The importance of elastin and fibulin‐5 on spine development: a study of elastin KO and fibulin‐5 KO on the development of vertebral body and intervertebral disc

Abstract

Introduction Idiopathic scoliosis is the most common scoliosis and generally develops during juvenile or adolescent growth spurt (Stehbens 2003). It was reported that elastic fibre system might play a role in some idiopathic scoliosis patients (Hadley‐Miller et al. 1994). Indeed, transgenic mice with defects in elastic fibre system (including elastin null and fibulin‐5 null) appear to develop severe kyphoscoliosis. The aim of this study was to understand how such defects exert their effect on the spinal column.Materials and methods Newborn elastin KO and 16‐week‐old fibulin‐5 KO mice spines were fixed in 10% formalin. Paraffin‐embedded sections (20 µm) were stained with haematoxylin & eosin (H&E) and alcian blue after the sections were dewaxed and rehydrated. The sections were examined by light microscopy.Results H&E staining revealed that those newborn elastin KO mice seem to have a delayed ossification in vertebral bodies compared to that of wild‐type. Also, cell morphology in IVD appears very much different. Cells in outer annular (OA) and endplate regions are much round‐like comparing fibroblast‐like cells in wild‐type. In addition, GAG expressions showed by alcian blue staining appear much sparse and irregular in the matrix of IVD in newborn elastin KO mice. Fibulin‐5 KO mice (16 weeks) seem to have many cell clusters or clones in the growth plate, which is an indication of abnormal growth. Our results reveal the importance of elastin and fibulin‐5 on the development of spine.Discussion Kypho‐scoliosis is a spinal deformity. Several different spinal tissues, e.g. muscle, vertebrae, IVD and ligament, are involved in the stability and load carriage of the spinal column.Some gene defects in these load‐bearing structures can lead to the scoliotic deformity, e.g. elastin null, fibulin‐5 null, collagen‐II null (Aszodi et al. 1998), perlecan null (Costell et al. 1999) and LTBP3‐null (Dabovic et al. 2002) as well as a mutant in a muscle‐specific protein (Blanco et al. 2001), but other defects [such as collagen‐IX KO's (Kimura et al. 1996)] do not. The relationship between defects in these structures and development of scoliotic is still unclear.