3D-Bioprinted Human Liver Tissue Functional, Replacement Organs the Goal
3D bioprinted human liver tissue was successfully created by the company Organovo, revealed at the annual Experimental Biology conference this week in Boston. The in-vitro mini-livers are just half a millimetre deep and 4 millimetres across but can perform most functions of the real thing. To create them, a printer builds up about 20 layers of hepatocytes and stellate cells - two major types of liver cell. Crucially, it also adds cells from the lining of blood vessels. These form a delicate mesh of channels that supply the liver cells with nutrients and oxygen, allowing the tissue to live for five days or longer. The cells come from spare tissue removed in operations and biopsies.
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Liver cells, in particular the parenchymal (stem cell) hepatocytes, are widely used in the laboratory to assess the potential toxicity or efficacy of drugs. Hepatocytes inside the body have a nearly unlimited capacity for replication, but this didn't work until now when they were used outside the body for various testing purposes. They also rapidly lost critical liver-specific functions, which includes filtering the blood, metabolizing and transporting drugs, and producing a myriad of critical proteins.
Organovo's ultimate goal is to create human-sized structures suitable for transplant; the big hurdle is being able to print larger branched networks of blood vessels to nourish such an organ.
"We have achieved excellent function in a fully cellular 3D human liver tissue. With Organovo's 3D bioprinted liver tissues, we have demonstrated the power of bioprinting to create functional human tissue that replicates human biology better than what has come before. Not only can these tissues be a first step towards larger 3D liver, laboratory tests with these samples have the potential to be game changing for medical research. We believe these models will prove superior in their ability to provide predictive data for drug discovery and development, better than animal models or current cell models," said Keith Murphy, Chairman and Chief Executive Officer at Organovo.
For the first time, human liver tissues have been generated that are truly three-dimensional and, fabricated using Organovo's proprietary NovoGenTM bioprinting platform, are highly reproducible and exhibit superior performance compared to standard 2D samples that are used until now.