Project description:Periosteum deficiency affects bone regeneration, especially in the case of the bone disorder congenital pseudarthrosis of the tibia (CPT). We investigated a new mouse model of CPT caused by Nf1 inactivation in boundary cap-derivatives, the Prss56Cre; R26tdTom; Nf1fl/fl model. To investigate altered healing in this CPT model, we generated a dataset of the injured periosteum and fracture callus at day-7 post fracture from Prss56Cre; R26tdTom; Nf1fl/fl mice.
Project description:Expression data from purified human long bone fracture callus Skeletal Stem Cells (SSCs) and Osteogenic Progenitor (hOPs) and Chondrogenic Progenitor (hCPs) cells
Project description:Skeletal stem/progenitor cells are critical for fracture repair by providing osteochondro precursors in the callus, which is impaired in aging. However, the molecular signatures of callus skeletan progenitor cells during aging is not known. We performed single-cell RNA sequencing on CD45-CD31-Ter119- skeletan progenitor cells isolated from young and aged mouse calluses.
Project description:Genome-wide comparative gene expression analysis of callus tissue of osteoporotic mice (Col1a1-Krm2 and Lrp5-/-) and wild-type were performed to identify candidate genes that might be responsible for the impaired fracture healing observed in Col1a1-Krm2 and Lrp5-/- mice. To investigate bone healing in osteoporosis, we performed fracture healing studies in wild-type mice (C57BL/6 genetic background) and the low bone mass strains Col1a1-Krm2 and Lrp5-/- (Schulze et al., 2010; Kato et al., 2002). Osteotomy was set in femora of female mice and stabilized by a semi-rigid fixator to allow fast bone healing (RM-CM-6ntgen et al., 2010). 21 days post surgery we analyzed the fracture calli by biochemical/histological methods, as well as micro-computed tomography, and observed impaired fracture healing in Col1a1-Krm2 and Lrp5-/- mice in comparison to wild-type. To identify genes that may be responsible for the impaired healing in osteoporotic mice, we performed microarray analysis of three independent callus samples of each genotype. The callus tissue was taken 10 days after surgery, because extensive bone formation took place at this point.
Project description:Gene expression profiling of purified stem and progenitor cell types from femoral fracture calluses of patients hemiarthroplasty or open reduction internal fixation procedures. We used microarrays to detail the global program of gene expression of stem and progenitor cells responsible for skeletal repair.
Project description:Fracture healing is a process that involves many cell populations. In this study we characterized gene expression in a subset of cells involved in fracture healing. αSMACreERT2 mice crossed with Ai9 reporter mice that express tdTomato fluorescent protein after Cre-mediated activation were used as an experimental model. αSMA-expressing cells were labeled by tamoxifen administration, then periosteal cells from the tibia were isolated two days later (controls), or tibial fractures were performed and periosteum/soft callus tissue was collected after 2 and 6 days. The tdTomato positive cell population was isolated by flow cytometry, and subjected to microarray analysis. Histology and cell surface marker analysis indicates that αSMACreERT2 labels a mainly mesenchymal population in the periosteum that expands after fracture, and contributes to both osteogenic and chondrogenic elements of the fracture callus. We were therefore able to examine gene expression in a defined population during the early stages of fracture healing. Total RNA was obtained from the tomato positive cells within the periosteal compartment of fractures from αSMACreERT2/Ai9 mice. Control animals were given 2 doses of tamoxifen, and periosteum was collected and labeled cells sorted (8-9 sex-matched mice per group). Fractures were performed after the second dose of tamoxifen, and tomato positive cells from periosteum/callus tissue were isolated 2 and 6 days after fracture (4-8 animals per sample pooled). 3 replicates for each sample are included.
Project description:Gene expression profiling of purified stem and progenitor cell types from stabilized bicortical femoral fracture calluses one week after injury induction. We used microarrays to detail the global program of gene expression of stem and progenitor cells responsible for skeletal repair.
Project description:Interleukin-6 (IL-6) is highly upregulated in response to skeletal injury, suggesting it plays a role in the inflammatory phase of fracture repair. However, the impact of IL-6 on successful repair remains incompletely defined. Therefore, we investigated IL-6 in fracture repair using 12-week old IL-6 global knockout mice (IL-6 KO) and two models of fracture repair: full fracture and stress fracture. Callus formation 14 days after full fracture did not differ between IL-6 knockout mice and controls. However, IL-6 KO mice had an enhanced response 7 days after stress fracture compared to control, with increased callus (p=0.020) and bone formation (p=0.045). IL-6 KO did not alter the recruitment of neutrophils or macrophages to the stress fracture callus. IL-6 KO also did not alter the number of osteoclasts in the stress fracture callus. Based on RNA-seq, IL-6 KO resulted in only modest alterations to the gene expression at early time points after stress fracture. Wnt1 was more highly upregulated in IL-6 KO callus at both day 1 (fold change 12.5 vs. 5.7) and day 3 (fold change 4.7 vs. 1.9) compared to controls. Finally, using tibial compression to induce bone formation, we found that IL-6 KO directly impacted osteoblast function, increasing the propensity for woven bone formation. Herein, we report that IL-6 knockout enhanced formation of callus and bone following stress fracture injury, likely through direct action on the osteoblast’s ability to produce woven bone. This suggests a novel role of IL-6 as a suppressor of intramembranous bone formation.