For a long time, scientists thought that the differentiation of Mesenchymal Stem Cells (MSCs) into bone cells was dictated by growth factors. This manuscript shed light on other ligands that play a crucial role in regulating MSCs fate. In concrete terms, it was demonstrated that the osteoinductive effect of BMP-2 peptide is 2 folds improved in the presence of adhesive RGD peptide. Compared to previous works highlighting this synergistic cooperation between RGD and BMP-2 peptides, the main strength of this work lies to the use of primitive human cells (hMSCs) and well-defined biomimetic material surfaces (controlled surface roughness and peptide densities). This work provides valuable insights to develop custom-designed in vitro cell culture models, capable of targeting the desired cell response.

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Ceramics possess osteoconductive properties but exhibit no intrinsic osteoinductive capacity. Consequently, they are unable to induce new bone formation in extra osseous sites. In order to develop bone substitutes with osteogenic properties, one promising approach consists of creating hybrid materials by associating in vitro biomaterials with osteoprogenitor cells. With this aim, we have developed a novel strategy of biomimetic modification to enhance osseointegration of hydroxyapatite (HA) implants. RGD-containing peptides displaying different conformations (linear GRGDSPC and cyclo-DfKRG) were grafted onto HA surface by means of a three-step reaction procedure: silanisation with APTES, cross-linking with N-succinimidyl-3-maleimidopropionate and finally immobilisation of peptides thanks to thiol bonding. Whole process was performed in anhydrous conditions to ensure the reproducibility of the chemical functionalisation. The three-step reaction procedure was characterised by high resolution X-ray photoelectron spectroscopy. Efficiency of this biomimetic modification was finally demonstrated by measuring the adhesion of osteoprogenitor cells isolated from HBMSC onto HA surface.

Abstract:The aim of the present work was to investigate the wetting behaviour of biomedical grade Ti-6Al-4V alloy surfaces textured by a femtosecond laser treatment. The material was treated in ambient atmosphere using an Yb: KYW chirped-pulse-regenerative amplification laser with a wavelength of 1030 nm and a pulse duration of 500 fs. Four main types of surface textures were obtained depending on the processing parameters and laser treatment method. These textures consist of: (1) nanoscale laser-induced periodic surface structures (LIPSS); (2) nanopillars; (3) a bimodal roughness distribution texture formed of LIPSS overlapping microcolumns; (4) a complex texture formed of LIPSS overlapping microcolumns with a periodic variation of the columns size in the laser scanning direction. The wettability of the surfaces was evaluated by the sessile drop method using distilled-deionized (DD) water and Hank's balanced salt solution (HBSS) as testing liquids. The laser treated surfaces present a hydrophilic behaviour as well as a high affinity for the saline solution, with equilibrium contact angles in the ranges 24.1-76.2. for DD water and 8.4-61.8. for HBSS. The wetting behaviour is anisotropic, reflecting the anisotropy of the surface textures.