In a paper published today in PLoS Computational Biology, researchers at the Institute for Bioengineering of Catalonia (IBEC) describe some important findings gleaned from looking at the effect of outside influences on healthy and unhealthy discs. They showed that weight or pressure on already degenerated discs has less effect on the transport of nutrients and cell products than on healthy ones – and that changes in cell density in discs are fundamental to the process of disc degeneration.
Using a computational model of the lumbar spine that takes into account nutritional and mechanical effects, the scientists looked at the effect of external “loading” on two important cell solutes related to disc metabolism: oxygen and lactate. Degenerative changes are supposed to be linked to a failure in the transport of nutrients from the peripheral blood vessels to the discs, which affects such solute concentration within the disc and depends on tissue composition and the disc’s response to mechanical loads. They found that the effect of loading was greater when compressing a healthy disc than a degenerated one, and promoted fluctuations of the concentration of the solutes.
“It’s essential for the healthy function of the spine that disc cells are provided with the nutrients necessary to tissue maintenance,” explains Andrea Malandrino of IBEC’s Biomechanics and Mechanobiology group, which carried out the research. “In a healthy disc, we see that sustained mechanical stress – which alters solute concentration – affects the transport of nutrients more drastically than in already degenerated ones, suggesting that loading in the healthy disc is important for maintaining proper metabolic balance. It’s safe to say that an alteration of cell number caused by this disturbance to the metabolic transport could result in the possible onset of disc degeneration.”
With the knowledge that both mechanical and cellular patterns contribute to maintaining a healthy condition, new avenues of research and development in the field of disc regenerative medicine have been opened up. “This will have a great impact not only in the field of spine modeling but on bioengineering modeling as a whole, as it highlights the importance of combining mechanical and biological processes,” says Damien Lacroix, head of the Biomechanics and Mechanobiology group.
Andrea Malandrino, Jérôme Noailly, Damien Lacroix , 2011,“The effect of sustained compression on oxygen metabolic transport in the intervertebral disc decreases with degenerative changes”. PLoS Computational Biology
This news has been covered on the BBC website today: http://www.bbc.co.uk/news/health-14403201