doi:10.1038/nindia.2014.160 Published online 25 November 2014
Researchers have synthesized a silk-protein-based hydrogel that can be used as a bioink for printing three-dimensional tissues such as cartilage, which can replace the damaged cartilage of osteoarthritis sufferers1.
Bioprinting is an emerging technique that employs bioinks to print the exact three-dimensional shapes of human tissues. However, current bioinks tend to be unstable and hence unable to replicate the exact three-dimensional shapes of specific tissues.
To produce a stable bioink that can print three-dimensional tissues and support their growth, the researchers synthesized a hydrogel by mixing gelatin with the silk protein fibroin. They then prepared two bioinks ― one by adding an enzyme derived from mushrooms and the other by agitating the hydrogel with sound waves. They assessed the efficacies of the two bioinks in printing mesenchymal stromal (stem) cells derived from human nasal inferior turbinate tissue and compared them with that of an alginate-based bioink.
Using a specially designed printer, the researchers deposited the bioinks loaded with the human stem cells through a nozzle in a layer-by-layer manner. Of the three bioinks, the enzyme-based one had the longest stability time of one month, during which time the bioink kept the human stem cells alive.
This long-term survival of the human stem cells in the enzyme-based bioink suggests that this bioink could be used for tissue regeneration. Human stem cells can differentiate into different types of cells. By analysing tissue-specific marker genes, the researchers found that the stem cells in the enzyme-based bioink retained their ability to grow into cartilage, bone or fat tissue.
“Currently, we are probing the efficiencies of the bioink to deposit monolayer of corneal cells and developing a cartilage-damaging disease model for screening potential drugs,” says Sourabh Ghosh, a senior author of the study.