Researchers seek to understand why human vertebral discs 'struggle' in microgravity, work to change disc profile after space flight

PHILADELPHIA — T2 mapping and other investigations that researchers at the University of California San Francisco performed show that, among astronauts who go into space, increased hydration up to about 13% occurs in some, but not all of the intervertebral discs.

“Those changes in water content related to changes in the disc height, so when those discs took on more water they gained more height and those discs that lost water lost height,” Jeffrey Lotz, PhD, professor and director of the Bioengineering Lab at the University of California San Francisco, said at the Philadelphia Spine Research Symposium, here.

Lotz presented these and other findings about the changes that the intervertebral disc (IVD) in the human spine undergoes in microgravity. He said the goal of his research, which is supported by NASA, is to establish pathomechanisms that will serve as the basis for developing future countermeasures to prevent back pain and disc herniation.

Jeffrey Lotz

Result of this work could be applied to crews who are involved in any future space missions to Mars.

“It is also clear that spaceships are really a back pain and disc herniation chain. You have lots of individuals signing and lining up to jump on board, so I think it’s also an opportunity for us to learn what might be factors driving back pain and disc herniation and some of those factors may be relevant to those of us on the ground,” Lotz said.

He discussed the biomechanical effects of microgravity on the spine, such as muscle atrophy, and how it impacts changed water content in the body, a biologic effect of microgravity. This can change osmotic pressure, which affects the cells and could impact vertebral profusion, Lotz said.

“There’s a lot of rationale for why discs in space could be struggling when they’re placed in this environment,” he said.

He and colleagues also observed bone marrow edema after space flight in an astronaut that was not presented beforehand. In addition, T1 and T2 MRI images showed some Modic changes adjacent to the IVD nucleus on the astronaut’s two lumbar levels that lost disc height — L2/3 and L3/4 — which were levels that were fairly immobile pre- and post-flight.

“Those bone marrow edema changes associated with an increase in the VAS for back pain [that] went from 0 to 5 post-flight suggesting that endplate damage had occurred in flight and triggered the back pain.”

Reference:

Lotz J. # S3.5. Presented at: Philadelphia Spine Research Symposium. Nov. 6-8, 2013. Philadelphia.

Disclosure: The research was supported by grants from NASA.