13th January 2021
Researchers have recently made a scientific step towards making 3D-printed body organs a reality. This new innovative process, which looks similar to making jello, enables scientists to scan a heart and reconstruct it in a soup of gelatin.
In the scientific journal “ACS Biomaterials Science & Engineering”,a team of researchers depicted, in October 2020, the way they repurposed a low-cost 3D printer to make it capable of turning an MRI scan of a human heart into a deformable real-life replica that can be held in one hand.
The new technique is named the Freeform Reversible Embedding of Suspended Hydrogels, or FRESH.
This scientific breakthrough could ultimately produce fully functioning 3D-printed hearts and thus provide medical device manufacturers with a new platform to test their products.
The process initially follows the typical 3D printing steps; researchers begin with a scan of a real heart and translate the data into something a 3D printer can read.
Afterwards, they run the 3D image through a “Slicer” program that virtually separates it into thin layers.
This is a necessary step since the device works by depositing layers of material one on top of another.
According to WIRED magazine, Adam Feinberg, a biomedical engineer at Carnegie Mellon University who co-authored the new paper, explained that the Slicer software essentially determines the path in which the material is going to be extruded for every layer and feeds that to the printer afterward.
What distinguishes this new technique, however, from regular 3D printing technology is the materials used both to build the final object and to hold it in place.
The special ingredient from which these artificial hearts are made is called alginate, a polymer that is, as the name suggests, derived from algae and more specifically seaweed.
This substance is injected into a container filled with gelatin, which helps support its structure during the manufacturing process; this is quite a departure from conventional extrusion-based 3D-printing, where the layers are simply deposited on a flat surface.
Feinberg noted that gelatin transforms into a solid gel when it cools down after being warmed up during the printing process.
After the printing process, researchers use a simple method to dissolve the excess of this substance and liberate the printed object: raising the temperature of the bath.
The heat melts away the support gel, leaving behind the 3D-printed structure to be extracted.
Up to this point, 3D-printed hearts have been created from scans of patients’ own organs, although they have been created with hard plastic.
By contrast, the new alginate heart has an elasticity that is comparable to the real organ’s tissue.
Feinberg further clarified that when the new alginate heart is squeezed or compressed, it deforms by the same amount of the applied force, making it more malleable than hard rubber or plastic.
As a result, this new technique enables surgeons to practice suturing, which would not be possible on plastic.
In addition, a custom-printed heart could be used to communicate to a patient the manner in which they would get the surgery.
In the same vein, in order to discover whether these artificial hearts would be capable of carrying blood, the team 3D-printed a separate section of a coronary artery, relying on the same previously described process.
The result was that the artery held onto the liquid without leaking when they pumped in fake blood.
Since an alginate heart costs around $10 in raw materials, this gives hope that hospitals will provide it at accessible prices.
Another potential ingredient for 3D-printing hearts is Collagen; this protein, which provides strength and structure to bones, muscles, skin, and tendons, could help produce organs that are closer to the real thing.
But the problem is that collagen is significantly expensive, as using it to create the same bio-printed heart would cost $2,000.
This makes Feinberg and his colleagues want to explore different materials that might offer a better quality-to-price ratio.
Feinberg explained that the team is considering applications “where the more realism with the collagen is probably worth it.”
However, he maintains that when doing research in a lab, which involves a lot of trial and error, a cheap yet reliable material like alginate is a better fit.
After all, there is still a lot of work to be done; Feinberg described the experiment as a steppingstone on the path towards reproducing a complete human cardiovascular system.
That way, surgeons could practice suturing arteries with blood still flowing.
Furthermore, the team hopes to eventually “cellularize” the printed organ replica, by adding human heart muscle cells to the structure to make it beat like a real heart.
Luckily, the required organisms are already grown in labs.
Presently, scientists are capable of making only 100 million cells at a time.
According to Feinberg, 100 billion cells would be needed to create a full-size heart, yet he remains optimistic that overcoming this obstacle is just a matter of time.
As it pertains to his own research, he believes that operational 3D bio-printed hearts will not be available for at least 10 more years.
The delay is due not only to the cell-production technology being behind the curve but also to the complex interconnected network of arteries that his team still needs to figure out how to reproduce.
There is no doubt, however, that the collaboration between biology and engineering has the potential to bring forth ground-breaking discoveries that would revolutionize the medical field in the upcoming decades.