Oxygen improves blood flow, restores more function in spinal cord injuries: U of A study

May 01, 2017

A new discovery at the University of Alberta will fundamentally alter how we view spinal cord function and rehabilitation after spinal cord injuries. Neuroscientists found that spinal blood flow in rats was unexpectedly compromised long after a spinal cord injury (chronically ischemia), and that improving blood flow or simply inhaling more oxygen produces lasting improvements in cord oxygenation and motor functions, such as walking.

Previous work had shown that while blood flow was temporarily disrupted at the injury site, it resumed rapidly, and it was more or less assumed that the blood flow was normal below the injury. This turns out to be wrong.

"We've shown for the first time that spinal cord injuries (SCI) lead to a chronic state of poor blood flow and lack of oxygen to neuronal networks in the spinal cord," says co-principal investigator Karim Fouad, professor, Faculty of Rehabilitation Medicine and Canada Research Chair for spinal cord injury. "By elevating oxygen in the spinal cord we can improve function and re-establish activity in different parts of the body."

Published in Nature Medicine on May 1, 2017, the study demonstrates chronic ischemic hypoxia (lack of blood and oxygen) after spinal cord injury and how blood flow plays a key role in the cause and treatment of motor disorders. Simply put, this could mean restored activity and ability in parts of the body that stopped working after spinal cord injury in the near future.

The discovery, like most "eureka moments" in science, happened by accident. The lead author Yaqing (Celia) Li, rehabilitation science post-doctoral fellow, and David Bennett, co-principal investigator and professor, Faculty of Rehabilitation Medicine, were looking at the injured spinal cord of a rat under a microscope and noticed the capillaries contracting in response to application of dietary amino acids like tryptophan.

"I thought, 'why would capillaries contract, when conventionally arteries are the main contractile vessels, and why should dietary amino acids circulating in the blood cause these contractions?'" says Bennett. "That is just plain weird, that what you eat should influence blood flow in the spinal cord." So they set out to answer these questions.

Li, Bennett and Fouad found that the AADC (Aromatic l-amino acid decarboxylase) enzyme that converts dietary amino acids into trace amines was upregulated in specialized cells called pericytes that wrap capillaries. Unexpectedly, these trace amines produced in the pericytes caused them to contract, clamping down on the capillaries and reducing blood flow. This surprising finding led them to make basic measurements of blood flow and oxygenation below the spinal cord, which led to the discovery of the chronic ischemic hypoxia. They reasoned that the capillaries were excessively constricted by these pericytes after SCI, since there is ample supply of tryptophan. So they decided to try blocking AADC to improve blood flow.

"Since blood flow below the injury is compromised, the neuronal networks function poorly with a lack of oxygen. So we blocked the AADC enzyme and found that it improved blood flow and oxygenation to the networks below the injury," Bennett says. "More importantly, this allowed the animals to produce more muscle activity."

As an alternative treatment to blocking the AADC enzyme in the spinal cord of rats, the neuroscientists exposed the animals to higher oxygen levels and even they were surprised to see what happened next.

"The rat could walk better!" Fouad says. "The change in oxygen restored function, albeit temporarily."

Though the team knows their discovery can have big implications in the world of neuroscience, rehabilitation and spinal cord injury, they are quick to mention a disclaimer.

"There is still a long way to go when it comes to treatment and helping patients with spinal cord injuries," says Fouad. "But this discovery has helped us understand the etiology of spinal cord injuries in a way we never did before. We can now design treatments that improve blood flow to produce long-term rehabilitation after SCI.

Possibly even simple therapies such as exercise or just breathing will play a role in preventing long-term hypoxia and damage to the spinal cord. It's a small but important step in the right direction, stemming from studying an obscure enzyme in the spinal cord -- and that's the beauty of basic science."
-end-


University of Alberta

Related Spinal Cord Injury Articles from Brightsurf:

Stem cells can help repair spinal cord after injury
Spinal cord injury often leads to permanent functional impairment. In a new study published in the journal Science researchers at Karolinska Institutet in Sweden show that it is possible to stimulate stem cells in the mouse spinal cord to form large amounts of new oligodendrocytes, cells that are essential to the ability of neurons to transmit signals, and thus to help repair the spinal cord after injury.

Spinal cord injury increases risk for mental health disorders
A new study finds adults with traumatic spinal cord injury are at an increased risk of developing mental health disorders and secondary chronic diseases compared to adults without the condition.

Co-delivery of IL-10 and NT-3 to enhance spinal cord injury repair
Spinal cord injury (SCI) creates a complex microenvironment that is not conducive to repair; growth factors are in short supply, whereas factors that inhibit regeneration are plentiful.

IU scientists study link between energy levels, spinal cord injury
A team of researchers from Indiana University School of Medicine, in collaboration with the National Institute of Neurological Disorders and Stroke, have investigated how boosting energy levels within damaged nerve fibers or axons may represent a novel therapeutic direction for axonal regeneration and functional recovery.

UBCO professor simplifies exercise advice for spinal cord injury
Professor Kathleen Martin Ginis says a major barrier to physical activity for people with a spinal cord injury is a lack of knowledge or resources about the amount and type of activity needed to achieve health and fitness benefits.

Robotic trunk support assists those with spinal cord injury
A Columbia Engineering team has invented a robotic device -- the Trunk-Support Trainer (TruST) -- that can be used to assist and train people with spinal cord injuries (SCIs) to sit more stably by improving their trunk control, and thus gain an expanded active sitting workspace without falling over or using their hands to balance.

Does frailty affect outcomes after traumatic spinal cord injury?
A new study has shown that frailty is an important predictor of worse outcome after traumatic spinal cord injury in patients less than 75 years of age.

Sleep and sleepiness 'a huge problem' for people with spinal cord injury
A new study led by a University of Calgary researcher at the Cumming School of Medicine (CSM) finds that fatigue and sleep may need more attention in order to prevent issues like stroke after spinal cord injury.

From spinal cord injury to recovery
Spinal cord injury disconnects communication between the brain and the spinal cord, disrupting control over part of the body.

Transplanting adult spinal cord tissues: A new strategy of repair spinal cord injury
Spinal cord injury repair is one of the most challenging medical problems, and no effective therapeutic methods has been developed.

Read More: Spinal Cord Injury News and Spinal Cord Injury Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.