AIM:Toexploretheeffectofglucocorticoidonautophagyandsenescenceinthechondrocytes. METHODS:The collagen II in the normal chondrocytes isolated from the SD rats was checked.After stimulation with glu-cocorticoid, LysoTracker Red staining, MDC staining and Western blot were used to detect the level of autophagy in the chondrocytes.The mTOR pathway related molecules were investigated by Western blot.Cell senescence was analyzed by SA-β-gal staining.RESULTS:A dose-dependent increase in the number of autophagic vacuoles was observed in the dexa-methasone-treated chondrocytes, which was demonstrated by the LysoTracker Red and MDC staining.The expression of LC3-II and beclin-1 was increased by dexamethasone, especially in the cells treated with dexamethasone for 4 d.However, P62 expression was decreased.SA-β-gal staining showed that the percentage of cell senescence was increased by dexam-ethasone.Surprisingly, the cell senescence induced by dexamethasone was exacerbated by the autophagic inhibitor 3-MA. CONCLUSION:Autophagy induced by dexamethasone protects chondrocyte from senescence.The mTOR pathway may be involved in the autophagy activation.

AIM:To explore the effect of leptin on the expression of degeneration-related genes in rat nucleus pulposus ( NP) cells and to detect the possible mechanism .METHODS:The normal NP cells isolated from SD rats were analyzed by immunochemistry and immunofluorescence for the collagen II and cytokeratin 19 expression.The NP cells were treated with leptin and/or interleukin-1β( IL-β).The mRNA expression of MMP-1, MMP-3, MMP-9, MMP-13, ADAMTS-4, ADAMTS-5, aggrecan and COL2A1 in the cells was detected by real-time PCR.Alcian blue staining and im-munochemistry were used to examine the expression of proteoglycan and collagen II .Activation of involved pathways was studied by Western blot .The inhibitors of the pathways were used to reveal the effect of these pathways on NP cells .RE-SULTS:The results of real-time PCR revealed that leptin alone up-regulated the mRNA expression of MMP-1, MMP-13, ADAMTS-4, ADAMTS-5 and COL2A1.The synergy of leptin and IL-βwas found in the increased expression of MMP-1, MMP-3 and ADAMTS-5.The NP cells treated with leptin showed less expression of collagen II .Both PI3K/Akt and JAK2/SATA3 pathways were activated by leptin , whereas only inhibitor of JAK 2/SATA3 pathway reversed the expression of MMP-1 and MMP-13.CONCLUSION:Leptin may promote catabolism in rat NP cells via JAK2/SATA3 pathways, which may be the mechanism mediating the association between obesity and intervertebral disc degeneration .

Objective To compare the clinical efficacy and radiologic changes between constrained and non-constrained titanium plate in anterior cervical corpectomy and fusion (ACCF) in elderly cervical spondylosis patients.Methods A total of 58 elderly cervical spondylosis patients who underwent ACCF were divided into group 1 (patients treated with constrained titanium plates,n =30) and group 2 (patients treated with non-constrained titanium plates,n=28).The Japanese Orthopedic Association (JOA) score,fusion rate,the loss of segmental height and cervical lordosis were recorded.The clinical efficacy and imaging features were compared between the two groups.Results The improvement rate of JOA score had no significant differences between group 1 and group 2 [(77.7±18.6)％ vs.(75.8±23.2)％,t=0.340,P＞0.05].At 3 months after operation,the fusion rate was higher in group 2 than in group 1 (89.3％ vs.63.3％,x2 =5.327,P＜0.05).At 3,6 and 12 months after operation,there were no significant differences in the loss of segmental cervical height and lordosis between group 1 and group 2 [(2.42±3.05)mm vs.(0.98±2.86)mm,(3.95±3.65)mm vs.(2.34±2.97)mm,(3.60±4.33)mm vs.(2.40±2.96)mm,(1.64±2.33)° vs.(0.66 ± ±2.14)°,(2.13∧±±3.79)° vs.(0.70±2.99)°,(2.39±4.26)° vs.(0.86±3.25)°,respectively,all P ＞0.05].Conclusions The clinical efficacy is similar in ACCF with the two types of titanium plates.The non-constrained titanium plate can increase the fusion rate in early time,but may aggravate the loss of segmental cervical height and lordosis,which should be used with caution in elderly osteoporosis patients.

We examined the biocompatibility and the safety of a-calcium sulfate hemihydrate (CSH)/multi-walled carbon nanotube (MWCNT) composites for bone reconstruction application. The biocompatibility of the CSH/MWCNT composites was evaluated by the measures which taking L929 fibroblast cells cultured in the extracted liquid of the composite soaking solution and putting bone marrow stromal cells planted on the composite pellets in vitro, respectively. The cell proliferation was evaluated by MTT test and further observed using an inverted optical microscope and a scanning electric microscope. The toxicity of the composites was evaluated by acute and subacute systemic toxicity test. Long-term muscle and bone implantation in vivo tests were also conducted. L929 fibroblast cells grew well in the extracted liquid, as well as bone marrow stromal cells that could adhere on the surface of sample pellets and proliferated rapidly. MTT test showed that there were no significant differences between the experimental and control groups (P > 0.05). In vivo test manifested that the composites were no toxicity, no irritation to skin and good for bone defect reconstruction. It was proved that a-calcium sulfate hemihydrate (CSH)/multi-walled carbon nanotube (MWCNT) composites exhibited excellent biocompatibility for the potential application in bone tissue engineering.
Animals ; Biocompatible Materials ; chemistry ; Bone Marrow Cells ; cytology ; Bone Substitutes ; chemical synthesis ; chemistry ; Calcium Sulfate ; chemistry ; Cell Line ; Cell Proliferation ; Fibroblasts ; cytology ; Materials Testing ; Nanotubes, Carbon ; chemistry ; Rabbits ; Stromal Cells ; cytology ; Tissue Engineering ; methods ; Toxicity Tests