Presently, if a patient is missing a section of bone due to accident or disease, it has to be replaced with bone harvested from elsewhere in their body. A new cell-containing gel, however, could one day be 3D printed right into the injury, where it would then harden.
First of all, there are already a variety of experimental materials that can be placed in a cavity where bone is missing. These serve as a sort of three-dimensional micro-structured scaffolding, which cells from the adjacent bone tissue gradually migrate into. Those cells proceed to reproduce, until they eventually replace the material with actual bone.
Seeking a faster alternative, scientists at Australia's University of New South Wales-Sydney have created a calcium phosphate-based "bio-ink" gel that already contains the patient's own live bone cells. In a technique known as ceramic omnidirectional bioprinting in cell-suspensions (COBICS), that non-toxic gel is 3D-printed directly into the patient's bone deficit. It proceeds to harden – within minutes of exposure to their bodily fluids – forming into a bone-like material consisting of mechanically interlocked bone mineral nanocrystals.
The cells within the now-solid material could then go on to reproduce, ultimately replacing it with natural living bone. Animal testing is now being planned, to see if this does indeed happen.
And while there are some other experimental bone-replacement materials that can be "pre-seeded" with cells, implants made of them typically have to be produced beforehand utilizing toxic chemicals and high-temperature furnaces. By contrast, the COBICS gel could simply be extruded straight into the bone.
"I imagine a day where a patient needing a bone graft can walk into a clinic where the anatomical structure of their bone is imaged, translated to a 3D printer, and directly printed into the cavity with their own cells," says Assoc. Prof. Kristopher Kilian, who is leading the study along with Dr. Iman Roohani. "This has the potential to radically change current practice, reducing patient suffering and ultimately saving lives."
A paper on the COBICS technology – which could also be used to produce living bone for use in research or drug testing – was recently published in the journal Advanced Functional Materials.
Source: UNSW Sydney