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Evidence uncovered during the project wound up unexpectedly contradicting previous work that suggested blood flow to the spinal cord was only temporarily compromised following an injury and returned to normal within a short period.

The U of A team found, in fact, that rats with spinal cord injuries exhibited long-term, chronic restricted blood flow at the injury site and below it, accompanied by a lack of oxygen to the network of neurons in the spinal cord. The level of oxygen was found to be less than half of what it should be, worse even than the low oxygen levels experienced at the base camp of Mount Everest.

In trying to better understand what was going on, the team looked at the behaviour of tiny blood vessels called capillaries in the spinal cord. In particular, the research focused on little-known cells called pericytes, which were found to wrap around the capillaries and act as valves controlling the blood flow into the vessels.

The study found that even though pericytes are cut off from brain control, they still produce a particular enzyme on their own that sets in motion a reaction that causes the pericytes to contract around the blood vessels.

“It turns out the blood flow below a spinal cord injury — the whole length of the spinal cord below an injury — is permanently impaired because of these pericytes excessively contracting,” said David Bennett, co-senior author of the study.

From there, the researchers then noted a number of potential pathways for treatment that could restore motor function.