3D-printed ear, bone and muscle structures come to life after implantation in mice

3D printed tissues and organs have shown real potential in addressing shortages of available donor tissue for people in need of transplants, but having them take root and survive after implantation has proven difficult to achieve.

In a positive move for the technology, researchers have used with a newly-developed 3D printer to produce human-scale muscle structures that matured into functional tissue after being implanted into animals.

Researchers have been exploring bioprinting as a means of replacing damaged tissue for several years now. The difficulty in replicating the complexities of human tissue has proven no simple undertaking, however, with scientists testing the waters with specialized bio-inks and various purpose-built printers in an effort to produce usable, engineered tissue.

Researchers at Wake Forest Baptist Medical Center have taken this latter path to engineering structures of adequate size and strength to implant in the human body. More than a decade in the making, the team's Integrated Tissue and Organ Printing System (ITOP) is claimed to overcome the limitations of previous bioprinting approaches. It spouts water-based gels that contain the cells, along with biodegradable polymers arranged in a latticed pattern and a temporary outer structure.

The researchers say that previously, engineered tissue structures without ready-made blood cells needed to be smaller than 200 microns in order for the cells to survive, but that their new approach solves this problem. They used ITOP to produce baby-sized ear structures measuring 1.5 in (3.8 cm) long, which were implanted under the skin of mice in the lab and went on to show signs of vascularization one and two months later.