Effect of Lipocalin-2 gene on osteogenic differentiation of bone marrow mesenchymal stem cells and bone strength of osteoporosis mice model

Abstract

Objective To investigate the role and mechanism of Lipocalin-2 gene in osteoporosis. Methods Reverse transcriptase-polymerase chain reaction (RT-PCR) assay and compared patients with osteoporosis (n=18) and non osteoporosis patients (n=18) expression of Lipocalin-2 blood samples by mRNA; mouse bone marrow mesenchymal stem cells with Lipocalin-2 gene, alkaline phosphatase (ALP) staining and alizarin red staining to detect cell osteogenic differentiation of Western cells, blotting detection of bone differentiation related gene expression of bone; a mouse model of osteoporosis, osteoporosis by mouse Lipocalin-2 gene, micro-CT detection of mouse tibia trabecular bone volume, the mechanical properties of the femur bending test. Results The relative expression of mRNA in patients with osteoporosis (1.693±0.359) Lipocalin-2 was higher than that of non osteoporotic group (1.108±0.234), P=0.019. Moreover, the relative expression of Lipocalin-2 mRNA in osteoporotic patients with osteoporotic fracture history (n=10, 2.172±0.624) is higher than that in patients without fracture history (n=8, 1.473±0.336). The protein level of Runx2 and osteocalcin (OCN) and the relative expression of mRNA in the bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation gene of Lipocalin-2 mice were higher than those in the control group. In the Lipocalin-2 group [(812.78±25.36) N/mm], the femoral flexural strength was higher than that in the control group [(744.36±31.54) N/mm], while in the LCN2-small interfering RNA (siRNA) group [(19.69±3.69) μm2], the trabecular area in the proximal tibia was larger than that in the control group [(14.77±4.25) μm2]. Conclusion The expression of Lipocalin-2 is increased in patients with osteoporosis, and the ability of osteogenic differentiation of stem cells is enhanced after downregulation of Lipocalin-2 gene. Down regulation of Lipocalin-2 gene can improve the degree of osteoporosis in mice, and its mechanism is related to Runx2 and OCN. Key words: Osteoporosis; Bone marrow mesenchymal stem cells; Human lipid carrier protein 2; Osteogenic differentiation