Origin matters: Differences in embryonic tissue origin and Wnt signaling determine the osteogenic potential and healing capacity of frontal and parietal calvarial bones

Abstract

Calvarial bones arise from two embryonic tissues, namely, the neural crest and the mesoderm. In this study we have addressed the important question of whether disparate embryonic tissue origins impart variable osteogenic potential and regenerative capacity to calvarial bones, as well as what the underlying molecular mechanism(s). Thus, by performing in vitro and in vivo studies, we have investigated whether differences exist between neural crest–derived frontal and paraxial mesodermal–derived parietal bone. Of interest, our data indicate that calvarial bone osteoblasts of neural crest origin have superior potential for osteogenic differentiation. Furthermore, neural crest–derived frontal bone displays a superior capacity to undergo osseous healing compared with calvarial bone of paraxial mesoderm origin. Our study identified both in vitro and in vivo enhanced endogenous canonical Wnt signaling in frontal bone compared with parietal bone. In addition, we demonstrate that constitutive activation of canonical Wnt signaling in paraxial mesodermal–derived parietal osteoblasts mimics the osteogenic potential of frontal osteoblasts, whereas knockdown of canonical Wnt signaling dramatically impairs the greater osteogenic potential of neural crest–derived frontal osteoblasts. Moreover, fibroblast growth factor 2 (FGF-2) treatment induces phosphorylation of GSK-3β and increases the nuclear levels of β-catenin in osteoblasts, suggesting that enhanced activation of Wnt signaling might be mediated by FGF. Taken together, our data provide compelling evidence that indeed embryonic tissue origin makes a difference and that active canonical Wnt signaling plays a major role in contributing to the superior intrinsic osteogenic potential and tissue regeneration observed in neural crest–derived frontal bone. © 2010 American Society for Bone and Mineral Research.

Diabetes-induced fibrotic matrix inhibits intramembranous bone healing

“…Parietal and frontal calvaria bones have a different embryonic origin (Behr et al 2010;Quarto et al 2010) and we speculate that the kinetics of enzyme development, or alternatively the stability of lysyl oxidase protein, may differ as a consequence. This notion is supported by data in Fig.…”

Opposite Spectrum of Activity of Canonical Wnt Signaling in the Osteogenic Context of Undifferentiated and Differentiated Mesenchymal Cells: Implications for Tissue Engineering

“…36,37 For differentiation conditions, mASCs were cultured in the osteogenic differentiation medium prepared with Dulbecco's modified Eagle's medium containing 10% fetal bovine serum, 100 IU/mL penicillin, and 100 IU/mL streptomycin plus 5 mMglycerophosphate, 100 mg/mL ascorbic acid, and 0.1 M all transretinoic acid (Sigma-Aldrich). For all other cells the osteogenic differentiation medium was a-minimum essential medium containing 10% fetal bovine serum, 100 IU/mL penicillin, and 100 IU/mL streptomycin plus 5 mM-glycerophosphate and 100 mg/mL ascorbic acid.…”

“…36,37 Stable transfected clones were isolated after 2 weeks of selection with 1 mg/mL G418 (Life Technologies) and retroviruses were generated after expansion. Retroviruses were used to infect ASCs and frontal and parietal osteoblasts for stable expression of DnTcf4, catenin S33Y, or Neo control.…”

“…5 Primer sequence and quantitative reverse transcription-polymerase chain reaction (QRT-PCR) conditions for the glyceraldehyde 3-phophate dehydrogenase, runt-related transcription factor 2 (Runx2), Alk Phos, osteocalcin axin2, c-myc, and cyclin D1 genes have been previously described. 36,37 Other primers are listed in Table 1. The results are presented as mean AE standard deviation of three independent experiments.…”

“…Nuclear fractions were prepared as previously described. 37,39 Each nuclear fraction (80 mg) was resolved by 12% Tris-HCl sodium dodecyl sulfate-polyacrylamide gel. Proteins were transferred to an Immobilon-P membrane (Millipore).…”