Molecular and Cellular Characterization of Mouse Calvarial Osteoblasts Derived from Neural Crest and Paraxial Mesoderm

Abstract

Cranial skeletogenic mesenchyme is derived from two distinct embryonic sources: mesoderm and cranial neural crest. Previous studies have focused on molecular and cellular differences of juvenile and adult osteoblasts. To further understand the features of mouse-derived juvenile osteoblasts, the authors separated calvarial osteoblasts by their developmental origins: frontal bone-derived osteoblasts from cranial neural crest, and parietal bone-derived osteoblasts from paraxial mesoderm. Cells were harvested from a total of 120 mice. Interestingly, the authors observed distinct morphologies and proliferation potential of the two populations of osteoblasts. Osteogenic genes such as alkaline phosphatase, osteopontin, collagen I, and Wnt5a, which was recently identified as playing a role in skeletogenesis, were abundantly expressed in parietal bone-derived osteoblasts versus frontal bone-derived osteoblasts. In addition, fibroblast growth factor (FGF) receptor 2, and FGF-18 were more highly expressed in the parietal bone-derived osteoblasts, suggesting a more differentiated phenotype. In contrast, FGF-2, and adhesion molecules osteoblast cadherins and bone morphogenetic protein receptor IB, the bone tissue-specific type receptor were overexpressed in frontal bone-derived osteoblasts compared with parietal bone-derived osteoblasts. The authors observed that although neural crest-derived osteoblasts represented a population of less differentiated, faster growing cells, they formed bone nodules more rapidly than parietal bone-derived osteoblasts. This in vitro study suggests that embryonic tissue derivations influence postnatal in vitro calvarial osteoblast cell biology.