Tensional forces influence gene expression and sutural state of rat calvariae in vitro.
BACKGROUND
Theories regarding the cause of craniosynostosis that are more than 15 years old cite the role that tensional forces play in the normal and abnormal development of the cranial suture. These theories highlight the effect of stress bands originating from the skull base to the vertex, guiding sutural development.


METHODS
In this study, the normally fusing posterior intrafrontal suture of the rat was subjected to 3 mN of tensional force for 30 minutes per day. The suture was then assessed for patency, proliferation, apoptosis, and transforming growth factor (TGF)-beta signaling components.


RESULTS
Sutures that were subjected to tensional force were histologically patent at the end of 14 days. This was in contrast to sutures that were maintained without force. Proliferative and apoptotic activity was increased also in sutures maintained open artificially. Interestingly, levels of active TGF-beta-signaling components were also increased in force-maintained sutures.


CONCLUSIONS
Sutural maintenance by mechanical force is concurrent with modulation of cellular activity and protein expression reminiscent of the open suture. This study demonstrates the dynamic reciprocity existing between biochemical activity and morphologic state. Although it is known that changes in TGF-betas and fibroblast growth factors can cause sutural fusion, this is the first study to demonstrate that abrogation of sutural closure is responsible for growth factor signaling modulation.
Tholpady
Sunil S
SS
Charlottesville, Va.; and Cambridge, Mass. From the Departments of Plastic and Reconstructive Surgery, Neurosurgery, and Cell Biology, University of Virginia Health Sciences Center, and Departments of Material Science and Engineering and Mechanical Engineering, Massachusetts Institute of Technology.
Freyman
Toby F
TF
Chachra
Debbie
D
Ogle
Roy C
RC
D000818:Animals; D000831:Animals, Newborn; D001696:Biomechanical Phenomena; D005786:Gene Expression Regulation / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012886:Skull / Q000033:anatomy & histology / Q000254:growth & development*
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