The development of a cell-based, biological replacement to restore, main­tain, and improve the function of damaged tissues and organs has become the en vogue frontier to developing potential novel approaches to patient cures. The intervertebral disc (IVD) undergoes very extensive degenerative changes (Figure 63-1) with the various macro- and microtraumas that come with age and daily life activities. Individual differences have been demon­strated in young individuals exhibiting the disc of an elderly person and vice versa. It is generally accepted that an extremely prevalent rate and degree of asymptomatic disc degeneration exists in the general population. There­fore, differentiating normal aging from symptomatic pathological degenera­tion is very difficult and cannot be assessed by simply identifying the most abnormal disc on imaging (Figure 63-2). At this time, controlled provocative lumbar discography (Figure 63-3) remains our best clinical test to identify a physiologically painful structurally compromised IVD. The term ‘‘disco­genic low back pain” is the term often used to indicate degenerative disc disease associated with concordant pain.

Relating recent findings regarding the molecular mechanisms in initiat­ing or propagating degenerative alterations of the IVD will be crucial to the ultimate success in the developments of biologic strategies to cure disco­genic low back pain.

For several reasons, it is extremely difficult to obtain suitable and suf­ficient numbers of target cells from intervertebral disc tissue. Removal of nucleus pulposus cells, the obvious target cells, would require opening of the annulus fibrosus to gain access. This would almost certainly cause damage to the annulus. In addition to the very restricted accessibility, the very low cell density in degenerated discs will further complicate the acquisition of ample usable cells for successful in vitro cultivation. Therefore only a limited number of scenarios are conceivable that would allow the withdrawal of suf­ficient cells from the disc to perform a disc cell–based approach without further damaging the already affected disc or accelerating its degeneration. Withdrawal of herniated disc material might be one scenario that would facilitate the removal of sufficient disc cells for in vitro cultivation. How­ever, the introduction of cells/implants after a surgical intervention on the same disc could be disputed since the outcome of microdiscectomy has been shown to be satisfactory for most patients with radiculopathy. That being said, the direct insult as well as the likely accelerated degenerative process of the surgical level post microdiscectomy predisposes that segment to dis­cogenic LBP postoperatively. This increased risk may justify cell implanta­tion to prevent postoperative acute and/or chronic discogenic LBP. Another potential clinical application would be the use of cell-based approaches to prevent the accelerated degeneration of discs adjacent to an interbody fusion level. Mechanical stress at segmental levels adjacent to fusion procedures is a known biomechanical issue. This is known to result in accelerated rates of degenerative disc disease and consequently discogenic low back pain at segments juxtapositioned to the fusion level (Figure 63-8). The disc mate­rial removed during the fusion procedure could be used as a source of cells to treat the adjacent disc. However, this would imply an intervention at an asymptomatic nondegenerated disc that only has the potential to degenerate in the future and is therefore rather questionable. Thus, at this time, autolo­gous disc cell transplantation is limited to a few clinical scenarios but has the potential to prove to be a powerful approach within these limitations.