Testing new medications and finding organs for transplant all rely on one limited—and occasionally ethically wibbly-wobbly—resource: human beings. But researchers from the University of Toronto may have an exciting solution to this problem: A new “person-on-a-chip” technology known as the AngioChip.
This leap forward may just be the boost medicine needs, as current methods just aren’t enough.
“In the last few years, it has become possible to order cultures of human cells for testing, but they’re grown on a plate, a two-dimensional environment,” said Professor Milica Radisic of U of T Engineering in a statement. “They don’t capture all the functional hallmarks of a real heart muscle, for example.”
The difficulties in growing tissues
The AngioChip is one of several brand new methods scientists have recently discovered to grow human tissue in labs—but with important differences that separate it from the rest. The team has created tiny, biodegradable scaffolds which cells grow on, producing organ tissue closer to the real thing than the normal tissue found in a petri dish.
“It’s a fully three-dimensional structure complete with internal blood vessels,” said Radisic. “It behaves just like vasculature, and there’s a lattice for other cells to attach and grow.”
According to the paper in Nature Materials, the AngioChip scaffold is constructed from a polymer known as POMaC, which is created in a series of thin layers with special channels boring through them. When the layers are stacked and melded together using UV light, these channels create the 3D structure of a synthetic blood vessel.
After the chip is completed, it is then bathed in a liquid filled with living cells. These cells attach to the inside and outside of the “blood vessels,” and then commence growing just like they would in the human body.
“Previously, people could only do this using devices that squish the cells between sheets of silicone and glass,” said Radisic. “You needed several pumps and vacuum lines to run just one chip. Our system runs in a normal cell culture dish, and there are no pumps; we use pressure heads to perfuse media through the vasculature. The wells are open, so you can easily access the tissue.”
Successes already shown
After going through the whole process using specific kinds of cells, the team actually managed to produce heart and liver tissues that function like they do in the human body. For example, when white blood cells were injected into a manufactured vessel, the cells squeezed through the vessel wall to reach the tissue on the other side—just like what happens naturally.
“Our liver actually produced urea and metabolized drugs,” added Radisic.
Not only did the tissues behave like, well, the real thing, but their technique can also connect tissues of different organs together—meaning the body as a whole system could be created, and could show how different parts of the body react together when exposed to a new medicine.
This could mean that, in theory, we could test drugs on tissue systems created by the AngioChip scaffold—skipping over animal and human testing entirely. Naturally, this would save time and money—and, therefore, lives.
But more than that, these lab-grown tissues could be used for those waiting for organ transplants. Currently, those who receive a transplant spend the rest of their lives taken medications to ensure their body does not reject the foreign tissue now nestled within—but AngioChip organs would be grown will cells right from the host, meaning the chance of organ rejection would plummet.
In fact, the team has already done a few proof-of-concept tests of this idea: They implanted AngioChip tissue into living animals. The artificial blood vessels actually connected with the real ones, and the polymer scaffold simply degraded given a few months.
All this being said, the potential for AngioChip tissues are quite obviously enormous.
“It really is multifunctional, and solves many problems in the tissue engineering space,” said Radisic. “It’s truly next-generation.”