The broad objective of this competitive renewal is to understand the mechanisms by which cells adhere and respond to orthopaedic implant surfaces, which lead to improved implant design for patients with debilitating musculoskeletal diseases. We have developed an in vitro mineralizing human osteoblast-implant system in which to study changes in extracellular matrix (ECM) formation and calcification in response to different implant materials. Previous work demonstrated that within 24 h osteoblasts adhere to orthopaedic implants through integrins, cell receptors for adhesion to ECM proteins. Small changes in implant topography and composition have resulted in significant differences in the response of osteoblasts to these materials within 24 h. The goals of this one year grant are (1) to continue our work on the effect of implant composition and topography on cell adhesion and ECM protein expression but determine if early differences in osteoblast responses result in changes in the pattern and extent of mineralization, (2) to determine if the integrin-mediated, intracellular signaling mechanisms generated in response to implant materials are similar to those activated after integrin-mediated binding of cells to ECM proteins, and (3) to study the effects of transforming growth factor beta (TGF-beta), on mineralization in our osteoblast-implant culture system. We are requesting only one year of support so that data can be obtained with the Rush-Presbyterian-St Luke's Medical Center, which, simultaneously, received NlAMS support in response to the 1994 Biomaterials Research Initiative. Their approach has been to enhance bone ingrowth into implants by the application of growth factors. In dog studies, the application of TGF-beta-hydroxyapatite-coated implants not only significantly increased bone ingrowth compared to control implants in other dogs but also enhanced bone formation in control implants in the contralateral limb. These data suggest that an anabolic systemic factor had been released. We plan to test TGF-beta in our osteoblast-implant in vitro system and assay for changes in cell proliferation, expression of bone matrix proteins and mineralization. This work would be the basis of a collaborative RO1 to be submitted in 1997 or 1998.
| Sofia, S; McCarthy, M B; Gronowicz, G et al. (2001) Functionalized silk-based biomaterials for bone formation. J Biomed Mater Res 54:139-48 |
| Krause, A; Cowles, E A; Gronowicz, G (2000) Integrin-mediated signaling in osteoblasts on titanium implant materials. J Biomed Mater Res 52:738-47 |
| Cowles, E A; Brailey, L L; Gronowicz, G A (2000) Integrin-mediated signaling regulates AP-1 transcription factors and proliferation in osteoblasts. J Biomed Mater Res 52:725-37 |
| Ahmad, M; Gawronski, D; Blum, J et al. (1999) Differential response of human osteoblast-like cells to commercially pure (cp) titanium grades 1 and 4. J Biomed Mater Res 46:121-31 |
| Ahmad, M; McCarthy, M B; Gronowicz, G (1999) An in vitro model for mineralization of human osteoblast-like cells on implant materials. Biomaterials 20:211-20 |
| Gronowicz, G; McCarthy, M B (1996) Response of human osteoblasts to implant materials: integrin-mediated adhesion. J Orthop Res 14:878-87 |
