Ultrafast 3D printing of lifelike organ models
Researchers at the University of Buffalo have fine-tuned the use of stereolithography for 3D printing of organ models that contain live cells. Described in the journal Advanced Healthcare Materials, the team’s technique is capable of printing the models 10 to 50 times faster than the industry standard — in minutes instead of hours — marking a major step in the quest to create 3D-printed replacement organs.
Conventional 3D printing involves the meticulous addition of material to the 3D model with a small needle that produces fine detail but is extremely slow, taking six or seven hours to print a model of a human part such as a hand, for instance. The lengthy process causes cellular stress and injury, inhibiting the ability to seed the tissues with live, functioning cells.
The method developed by the Buffalo group takes a different approach that minimises damage to live cells. Funded by the US National Institute of Biomedical Imaging and Bioengineering (NIBIB), the rapid, cell-friendly technique is a significant step towards creating printed tissues infused with large numbers of living cells.
Instead of a needle moving across a surface slowly building the details of the 3D model, the team developed a system that enables a small 10 cm model of a human hand to rise — quite dramatically — out of a vat of liquid in a matter of minutes. The stereolithographic method employs projected light at the bottom of the tank that penetrates up through the mix of hydrogel and live cells. The light polymerises the hydrogel/cell mixture at precise positions in the model, building entire layers of the model continually, rather than one pinpoint at a time.
“This is a significant step towards the printing of biologically active 3D tissues,” said Dr David Rampulla, Director of the NIBIB program in Synthetic Biological Systems. “This new technique combines a hydrogel mix that is very cell friendly with the rapid printing process, which spares cells from being suspended in a cell-damaging environment for an extended period. The combination has allowed the team to introduce live cells into their 3D-printed tissues, with the vast majority of cells remaining alive and functional.”
With an eye on moving from small models of organs to full-sized replacement organs in the future, the engineering team successfully used the new method to print tissues containing inner branching networks that mimic blood vessels. As noted by Associate Professor Rougang Zhao, leader of the team, “To keep alive cells that are deep inside a full-sized printed organ is one of the many challenges in creating functional replacement organs. We found that our method performed well in terms of creating branched, vessel-like networks to facilitate delivery of nutrients to cells embedded throughout the printed tissue.”
Going a step further, the team introduced live endothelial cells into the branching canals of their 3D-printed tissues. The endothelial cells adhered to the walls of the artificial vasculature and expanded to form an endothelial lining similar to that found in actual blood vessels.
The research team is now working to increase the size of the printed tissues while maintaining structural integrity and cell viability. Their work is a significant step towards the goal of one day printing replacement organs — a biomedical advance that could save countless lives lost because of the pervasive shortage of donor organs.
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