Identification of differentially expressed microRNAs involved in non-traumatic osteonecrosis through microRNA expression profiling.

Accumulating evidence has recently indicated a vital role of microRNAs (miRNAs) in the development of various bone diseases. However, the biological role of miRNAs in the pathogenesis of non-traumatic osteonecrosis of femoral head (ONFH) has not yet been investigated. The present study aimed to profile the differential miRNA expression between non-traumatic ONFH and femoral neck fracture and to develop further understanding of the molecular mechanisms involved in the pathogenesis of non-traumatic ONFH. Femoral heads from 4 patients with non-traumatic ONFH and 4 with femoral neck fracture were used to analyze the miRNA expression profiles in bone tissue using the Exiqon miRCURY™ LNA Array (v.18.0). The results of miRNA microarray analysis were further confirmed by real-time quantitative polymerase chain reaction (qPCR). The differentially expressed miRNA target genes and signaling pathways involved were predicted by bioinformatics analysis. MiRNA microarray chip analysis revealed that 22 miRNAs were significantly up-regulated and 17 were significantly down-regulated in the non-traumatic ONFH samples compared with the femoral neck fracture samples. The real-time qPCR also confirmed the microarray data. Bioinformatics analysis demonstrated that toll-like receptor (TLR), neurotrophin and NOD-like receptor signaling pathway were most likely to be regulated by these differential miRNAs. This miRNA microarray study reveals significant differences in miRNA expression between patients with non-traumatic ONFH and those with femoral neck fracture. Our data also manifests that the signaling pathways regulated by these differentially expressed miRNAs might be important in the pathogenesis of non-traumatic ONFH.