ABSTRACT
BACKGROUND:Our previous studies have found that polygonatum sibiricum polysaccharide (PSP) promotes osteogenic differentiation of bone marrow mesenchymal stem cel s (BMSCs) by Wnt/β-catenin signaling pathway, but the molecular mechanism is unclear.OBJECTIVE:To investigate the effect of PSP promoting the osteogenic differentiation via Wnt signaling pathways in BMSCs after LRP5 silencing. METHODS:LRP5 interference vectors were constructed and then transfected into C57BL/6 mouse BMSCs cultured in vitro. The transfection efficiency of cel s was calculated under fluorescence inverted microscope and the expression of LRP5 protein was detected by western blot assay. The osteogenic potential of BMSCs after LRP5-siRNA transfection was analyzed by alkaline phosphatase staining, alizarin red staining and western blot assay. Effect of PSP on the osteogenic differentiation of LIRP5-silenced mouse BMSCs was detected by real-time PCR and dual luciferase assay. RESULTS AND CONCLUSION:Compared with the control group, the mineralization ability, the mRNA expressions of Runx2 and Osterix, and the protein expression of LRP5 were significantly decreased in the LRP5-siRNA group (P<0.05). PSP could promote LRP5-siRNA transfected mouse BMSCs differentiating into osteoblasts and significantly upregulated the expressions ofβ-catenin and Osterixin, and also induced the high expression of luciferase reporter gene (TOPFlash) containing wild type TCF binding sites (P<0.05). To conclude, LRP5 plays an important role in the process of mouse BMSCs differentiating into osteoblasts. PSP can promote the osteogenic differentiation of mouse BMSCs by activating the Wnt/β-catenin signaling pathway independent on LRP5.
ABSTRACT
BACKGROUND: Bone marrow-derived mononuclear cells (BM-MNCs) hold the potential of differentiating into osteoclasts. Polygonatum sibiricum polysaccharide (PSP) may inhibit the differentiation of BM-MNCs into osteoclasts and it is expected to become a new drug for the treatment of osteoporosis. OBJECTIVE: To investigate the effect of PSP on the differentiation of mouse BM-MNCs into osteoclasts induced by receptor activator of nuclear factor kappa-B ligand (RANKL) and bone resorption in vivo. METHODS: Mouse bone marrow-derived macrophages cultured in vitro, the effect of macrophage colony stimulating factor and PSP (5, 10, 20, 40, 80,160, 320, 640, 1280, 2560 mg/L) on the proliferation of mouse BM-MNCs was detected by cell counting kit-8 assay to determine the PSP concentration range; the mouse BMMs were cultured and induced in DMEM medium containing macrophage colony stimulating factor, RANKL and 5, 10, 20, 40, 80,160, 320, 640 mg/L PSP, respectively; those cultured without PSP served as control group. The morphological changes of cells were observed under an inverted microscope.; the number of osteoclasts was detected by tartrate-resistant acid phosphatase staining; the mRNA expression levels of osteoclast-related genes including tartrate-resistant acid phosphatase, matrix metalloproteinase-9, cathepsin K, and nuclear factor of activated T cells c1 were evaluated by quantitative real-time PCR. A mouse model of calvarial osteolysis induced by lipopolysaccharide was established to receive PSP intervention, and then micro CT scanning, three-dimensional reconstruction and relevants software were used for quantitative analysis of bone volume/volume percentage, trabecular number, trabecular bone spacing and thickness. The number of osteoclasts was identified by tartrate-resistant acid phosphatase staining and quantitative analysis of bone resorption area was conducted. RESULTS AND CONCLUSION: Compared with the control group, the concentration of PSP below 640 mg/L showed no significant effect on the proliferation of BMMs (P > 0.05). Different concentrations of PSP (40-640 mg/L) significantly reduced the number of osteoclasts, osteoclast differentiation and maturation, and the mRNA expression levels of tartrate-resistant acid phosphatase, matrix metalloproteinase-9, cathepsin K, and nuclear factor of activated T cells c1 TRAP, MMP-9, CtsK and NFATc1 (P < 0.05). Compared with lipopolysaccharide, PSP could effectively alleviate the lipopolysaccharide-induced calvarial osteolysis, and the bone volume/volume percentage, trabecular number, and trabecular bone spacing were significantly decreased (P < 0.05); additionally, the number of osteoclasts and the area of bone resorption were decreased significantly (P < 0.01). To conclude, PSP can inhibit the differentiation and maturation of mouse BMMs to osteoclasts and alleviate lipopolysaccharide-induced calvarial osteolysis.
ABSTRACT
BACKGROUND:Posterior lamina resection often causes loss of spinal stability, so screw rod internal fixation technology is needed to maintain the stability of lumbar spine. Finite element analysis can be used to simulate the stress distribution of the spine and internal fixation system after spinal surgery. OBJECTIVE: To build three-dimensional finite element model of spinal L1 to L3, analyze the spinal stability and stress distribution after the total laminectomy and insertion of bilateral pedicle screw using finite element method. METHODS: L1-L3 CT data could be colected from an adult healthy male volunteer. Mimics14.01, 3-matic(V6.0) and Ansys 15.0 could be used to set up the intact lumbar spine finite element model of L1-L3 (group A), the L1-L3 finite element model after L2 total laminectomy (group B), and the finite element model of L2 total laminectomy and insertion of bilateral pedicle screw (group C). We used software to simulate flexion, extension, lateral bending and axial rotation, and three kinds of models received finite element analysis. RESULTS AND CONCLUSION: (1) Based on the maximum of Von Mises under different motion states, the maximum stress was significantly lower in group A than in group B (P< 0.05). The maximum stress was significantly lower in group B than in group C (P < 0.05). (2) Based on the total deformation under different motion states, the total deformation was significantly lower in group A than in group B (P < 0.05). The total deformation was significantly lower in group C than in groups A and B (P < 0.05). (3) After the total laminectomy, vertebral body stress increased, especialy in the lamina, pedicle and joints. The range of motion of the vertebral body increased, which influenced the stability of the vertebral body. Internal fixation could decrease range of motion. Stress concentrated on the screw. Stress on the vertebral plate and pedicle decreased. The stability of vertebral body increased. Excessive stress concentrated on screw system wil increase the risk of screw breakage.