The ability to grow new organs from engineered tissue could reduce the need for whole-organ transplantation. But growing new organs with the correct architecture is hard for large, complex organs such as the liver.
Sangeeta N. Bhatia and Kelly R. Stevens of Massachusetts Institute of Technology, Christopher S. Chen of Boston University, and coworkers have engineered patterned “seeds” for planting and growing new liver tissue in the body (Sci. Transl. Med. 2017, DOI: 10.1126/scitranslmed.aah5505).
The researchers constructed the seeds by organizing three types of human cells in a hydrogel matrix. First they made aggregates of liver cells and connective tissue cells. Then they interspersed those aggregates in a hydrogel between cords made of blood-vessel cells.
They implanted the seeds in mice at sites far from the animals’ liver and chemically injured the liver to mimic chronic liver damage. In response, the mouse liver released chemical signals to trigger liver regeneration. These chemicals also caused the tissue seeds to grow by as much as 50-fold over the course of 11 weeks. The expanded tissue produced human drug-metabolizing enzymes and other liver-specific proteins, indicating that it was functioning properly as liver tissue.
Bhatia hopes that such seeds can be designed to grow inside humans. “The idea is to augment a patient’s liver function by implanting this liver seed in the belly—where they sometimes put kidney transplants—and it can grow into a supportive cell mass,” she says.