Nanotopographical responsiveness has been observed in diverse cell types including fibroblasts, osteoblasts, osteoclasts, endothelial, smooth muscle, epithelial, and epitenon cells. "This is intriguing from a biomaterials perspective," says McNamara, "as it demonstrates that surface features of just a few nanometres can influence how cells will respond to, and form tissue on, materials."
Stem cells detect surface features with a variety of mechanosensors, including integrin-linked focal adhesions. These respond to the mechanical constraints of the surface by inducing signalling cascades, such as the ERK-MAPK pathway. When the cell's rearranging cytoskeleton physically pulls on components of the cell's nucleus, this force works together with chemical signalling. Together these indirect (biochemical signal-mediated) and direct (force-mediated) factors can modulate nuclear components, altering gene expression to direct stem cell responses.
One interesting finding has been that topography can in some cases have the same effect as biochemical differentiation factors. The potential to eliminate the need for the latter opens the door to development of improved clinical prostheses with topographies that can directly modulate stem cell fate. In particular, the authors envisage applications involving engineered topography components for stem cells in regenerative medicine, for instance, in orthopaedics and dental implants. A combination of different topographies could be used to differentially functionalise implants for distinct applications, or demarcate particular "zones" within a single device.
Orthopaedic implants designed with specific regions tailored to integrate with bone and improve the chances of implant fixation might be seamlessly join other areas of the implant programmed to reduce excessive bony ingrowth, for exa
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SAGE Publications UK