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1. Engineering Better Healthcare

1. Measuring edema
2. Understanding stroke
3. In the bones
4. Regaining movement
5. Regenerative medicine for the spine

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1. Defusing a time bomb
2. Feeding the machine
3. Untangling the mysteries of labour onset

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3. Researchers in the making
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Regaining movement

In the lab of AHFMR Senior Scholar Dr. Vivian Mushahwar at the University of Alberta, it sometimes seems that the impossible might just be possible. Her team is attempting to restore the ability to stand and walk in people with spinal cord injuries—and they have done just that with animal models.

The crux of Dr. Mushahwar's approach is deceptively simple: tap into the circuits of the nervous system and imitate what the brain would have told them in order to stand and walk. These circuits are networks of neurons (nerve cells) that stimulate groups of muscles in a coordinated fashion rather than stimulating them individually. Damage to the spinal cord does not affect the circuits themselves, but makes it impossible for messages from the brain to reach the circuits as well as for messages from the circuits to reach the brain.

Rather than use the conventional approach to electrical stimulation—placing electrodes on the skin or in individual muscles—Dr. Mushahwar has developed a new technique called intraspinal microstimulation (ISMS). It involves implanting very fine wires inside the spinal cord and passing electrical pulses through these wires to elicit movement of the legs.

"ISMS activates entire circuits rather than individual muscles," explains Dr. Mushahwar. "We do this from a tiny implant in the five-centimetre region of the spinal cord that controls locomotion. Just one 30-micron wire [thinner than a human hair] can activate all muscles in a coordinated fashion. As few as four wires can stimulate a walking motion."

ISMS has been an unqualified success in animal models—the animals are able to stand and walk for much longer periods of time than anything achieved with conventional technology. Dr. Mushahwar says that one of the reasons for this success is the activation of the muscles in a much more natural way by ISMS than by conventional electrical stimulation. This reduces fatigue tremendously.

Some challenges still still need to be solved before this technology can work in humans; one is designing an electrode that can flex with the spinal cord. Much of this work is underway as part of an AHFMR Interdisciplinary Team Grant on neural prostheses.

Dr. Mushahwar notes that this project illustrates the highly multidisciplinary nature of biomedical engineering. "This research could not be done without a team. We need people to develop the wires, physiologists and neuroscientists who understand neural processing, electrical engineers to develop circuits, chemical and materials engineers, tissue engineering specialists, nanotechnologists; the list goes on.

"There are so many opportunities in biomedical engineering—it goes far beyond standard medical devices and includes things like tissue engineering, artificial skin, bone replacement, imaging, and artificial valves. Alberta has great strengths in the basic sciences that fuel these innovations in biomedical engineering. We have the breadth to make technology development work."