Differential gene expression between juvenile and adult dura mater: a window into what genes play a role in the regeneration of membranous bone.
BACKGROUND
Although reossification of large calvarial defects is possible in children, adults lack this tissue engineering capacity. In this study, the authors compared the differences in gene expression between juvenile and adult dura mater using a mouse cDNA microarray with 42,000 unique elements.


METHODS
Non-suture-associated parietal bone was harvested from 6-day-old and 60-day-old mice. The dura mater was carefully dissected from the calvarial disk and snap-frozen. RNA was extracted from pooled dura mater for microarray analysis. The 25 most differentially expressed genes were listed, as were selected bone-related genes. In addition, quantitative real-time reverse-transcriptase polymerase chain reaction confirmation of selected genes-BMP-2, BMP-4, and BMP-7; and osteopontin (OP), osteocalcin (OC), and FGFR-1-was performed.


RESULTS
Juvenile dura mater expressed significantly greater amounts of BMP-2 and OP. Minimal difference in OC expression was observed between juvenile and adult dura mater. Extracellular matrix proteins (Col3a1, 5a1, 6a1, and fibronectin 1), osteoblast differentiation markers (Runx2/Cbfa1, Itm2a, and FGFR-1), and the growth factor Ptn were among other genes with greater expression in juvenile dura mater. Markers of osteoclasts (Acp5, MMP9, Ctsk) and the multiple candidate gene Ntrk2 were also expressed at higher levels in the juvenile dura mater.


CONCLUSIONS
These findings suggest a more differentiated osteoprogenitor population to exist along with a greater presence of osteoclasts in the juvenile dura mater relative to adults. In addition to establishing a baseline difference in gene expression between juvenile and adult dura mater, new genes potentially critical to the regenerative potential of juvenile calvaria were identified.
Wan
Derrick C
DC
Stanford and San Francisco, Calif. From the Department of Surgery, Stanford University School of Medicine, Stanford University, and the Departments of Surgery and Cell and Tissue Biology, University of California, San Francisco.
Aalami
Oliver O
OO
Wang
Zhen
Z
Nacamuli
Randall P
RP
Lorget
Florence
F
Derynck
Rik
R
Longaker
Michael T
MT
D000367:Age Factors; D000818:Animals; D001861:Bone Regeneration / Q000235:genetics*; D015870:Gene Expression; D006133:Growth Substances / Q000096:biosynthesis; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D023421:Models, Animal; D020411:Oligonucleotide Array Sequence Analysis; D010294:Parietal Bone / Q000378:metabolism
D006133:Growth Substances