Grant: Travel Awards - Institute Community Support

The success of orthopaedic and dental implant materials depends on proper balance of bone formation and resorption around the implant. Osteoblasts, which form bone, adhere and sense their environment via focal adhesions. Changes to the substratum topography, is a desirable way to influence cell behaviour, as it persists for the lifespan of the implant. By understanding the response of osteoblasts to different topographies, implant design can be improved. The aim of this study was to assess the influence of nanotopographies on osteoblast adhesion, migration and fibrillogenesis. Rat calvarial osteoblasts were seated on glass slides, with nanotopographies etched into the surface (lines, dots). Immunocytochemistry was used to assess adhesion site anchoring proteins vinculin, tensin and extracellular matrix (ECM) molecule fibronectin. Time-lapse video (TLV) was used to analyze cell migration on the surfaces. Focal contacts formed at the peaks of topographies in cells on dot surfaces, while cells on grooved surfaces formed focal contacts parallel to the long axis of the topography. Cells on smooth surfaces formed large adhesion plaques with random orientation. Fibrillar adhesions showed similar, but less pronounced patterning as focal contacts. TLV showed cells on line surfaces migrated in the direction of the topography while cells on other surfaces migrated randomly. No significant difference was seen in migration velocity or distance travelled between surfaces, but cells on lines and dot surfaces tend to travel faster and farther than on smooth surfaces. After 24 and 72 hours, cells on grooved surfaces developed fibronectin fibrils aligned with the topography, while fibronectin on dot and smooth surfaces had a random orientation. Substratum nanotopography has the potential to manipulate osteoblast adhesion, migration and ECM secretion. Understanding how nanotopographies affect osteoblast physiology allows the design of novel implants that facilitate osseointegration.