'Cell or Not to Cell' that is the Question: For Intervertebral Disc Regeneration?

Abstract

Anatomy of the Intervertebral Disc he Human Intervertebral Disc (IVD) is a ibrocartilagenous structure positioned between each connecting vertebra of the spinal column. Mechanically, the IVD transmits load, arising from body weight and muscle activity, and permits a range of spinal movement including bending, lexion and torsion [1]. he normal IVD is composed of three morphologically distinct regions: the Cartilaginous End Plates (CEP), the highly organised Annulus Fibrosus (AF) and the central gelatinous Nucleus Pulposus (NP), which operate collectively to mechanically transfer loads and disperse energy evenly throughout the spine. he CEP is a layer of hyaline cartilage which separates the AF and NP from the adjacent vertebral body and facilitates difusion of nutrients and oxygen to the avascular internal structures of the IVD [2,3]. he AF can be further subdivided into the outer and the inner AF. he outer AF contains large amounts of ibrous collagen type I orientated into lamellae, providing resistance to tensile forces from bending and twisting of the vertebral column [4]. he inner AF is a transition zone between the randomly organised, hydrated NP and the highly organised, ibrous outer AF, with characteristics of both tissue types observed in this region. he NP has a gelatinous matrix composed of randomly arranged collagen type II ibres, radially arranged elastin ibres and small amounts of collagen types VI, IX and XI, all of which are embedded in a highly hydrated matrix rich in proteoglycans (mainly aggrecan) [5]. he hydrated proteoglycans provide viscoelasticity and resistance to compression whilst the collagen crosslinks confer tensile strength [6].