J Biomed Mater Res A. 2015 Apr 22. doi: 10.1002/jbm.a.35487. [Epub ahead of print]

Cell response to hydroxyapatite surface topography modulated by sintering temperature.

Mealy J¹, O'Kelly K.

Abstract

Increased mesenchymal stem cell (MSC) activity on hydroxyapatite (HA) bone tissue engineering scaffolds will improve their viability in diffusion-based in vivo environments and is therefore highly desirable. This work focussed on modulating the sintered HA surface topography with a view to increasing cell activity; this was achieved by varying the sintering temperature of the HA substrates. Cells were cultured on the substrates for periods of up to 19 days and displayed a huge variation in viability. MSC metabolic activity was measured using a resazurin sodium salt assay and revealed that surfaces sintered from 1250-1350 °C significantly outperformed their lower temperature counterparts from day one (p≤0.05). Surfaces sintered at 1300 °C induced 57% more cell activity than the control at day 16. No significant activity was observed on surfaces sintered below 1200 °C. It is suggested that this is due to the granular morphology produced at these temperatures providing insufficient contact area for cell attachment. In addition, we propose the average surface wavelength as a more quantitative surface descriptor than those readily found in the literature. The wavelengths of the substrates presented here were highly correlated with cell activity (R² =0.9019); with a wavelength of 2.675µm on the 1300 °C surface inducing the highest cell response. This article is protected by copyright. All rights reserved.