Researchers Are Growing Human Livers From Stem Cells In Mice
The research raises the possibility that we will be able to grow new livers inside humans in the near future.
The study was published in the journal Nature on July 3.
Cellular orchestra
Since the discovery of stem cells more than 30 years ago — those mystical cells that can become any type of cell in the body — scientists have been trying to build complete complex organs. The many different cells in complex organs grow in concert as chemical changes turn different genes inside cells on and off. This produces new chemical changes and the cycle continues.
Because of this complexity, many scientists have dismissed the possibility as impractical — mere science fiction.
Instead of trying to build an entire liver, the researchers Yokohama City University in Japan started with just trying to recreate the tiny bud that forms at the beginning of liver development.
The researchers first "seeded" lab dishes with human stem cells and used chemicals to mimic the natural processes that form liver buds.
They then planted the buds into the bodies of mice with failing livers. Once hooked up to the animals' blood vessels, each bud began to grow into a fully functional liver, significantly extending the lives of the mice.
"Our study demonstrates a proof-of-concept that organ-bud transplantation offers an alternative approach to the generation of a three-dimensional, vascularized organ," the scientists said in their paper. "These results highlight the enormous therapeutic potential using in vitro-grown organ-bud transplantation for treating organ failure."
A desperate need
Liver disease rates are climbing in the United States and in countries like Britain. Some evidence suggests the disease is targeting people as young as 30 — much earlier than in previous generations.
Startlingly, alcohol is no longer the only culprit. Obesity and refined sugar consumption are causing fatty liver disease, a mostly reversible precursor to the much more dangerous hepatitis and the final and often fatal cirrhosis.
Many patients with cirrhosis don't stand a chance without a transplant.
But the line of folks waiting for a transplant is long — though almost 6000 patients received new livers in 2011, almost another 3000 died in waiting in line, according to Nature News.
So, the scientists noted in their paper, the "critical shortage of donor organs for treating end-stage organ failure highlights the urgent need for generating organs from human-induced pluripotent stem cells."
It will still be years before such a treatment is available for human patients. The scientists will monitor the subjects over the next several months to see if the newly grown livers develop cancers or degenerate.