Tissue engineers have been developing ways to replace bone using tissue grown in devices called bioreactors, reported Geri Piazza yesterday in a National Health Institute paper. He says these devices can coax cells to grow into 3D shapes using certain growth factors. Bioreactors can work inside or outside of the body as long as the right cells and growth factors are present. They can also be printed in different shapes to match specific wounds.
A team of researchers led by Dr. Antonios G. Mikos of Rice University set out to use 3D printing to create bioreactors that could form bone tissue into precise shapes to heal jaw defects. Their study appeared on March 18, 2019, in the Proceedings of the National Academy of Sciences.
Using a 3D printer, the researchers created hollow rectangular bioreactors. The team packed them to test both natural or synthetic materials as the matrix for cells to grow into precise 3D shapes of bone tissue. They filled 15 bioreactors with crushed rib bone and nine with a synthetic bone matrix.
Next, they implanted the 24 bioreactors onto the ribs of six female sheep with jaw defects. Ribs have a sleeve around them that’s enriched with the cells and growth factors needed to generate bone. Ribs also are easy for a surgeon to access, and the many ribs enable several devices to be implanted at the same time.
At the same time, surgeons used temporary material to fill the voids in the jawbones. This helped prepare the sheep's jaws for the eventual implantation of the new bone tissue.
Nine weeks later, 83 percent of the 24 bioreactors were suitable for transfer to the jaw. Both the natural and synthetic materials generated solid tissue. There were no significant differences between the materials in bone density, bone height, bony surface area, or mineralized surface area. The natural materials were slightly stronger and more mature, so the team replaced the temporary material in the jawbone with the newly formed natural bioreactor tissue.
