Potential Gene Therapy for Intervertebral Disc Degeneration

Degenerative spinal disorders including low back pain are one of the most common and costly problems for modern society. It has been recognized that these disorders are directly or indirectly associated with intervertebral disc degeneration. The disc is a cartilaginous connective tissue, composed of the nucleus pulposus(NP), annulus fibrosus and endplates, which connects adjacent vertebrae (the functional spinal unit) and plays major roles in promoting the flexibility and stability of the lumbar spine. The NP is comprised of chondrocytic cells (nucleus pulposus cells) in an extensive extra-cellular matrix such as proteoglycan or collagen. Large molecules of proteoglycan exist in collagen networks and the high osmotic pressure produced by proteoglycan can result in inbibing water into the encapsulated NP, leading to high positive pressure inside the disc (Nachemson et al., 1970). The maintainance of this high positive presure inside of the disc is important in ensuring the biomechanical strength of the disc (Figure 1).