Relationship Between Apoptosis of Endplate Microvasculature and Degeneration of the Intervertebral Disk.

Objective: To explore the relationship between intervertebral disk degeneration and endplate microvasculature, and to determine the role of apoptosis in the pathophysiology underlying end plate microvasculature.

Methods: Twelve 6-month-old rabbits were randomly divided into group A (control group where animals underwent a sham operation, in which the loading device was implanted but without loading) and group B (degeneration group, where a calibrated spring within the loading device would immediately create static shear force of 50 N to the disk of L4-5). Paraffin-embedded midsagittal sections of the L4-5 disk were obtained 4 weeks after surgery in the both groups. Sections were stained with cluster of differentiation (CD) 31 immunohistochemistry to measure the blood vessel density in the endplate, with CD31 immunofluorescence and terminal dUTP nick-end labeling (TUNEL) to detect the apoptosis of vascular endothelial cells in the endplate.

Results: After 4 weeks, the microvasculature density was 91 ± 8 vessels/mm in group A and 47 ± 2 vessels/mm (P < 0.001) in group B, demonstrating that vessels were reduced in the endplate of intervertebral disk degeneration. CD31 immunofluorescence and TUNEL showed that apoptosis of vascular endothelial cells exists in the endplate of intervertebral disk degeneration.

Conclusions: The results of this study suggest that apoptosis of vascular endothelial cells results in a decrease in endplate microvasculature density, further affecting the pathologic process of intervertebral disk degeneration.