No abstract

The natural environment of a living cell is not only organized on a micrometer, but also on a nanometer scale. Mimicking such a nanoscale topography in implantable biomaterials is critical to guide cellular behavior. Also, a correct positioning of cells on biomaterials is supposed to be very important for promoting wound healing and tissue regeneration. The exact mechanism by which nanotextures can control cellular behavior are thus far not well understood and it is thus far unknown how cells recognize and respond to certain surface patterns, whereas a directed response appears to be absent on other pattern types. Focal adhesions (FAs) are known to be involved in the process of specific pattern recognition and subsequent response by cells. In this study, we used a high throughput screening "Biochip" containing 40 different nanopatterns to evaluate the influence of several nanotopographical cues like depth, width, (an)isotropy and spacing (ridge-groove ratio) on osteoblast behavior. Microscopical analysis and time lapse imaging revealed that an isotropic topography did not alter cell morphology, but it highly induced cell motility. Cells cultured on anisotropic topographies on the other hand, were highly elongated and aligned. Time-lapse imaging revealed that cell motility is highly dependent on the ridgegroove ratio of anisotropic patterns. The highest motility was observed on grooves with a ratio of 1:3, whereas the lowest motility was observed on ratios of 1:1 and 3:1. FA measurements demonstrated that FA-length decreased with increasing motility. From the study it can be concluded that osteoblast behavior is tightly controlled by nanometer surface features.

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Bone-implant material development is proceeding at a high pace, and has shifted from straightforward biomaterial testing to more advanced cell-targeted approaches for surface modification and design.It has been long known that cells can recognize and respond to topographical features by changing their morphology and behavior. The progress in surface analytical devices, as well as in techniques for production of topographical features on the nanometer scale allow for the characterization of natural tissues and the reproduction of biomimetic nanofeatures in material surfaces. In this review some of the most common surface-characterization and surface-manufacturing techniques will be addressed and results from in vitro and in vivo studies will be presented. Knowledge on biomaterial nanotopography can be exploited for active stimulation and control of cellular behavior like attachment, migration, spreading, gene expression, proliferation, differentiation and secretion of matrix components.

Organised nanotopography mimicking the natural extracellular matrix can be used to control morphology, cell motility, and differentiation. However, it is still unknown how specifi c cell types react with specifi c patterns. Both initial adhesion and preferential cell migration may be important to initiate and increase cell locomotion and coverage with cells, and thus achieve an enhanced wound healing response around an implantable material. Therefore, the aim of this study was to evaluate how MC3T3-E1 osteoblast initial adhesion and directional migration are infl uenced by nanogrooves with pitches ranging from 150 nm up to 1000 nm. In this study, we used a multipatterned substrate with fi ve different groove patterns and a smooth area with either a concentric or radial orientation. Initial cell adhesion measurements after 10 s were performed using atomic force spectroscopy-assisted single-cell force spectroscopy, and demonstrated that nascent cell adhesion was highly induced by a 600 nm pitch and reduced by a 150 nm pitch. Addition of RGD peptide signifi cantly reduced adhesion, indicating that integrins and cell adhesive proteins (e.g. fi bronectin or vitronectin) are key factors in specifi c cell adhesion on nanogrooved substrates. Also, cell migration was highly dependent on the groove pitch; the highest directional migration parallel to the grooves was observed on a 600 nm pitch, whereas a 150 nm pitch restrained directional cell migration. From this study, we conclude that grooves with a pitch of 600 nm may be favourable to enhance fast wound closure, thereby promoting tissue regeneration.