Project description:Gene expression profile at single cell level of calvarial bone stromal cells after drill hole lesion injury (1 mm) at post-lesion day 14 (PLD14) from injured calvarial bones and corresponding unijured controls. Adult wild type animals and endothelial-specific Fbxw7 mutants to study Notch gain-of-function were used.
Project description:In newborn humans, and up to approximately 2 y of age, calvarial bone defects can naturally regenerate. This remarkable regeneration potential is also found in newborn mice and is absent in adult mice. Since previous studies showed that the mouse calvarial sutures are reservoirs of calvarial skeletal stem cells (cSSCs), which are the cells responsible for calvarial bone regeneration, here we hypothesized that the regenerative potential of the newborn mouse calvaria is due to a significant amount of cSSCs present in the newborn expanding sutures. Thus, we tested whether such regenerative potential can be reverse engineered in adult mice by artificially inducing an increase of the cSSCs resident within the adult calvarial sutures.First, we analyzed the cellular composition of the calvarial sutures in newborn and in older mice, up to 14-mo-old mice, showing that the sutures of the younger mice are enriched in cSSCs. Then, we demonstrated that a controlled mechanical expansion of the functionally closed sagittal sutures of adult mice induces a significant increase of the cSSCs. Finally, we showed that if a calvarial critical size bone defect is created simultaneously to the mechanical expansion of the sagittal suture, it fully regenerates without the need for additional therapeutic aids. Using a genetic blockade system, we further demonstrate that this endogenous regeneration is mediated by the canonical Wnt signaling.This study shows that controlled mechanical forces can harness the cSSCs and induce calvarial bone regeneration. Similar harnessing strategies may be used to develop novel and more effective bone regeneration autotherapies.
Project description:Axin2-expressing calvarial suture stem cells can contribute to calvarial development, homeostatic maintenance, repair, and regeneration. We used microarray to examine the gene expression profiles of Axin2-expressing suture stem cells and Axin2-negative cells in suture mesenchyme.
Project description:Background: It has widely been observed that young children are capable of reossifying large calvarial defects, while adults lack this endogenous tissue-engineering capacity. The ability of juvenile animals to regenerate calvarial defects has been investigated in multiple animal models, including mice. In this study, the authors used cDNA microarrays to investigate the expression of osteogenesis-associated genes upstream and downstream of Runx2 in juvenile and adult mouse calvaria. Methods: Nonsuture-associated parietal bone discs were harvested from 6-day-old (n = 50) and 60-day-old (n = 35) male CD-1 mice. After separation of the underlying dura mater and overlying pericranium, the calvarial discs were snap-frozen and RNA was extracted from pooled samples of calvaria for microarray analysis. Genes analyzed included cytokines, receptors, and cell-surface and matrix proteins both upstream and downstream of Runx2. Results: Genes associated with the Runx2 pathway had notably higher levels in the juvenile versus adult calvaria. All genes except for osteocalcin were expressed at least twofold higher in the juvenile calvaria. This pattern was validated with quantitative real-time polymerase chain reaction. In addition, mRNA for potent osteoinductive growth factors was present at higher levels in the juvenile compared with the adult calvaria. Conclusions: These findings reflect a genomic environment of active osteoblast differentia-tion and ossification in the juvenile calvaria compared with the adult aquiescent calvarial tissue. These data suggest that a decreased osteogenic potential of adult calvarial osteoblasts may, in part, explain the inability of adult animals to heal calvarial defects.
Project description:Axin2-expressing calvarial suture stem cells can contribute to calvarial development, homeostatic maintenance, repair, and regeneration. We used microarray to examine the gene expression profiles of Axin2-expressing suture stem cells and Axin2-negative cells in suture mesenchyme. Three of Axin2+/GFP+ and three of Axin2-/GFP- cell samples were collected from mice carrying Axin2rtTA and TREH2BGFP transgenes. Each samples were isolated from 6-8 Axin2rtTA; TRE-H2BGFP mice and sorted by the GFP intensity.
Project description:Thyroid hormone has a positive effect on endochondral bone growth. Few studies have looked at the interaction between thyroid hormone exposures and intramembranous bone derived cells. We used microarray as one tool to determine the gene expression profile of intramembranous (calvarial) derived murine pre-osteoblsts after thyroxine exposure.
Project description:Recently, serotonin and serotonin reuptake inhibitor (SSRI) drugs have been shown to have an effect on the development and maintenance of bone. However, little is known about its role in craniofacial development. We used microarray as one tool to determine the gene expression profile of intramembranous (calvarial) derived murine pre-osteoblasts after citalopram (SSRI) exposure.
Project description:Thyroid hormone has a positive effect on endochondral bone growth. Few studies have looked at the interaction between thyroid hormone exposures and intramembranous bone derived cells. We used microarray as one tool to determine the gene expression profile of intramembranous (calvarial) derived murine pre-osteoblsts after thyroxine exposure. We isolated whole RNA from MC3T3-E1 cells treated with proliferation media or proliferation media with thyroxine at a dose of 10^-6 mol./liter for 3 or 7 days in culture. We then used an Affymetrix array and compared expression profiles between control and experimental treatments.
Project description:Recently, serotonin and serotonin reuptake inhibitor (SSRI) drugs have been shown to have an effect on the development and maintenance of bone. However, little is known about its role in craniofacial development. We used microarray as one tool to determine the gene expression profile of intramembranous (calvarial) derived murine pre-osteoblasts after citalopram (SSRI) exposure. We isolated whole RNA from MC3T3-E1 cells treated with proliferation media or proliferation media with SSRI at a dose of 10^-4 mol./liter for 3 or 7 days in culture. We then used an Affymetrix array and compared expression profiles between control and experimental treatments.