Angiogenic microRNA-210 is present in cells surrounding osteonecrosis

A role of microRNAs (miRNAs), which are ≈ 22-nucleotide non-coding RNAs, has recently been recognized in human diseases. The objective of this study was to identify the expression pattern of miRNA (miR)-210, known to be associated with angiogenesis, in bone from patients with osteonecrosis (ON) of the femoral head. The expression of miR-210 in bone from 10 patients with osteoarthritis (OA) of the hip and ten with ON was analyzed by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and by in situ hybridization. In addition, immunohistochemical staining for von Willebrand factor (vWF) and vascular endothelial growth factor (VEGF) was performed to identify the miR-210 expressing cells. We found that in ON samples, the expression of mature, primary miR-210, VEGF, matrix metalloproteinase (MMP)-2, and MMP-7 was significantly higher than that of OA samples. Section in situ hybridization of mature miR-210 revealed that mature miR-210 is expressed around the necrotic area. vWF and VEGF were also strongly expressed in the miR-210 expressing cells. This study shows that miR-210 is intensely expressed in ON, and might play a role in ON pathogenesis. The present study provides a solid basis for further functional analyses of miRNAs in ON.