Complex cell physiology on topographically and chemically designed material surfaces

A crucial factor for ingrowth of permanent implants in the bone is the rapid cellular acceptance. The topographical features often follow mechanical aspects for implant stability. But several of these implants fail due to insufficient cell adhesion. Cells are able to perceive the physicochemical properties of their surrounding and to pass these signals into the cell to modulatetheir adhesion structures, growth or production of extracellular matrix. However, the complex cell physiology at the material interface is not yet fully understood, particular on stochastically structured topographies resulting from industrial production. We could find out that corundum blasted titanium hampered the organization of actin filaments inside the cells, clustered adhesion components, e. g. beta-1 integrins and tensin, and the cells bridged the valleys which reduces cellsubstrate contacts. These morphological changes strongly diminished the mineralization of osteoblasts. To shed light on cause and effect we reduced the physical complexity of the material surface by introduction of regular micro-structures (pillars, grooves) using deep reactive ion etching. Now it was more obvious what cells are doing on sharp edged topographies - the actin filaments of our cells were clustered around the pillars. As a result the intracellular calcium signaling and the protein synthesis were impaired. Our recent findings indicated an attempted phagocytosis of the micro-pillars by osteoblasts. Therefore we conclude that implants used in orthopedic surgery should avoid any sharp-edged topographical features that could induce phagocytosis by the surrounding cells, which is an unnecessarily energy consuming process. © 2017 Trans Tech Publications, Switzerland