Degeneration and calcification of the cervical endplate is connected with decreased expression of ANK, ENPP- 1, OPN and TGF - β1 in the intervertebral disc

Abstract

The aim of this study was to clarify the relationship between the expression of ALP, ANK, ENPP-1, OPN and TGF-β1 in the intervertebral disc (IVD), and cervical vertebral endplate calcification and degeneration. Sixty cervical IVDs were excised from 30 human cadavers. Each cadaver was assessed macroscopically for degeneration (Thompson's classification), and then underwent histological processing, regular staining (hematoxylin and eosin, Masson-Goldner trichrome and alcian blue-PAS), immunohistochemistry (ALP, ANK, ENPP-1, OPN and TGF-β1), microscopic degeneration grading (Boos classification), and assessment of endplate calcification. The mean age ± SD of the cadavers was 51.4 ± 19.5. The percentage of endplate calcification significantly correlated with the degree of endplate and IVD degeneration graded using Boos's score (both r = 0.91; p < 0.0001). The intensity and number of stained cells per FOV markedly decreased, for ANK, ENPP-1, and TGF-β1, with the grade of IVD degeneration, regardless of the analyzed IVD region. This was not true only for ALP, which demonstrated an increasing trend corresponding to the degree of IVD degeneration. The expression of OPN was low throughout all analyzed regions, regardless of the degree of degeneration. Modulating the expression of the abovementioned proteins, especially ANK and TGF-β1, may be a new way to prevent degeneration and calcification of the IVD.