Using their “person-on-a-chip” technology, the team developed a unique method of growing heart cells around a silk suture called Biowire. They also used the technology to grow scaffold for heart cells, which similar to the sheets of Velcro, snaps together.
Much of what we call culturing of human cells in the lab is limited to a slab of cells multiplying in a petri dish. It may have driven many findings, but it has limited use. What would be a lot better is three-dimensional human tissue created in the lab but functioning as it would inside the human body.
Many research groups around the world are making concrete steps to actualize this. However, a team of engineers from the University of Toronto is ahead of the pack. The team led by Professor Milica Radisic developed a technology called AngioChip that first creates small, intricate scaffolds on which individual cells will grow to generate realistic human tissue.
In building the scaffold, the team used a material called POMaC. POMaC is a polymer with the desirable characteristics of being biocompatible and biodegradable. The team first assembles a series of thin layers. Then they create a pattern of channels with these thin layers. Each channel has a width of 50 to 100 micrometers. Afterwards, they stack the layers into a 3D structure of synthetic blood vessels.
With the addition of each layer, the team uses UV light to cross-link the polymer and bond it to the layer directly underneath. After completing the scaffold structure, the team then introduces liquid containing living cells to bath the structure. The living cells then attach to the outside and inside of the channels and start multiplying as they would in the human body.
The technology has enabled the team to create model versions of both heart and liver tissues that are as close to the real deal as any artificially engineered tissue. The heart tissue contracted with regular rhythm, and the liver tissue metabolized drugs and produced urea.
Going forward, the technology demonstrates versatility in that connection between two artificial organs is possible using the system of blood vessels of each organ.
The area where AngioChip carries more potential is in pharmaceutical testing. Currently, animal testing and controlled clinical trials carry huge financial costs as well as ethical concerns. Drug testing on human tissues grown in the lab, while still in its infancy, has been limited by the two-dimensional environment of a plate in which the tissues are grown.
The more realistic AngioChip platform provides a succinct way for drug companies to ascertain dangerous side effects of drugs they plan to introduce as well as the interactions between organ compartments. This could lead to countless lives being saved and reduced health costs for avoidable complications.
When implanted with heart cells the polymer scaffold contracts with a regular rhythm, just like a real heart tissue. (Image: Boyang Zhang)
In addition, specialists could use the technology to validate and understand the effectiveness of current drugs as well as study an extensive collection of chemical compounds to discover new drugs.
Radisic believes that the technology can also find use in the replacement of organs damaged by disease. This is an exciting proposition, especially noting that cells belonging to anyone can seed the platform. Therefore, engineered-tissues will be genetically identical to the intended host, effacing the risk of organ rejection. Then after several months, the polymer scaffold itself simply biodegrades, leaving a fully biological implant.
The full research was published in the journal Nature Materials.