There are more than 100,000 people on the national transplant list waiting for major organs. Every 10 seconds another name is added to the list, and sadly, 21 people die every day without receiving a lifesaving transplant. However, 3D printing has become more popular and proven time and again its ability to save and improve lives. The relatively cheap and quick method of creating objects may be able to reduce those numbers to zero.

Using plastic-like materials and living cells from humans, rabbits, rats, and mice, researchers from Wake Forest University have used a bioprinter, a 3D printer that prints human tissue, to create muscle, bone, and ear structures. And, for the first time, the living cells survived the printing process. The researchers also successfully implanted their 3D-printed structures into rodents. If the technology works as well for humans as it does on rodents, doctors may be able to use a patient’s own cells to print them a new bone, muscle, or piece of cartilage one day.

"We show that we can grow muscle. We make ears the size of baby ears. We make jawbones the size of human jawbones,” lead researcher Dr. Anthony Atala of the Wake Forest University Institute for Regenerative Medicine, said to NBC News. "We are actually printing the scaffolds and the cells together."

Typical 3D printers superheat plastics or metals and push the melted goo through a tube onto a platform which moves on the x-, y-, and z-axis. The material cools quickly, and as it does the printer head adds new layers, building up the object.

The researchers described in Nature Biotechnology how they created an integrated tissue-organ printer (ITOP) which can print stable, human-scale objects of any shape. They do this by using CT scans or MRI data of the patient’s body part and design software similar to that used in commercial 3D printing. The ITOP layers hydrogels — water-based solutions with human cells inside — and biodegradable materials using multiple nozzles to give the printed tissue structure and strength.

Once implanted into a rodent, the biodegradable materials slowly dissolved, leaving just the ear or piece of bone or cartilage. The ears were planted under the skin of mice. Two months later, they had kept their shape and cartilage was forming around them. Two weeks after muscles were implanted, the researchers noted they had prompted nerve function inside the rats. As for the bone implants, after five months a blood vessel system had formed.

"They were able to get large constructs that were viable long enough to be implanted, which is not trivial at all," Gordana Vunjak-Novakovic, biomedical engineer at Columbia University, told The Verge. "This is an important study that shows, convincingly and elegantly, that custom-designed tissues can be produced in lab in the anatomically correct clinical sizes and shapes, and with channels facilitating infiltration of cells and fluids."

As innovative and exciting as this development is, it’s still a long ways away from implementation. The researchers have yet to implant anything inside humans and are still unsure if that’s safe. Recreating human body parts is quite a challenge, but we’ve seen it done before on the small scale at Carnegie Mellon University, so it’s likely only a matter of time before organ transplant lists become a thing of the past.

Source: Atala A, et al. A 3D bioprinting system to produce human-scale tissue constructs with structural integrity. Nature Biotechnology. 2016.