Project description:In recent decades, the field of bone mechanobiology has sought experimental techniques to unravel the molecular mechanisms governing the phenomenon of mechanically-regulated fracture healing. Each cell within a fracture site resides within different local micro-environments characterized by different levels of mechanical strain - thus, preserving the spatial location of each cell is critical in relating cellular responses to mechanical stimuli. Our spatial transcriptomics based “mechanomics” platform facilitates spatially-resolved analysis of the molecular profiles of cells with respect to their local in vivo mechanical environment by integrating time-lapsed in vivo micro-computed tomography, spatial transcriptomics, and micro-finite element analysis. We investigate the transcriptomic responses of cells as a function of the local strain magnitude by identifying the differential expression of genes in regions of high and low strain within a fracture site. Our platform thus has the potential to address fundamental open questions within the field and to discover mechano-responsive targets to enhance fracture healing.
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:Patients with Neurofibromatosis Type 1 (NF1) present with fracture pseudarthroses, though the exact mechanism underlying this abnormal healing remains unknown. Here, we performed spatial transcriptomics to spatially-define the molecular signatures across endochondral healing following fracture. Integrating single-cell sequencing of patient fracture-derived primary cells, our results provide a dynamic cellular context to the molecular dysregulation associated with somatic fracture healing defects in NF1.
Project description:The association between DM and impaired fracture healing including delayed union and nonunion has been documented in clinical and experimental settings. We examine miRNA expression specific for impaired fracture healing in diabetic rat.
Project description:The association between DM and impaired fracture healing including delayed union and nonunion has been documented in clinical and experimental settings. We examine mRNA expression specific for impaired fracture healing in diabetic rat.
Project description:Fracture non-union is a complex clinical condition affecting many patients worldwide; however, known risk factors alone cannot help in predicting individual risk of progressing towards healing complications. The identification of novel biomarkers in the serum of fracture patients is crucial for early diagnosis and timely patient treatment. This study focused on the identification of microRNA (miRNA) that could correlate to the process of fracture healing. Toward this aim, serum of fracture patients and healthy volunteers was screened by RNA sequencing to identify differentially expressed miRNA at different times after injury. The results were correlated to miRNA that were found to be differentially secreted in the conditioned medium of human bone marrow mesenchymal stromal cells (BMSCs) during in vitro osteogenesis.
Project description:Phosphate is essential for healthy bone growth and plays an essential role in fracture repair. Although phosphate deficiency has been shown to impair fracture healing, the mechanisms involved in impaired healing are unknown. More recently, studies have shown that the effect of phosphate deficiency on the repair process varied based on the genetic strain of mice, which is not characterized. We used data from microarrays to (1) determine the effects of phosphate restriction on the biologic functions identified from the gene expression in fracture calluses; and (2) examine whether there are genetic differences within the primary biologic functions.
Project description:Sprague-Dawley rats were placed on an ethanol-containing or pair-fed Lieber and DeCarli diets for 4 wks prior to surgical fracture. Following insertion of a medullary pin, a closed mid-diaphyseal fracture was induced using a Bonnarens and Einhorn fracture device. At 3 days post-fracture, the region of the fracture calluses were harvested from the right hind-limb. RNA was extracted and microarray analysis was conducted against the entire rat genome to study the effects of alcohol-consumption on the fracture healing. The experiments were on four rat subjects, i.e., pair-fed rats with subsequent surgical fracture or no surgical fracture, and alcohol-fed rats with subsequent surgical fracture or no surgical fracture. Each rat subject described above has three replicates so 6 kinds of pairing can be made and each pairing has a dye-swap replicate (thus, a total 12 array experiments). The focus of this study is on the pair-fed fracture subject vs. alcohol-fed fracture subject.
Project description:Time-point expression analysis of fractures calluses at 1, 3, and 5 days post-fracture in young and old BALB/c mice. Femur fractures were generated on female c57BI6 mice in triplicate: 8 month old retired breeders (old mice) and 6 week old mice (young mice) were used. 1, 3, and 5 days post-fracture, fracture calluses were dissected and total RNA isolated. Expression profiling was performed using Affymetrix's Mouse Genome 430 2.0 array.