CircRNA hsa_circ_0074834 promotes the osteogenesis-angiogenesis coupling process in bone mesenchymal stem cells (BMSCs) by acting as a ceRNA for miR-942-5p

Zhengxiao Ouyang,Tingting Tan,Daishui Yang,Xiaoning Guo,Jia Wan,Tang Liu,Guangyao Jiang,Xianghong Zhang,Yanling Zhou

doi:10.1038/s41419-019-2161-5

Abstract

Bone tissue has a strong ability to repair itself. When treated properly, most fractures will heal well. However, some fractures are difficult to heal. When a fracture does not heal, it is called nonunion. Approximately, 5% of all fracture patients have difficulty healing. Because of the continuous movement of the fracture site, bone nonunion is usually accompanied by pain, which greatly reduces the quality of life of patients. Bone marrow mesenchymal stem cells (BMSCs) play an important role in the process of nonunion. Circular RNAs (circRNAs) are a unique kind of noncoding RNA and represent the latest research hotspot in the RNA field. At present, no studies have reported a role of circRNAs in the development of nonunion. After isolation of BMSCs from patients with nonunion, the expression of circRNAs in these cells was detected by using a circRNA microarray. Alkaline phosphatase and Alizarin red staining were used to detect the regulation of osteogenic differentiation of BMSCs by hsa_circ_0074834. The target gene of hsa_circ_0074834 was detected by RNA pull-down and double-luciferase reporter assay. The ability of hsa_circ_0074834 to regulate the osteogenesis of BMSCs in vivo was tested by heterotopic osteogenesis and single cortical bone defect experiments. The results showed that the expression of hsa_circ_0074834 in BMSCs from patients with nonunion was decreased. Hsa_circ_0074834 acts as a ceRNA to regulate the expression of ZEB1 and VEGF through microRNA-942-5p. Hsa_circ_0074834 can promote osteogenic differentiation of BMSCs and the repair of bone defects. These results suggest that circRNAs may be a key target for the treatment of nonunion.

Highlights

Bone nonunion is a common orthopedic disease
The results showed that the expression of circRNAs was largely different in Bone marrow mesenchymal stem cells (BMSCs) from patients with nonunion and normal fracture healing (Fig. 1a, b)
The results of the microarray analysis were verified by quantitative real-time polymerase chain reaction (qRT-PCR) and showed that the expression of hsa_circRNA_0074834 was significantly increased in BMSCs isolated from normal bone fracture healing patients compared with bone nonunion patients (Fig. 1c)

Summary

Introduction

Bone nonunion is a common orthopedic disease. It often occurs in large bone fractures, which limits patient motor ability and brings a heavy financial burden to patients[1,2]. Studies have reported differences in BMSC origin between patients with nonunion and patients with normal bone healing. Hernigou et al.[6] found that BMSCs in the bone marrow cavity of patients with nonunion decreased in content and distribution, and in vitro studies found that the proliferation of BMSCs from nonunion patients decreased. Mathieu et al.[8] built on previous studies and showed that the proliferative capacity and osteogenic differentiation ability of BMSCs in patients with atrophic nonunion were worse than those of normal BMSCs, but under normal conditions, BMSC function could be restored. The reasons for the decreased proliferation of BMSCs from nonunion patients are still unclear, and further research is needed

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Conclusion