As the aging population increases more individuals are being defined as partially edentulous. Standards of care have expanded to include the use of Dental implants. To be successful the implant must integrate with the surrounding hard tissues, a process known as osseointegration. The definition of osseointegration is vague with respect to cellular influences of the microtopography at the molecular level. How these surfaces influence molecular pathways of osteoblast differentiation during osseointegration is not known. Integration of predictable implant surface topography with clinical outcomes depends on a well defined understanding of the three dimensional biology at the cellular and molecular level. Our hypothesis is that the effect of Dental implant surface microtopographies on osteoblast differentiation and motility is regulated through focal adhesion kinase (FAK) signaling pathways. FAK is an intracellular tyrosine kinase that is associated with integrin receptors. Our overall strategy is to perform cell adhesion and differentiation, and migration studies with human palatal mesenchymal pre-osteoblast cells on a series of well characterized titanium implant surface microtopographies 600g grooved versus 50um Al2O3 sandblasted). We will determine if microtopography effects are modulated through FAK. Real time PCR and Western blotting strategies will be used on RNA and protein isolated from wild type controls, or cells whose level of FAK gene and protein expression has been reduced using siRNA-FAK, FRNK dominant negative constructs, or Y925F HA-tagged FAK mutants. This will allow us to determine if FAK, FAK-phosphotyrosine, or FAK-MAPK pathways are modulated by implant surface microtopographies. Scanning electron microscopy will allow us to evaluate static phenotypic changes. Live imaging of labeled cells will allow for evaluation of dynamic changes in real time. The significance of this work is that it would yield insight into how osseous tissues may be engineered in a controlled and predictable site specific manner with respect to conductive and inductive effects of the biomaterial surface by alteration of the implant surface microtopography. This would allow for a controlled, localized, site specific tissue engineering approach in association with Dental implant therapy.
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| Ko, Y Joon; Zaharias, Rebecca S; Seabold, Denise A et al. (2007) Osteoblast differentiation is enhanced in rotary cell culture simulated microgravity environments. J Prosthodont 16:431-8 |
