A researcher’s team from Carnegie Mellon University (CMU) has published a paper in Science that details a new technique allowing anyone to 3D bioprint tissue scaffolds out of collagen, the major structural protein in the human body.
The Freedom reversible Embedding of Suspended Hydrogels (FRESH) technique, has allowed the researchers to overcome many challenges associated with existing 3D bioprinting methods, and to achieve unprecedented resolution and fidelity using soft and living materials.
Human body organs such as the heart are built from specialized cells that are held together by a biological scaffold called the extracellular matrix (ECM). This ECM proteins network provides the structure and biochemical signals that cells need to carry out their normal function. However, rebuilding the complex ECM architecture using traditional biofabrication methods has remained a challenge as of now.
“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,” said Adam Feinberg, a professor of biomedical engineering (BME) and materials science & engineering, whose lab performed this work. “By using MRI data of a human heart, we were able to accurately reproduce the patient-specific anatomical structure and 3D bioprint collagen and human heart cells.”
“Collagen is an extremely desirable biomaterial to 3D print with because it makes up literally every single tissue in your body,” said Andrew Hudson, a BME Ph.D. student in Feinberg’s lab and co-first author on the 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 the air it just forms a puddle on your build platform. So we’ve developed a technique that prevents it from deforming.”
The FRESH 3D bio-printing method allows collagen to be deposited layer-by-layer with a support bath of gel, giving the collagen a chance to solidify in place before it is removed from the support bath. With FRESH, the support gel can be easily melted away by heating the gel from room temperature to body temperature after the print is complete. This way, the researchers can remove the support gel without damaging the printed structure made of collagen or cells.
The method is not just limited to collagen, but also to a wide range of other sift gels including fibrin, alginate and hyaluronic acid can be 3D bioprinted using the FRESH technique, providing a robust and adaptable tissue engineering platform. Importantly, the researchers also developed open-source designs so that nearly anyone, from medical labs to high school science classes, can build and have access to low-cost, high-performance 3D bioprinters.
Also, FRESH has applications in many aspects of regenerative medicine, from wound repair to organ bioengineering, but it is just one piece of a growing biofabrication field.
“Really what we’re talking about is the convergence of technologies,” Feinberg said. “Not just what my lab does in bioprinting, but also from other labs and small companies in the areas of stem cell science, machine learning, and computer simulation, as well as new 3D bioprinting hardware and software.”
“It is important to understand that there are many years of research yet to be done,” Feinberg added, “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.”
Other collaborators on the paper include co-first author Andrew Lee, a BME Ph.D. student in Feinberg’s lab; BME postdoctoral researcher Dan Shiwarski; BME Ph.D. students Joshua Tashman, TJ Hinton, Sai Yerneni, and Jacqueline Bliley; and BME Research Professor Phil Campbell.
Source: Carnegie Mellon University