Effect of vertebral endplates′permeability on the biologic characters of rat nucleus pulposus cells cultured in vitro

English Keywords:Disc degeneration  Organ culture model  Nutritional pathway  Endplate  Rat

English Abstract:

  【Abstract】 Objective：To observe the effect of vertebral endplates′ permeability on the biologic characters of rat nucleus pulposus cells cultured in vitro.Method：Lumbar intervertebral discs，plus adjacent vertebral endplates，were harvested from 20 male Spragua-Dawley（SD） rats（4 weeks old，n=6/animal）.The intervertebral discs were randomly divided into three groups：control group（group A），superior endplate blocked with bone wax（group B），and superior and inferior endplates blocked with bone wax（group C），all specimens were cultured in vitro. The cell viability，the expression of mRNA of collagen Ⅱ and aggrecan were assessed by using Mitotracker Green probe and RT-PCR before culturing and on the 7th and 14th days after culturing.The expression of collagen Ⅱ，aggrecan and matrix metalloproteinase-3（MMP-3） were assessed by using immunohistochemistry staining methods before culturing and the 14th day after culturing.Result：The fluorescence intensity of fresh intervertebral disc was the maximum.There was no significant difference with respect to fluorescence intensity between three groups and fresh disc on the 7th day（P>0.05），and no significant difference was found among three groups（P>0.05）.There was a significant decrease with respect to fluorescence intensity between three groups（group A：19%，group B：22%，group C：30%） and fresh disc on the 14th day（P<0.05）.A significant downregulated mRNA expression of collagen Ⅱ and aggrecan in three groups on the 7th and 14th days was noted（P<0.05）.No significant difference was found among three groups on the 7th day and between group A and B on the 14th day（P>0.05），but for group C，significant difference was noted compared with group A and B on the 14th day（P<0.05）.Conclusion：Decreasing the permeability of bilateral vertebral endplates of rat intervertebral discs cultured in vitro can accelerate disc degeneration through affecting the biologic characters of nucleus pulposus cells in the short term.