| AVS 59th Annual International Symposium and Exhibition | |
| Biomaterial Interfaces | Tuesday Sessions |
| Session BI-TuP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | M. Foss, Aarhus University, Denmark |
| Authors: | O.Z. Andersen, Aarhus University, Denmark A. Keller, Aarhus University, Denmark D.C.E. Kraft, Aarhus University, Denmark F. Besenbacher, Aarhus University, Denmark M. Foss, Aarhus University, Denmark |
| Correspondent: | Click to Email |
Proliferation of stem cells has been observed to be affected by surface roughness in the micro and nanometer range. Furthermore, when cultured on line patterns with dimensions in the sub-micrometer regime these have been found to adopt elongated morphologies and align with respect to patterns, often called contact guidance. Contact guidance has been observed to induce stem cell differentiation towards neurogenic and myogenic lineages. We have investigated the effect of rippled silicon substrates with different height and periodicity in the nanometer range on the behavior of human derived adult stem cells.
The substrates were prepared by irradiating silicon substrates with xenon ions with different energies and fluxes at angles of either 65 or 67º with respect to the surface normal. From this, substrates with nanoripples of different heights (h) and periodicities (λ) were obtained. As determined by AFM measurements the prepared substrates had ripple features ranging from h=3 nm with λ=50 nm up to h=70 nm with λ=650 nm. The cellular response towards these surfaces was investigated using human dental pulp stem cells (hDPSC). The cells (2,500 cell/cm2) were cultured for periods of 1, 3 and 4 days, fixed and used for assessing cellular proliferation, morphology, alignment with respect to the ripple structures and expression of the osteogenic markers Runx2 and ALPL and the myogenic markers GATA4 and MyoD1.
It is found that the ripple structures influenced cellular proliferation. An increase in proliferation was observed up until ripple structures with h=8 nm and λ=170 nm followed by a decrease as the ripples structures further increased in size. The decrease in proliferation for larger ripple structures was found to correlate with an increasing number of cells undergoing contact guidance. Furthermore, it was found that the cells cultured on the ripple surfaces with features larger than h=8 nm and λ=170 nm had up-regulated expression of the myogenic markers.
The increasing ripple size is associated with larger RMS roughness values. Hence, the increase in cellular proliferation as the ripples grows in size, correlate well with literature on cellular behavior on rough samples. The decrease in proliferation observed with the larger ripple structures correlates with the increasing degree of contact guidance observed for these samples. We speculate that it could be related to changes in the cellular expression profiles. This is supported by the data from the immunohistochemistry. Especially the finding that the expression of MyoD1 is up-regulated with the larger ripple structures as this regulatory protein is known to be associated with cell cycle arrest.