While in its early stages, bioprinting of human tissue is an emerging technology that is opening up some exciting possibilities, including the potential to one day 3D print entire human organs. This scientific objective has now grown a little bit closer, with researchers at Carnegie Mellon University reporting a breakthrough that enabled the printing of full-scale heart components that in some cases functioned similarly to the real thing.
The specialized cells that make up the various organs in the human body are glued together by what is known as an extracellular matrix (ECM). This is a web of proteins that not only holds everything together, but also provides the biochemical signaling needed for an organ's regular, healthy function. Collagen is a protein that plays a key role in this structural integrity, but when it comes to bioprinting, also brings some unique and notable challenges.
"Collagen is an extremely desirable biomaterial to 3D print with because it makes up literally every single tissue in your body," explains Andrew Hudson, co-first author on the new paper. "What makes it so hard to 3D print, however, is that it starts out as a fluid – so if you try to print this in air it just forms a puddle on your build platform. So we've developed a technique that prevents it from deforming."
The technique Hudson refers to centers on a specially developed hydrogel, which the team was able to use as a temporary support structure to prevent the collagen from collapsing in a heap. The gel serves as a bath, allowing the collagen to be deposited layer-by-layer to form a solid structure within it. The support gel could then be removed from the equation by simply heating it to room temperature, leaving the printed collagen structure in place.
The team used this technique to construct an array of interesting, proof-of-concept heart components at human scale, and not just one based on collagen alone. They also enlisted cardiomyocytes, or cardiac muscle cells, and used heart imaging data to recreate blood vessels, heart valves that open and close and ventricles that contract.
"What we've shown is that we can print pieces of the heart out of cells and collagen into parts that truly function, like a heart valve or a small beating ventricle," says Adam Feinberg, a professor of biomedical engineering and materials science and engineering, whose lab performed this work. "By using MRI data of a human heart, we were able to accurately reproduce patient-specific anatomical structure and 3D bioprint collagen and human heart cells."
There remains a huge gap between these heart components and a complete, functioning 3D-printed heart that could help address the huge organ shortage around the world, but it is another promising step forward. The researchers are working towards commercialization of the technology through a spin-off company called Fluidform.
"It is important to understand that there are many years of research yet to be done," adds Feinberg. "But there should still be excitement that we're making real progress towards engineering functional human tissues and organs, and this paper is one step along that path."
The team's research was published in the journal Science, and you can hear from the scientists in the video below.
Source: Carnegie Mellon University
