Project description:Osteoporosis is the consequence of altered bone metabolism resulting in the systemic reduction of bone strength and increased risk of fragility fractures. MicroRNAs (miRNAs) regulate gene expression on a post-transcriptional level are known to take part in the control of bone formation and bone resorption. Recently, targeted secretion of miRNAs from cells originating from various tissues has been described, which allows for their minimal-invasive detection in serum/plasma and use as biomarkers for presence and progression of pathological conditions. One pilot study has reported circulating miRNAs in serum and tissue of fracture patients. However, further studies are required to explore whether a dysbalance in bone homeostasis of fracture patients can reliably be reflected by specific circulating miRNAs, and whether these miRNAs might serve as drugable targets. Here, we report results from a comprehensive multiplex study of 175 miRNAs in serum samples obtained from 7 patients with osteoporotic fractures at the femoral neck, and 7 age-matched controls. Following elaborate quality control statistical analysis of this exploratory dataset identified 9 microRNAs with altered serum levels in response to fracture (adjusted p-value < 0.1). Of these, hsa-miR-10a/b gave excellent discrimination of both groups (AUC = 1.0), and clustering of samples based on the top10 miRNAs confirmed the high discriminatory power of circulating microRNAs for osteoporotic fractures. In the next step 3 miRNAs with unknown roles in osteogenic differentiation and 4 miRNA from a previous study were tested for their effects on osteogenic differentiation. Of these, 3 miRNAs showed robust effects on osteogenic differentiation. Overall, these data provide important insights into changes in serum miRNA in post-traumatic patients. Future studies will show, whether this knowledge can be used to improve current diagnostic methodologies to predict fracture risk and design novel treatment strategies for osteoporosis patients. Two groups with n=7 per group; one groups represents cases with osteoporotic fractures, the control group is age-matched without fractures

Project description:Osteoporosis is the consequence of altered bone metabolism resulting in the systemic reduction of bone strength and increased risk of fragility fractures. MicroRNAs (miRNAs) regulate gene expression on a post-transcriptional level are known to take part in the control of bone formation and bone resorption. Recently, targeted secretion of miRNAs from cells originating from various tissues has been described, which allows for their minimal-invasive detection in serum/plasma and use as biomarkers for presence and progression of pathological conditions. One pilot study has reported circulating miRNAs in serum and tissue of fracture patients. However, further studies are required to explore whether a dysbalance in bone homeostasis of fracture patients can reliably be reflected by specific circulating miRNAs, and whether these miRNAs might serve as drugable targets. Here, we report results from a comprehensive multiplex study of 175 miRNAs in serum samples obtained from 7 patients with osteoporotic fractures at the femoral neck, and 7 age-matched controls. Following elaborate quality control statistical analysis of this exploratory dataset identified 9 microRNAs with altered serum levels in response to fracture (adjusted p-value < 0.1). Of these, hsa-miR-10a/b gave excellent discrimination of both groups (AUC = 1.0), and clustering of samples based on the top10 miRNAs confirmed the high discriminatory power of circulating microRNAs for osteoporotic fractures. In the next step 3 miRNAs with unknown roles in osteogenic differentiation and 4 miRNA from a previous study were tested for their effects on osteogenic differentiation. Of these, 3 miRNAs showed robust effects on osteogenic differentiation. Overall, these data provide important insights into changes in serum miRNA in post-traumatic patients. Future studies will show, whether this knowledge can be used to improve current diagnostic methodologies to predict fracture risk and design novel treatment strategies for osteoporosis patients.

Project description:MicroRNAs (miRNAs) are important regulators of gene expression, with documented roles in bone metabolism and osteoporosis, suggesting potential therapeutic targets. Our aim was to identify miRNAs differentially expressed in fractured vs nonfractured bones. Additionally, we performed a miRNA profiling of primary osteoblasts to assess the origin of these differentially expressed miRNAs. Total RNA was extracted from (a) fresh femoral neck trabecular bone from women undergoing hip replacement due to either osteoporotic fracture (OP group, n=6) or osteoarthritis in the absence of osteoporosis (Control group, n=6), matching the two groups by age and body mass index, and (b) primary osteoblasts obtained from knee replacement due to osteoarthritis (n=4). Samples were hybridized to a microRNA array containing more than 1900 miRNAs. Principal component analysis (PCA) plots and heat map hierarchical clustering were performed. For comparison of expression levels, the threshold was set at log fold change > 1.5 and a p-value < 0.05 (corrected for multiple testing). Both PCA and heat map analyses showed that the samples clustered according to the presence or absence of fracture. Overall, 790 and 315 different miRNAs were detected in fresh bone samples and in primary osteoblasts, respectively, 293 of which were common to both groups. A subset of 82 miRNAs was differentially expressed (p < 0.05) between osteoporotic and non-osteoporotic samples. The eight miRNAs with the lowest p-values (and for which a validated miRNA qPCR assay was available) were assayed, and two were confirmed: miR-320a and miR-483-5p. Both were over-expressed in the osteoporotic samples and expressed in primary osteoblasts. miR-320a is known to target CTNNB1 and predicted to regulate RUNX2, while miR-483-5p down-regulates IGF2. We observed a reduction trend for this target gene in the osteoporotic bone.In conclusion, we identified two osteoblast miRNAs over-expressed in osteoporotic fractures, which opens novel prospects for research and therapy.

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