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A bilateral New Zealand white rabbit model of distraction osteogenesis (DO) was used to investigate the relationship between strain environment and bone regeneration during limb lengthening. In seven (n = 7) rabbits, a stiffener was applied to the fixator on one side to reduce strains within the gap tissue after lengthening was completed. Animals were euthanized six days later and their distraction zones were harvested trod analyzed for changes in new bone volume and architecture. Nonlinear finite element analyses (FEA) were performed to predict changes in the gap strain environment. FEA results predicted a nearly uniform sevenfold decrease in average strain measures within the distraction zone. No change in total average new bone volume and significant decreases in both bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) were observed in tibiae in which gap strains were reduced experimentally, compared to contralateral controls. These results suggest that fixator stiffening influenced the architecture but not the amount of newly formed bone. This animal model of distraction might be used to study the mechanisms by which strain fields affect events in bone repair and regeneration, such as cell proliferation, precursor tissue differentiation, and altered growth factor and nutrient delivery to tissues.

The effects of osteogenin and recombinant bone morphogenetic protein 2B (rhBMP-2B) on human monocytes were assessed. The results showed that these osteoinductive factors could induce a chemotactic response in human monocytes. In addition, high concentrations of these substances could stimulate an increase in expression of transforming growth factor type beta-1. These results indicate that osteogenin and related BMPs could initiate bone induction through monocyte recruitment and cytokine synthesis.

To maintain skeletal integrity and prevent fractures, degradation and rebuilding of bone must occur in synchrony. Transforming growth factor-?1 is now found to coordinate this restructuring process: the molecule is released during bone degradation and stimulates bone rebuilding (pages 757-765)., Although often depicted in the lay media and cartoons as a hunk of mineralized rock, bone in reality is a highly dynamic and specialized organ. As a connective tissue, bone [...]