Effects Of Exogenous Vascular Endothelial Growth Factor On Proteoglycan In The Rabbits’ Degenerated Intervertebral Discs

Objective: To investigate the effects of exogenous vascular endothelial growth factor(VEGF) on proteoglycan (PG) in the rabbits’ degenerated intervertebral discs, discuss thefeasibility of injecting exogenous VEGF in treating intervertebral disc degeneration.Methods: Thirty-two New Zealand white rabbits were randomly divided into two groupswith sixteen in each: the experimental group and the control group, all the rabbits werereceived annulus fibrosus puncture to construct the rabbit model of degeneratedintervertebral disc. Two monthes later, all the rabbits were received MRI examination andevaluate the intervertebral disc degeneration grade with improved Thompson classificationmethod, then the experimental group received an injection of20μl BSA solution containingVEGF but the control group just received an injection of20μl BSA solution. Four weekslater, all rabbits were killed and the content of VEGF and PG in intervertebral discs werequantitative determination by enzyme-linked immunosorbent assay.Results: The second day after annulus puncture, a rabbit in the control group was dead,others were recovered well.(1) MRI examination result: The T2signals of L2/3、L3/4、L4/5and L5/6intervertebral discs ofall the rabbits presented a reduction though to various degrees, which showed theconstruction of the rabbit model of degenerated intervertebral disc were success. There wasno significant difference in the amount of intervertebral disc degeneration grade betweenthe control group and the experimental group (P=0.886,P>0.05). (2) The content of VEGF: In the control group, the content of VEGF in gradeⅠ,Ⅱ,Ⅲ andⅣ were122.29±42.80ng/L,124.51±31.68ng/L,128.59±27.65ng/L,48.77±28.20ng/Lrespectively. The variance analysis showed that there were no significant difference amonggradeⅠ,ⅡandⅢ(P＞0.05), grade Ⅳ was significant lower than the other three grades(P＜0.05). In the experimental group, the content of VEGF in gradeⅠ,Ⅱ,Ⅲand Ⅳwererespectively154.87±30.56ng/L,148.86±24.67ng/L,163.46±26.71ng/L,55.15±20.04ng/L,the variance analysis showed that there was significant difference among each grade；gradeⅣ was significant lower than the other three grades(P＜0.05).(3) The content of PG: In the control group, the content of PG in gradeⅠ,Ⅱ,Ⅲ andⅣwere136.44±28.40ng/L,87.57±18.62ng/L,64.33±21.88ng/L and21.96±9.63ng/Lseparately. The variance analysis showed that there were significant difference among eachgrade, with aggravation of the degeneration degree, the content of PG showed a trend ofdecrease. In the experimental group, the content of PG in gradeⅠ,Ⅱ,Ⅲ and Ⅳarerespectively154.48±16.95ng/L,99.36±13.77ng/L,60.71±12.53ng/L,19.52±7.69ng/L.The variance analysis showed that there were significant difference among each grade,with aggravation of the degeneration degree, the content of PG showed a trend of decrease.(4) The comparison results of VEGF and PG in the same grade degeneration discs: In thecontrol group and experimental group, when the degeneration grade is Ⅰ, the content ofVEGF and PG in the two groups have significant difference (P＜0.05), the experimentalgroup is higher than the control group; when the degeneration grade isⅡ, the content ofVEGF and PG in the two groups have significant difference (P＜0.05), the experimentalgroup is higher than the control group; when the degeneration grade is Ⅲ, the content of VEGF in the two groups has significant difference (P＜0.05), the experimental group ishigher than the control group, but the content of PG in the two groups has nosignificant difference (P＞0.05); when the degeneration grade is Ⅳ, the content of VEGFand PG in the two groups have no significant difference (P＞0.05).Conclusion: Constructing the rabbit model of degenerated intervertebral disc by annulusfibrosus puncture possesses such advantages as high operability and good repeatability, theintensity of T2signals reflect the degree of intervertebral disc degeneration can achieveaccurate、direct-viewing effects. According to the improved Thompson classificationmethod, when the degeneration degree reach ⅠorⅡ, exogenous VEGF can promote PGsynthetic in intervertebral disc; when the degeneration degree reach Ⅳ, the content ofVEGF and PG were significantly reduced, which prompts that the intervertebral disc hasbeen severe fibrosis, the vascular buds in the annulus fibrosus could have beenischemia、atrophy even atresia. So in the incipient stage of intervertebral disc degeneration,exogenous VEGF can increase the concentration of VEGF in intervertebral disc, which canpromote PG synthetic, may reach the target that delay even cure intervertebral discdegeneration.