Project description:Over 6.8 million fractures are reported annually in the US, accounting for 20% of all musculoskeletal injuries. Approximately 10% of fractures will experience delayed- or non-union. Parathyroid hormone (PTH) analogs and anabolic osteoporosis therapeutics can stimulate fracture repair in animal models and patients with chronic nonunion. Previous studies have demonstrated that small molecule salt inducible kinase (SIK) inhibitors mimic PTH action in vitro and in vivo. Therefore, we hypothesize that YKL-05-099, a small molecule SIK inhibitor, will accelerate fracture callus osteogenesis.
Project description:Cartilage mineralization is a tightly controlled process, imperative for skeletal growth and fracture repair. However, in osteoarthritis (OA), cartilage mineralization may impact the joint range of motion, inflict pain and may increase chances for joint effusion. Here we attempt to understand the link between inflammation and cartilage mineralization by targeting SIRT1 and LEF1, both reported to have contrasting effects on cartilage.
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.
Project description:To further understand the molecular complexity of fracture repair, we investigated miRNA profiling during the first 14 days post fracture. miRNA expression was investigated at post-fracture days 1, 3, 5, 7, 11, 14 as well as in intact (unfractured bone).
Project description:Skeletal tissue is known to respond to mechanical stress. Ultrasound stimulation is one of mechanical stress and low intensity pulsed ultrasound (LIPUS) devices have been clinically utilized to promote the fracture healing. However, it is still not clear which skeletal cells, especially osteocytes or osteoblasts, mainly respond to LIPUS stimulation and how they contribute to fracture healing. To examine that, we utilized medaka known to have bones without embedded osteocytes and zebrafish known to have bones with embedded osteocytes as an in vivo model. Interestingly, fracture healing was accelerated by ultrasound stimulation in zebrafish but not in medaka. To examine the molecular events induced by LIPUS stimulation in osteocyte, we performed RNA-sequencing with the murine long bone osteocyte Y4 (MLO-Y4) cell line exposed to LIPUS. 179 genes reacted to LIPUS stimulation and functional cluster analysis defined that several molecular signatures related in immunity, secretion and transcription. Especially, most of isolated transcription related genes were modulated by LIPUS also in vivo experiments using zebrafish. Target genes analysis showed that inflammatory response and bone formation in fracture healing could be transcriptionally regulated in osteocytes by LIPUS stimulation. Among these transcription genes, early growth response (Egr) 1,2, JunB, Forkhead box Q1 (FoxQ1) and nuclear factor of activated T cells (NFAT) c1 were not altered by LIPUS in medaka unlike zebrafish suggesting that these genes would be key transcriptional regulator of LIPUS-dependent fracture healing through osteocytes. In this study, we revealed bone-equipped osteocytes is necessary for LIPUS-induced promotion of fracture healing through the transcriptional control of target genes presumably to activate neighboring cells involved in fracture healing event.
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: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:Osteoporosis and bone fragility fracture are multifactorial pathologies whose genetic component is still poorly characterized. The present experiment aims to identify genes differentially expressed in the bone-forming cell; the osteoblast. To do this, we obtain primary osteoblasts from bone explants of women undergoing hip replacement to later obtain RNA. The cases are women with a fragility bone fracture of the hip. The controls are women with severe osteoarthritis.Microarray analysis yielded 2542 differentially expressed transcripts belonging to 1798 annotated genes, of which 45.6% (819) were overexpressed, and 54.4% (979) underexpressed (fold-change between -7.45 and 4.0). Among the most represented pathways indicated by transcriptome analysis were chondrocyte development, positive regulation of bone mineralization, BMP signaling pathway, skeletal system development and Wnt signaling pathway. Then, we selected SNPs in genes related to epigenetic mechanisms to study their association with bone mass in a cohort of 1028 Spanish women. We used microarrays to compare the overall gene expression between primary osteoblasts from women with fragility fracture with that of control women undergoing hip replacement due to severe osteoatritis.
Project description:mRNA gene expression was measured in intact female Sprague-Dawley rats at 6 (young), 26 (adult) and 52 (older) weeks of age at the time of fracture. Samples were collected at 0, 0.4, 1, 2, 4, and 6 weeks after fracture. RNA from two rats were pooled for each Affymetrix Rat U34A array. Mid-shaft, simple, transverse left femoral fractures were induced after retrograde intramedullary rod fixation with a Bonnarens and Einhorn device. Samples were collected from one third of the femoral length, centered on the fracture site, including the external callus, cortical bone, and marrow elements. Keywords = rat Keywords = fracture Keywords = age Keywords = time Keywords = femur Keywords: other
Project description:To further understand the molecular complexity of fracture repair, we investigated miRNA profiling during the first 14 days post fracture.