A team of researchers from Carnegie Mellon University 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. This first-of-its-kind method brings the field of tissue engineering one step closer to being able to 3D print a full-sized, adult human heart.
The technique, known as Freeform Reversible Embedding of Suspended Hydrogels (FRESH), 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.
Each of the organs in the human body, such as the heart, is built from specialized cells that are held together by a biological scaffold called the extracellular matrix (ECM). This network of ECM proteins provides the structure and biochemical signals that cells need to carry out their normal function. However, until now it has not been possible to rebuild this complex ECM architecture using traditional biofabrication methods.
Over 4000 patients in the United States are waiting for a heart transplant, while millions of others worldwide need hearts but are ineligible for the waitlist. The need for replacement organs is immense, and new approaches are needed to engineer artificial organs that are capable of repairing, supplementing, or replacing long-term organ function. Feinberg, who is a member of Carnegie Mellon's Bioengineered Organs Initiative, is working to solve these challenges with a new generation of bioengineered organs that more closely replicate natural organ structures.
The FRESH 3D bioprinting method developed in Feinberg's lab allows collagen to be deposited layer-by-layer within 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.
This method is truly exciting for the field of 3D bioprinting because it allows collagen scaffolds to be printed at the large scale of human organs. And it is not limited to collagen, as a wide range of other soft 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.