Modulation of Cellular Colonization of Porous Polyurethane Scaffolds via the Control of Pore Interconnection Size and Nanoscale Surface Modifications.

Full-scale cell penetration within porous scaffolds is required to obtain functional connective tissue components in tissue engineering applications. For this aim, we produced porous polyurethane structures with well-controlled pore and interconnection sizes. Although the influence of the pore size on cellular behavior is widely studied, we focused on the impact of the size of the interconnections on the colonization by NIH 3T3 fibroblasts and Wharton's jelly-derived mesenchymal stem cells (WJMSCs). To render the material hydrophilic and allow good material wettability, we treated the material either by plasma or by polydopamine (PDA) coating. We show that cells weakly adhere on these surfaces. Keeping the average pore diameter constant at 133 µm, we compare two structures, one with LARGE (52 µm) and one with SMALL (27 µm) interconnection diameters. DNA quantification and extracellular matrix (ECM) production reveal that larger interconnections is more suitable for cells to move across the scaffold and form a three-dimensional cellular network. We argue that LARGE interconnections favor cell communication between different pores, which then favors the production of the ECM. Moreover, PDA treatment shows a truly beneficial effect on fibroblast viability and on matrix production, whereas plasma treatment shows the same effect for WJMSCs. We, therefore, claim that both pore interconnection size and surface treatment play a significant role to improve the quality of integration of tissue engineering scaffolds.

Grafting of bioactive polymers onto titanium surfaces and human osteoblasts response.

In this paper, the adhesion of human osteoblast-like cells (line MG63) onto functionalized pure Titanium (Ti cp) has been studied. The Titanium surfaces were functionalized by grafting bioactive polymers bearing anionic groups such as sodium sulfonate. The grafting was achieved under inert atmosphere, by radical polymerization of sodium styrene sulfonate NaSS after the activation of the surface. ATR/FTIR and XPS were used to analyse the chemical composition of the grafted and non grafted titanium surfaces. The efficiency of the grafting was evidenced by the high amounts of grafted polyNaSS (5 microg/cm(2)), measured by Toluidin Blue colorimetric method. Biological tests have been investigated to highlight the influence of the grafting polymer on the cell response. Human osteoblast-like cells were cultured on titanium surfaces. Differences in the adhesion strength of cells were observed. Mineralization of osteoblast-like cells was studied after 28 days of culture and the amount of calcium formed were evaluated. Surface modification by bioactive polymers bearing anionic groups appears as an effective way to stimulate the bone regeneration over that, as provided by titanium as suggested by basic studies and in vitro results.