Interleukin-1 inhibits Sox9 and collagen type Ⅱ expression via nuclear factor-κB in the cultured human intervertebral disc cells

Background The most significant biological change in intervertebral disc degeneration is the decrease of chondrocyte specific gene and protein expression of Sox9 and collagen type Ⅱ. Interleukin-1 （IL-1） is not expressed in the normal intervertebral disc tissue but increases in the degenerated intervertebral disc tissue. This suggests that IL-1 may play a role in regulation of the expression of Sox9 and collagen type Ⅱ. Methods Human intervertebral disc cells were isolated and cultured. Sox9 and collagen type Ⅱ expression during treatment with IL-1, with or without the nuclear factor-κB （NF-κB） activity inhibitor curcumin, were detected by using reverse transcription-polymerase chain reaction （RT-PCR） and Western blotting, and the activity of the NF-κB signaling pathway was detected by the electrophoretic mobility shift assay （EMSA）. Results IL-1 lowered the mRNA level and protein expression of Sox9 and collagen type Ⅱ in the cultured intervertebral disc cells in a dose dependent manner （P 〈0.05）, and this effect was attenuated by curcumin. Curcumin alone had no effect on Sox9 and collagen type Ⅱ expression （P 〉0.05）. IL-1 at concentrations of 0.1 ng/ml, 1 ng/ml and 10 ng/ml could stimulate the activity of NF-κB in the intervertebral disc cells in a dose dependent manner （P 〈0.05） that was inhibited by curcumin. Conclusions We demonstrated the previously unknown function of IL-1 in inhibiting Sox9 and collagen type Ⅱ via NF-κB in the intervertebral disc cells. This inhibition can be attenuated by curcumin, which is an effective NF-κB activity inhibitor.

Effect of morselized bones on binding of the canine hydroxyapatite-coated femoral stem

Background Non-cement femoral stems are recognized in clinical use, but there are still some problems. The aim of this research was to make non-cement femoral stems to be press-fit with the medullary cavity. Methods Twenty-four healthy adult mongrel dogs were randomly divided into experimental and control groups. In the right hip joint, an artificial femoral bone replacement surgery was conducted. For the experimental group, the replacement surgery of hydroxyapatite （HA）-coated femoral stems was done, while autogeneous morselized bone was implanted into the medullary cavity. For the control group, morselized bone was not implanted. At postoperative 1, 3, 6 months, a test for interfacial shear characteristics was conducted in the MTS810 Tester. The comparison between the two groups＇ bone-prostheses in shear strength for their interface from shearing destruction was made. A histological observation to check prosthesis-bone interface contact ratios and bone growth was carried out. Results For the experimental group, shear strength was 0.317 MPa in 1 month, 1.447 MPa in 3 months, and 1.621 MPa in 6 months. For the control group, shear strength was 0.195 MPa in 1 month, 1.023 MPa in 3 months, and 1.483 MPa in 6 months. The difference was statistically significant. Stereomicroscope-based observation showed that the number of trabecular bones in the experimental group was larger than that of the control group, and bone growth of the former group was better than that of the latter group. Inverted microscopic observation showed that the binding degree between the prosthesis and trabecular bone of the experimental group was higher than that of the control group. Comparatively, the experimental group＇s trabecular bone had more stromal cells. Conclusions The morselized bones can effectively improve the biological bonding strength and bone-contact ratios in the short term for the HA-coated femoral stem and accelerate the bonding process. The use of morselized autogenous bones played a good role in bone in-growth of the femoral bone stem surface.