Scientists at the University of Buffalo are one step closer to 3D printing human organs. The new development uses stereolithography printers and hydrogels to create biological structures. Although nobody is going to be downloading new spleens from Thingiverse anytime soon, their technique overcomes some of the obstacles to making human replacement parts a reality.

Speeding Up Biological Printing

Stereolithography, or SLA, printing uses ultraviolet light to turn a photo-sensitive liquid resin into a solid plastic object. 3D bioprinting does the same thing using hydrogels to create a soft, hydrophilic lattice structure. This lattice acts as a scaffold for the cells, allowing them to grow and form a cohesive organ.

“Our method allows for the rapid printing of centimeter-sized hydrogel models,” University of Buffalo researcher Chi Zhou explained. “It significantly reduces part deformation and cellular injuries caused by the prolonged exposure to the environmental stresses you commonly see in conventional 3D printing methods.”

Developing a gentler approach to building organs was only one part of the research team’s focus. They also wanted to reduce the time it takes to print a biological specimen.

“The technology we’ve developed is 10-50 times faster than the industry standard,” the study’s co-lead author, Ruogang Zhao, said. “It works with large sample sizes that have been very difficult to achieve previously.”

One Step on a Long Road

The new research does not mean 3D printed replacement organs are ready for primetime. Zhao and Zhou’s work addresses one of the many obstacles researchers face. Right now, 3D bioprinting has been focused on laboratory applications with so-called organs-on-chips that let scientists conduct research without using animal experimentation.

Researchers at Harvard University’s Wyss Institute were the first to create an entirely 3D-printed organ-on-a-chip. They developed a 3D printing technique based on fused deposition modeling (FDM) that combined six bioinks to integrate human heart tissue and bio-compatible sensors into a Heart Chip.

“This new programmable approach to building organs-on-chips not only allows us to easily change and customize the design of the system but also drastically simplifies data acquisition,” Harvard researcher Johan Ulrik Lind said.

Recently, the Nature journal Scientific Reports published a Special Collection of the latest research in 3D printing biomaterials. Editors Madhuri Dey and Ibrahim T. Ozbolat, researchers at Pennsylvania State University, identified several issues holding the field back:

• The variety of available bioinks cannot recreate the full capabilities of an organ.
• Researchers must choose between cell-friendly natural hydrogels and structurally-sound synthetics.
• Shear stresses induced by 3D printers damage cells and alter gene expression.
• Bioprinting organoids for research is a slow process.
• Printing blood vessels in the quantity and density required is still a challenge.

The University of Buffalo research has helped push the field a little further down the road by speeding up the process and possibly making it easier to 3D print blood vessels. Laboratories around the world are making similar step-by-step advances. When they all converge, 3D printing will have enabled a revolution in healthcare.