U of T researchers' tattoo treatment helps monitor stem cells
A tracer ink gives researchers the ability to monitor stem cells in unprecedented detail after they're injected.
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As if body art couldn’t get any more extreme, University of Toronto engineers have created a way to get inked at a cellular level.
The new chemical mixture is being hailed as a tattoo for stem cells — a tracer “ink” that gives researchers the ability to monitor stem cells in unprecedented detail after they’ve been injected into the body.
U of T biomedical engineering professor Hai-Ling Margaret Cheng said the skin-deep discovery holds the potential to revolutionize stem cell research and give scientists the ability to maximize the effectiveness of their therapies.
“You can’t overcome hurdles without seeing the cells, and hopefully this new technology will help make stem cell therapy a reality that much sooner,” said Cheng, a biomedical engineer specializing in medical imaging.
She is working with colleague Xiao-an Zhang, an assistant professor of chemistry at U of T Scarborough, whose group developed a unique chemical compound known as a contrast agent. This tracer is made of manganese, an element that naturally occurs in the body, and is called MnAMP. Stem cells are bathed in the green solution, rendering them traceable inside the body under MRI.
The research, published last month in the Journal of Magnetic Resonance Imaging, breaks down the science behind the stem cell “tattoo.”
First, the contrast agent’s “ink” enters a stem cell by penetrating its membrane. Once inside, it kickstarts a chemical reaction that prevents it from seeping out the same way it came in.
Previous versions of these “contrast agents” easily escaped cells.
By figuring out a way to contain the ink within the cell’s walls, researchers gained the ability to track the cells once they were inside the body.
According to Cheng, there already are some basic contrast agents available for humans, although none are capable of tracking cells over a long period of time.
Current contrast agents work by illuminating the deepest and darkest corners of a person’s insides so they can show up clearer under X-rays, computed tomography (CT) scans and MRIs.
For example, patients may be instructed to swallow a thick, chalky-tasting solution called barium sulfate prior to a scan of their gastrointestinal tract. The pasty substance coats the esophagus, among other areas of the body, making them stand out after the results of an x-ray examination or CT scan.
Before this development for stem cells, scientists had to resort to surgery to get a literal glimpse of the cells’ fate after they were injected into an animal’s body. Now, they have the ability to track the results in real time, without having to put the patient under the knife.
“We were blind once the cells were introduced into the body,” said Cheng. “This will allow us to see cells in a non-invasive manner using MRI and to monitor them for, potentially, a very long time.”
For now, the technology is still in early development and must undergo more animal testing. While Cheng has already proven that tattooing a mouse’s embryonic stem cell doesn’t affect its ability to transform into a functional heart cell, rat and eventually pig (which better mimic a human’s size) models are up for evaluation next.
In those test cases, researchers will cut off and reduce blood flow in the animals to mimic the effects of damage caused by a heart attack in humans. Cardiac cells “pre-tagged” with Cheng’s technology will then be injected into the damaged tissue.
Scientists, using MRI, will monitor the tattooed stem cells in action, such as where they’re travelling to in the body.
“This will allow us to track the stem cells non-invasively and to more easily determine if the new cells are responsible for restoring normal heart rhythm,” said Cheng, who is hopeful the technology can proceed to human clinical trials in about 10 years.
Before then, the chemical compound will also have to pass rigorous toxicology tests to ensure it is safe for use in humans.
“If my children can benefit from this, then I’ll be very happy,” she said.
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