Researchers have developed new biomaterials that can be manipulated to transform into different shapes, a 4D bio-printing achievement that also represents an advancement in tissue engineering.
Engineers at the University of Illinois Chicago (UIC) created the materials using a new cell-laden bio-ink they developed that can bio-print 4D objects and other constructs. 4D printing goes a step beyond 3D printing in that the objects that are fabricated can be programmed to move or change shape autonomously.
While 3D printing of biological materials has come a long way, the fabrication of living 4D materials holds even greater promise for creating bio-compatible solutions to treat and solve real-life medical conditions.
For this to be possible, scientists have sought to create bio-inks that allow for living cell printing with easy preparation, defined composition, and controlled physical properties, researchers said. The bio-ink developed by the team checks all of these boxes, said Aixiang Ding, the postdoctoral research associate at UIC.
“This is the first system that meets the demanding requirements of bioprinting 4D constructs: load living cells in bio-inks, enable printing of large complex structures, trigger shape transformation under physiological conditions, support long-term cell viability and facilitate desired cell functions such as tissue regeneration,” he said.
Supporting the Evolution of Tissues
The bio-ink the team developed is comprised of tightly-packed, flake-shaped microgels and living cells, and can fabricate bio-constructs that can change shape under certain physiological conditions.
“This bio-ink system provides the opportunity to print bio-constructs capable of achieving more sophisticated architectural changes over time than was previously possible,” said research leader Eben Alsberg, a professor with appointments in the departments of biomedical engineering, mechanical and industrial engineering, pharmacology and regenerative medicine, and orthopedics.
Some of these constructs include 4D cartilage-like tissues, as well as other tissues that due to their capability to change shape, can potentially also grow and change when used as implants within the body, he said.
“These cell-rich structures with pre-programmable and controllable shape morphing promise to better mimic the body’s natural developmental processes and could help scientists conduct more accurate studies of tissue morphogenesis and achieve greater advances in tissue engineering,” Alsberg said.
Researchers also produce complex, multiple 3D-to-3D shape transformations in bio constructs that were fabricated in a single printing.
Specific Properties, Potential Uses
There are a number of properties of the bio-inks and the 4D-printing system that show promise to support the fabrication of living tissues that can be viable for use long-term.
The bio-inks have what are called shear-thinning and rapid self-healing properties, enabling smooth extrusion-based printing with high resolution and high fidelity without a supporting bath.
Moreover, once stabilized by light-based crosslinking, the printed bio-constructs remain intact while bending, twisting or undergoing any number of multiple deformations.
“With this system, cartilage-like tissues with complex shapes that evolve over time could be bioengineered,” Alsberg said.
Researchers published a paper on their work in the journal Advanced Materials.
The team plans to continue to develop the system to create viability for clinical applications of tissue engineering, researchers said. Ultimately, they hope to use the platform and others like to 4D-print donor tissues and even organs to meet the current demand for such bio-materials in medicine.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.