Stretching the boundaries of tissue engineering

Kibret Mequanint’s work in the area of tissue engineering has taken the next step toward helping thousands of Canadians with vascular problems.

Growing blood vessels in his lab, the associate chemical engineering professor’s alternative to synthetic vessels allows for less chance of patient rejection following, for example, bypass surgery. There are more than 23,000 bypass surgeries in Canada each year.

“These synthetic materials are no good and nature is not kind enough to supply us with spare parts to take from here and there. So why can’t we then fabricate a natural tissue?” Mequanint asks. “It is essentially making a spare part in a lab and one day being able to use it. All the people working in tissue engineering, their Holy Grail is getting it into the clinic.”

While the major clinical application is still a few years off, what is available now is the opportunity to use these tissues to study disease.
“For example, if you want to develop a drug for treating cardiovascular disease, you can test the drug on this tissue in order to test the affect of the drug,” he says. “Translation from mice doesn’t really transfer to humans that well, so it creates this gap. This can close that gap.”

Mequanint’s research involves taking cells from patients when they are diagnosed with vascular disease. After making a tubular template of the blood vessel, it is then covered with the patient’s own cells. This matures in bioreactor (incubator) where the cells break down the template and replace it with their own special proteins, similar to what the body would produce on its own.

After the cells have dismantled the template Mequanint built, there is nothing foreign about the engineered vessels, thus lowering the chance of rejection considerably.

But until now, the one stumbling block has been developing a blood vessel substitute with sufficient amounts of elastin, the protein allowing vessels to act similar to a rubber band, Mequanint says.

Elastin, for the most part, peaks sometime just before birth and shuts down a couple months afterward. Most patients for this procedure are in their 50s and 60s and out of elastin.

“In taking cells from these folks, our goal is to tweak these cells such that they would produce it … and that each cell should be able to somehow go back in their earlier stages of development,” Mequanint says. “Basically, we’re trying to remind cells that you may have done it once upon it a time, so is there any way you can do it again?”

This latest research was recently profiled on the cover of Tissue Engineering magazine.

While Mequanint’s work solves part of the challenge, developing something for clinical application is easier said than done. “We are a step closer. We can, in fact, say these cells are capable of making the critical component needed,” he says. “Now that we found this missing protein, it will hopefully speed the process. We think we are much more ahead now, and we’ll see what happens.

“I never lose sight of what my ultimate goal is and that is to develop a product for clinical use. You can always do great science, but unless it goes beyond the science it will just sit there on the shelf and nothing will happen.”