AsianScientist (Jan. 5, 2018) – In a study published in the journal Macromolecular Rapid Communications, a team of scientists in Japan report a method to print complex biological structures for use in regenerative medicine.
Printed replacement human body parts might seem like science fiction, but this technology is rapidly becoming a reality with the potential to greatly contribute to regenerative medicine. Before any real applications can be developed, however, bioprinting must overcome several technical challenges.
Processing the bio-ink—making it stick to itself to retain the printed gel structure—has proven to be particularly difficult, especially in inkjet printing. Few methods currently exist for gluing bio-ink droplets together, and current methods do not work for every kind of cell.
In the present study, researchers at Osaka University in Japan have refined an enzyme-driven method to stick biological ink droplets together, enabling complex biological structures to be printed.
“Printing any kind of tissue structure is a complex process. The bio-ink must have low enough viscosity to flow through the inkjet printer, but also needs to rapidly form a highly viscose gel-like structure when printed,” said Associate Professor Shinji Sakai of Osaka University, who led the study.
“Our approach meets these requirements while avoiding sodium alginate. In fact, the polymer we used offers excellent potential for tailoring the scaffold material for specific purposes,” he added.
Currently, sodium alginate is the main gelling agent used for inkjet bioprinting, but may be incompatible with certain cell types. The researchers’ new approach is based on hydrogelation mediated by an enzyme, horseradish peroxidase, which can create crosslinks between phenyl groups of an added polymer in the presence of the oxidant hydrogen peroxide.
Although hydrogen peroxide can damage cells, the researchers carefully tuned the delivery of cells and hydrogen peroxide in separate droplets to limit their contact and keep the cells alive. More than 90 percent of the cells were viable in biological test gels prepared in this way.
“Advances in induced pluripotent stem cell technologies have made it possible for us to induce stem cells to differentiate in many different ways,” said co-author Professor Makoto Nakamura of Osaka University. “Now we need new scaffolds to achieve full three-dimensional printing of functional tissues. Our approach is highly versatile and should help all groups working towards this goal.”
The article can be found at: Sakai et al. (2017) Drop-On-Drop Multimaterial 3D Bioprinting Realized by Peroxidase-Mediated Cross-Linking.
Source: Osaka University.
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