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Objective To investigate the effect of moderate treadmill exercise together with modified hydroxyapatite chitosan composite hydrogel (CS/HA-g-CS) implantation on repair of full-thickness defects of articular cartilage in rats.Methods Full-thickness cartilage defects were drilled in the patellar groove of bilateral femoral condyles in a total of 24 male SD rats before they were randomly assigned into 4 groups.The control group (BC group) was subjected to no exercise or CS/HA-g-CS implantation;the chitosan group (CHI group) to CS/HA-g-CS implantation without exercise;the moderate treadmill exercise group (MIR group) to exercise 4 weeks after modeling without CS/HA-g-CS implantation;the CHI + MIR group to moderate treadmill exercise plus CS/HA-g-CS implantation 4 weeks after modeling.Half of the animals were sacrificed at week 8 and half at week 16 after operation.Femoral condyles were harvested for gross observation and histochemical measurement by O' Driscoll scoring system.mRNA expressions of glycosaminoglycan,collagen type Ⅱ and BMP-2 were detected by RT-PCR.Results Gross observation revealed:at 8 weeks after modeling,the CHI + MIR group was significantly better than the other 3 groups,with the BC group in the poorest (P ＜ 0.05);at 16 weeks after modeling,the BC group was significantly poorer than the other 3 groups (P ＜0.05) among which there were no significant differences (P ＞ 0.05).O 'Driscoll scoring revealed:at both 8 and 16 weeks after modeling,the CHI + MIR group was significantly better than the other 2 groups and the BC group significantly poorer than the other 3 groups (P ＜ 0.05) but there was no significant difference between the MIR and CHI + MIR groups(P ＞ 0.05).The expressions of collagen type Ⅱ,glycosaminoglycan and BMP-2 were significantly higher in the CHI + MIR group than in the other 3 groups (P ＜ 0.05) and significantly lower in the BC group than in the other 3 groups (P ＜ 0.05).Conclusions Moderate treadmill exercise together with CS/HA-g-CS implantation has significant positive effects on repair of full-thickness defects of articular cartilage in rats than merely moderate treadmill exercise or CS/HA-g-CS implantation alone.The defective cartilage repaired by moderate treadmill exercise together with CS/HA-g-CS implantation contains more collagen type Ⅱ and glycosaminoglycan and shows morphology of nearly normal cartilage.
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Objective To apply iTRAQ technology to observe changes in protein expression group in the process of inducing C2C12 cells differentiation towards osteoblast by BMP-2.Methods The myoblast C2C12 cells were seeded in BMP-2 induced differentiation system for differentiation induction.In the 7th day,differentiation protein was extracted and labeled with iTRAQ reagent.Then,mass spectrometric detection,data analysis of differentially expressed proteins,and analysis of biological information were carried out.Results 23 significantly differentially expressed protein spots were screened by BMP-2-induced myoblast C2C12 differentiated cell protein expression profile analysis,where the protein was labeled with iTRAQ reagent.8 protein points were up-regulated,and 15 protein points were down-regulated.Trend classification found that the above differential protein had differential expression in each period of C2C12 cell osteogenic differentiation (1-7 days).Part of up-regulated protein in the early differentiation period showed high expression level;part of up-regulated protein in the late differentiation period showed high expression level;similarly,part of down-regulated protein in the early differentiation period presented low expression level;part of down-regulated protein in the late differentiation period showed low expression level.Preliminary identification showed SERCA3,Cytochrome bS,S100A4,ATPase inhibitor and ATPIF1 presented dynamic changes,which suggests that these proteins may be related to inducing osteogenic differentiation mechanism.Conclusion The results of differential protein expression trend show the necessity of full monitoring of C2C 12 cells osteogenic differentiation and indicate that iTRAQ technology is an effective method of studying protein changes of cellular molecule.Five proteins including SERCA3,Cytochrome b5,S100A4,ATPase inhibitor and ATPIF1 can be used as candidate targets for osteogenic differentiation mechanism research.