Researchers at Texas A&M University have combined 3D printing, biomaterial engineering and stem cell biology to create superior, personalised bone grafts.
When implanted at the site of repair, the researchers said these grafts will not only facilitate bone cells to regrow vigorously, but also serve as a sturdy platform for bone regeneration in a desired, custom shape.
“Materials used for craniofacial bone implants are either biologically inactive and extremely hard, like titanium, or biologically active and too soft, like biopolymers,” said Roland Kaunas, associate professor in the Department of Biomedical Engineering at Texas A&M University
“In our study, we have developed a synthetic polymer that is both bioactive and mechanically strong. These materials are also 3D printable, allowing custom-shaped craniofacial implants to be made that are both aesthetically pleasing and functional.”
A detailed report on the findings was published online in Advanced Healthcare Materials in March.
Each year, about 200,000 injuries occur to bones of the jaw, face and head. For repair, physicians often hold these broken bones in place using titanium plates and screws so that surrounding bone cells can grow and form a cover around the metal implant.
Despite its overall success in aiding bone repair, one of the major drawbacks of titanium is that it does not always integrate into bone tissue, which can then cause the implant to fail, requiring another surgery in advanced cases.
Biocompatible polymers, particularly a type called hydrogels, offer a preferable alternative to metal implants. These squishy materials can be loaded with bone stems cells and then 3D printed to any desired shape. Also, unlike titanium plates, the body can degrade hydrogels over time. However, hydrogels also have a known weakness.
Akhilesh Gaharwar, associate professor in the Department of Biomedical Engineering, explained: “Although the pliability of hydrogel-based materials makes them good inks for 3D bioprinting, their softness compromises the mechanical integrity of the implant and the accuracy of printed parts.”
To increase the stiffness of the hydrogel, the researchers developed a nanoengineered ionic-covalent entanglement or ‘NICE; recipe containing just three main ingredients: an extract from seaweed called kappa carrageenan, gelatin, and nanosilicate particles that both stimulate bone growth and mechanically reinforce the NICE hydrogel.
First, they uniformly mixed the gelatin and kappa carrageenan at microscopic scales and then added the nanosilicates. Gaharwar said the chemical bonds between these three items created a much stiffer hydrogel for 3D bi