Exact replicas of a man’s thumb bones have been made for the first time using a 3D printer. The breakthrough paves the way for surgeons to replace damaged or diseased bones with identical copies built from the patients’ own cells.
“In theory, you could do any bone,” says Christian Weinand of the Insel Hospital in Berne, Switzerland, head of the team that copied his thumb bones. “Now I can put spares in my pocket if I want,” he says.
Firstly, you need a 3D image of the bone you want to copy. If the bone has been lost or destroyed, you can make a mirror image of its surviving twin.
This image is then fed into a 3D inkjet printer, which deposits thin layers of a pre-selected material on top of one another until a 3D object materialises.
Weinand loaded the printer with tricalcium phosphate and a type of polylactic acid – natural structural materials found in the human body. The resulting bone “scaffolds” contained thousands of tiny pores into which bone cells could settle, grow and eventually displace the biodegradable scaffold altogether.
The team extracted CD117 cells from bone marrow left over after hip-replacement operations. CD117 cells grow into primordial bone cells called osteoblasts, which the team syringed onto the bone scaffolds in a gel designed to support and nourish them. Finally, the scaffolds were sewn under the skin on the backs of mice where they grew for up to 15 weeks, until the scaffold had changed into human bone.