Expressions of Matrix Gla Protein (MGP) in the Spinal Ligaments

—Effects of Age and Calcification/Ossification—

Abstract

Matrix γ-carboxyglutamic acid (Gla) Protein (MGP), a mineral binding vitamin K-dependant protein exists in the matrix of cartilage and in the media of the aortic wall and is considered as a regulator of physiological or pathological calcification. Calcification or ossification of the spinal ligaments have received attention in a number of reports, as in some cases the spinal cord is compressed and myelopathy occurs. In the present study, to investigate the role of MGP in the calcification or the ossification of the spinal ligaments, we examined expression of MGP in the lumber spinal yellow ligaments of human. In immunohistochemical study we found the diffuse staining of MGP in the matrix of yellow ligaments and MGP was accumulated at the enthesis of the ligament and the circumference of the site of pathological calcification. There was a tendency in staining of MGP that they were better stained in young patients than old ones. Semiquantitative RT-PCR to amplify MGPm-RNA was performed to measure the quantity of MGP mRNA in the yellow ligaments, showing that the quantity of MGP mRNA was decreased in proportion to aging. These results suggest that expression of MGP in spinal ligament could be a potential clue for elucidating how heterotoropic calcification or ossification develops in ligament tissue.