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Large-Scale Process Devised for Lab-Made Liver Tissue

Liver illustration

(Mikael Häggström, Wikimedia Commons)

5 December 2017. Researchers in Japan and the U.S. created techniques for producing liver tissue in large quantities in the lab for transplant or drug testing. The team from Cincinnati Children’s Hospital Medical Center in Ohio and Yokohama City University in Japan describes its process in today’s issue of the journal Cell Reports.

The team led by Hideki Taniguchi and Takanori Takebe are seeking ways of producing liver cells and tissue from stem cells in larger quantities than current processes. Taniguchi studies regenerative medicine at Yokohama City University, while Takebe is on the faculty at both Yokohama City University and Cincinnati Children’s Hospital. The researchers focus particularly on producing organoids, three-dimensional clusters of cells from stem cells that can form into organs.

In earlier studies, Takebe transformed induced pluripotent stem cells — often called adult stem cells, since they are not derived from embryonic tissue — into organoids, or buds, for pancreas, kidney, and liver tissue, which showed therapeutic potential in lab mice. The problem for the researchers, is scaling up that process and making it reliable enough for day-to-day clinical or lab applications.

For their solution, the Yohohama-Cincinnati team devised plates with tiny dimple-like wells to grow liver buds, which required a number of versions to optimize the plate’s construction for transforming stem cells. The plate is coated with a film containing the growth cultures needed to transform the stem cells, and stem cells seeded into the wells.

The researchers seeded the plates with 3 types of precursor cells derived from stem cells. Hepatic endoderm cells resemble early embryonic liver cells, but are derived in this case from induced pluripotent stem cells. Endothelial cells like those in blood vessels are derived from human umbilical cord cells. And mesenchymal stem cells are derived from bone marrow that transform into connective tissue like bone and cartilage.

The team reports its process produces more than 20,000 liver buds in each batch that self-assemble and grow in the plates, and are harvested with an ordinary lab pipette. A preliminary quality analysis shows the liver buds are similar to organoids produced earlier is smaller lab quantities. The researchers then assessed the liver buds’ genetic properties and protein production, and found the new organoids are more like adult liver tissue than two-dimensional organoids generated with earlier methods.

The researchers refined their processes to produce organoids solely from induced pluripotent stem cells, with these adult stem cells generating the 3 types of precursor cells needed to produce liver buds. The team tested the liver buds in lab mice induced with liver failure, and found the organoids can restore liver functions in the mice, including production of the protein albumin and metabolites of the inflammation drug diclofenac given to the test mice.

The authors conclude their techniques can be the basis of a production-scale process for functioning liver buds that meets current manufacturing standards for clinical-grade biological products. “The ability to do this,” says Takebe in a Cincinnati Children’s statement, “will eventually allow us to help many people with final-stage liver disease. We want to save the lives of children who need liver transplants by overcoming the shortage of donor livers available for this.”

Healios Inc., a company in Tokyo developing regenerative medicine treatments from adult stem cells, licenses the technology from Yokohoma City University. Both Takebe and Taniguchi are scientific board members of the company.

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