As alterations in microfabricated substratum topography have been shown to influence osteoblast differentiation, we hypothesized that substratum topography composed of a gradient of parallel microgrooves could differentially regulate intracellular signaling cascades related to osteoblast differentiation, subsequently leading to the activation of the osteoblast specific transcription factor Cbfa1.
The application of microgroove gradients for the investigation of osteoblastic differentiation by the activation of Cbfa1 transcription factor has not been reported previously.
This is in accordance with the Cbfa1 pattern of expression on the microgrooved substrate areas compared to the unpatterned control regions.
Cbfa1 is a "master" regulator of osteoblast differentiation from mesenchymal precursors and bone formation and can directly stimulate transcription of osteoblast-related genes such as those encoding osteocalcin, type I collagen, osteopontin, and collagenase 3 [6, 13].
In the present study, a low level and randomly distributed immunofluorescent staining for Cbfa1 was observed on smooth surfaces, while a more intense and evident staining was seen on the microgroove gradient.
Real-time PCR showed significant increases in Cbfa1 and osteocalcin gene expression in cells cultured on rough and grooved implant microtopographies .
The nuclear translocation of ERK V correlated closely with the timing of translocation of the Cbfa1 .
The key finding of the present investigation was that Cbfa1 was activated and upregulated in osteoblasts cultured on gradient microgrooved topographies, thus supporting previously reported data regarding osteoblastic responses due to microgroove geometries.
Since mice missing both copies of the Cbfa1 gene create no osteoblasts, the animals never replace their cartilage, which is insufficient to support breathing lungs.
The protein encoded by Cbfa1 fills the bill, they found.
One question raised by the new research is whether doctors may someday use Cbfa1 or its protein to generate new bone in adults, perhaps to treat osteoporosis, a condition in which bone structure decays.