July 11, 2022 – Nearly 1 out of every 100 children in the United States are born with heart defects. The effects can be devastating, requiring the child to rely on implanted devices that must be changed over time.
“Mechanical solutions don’t grow with the patient,” says Mark Skylar-Scott, PhD, a professor of bioengineering at Stanford University. “That means the patient will need multiple surgeries as they grow.”
He and his team are working on a solution that could provide those children with a better quality of life with fewer surgeries. Their idea: Using 3D “bioprinters” to craft the tissues doctors need to help a patient.
“The dream is to be able to print heart tissue, such as heart valves and ventricles, that are living and can grow with the patient,” says Skylar-Scott, who’s spent the past 15 years working on bioprinting technologies for creating vessels and heart tissue.
The 3D Printer for Your Body
Regular 3D printing works much like the inkjet printer at your office, but with one key difference: Instead of spraying a single layer of ink onto paper, a 3D printer releases layers of molten plastics or other materials one at a time to build something from the bottom up. The result can be just about anything, from auto parts to entire houses.
Three-dimensional bioprinting, or the process of using living cells to create 3D structures such as skin, vessels, organs, or bone, sounds like something out of a science fiction movie, but in fact has existed since 1988.
Where a 3D printer may rely on plastics or concrete, a bioprinter requires “things like cells, DNA, microRNA, and other biological matter,” says Ibrahim Ozbolat, PhD, a professor of engineering science and mechanics, biomedical engineering, and neurosurgery at Penn State University.
“Those materials are loaded into hydrogels so that the cells can remain viable and grow,” Ozbolat says. “This ‘bio-ink’ is then layered and given time to mature into living tissue, which can take 3 to 4 weeks.”
What body parts have scientists been able to print so far? Most tissues created through bioprinting to date are quite small – and nearly all are still in different phases of testing.
“Clinical trials have started for cartilage ear reconstruction, nerve regeneration, and skin regeneration,” Ozbolat says. “In the next 5 to 10 years, we can expect more clinical trials with complex organ types.”
What’s Holding Bioprinting Back?
The trouble with 3D bioprinting is that human organs are thick. It takes hundreds of millions of cells to print a single millimeter of tissue. Not only is this resource-intensive, it’s also hugely time-consuming. A bioprinter that pushed out single cells at a time would need several weeks to produce even a few millimeters of tissue.
But Skylar-Scott and his team recently achieved a breakthrough that may help significantly cut back on manufacturing time.
Instead of working with single cells, Skylar-Scott’s team successfully bioprinted with a cluster of stem cells called organoids. When several organoids are placed near each other, they combine – similar to how grains of rice clump together. These clumps then self-assemble to create a network of tiny structures that resemble miniature organs.
“Instead of printing single cells, we can print with bigger building blocks [the organoids],” Skylar-Scott says. “We believe it is a quicker way of manufacturing tissue.”
While the organoids speed up production, the next challenge to this manner of 3D bioprinting is having enough materials.
“Now that we can manufacture things with a lot of cells, we need a lot of cells to practice,” says Skylar-Scott. How many cells are needed? He says “a typical scientist works with 1 to 2 million cells in a dish. To manufacture a big, thick organ, it takes 10 to 300 billion cells.”
How Bioprinting Could Change Medicine
One vision for bioprinting is to create living heart tissue and whole organs for use in children. This might reduce the need for organ transplants and surgeries since the live tissues would grow and function along with the patient’s own body.
But many issues need to be solved before key body tissues can be printed and viable.
“Right now we are thinking small instead of printing a whole heart,” Skylar-Scott says. Instead, they are focused on smaller structures like valves and ventricles. And those structures, Skylar-Scott says, are at least 5 to 10 years out.
Meanwhile, Ozbolat envisions a world where doctors could bioprint exactly the structures they need while a patient is on the operating table. “It is a technique where surgeons will be able to drag the print directly on the patient,” Ozbolat says. Such tissue printing technology is in its infancy, but his team is dedicated to bringing it further along.