3D printing allows the scaffolding and living tissue to be printed together.
In order to construct veins and capillaries, they first print out a tubular construct made of dis-solvable material; they then coat the outside of that tube with muscle cells and the inside with venous barrier cells. A heart valve can be constructed in the same way; first by using dis-solvable scaffolding followed by outer muscular cells and interior barrier cells.
Researchers at Wake Forest have even successfully laid down heart cells; the completed tissue then begins to beat.
"Liver structures we print today last 30 days. They secrete urea, albumin and they produce [stem] layers. We're reproducing embryonic development of the kidney," Atala said.
Scaling up that tissue production is the challenge today, Atala said.
3D printed faces and skulls
While printing actual tissue holds the key to someday replacing body parts, another promising area is 3D printed bones. Today, 3D printing is used to create structural support.
For example, if a patient has been in an accident and lost part of their skull, physicians can create an exact 3D virtual image of the patient's skull through CT scans and use it to print out a hard polymer section of the skull. But 3D printers have yet to tackle the printing of actual bone.
At best, 3D printers represent an evolutionary step toward more advanced cranialfacial reconstruction, according to Dr. Amir Dorafshar, co-director of the Facial Transplantation Program at Johns Hopkins University.
Still, 3D printing has advanced surgery by leaps and bounds.
Less than 10 years ago, cranialfacial surgeons would act as artists, spending hours in an operating room trying to put the jigsaw puzzle of a smashed or deformed skull back together.
Through the use of 3D imaging, surgeons can perform the surgery on a computer screen before entering the operating room, affording them an exact model to follow once the scalpel begins its cuts.
Amir said where 3D printing is also evolving craniofacial surgery in its ability to produce exact surgical guides that are placed over the section of a patient's head or face. The plastic guides allow surgeons to make their cuts without fear of mistakes.
"Today, the gold standard is still to take tissue and bone from another part of the patient's body and transplant it," Dorafshar said.
The revolution will be when physicians can print up a bioactive bone scaffolding that includes a vascular structure to supply the living bone with nutrients and oxygen. "Imagine one day when we can recreate vascularized bone," Dorafshar said.
"I can assure you people will look back on these technologies someday and say, "Boy, weren't these primitive," Atala said.
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