Bioprinting Technique Makes It Easier to Study Human Tissues and Organs

A new method for bioprinting human tissues uses natural materials to produce artificial but lifelike organ tissue models.

Researchers have developed an easy-to-use bioprinting technique for creating human tissues and organ models that they hope will be used by scientists to improve healthcare and pharmaceutical solutions for disease and other medical conditions. Bioengineers at the University of California San Diego (UCSD) developed the method, which works with natural materials and produces artificial but lifelike organ tissue models. They described it in a UCSD news release.

bioprinting 3D
Bioengineering graduate student Michael Hu (left) and undergraduate student Xin Yi (Linda) Lei construct a vascularized gut model using their team’s new 3D bioprinting technique. (Image source: David Baillot/UC San Diego Jacobs School of Engineering)

Everyday Models

While many bioprinting efforts today are aimed at creating artificial tissues or even organs that can one day be used for implantation within the human body, the UCSD team had a different purpose with their research, said Michael Hu, a bioengineering Ph.D. student at the UC San Diego Jacobs School of Engineering. “We want to make it easier for everyday scientists—who may not have the specialization required for other 3D-printing techniques—to make 3D models of whatever human tissues they’re studying,” he said.

There are two key aspects of the method that make it unique among existing bioprinting techniques, Hu told Design News. For one, it “requires absolutely minimal specialization to perform, and because of this, it is very accessible and has a low barrier of entry to use,” he said.

The method also is compatible with a large variety of natural materials, which allows researchers to better replicate the environment within the body with the models fabricated using the technique. This makes them “more relevant to humans when it comes to testing new drugs, which is currently done on animal models,” Hu said.

To prove that their method works, researchers bioprinted blood-vessel networks capable of keeping a breast cancer tumor alive outside the body and a model of a vascularized human gut.

Simple Enough

Researchers took care to ensure that the method they developed was simple enough even for scientists unfamiliar with this type of printing to use. To create a living blood vessel network, researchers first digitally designed a scaffold using Autodesk. Then they used a commercial 3D printer to print the scaffold using a water-soluble material called polyvinyl alcohol.

After completing this step, researchers poured a thick coating made of natural materials—fibrinogen, a compound found in blood clots, and Matrigel, a commercially available form of actual mammalian extracellular matrix—over the scaffold. They let it cure and solidify and then flushed out the scaffold material inside to create hollow blood-vessel channels.

For a penultimate step in the process, they coated the insides of the channels with endothelial cells—the same cells that line the insides of blood vessels. The last step of the process involves flowing cell-culture media through the vessels to keep the cells alive and growing.

“You don’t need anything complicated to adopt this into your lab,” said Prashant Mali, a bioengineering professor at the UC San Diego Jacobs School of Engineering. “Our hope is that multiple labs will be able to work with this and experiment with this. The more it gets adopted, the more impact it could have.”

Identifying the Right Materials
Identifying the materials was one of the more difficult aspects of the research, as the team was set on using natural materials that come as close to what’s found in the body as possible, but also materials compatible with the 3D-printing method. In the end, researchers used a “mixture between human and artificial versions” of the types of tissue they printed, Hu told Design News. “In the case of the connective and gastrointestinal tissue, they do not contain any human tissue, [or] primary tissue,” he said. “Everything is grown from cultured cells. In the case of the tumor tissue, however, we actually did optimize the system so that the 3D prints contained and sustained living tumor tissue from an actual breast tumor.”

Researchers hope that they can apply the system to make tumor models like the one he described that can be used to test anti-cancer drugs outside the body, said Hu, who is particularly interested in studying breast-cancer tumor models.

“Breast cancer is one of the most common cancers—it has one of the largest portions of research dedicated to it and one of the largest panels of pharmaceuticals being developed for it,” he said. “So any models we can make would be useful to more people.”

The team plans to move forward with their research to extend and refine the technique, Hu said. “From this point on, we have a few pursuits, which primarily include developing more accurate tumor models that do not rely on living tumor tissue; testing and optimizing compatibility of the method with more tissue types than those already published; and optimizing conditions within the printed constructs that better mimic the body as a whole,” he said.

Researchers published a paper on their work in the journal Advanced Healthcare Materials.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for 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.

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