The future of biological repair of intervertebral discs

The spinal column is a very efficient and resistant structure that allows to stay in an upright position and to carry out multiple movements.

Functioning of the spine

The spinal column works through the collaboration of mobile elements with other semi-rigid ones. Among these elements are the intervertebral discs, which function as if they were a pneumatic shock absorber between the different intervertebral bodies, with a rigid external ring (annulus fibrosus) and a rubbery substance inside (nucleus pulposus), which allows the maintenance of axial loads and a certain degree of mobility.

The disc is a structure that maintains all these characteristics thanks to a perfect balance in the conditions of nutrition and hydration that it maintains in its interior. The rupture of this balance can cause different degenerative changes, mainly derived from the lack of hydration and cell death, which modifies the biomechanical characteristics and can sometimes fracture and cause different clinical problems (such as disc herniation, vertebral instability or disc protrusion associated with lumbar stenosis). In reality, this is a natural aging process.

Research on the biological repair of intervertebral discs

For years, different lines of research have been developed with the intention of restoring the physiological characteristics of a damaged disc. In fact, several investigations have been carried out for years in animal models and, in some cases, some limited clinical trials have been initiated in humans.

One of the major problems encountered by specialists is that the human intervertebral disc is unique. The human species is bipedal and is subjected to forces that are not easy to find in an animal model, which is why many of the tests that have been successful in animals have failed in more evolved animal models such as apes. For this reason, a model capable of reproducing the biological alterations suffered by the intervertebral discs in aging is still being sought in order to find a suitable treatment.

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Work has also been carried out along multiple lines of research, ranging from the use of growth factors, through the injection of protein factors that stimulate disc cells; gene therapy, with the injection of genetic transducers; and finally cell therapy, incorporating cell cultures, including the use of stem cells.

Future of the treatment of intervertebral disc degeneration

All these lines have encountered different difficulties that do not allow their clinical use. On the one hand, the growth factors that are injected have a very short survival time within the intervertebral disc, so their mechanism of action is very limited. Gene therapy carries certain risks that the desired treatment may affect undesired cell groups. Finally, cell cultures are the ones that have so far had the best response in the laboratory, managing to reproduce the structure of the disc. However, these results are not reproduced in clinical trials, since they involve an injection of young cells that have been previously damaged by being in an environment with poor hydration.

Therefore, despite the efforts made so far, the clinical future is still far from the definitive solution to treat the degeneration of intervertebral discs.

For more information consult a specialist in Traumatology.