A two-part water-based gel made of synthetic DNA and peptide could bring the inventors of a 3D bioprinter closer to being able to print organs for transplant, or to replace animal testing. The teams led by Dongsheng Liu (Tsinghua University) and Will Shu (Heriot-Watt University) faced two main challenges: finding a matrix or scaffold to support the live cells in 3D, and being able to produce a consistent product which would not be rejected by transplant recipients.
Shu explains: "The first challenge was that if we used a normal gel it was not possible to mix live cells with it for 3D printing. Colleagues at Tsinghua University in Beijing developed a gel which, like some proprietary glues, comes as two separate liquids into which cells can be added. These do not turn into a gel until the two liquids are actually mixed together during the printing process.
Liu said, "The formation of our new DNA gel does not involve heat, UV, salt or other harsh conditions. In combination with Shu's delicate 3D printing system, we have been able to demonstrate we can produce a three-dimensional matrix containing highly viable live cells."
"Most importantly, working with the wider team led by Rory Duncan, we have also have run specialized imaging tests to prove that the cells we used remained alive and functioning at sub-cellular level after this process was complete." Shu explains.
Another other major advantage for Liu's team is the ability to manipulate the exact rigidity of the gel and the printed object by changing only one base in the DNA sequence, as well assuring consistency in the end product.
Traditionally 3D printing gels have been based on natural products, for example collagen or materials extracted from seaweed, and not only is it hard to mix the live cells into these it is also hard to control the rigidity of the gel as well as to standardize it for production purposes. The new two-part synthetic DNA-based gel answers those challenges as well as producing a matrix which would not be rejected by recipients if the team reach their long-term goal of printing artificial organs for transplant.
Shu adds: "Our eventual aim is to 3D print organs for transplant, as well as producing alternatives to the testing of drugs on animals. This new gel in combination with our 3D live cell printer is a huge step forward towards these potential long-term medical benefits."
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"Rapid Formation of a Supramolecular Polypeptide–DNA Hydrogel for In Situ Three-Dimensional Multilayer Bioprinting." Angewandte Chemie International Edition. dx.doi.org/10.1002/anie.201411383