The governing factor associated with the selection of materials for use within the human body is biocompatibility. Biocompatibility is defined as the ability of a material to perform with an appropriate host response in a specific application. Until recently determinations of biocompatibility have been associated with phenomenological responses and have concentrated on evaluating the effect of the host environment on the material, and also the effect of the material on the surrounding environment. Whilst such studies have provided valuable information, in order to realise the full potential of biomaterials in medical applications we must gain a more comprehensive understanding of interactions occurring at the implant interface.

In order to assess the response of a primary human osteoblast, bone forming cell, to a range of materials with different surface textures, nano-topographies, we have used a combination of highly specific primary antibodies, which are in turn exposed to specific secondary antibodies conjugated to different fluorochromes. In order to evaluate the effect of the different surfaces on the organisation of the cellular cytoskeleton we used a specific stain for F-actin (fibrous actin, a protein which forms microfilaments, which in turn are major components of the contractile machinery of the cell) and b-tubulin (the major component of microtubules, which form the cellular cytoskeleton which maintains the internal organisation of the cell). The intact interfaces were analysed using a combination of confocal laser scanning microscopy (CLSM) and image analysis. Images of the same cell were captured at two different wavelengths, correlating to the different fluorochromes, thus allowing for evaluation of the interaction between the two different components in both a qualitative and quantitative assessment. The captured images were then transferred to an image analysis system, which quantified the general morphology of the cell. This was achieved by selecting mathematically defined parameters which are associated with changes in morphology due to different magnitudes of adhesion and spreading.

When used in conjunction with biological assays, data obtained from these laboratory methods can be used to provide initial data on the suitability of proposed materials for use in the human body. The controlled nature of these experiments also provides the potential for optimising material characteristics and ultimately increasing the success rate currently associated with synthetic implants.