Biologically grown discs may one day alleviate back pain

Aug 15, 2011, 9:17 GMT

Washington - Natural, biological discs could soon be the answer to the back pain that paralyzes so many people still in their productive years. Initial tests, in which researchers in the United States grew discs from the cells of sheep and implanted them in rats, have been successful.

Following the implants, the rats were able to move naturally, and after six months they had integrated into the rats' spines almost like natural discs, according to a report in the Proceedings of the US Academy of Science.

Disc problems are the main cause of back and neck pain, generating huge health costs, the researchers say in their report.

In most cases, these ailments are treated by conservative therapies, such as physiotherapy and medication. Another option is surgical intervention, in which discs that are no longer functional can be replaced with mechanical implants, for example.

Medical experts are divided on the benefits of implants of this kind. In addition, the implants often fail as a result of becoming loose, slipping out of place or wearing out over the years.

Researchers led by Robby Bowles of Cornell University in Ithaca, New York state, tested purely biological disc implants. Initially they created a kind of pouring model of the disc to be replaced on the basis of computer tomography images. Then they used this model to build up an implant with the aid of cells taken from the discs of sheep.

Discs consist of an internal core with a high water content and an outer fibrous ring. The researchers built up this construction using the various cell types.

They then transplanted the biological discs into the spinal column in the tails of the rats, after first removing the corresponding discs from the rodents. The implant could readily be fitted into the gap between the vertebrae, the researchers said.

After six months it was clear that the biologically produced discs had retained their height and that they had become integrated into the surrounding spinal tissue. The cells had formed a so-called extra-cellular matrix that hardly differed at all from the natural discs in their biochemical composition.

The mechanical properties of the implants, such as reaction to being put under pressure, were similar to those of natural discs.

But before this kind of biological disc can be tested on humans, many issues have to be cleared up. Human discs are much larger than those in the tail of a rat, and the mechanical characteristics required of an implant are correspondingly greater.

It is also unclear how the implanted tissue would react if implanted into an infected environment. The rats' discs were healthy before the implants. In the case of patients needing a new disc, the situation is very different. In addition, the cells of sheep are not suited to creating the implants needed for use in humans.