Uric Acid Promotes Osteogenic Differentiation and Inhibits Adipogenic Differentiation of Human Bone Mesenchymal Stem Cells.

To investigate the effect of uric acid on the osteogenic and adipogenic differentiation of human bone mesenchymal stem cells (hBMSCs). The hBMSCs were isolated from bone marrow of six healthy donors. Cell morphology was observed by microscopy and cell surface markers (CD44 and CD34) of hBMSCs were analyzed by immunofluorescence. Cell morphology and immunofluorescence analysis showed that hBMSCs were successfully isolated from bone marrow. The number of hBMSCs in uric acid groups was higher than that in the control group on day 3, 4, and 5. Alizarin red staining showed that number of calcium nodules in uric acid groups was more than that of the control group. Oil red-O staining showed that the number of red fat vacuoles decreased with the increased concentration of uric acid. In summary, uric acid could promote the proliferation and osteogenic differentiation of hBMSCs while inhibit adipogenic differentiation of hBMSCs.

CUL4B promotes proliferation and inhibits apoptosis of human osteosarcoma cells.

Cullin 4B (CUL4B) is a component of the Cullin4B-Ring E3 ligase complex (CRL4B) that functions in proteolysis and is implicated in tumorigenesis. Here, we report that CUL4B is associated with tumorigenesis by promoting proliferation and inhibiting apoptosis of human osteosarcoma cells. We performed RNA interference (RNAi) with a lentiviral vector system to silence the CUL4B gene using osteosarcoma SAOS-2 cells. The negative control included the normal target cells infected with the negative control virus whereas the knockdown cells included the normal target cells transfected with the RNAi target virus. We assessed the inhibition resulting from the decreased expression of the CUL4B gene on the proliferation rate of SAOS-2 cells, and also evaluated the cell cycle distribution, apoptosis and clonability. Compared with the negative control, the CUL4B gene expression was significantly inhibited in the SAOS-2 cells at the mRNA and protein levels in the knockdown group (P<0.01). Furthermore, in the knockdown group, the cell proliferation rate and clonability were also significantly inhibited (P<0.01). The apoptosis rate increased significantly (P<0.05). A significant decrease in the number of cells in the G1 phase (P<0.01) and significant increases in the S (P<0.01) and G2 phases (P<0.05) were observed. The silencing of CUL4B gene expression can effectively inhibit osteosarcoma cell proliferation and induce apoptosis. These findings may provide a novel biomarker for the treatment of osteosarcoma.

[A modified goat model of acute spinal cord compression injury from a percutaneous balloon catheter: method feasibility and preliminary observation].

OBJECTIVE: To establish a goat model of acute spinal cord compression injury through a modified percutaneous technique with a Foley double-lumen urine catheter and explore the method feasibility and preliminary observation. METHODS: Twelve adult male Chongming goats were randomly divided into 3 groups:control (A, n = 4), 0.5 ml compression (B, n = 4) and 1 ml compression (C, n = 4). After local anesthesia, all animals received epidural balloon catheter (5Fr) insertion via a percutaneous trans-lumbosacral interlaminar space technique that mimicked the method used in vascular access for angiography. The balloon catheter was advanced under fluoroscopic guidance until its distal tip reached the middle of T6 level.One week later, for groups B and C, the balloon was inflated by half-strength contrast material, 0.5 ml and 1 ml, respectively. The balloon was left inflated for 30 min and then deflated. The images of computed tomography (CT) and magnetic resonance (MR) were taken before and after surgical procedures.Quantitative assessment of spine canal occupying rate was accomplished by an off-line software program based on CT results. Motor function was assessed by the modified Tarlov scale. Two animals of each group were sacrificed after a total observation period of 48 h and 72 h respectively.Spinal cords from the injured level were then obtained for pathologic examinations. RESULTS: All animals underwent successful catheterization occupying 6.8%±0.7% (Group A), 6.7%±0.7% (Group B) and 6.6%±0.6% (Group C) of spine canal respectively. After inflation, the occupying rate of groups B and C achieved 43.4%±2.5% and 88.1%±2.3% respectively.Ventral compression of spinal cord was noted on MR images.Hindlimb movement remained normal after catheter insertion in all groups. All animals in group B and C became paraplegic after inflation. And a positive correlation existed between injection volume and Tarlov score. Pathological findings confirmed neuron atrophy, increased gap around neurons, mild demyelination and vacuolar degeneration both in groups B and C at 48 h after injury. Pathological changes deteriorated at 72 h after injury. CONCLUSION: The results of behavioral evaluation, radiographic images and pathological examination reveal an evidence of acute spinal cord injury. Percutaneous epidural balloon catheter insertion differs from previous techniques by avoiding surgical exposure and associated artifacts, yet it offers injury mechanisms similar to those of human spinal cord injury. As a new means of modeling spinal cord injury in animals, this technique has many potential applications.