Latest on disc regeneration

[fortitudine]

From Orthopedics, Dec.2006

Disk Regeneration
By Alexander Vaccaro, MD
ORTHOPEDICS 2006; 29:1074

December 2006

Disk regeneration, through direct growth factor application and genetic and tissue engineering, can arrest and may reverse the phenotypic expression of disk degeneration. In this issue of Orthopedics, Dr Alexander Vaccaro of the Rothman Institute discusses the future of disk regeneration.

Alexander Vaccaro, MD
Alexander Vaccaro

In light of years of failed cartilage regeneration and research in joints, is disk regeneration really a possibility?

For the first time ever in the clinical setting, OP-1, or bone morphogenetic protein (BMP) 7, will be evaluated in a clinical pilot study approved by the US Food and Drug Administration to determine its potential as a disk regeneration growth factor in patients suffering from symptomatic lumbar disk disease. It is clear from in vitro laboratory and in vivo animal studies that disk regeneration, through direct growth factor application and genetic and tissue engineering, has the ability not only to arrest, but also possibly to reverse the phenotypic expression of disk degeneration.

What are the most promising areas of disk regeneration research?

Laboratory studies at the University of Pittsburgh, Northwestern University, and Thomas Jefferson University have demonstrated the ability to apply specific growth factors to susceptiple cell lines and transfer genes of interest into the nucleus pulposus of the intervertebral disk to upregulate the production of proteoglycans and collagen type II, two important matrix constituents of the healthy intervertebral disk.

Animal disk degeneration models developed at Thomas Jefferson University have demonstrated the upregulation of specific gene markers which, when exposed to the native disk cell population, result in accelerated disk degeneration. Targeting these marker genes may reverse this occurrence and possibly inhibit the natural aging process or the pathologic acceleration of disk degeneration. The application of cellular engineering through stem cell manipulation with various signaling cues (growth factors) may lead to the successful repopulation of the relatively acellular nucleus pulposus.

Are significant risks involved in trying to regenerate the disks in situ?

The risks identified with genetic engineering, such as uncontrolled viral dissemination, are obviated through direct growth factor application or cellular engineering. Also being investigated are less virulent virus carriers that may be so attenuated they have little risk of traveling beyond the relatively avascular cellular environment.

How can the current nonfusion options for surgical instrumentation potentially lead to disk regeneration?

SpineThe thought exists that controlled and stable disk motion may improve the nutrition and vascular supply to the intervertebral disk and replenish vital lost nutrients important for nucleus pulposus cellular viability. The application of posterior motion-sparing implants may allow for this type of controlled, stable motion, protecting the spinal unit from further accelerated pathologic disk degeneration.

What is the goal of growth factor injections into the intervertebral disk?

The injections of specific growth factors into the nucleus pulposus may induce active mesenchymal cells within the disk to transform into nucleus pulposus cells or induce the replication or multiplication of existing nucleus pulposus cell lines, important in the production of vital matrix molecules such as aggregans and collagen type II.

How well will disk regeneration fit into the realm of treatment options for chronic low-back pain?

The biggest problem with low-back pain is that obvious radiographic evidence of degenerative disk disease may or may not be present in an individual suffering from low-back pain. Even if technologies are developed that can reverse the phenotypic expression of spinal degenerative disease (disk height loss, endplate sclerosis, loss of cellular content, and matrix constituents), this may not result in the subjective improvement of patient reports of back pain, a fact that has frustrated spinal care physicians for decades.
Author

Dr Vaccaro is from the Rothman Institute, Philadelphia, Pa.

[Eddie G]

Cool Stuff.

Dr. Vaccaro was the surgeon who approved the disk replacement for my Workers Comp case. He only did Charite at the time so I didn't go to him for my surgery. He was very thorough, caring, and smart. If he did Prodisc or Maverick I would have gone to him.

This is great news for spine patients. Regeneration is the next logical step in spine surgery and it's nice to see they are pushing forward with it. If stem cells are used, the newest technology takes stem cells from the embryotic sac, not damaging the baby at all, which should keep the religious fanatics quiet.