and orientation depend on the surface texture. A contact guidance effect is induced by the periodic surface structures and the cells develop a highly stretched shape. Laser treatment increases cell proliferation on Grade 2 Ti surfaces (∼ 90% in comparison with ∼ 52% for the control polished surfaces). Cell proliferation is not significant on Ti-6Al-4V laser treated surfaces. Differentiation into an osteogenic lineage is verified at different levels for all surfaces of both Ti alloys, by observation of osterix (OSX), osteopontin (OPN) and osteocalcin (OCN) expression.