Ectopic Ossification of Human Spinal Ligaments Caused by Mesenchymal Stem Cell Abnormalities

Ectopic ossification of the spinal ligament and its progression compresses the spinal cord, resulting in serious neurological deficiencies. Surgery is an established therapy that has had considerable success, but it is often associated with a higher risk of re-progression of ossification followed by neurological complications. Because the detailed mechanism of the onset and development of ectopic ossification have not been clarified, pharmaceutical treatment for this disease has yet to be established. However, a safe and effective treatment is required to improve the quality of life of patients. The disease is thought to be multifactorial, being influenced by both genetic factors and several environmental factors such as mechanical stress. In this review, we discuss recent progress in disease research, with particular focus on what causes initial ossification and which type of abnormality occurs. Mesenchymal stem cells of patients with ossification are thought to misdifferentiate into osteoblasts instead of target ligament cells because they have high osteogenic ability. Elucidation of the genetic and epigenetic transformation of these cells in spinal ligament tissue is crucial to understanding the disease mechanism.