Test-Tube Replacement Organs

By Patrick J. Kiger, Science Channel

Researchers at Wake Forest University announced this week that they had successfully used immature human liver and endothelial cells to grow a tiny miniature version of a working human liver in a laboratory.

The experiment, conducted at the university medical center's Institute for Regenerative Medicine, succeeded in creating liver sections about half an inch in diameter. It marked the first time that human cells had been used to grow a liver. The advance may pave the way for a development that futurists have long envisioned: In vitro transplant organs fashioned from a patient's own cells, which would eliminate the need for carefully-matched donors. Additionally, such replacements would eliminate the need for a transplant patient to take powerful--and hazardous-- immunosuppressant drugs to prevent the new organ from being rejected by his or her body.

As this CBS News story explains, the Wake Forest researchers started with animal livers that they treated with a mild detergent to most of the components of liver cells, leaving behind only a collagen "skeleton."

They then filled that collagen frame with two types of human cells--immature liver cells known as progenitors, and endothelial cells that line blood vessels.

"Our hope is that once these organs are transplanted, they will maintain and gain function as they continue to develop," lead researcher Pedro Baptista told CBS News.

The manmade liver is the latest in a series of breakthroughs in in-vitro growth of replacement organs. As this New Scientist article details, in 2006, Wake Forest researchers managed to grow artificial bladders in the lab and surgically graft them onto the bladders who seven children stricken with incontinence and serious kidney problems.

More recently, in March, British and Italian researchers successfully transplanted into a 10-year-old boy a trachea grown from his own stem cells, attached to a collagen scaffold. Here's a press release describing the procedure.

Researchers' success in growing hearts and lungs and transplanting them into rats suggests that similar breakthroughs may be ahead for humans, as well. But Singularity Hub senior editor Aaron Saenz points out in this post, there are still considerable hurdles to overcome before the transplantation of in vitro replacement organs can be used to help human patients.

"There's a lot more growth needed to create a functional replacement, and it won't be as easy as simply allowing the liver cells to keep reproducing in thicker clusters," Saenz writes. "There are real concerns about how to get the cells to receive nutrients while in the bioreactor and to grow along the entire scaffold." Growing a full-size functional human liver, he says, will require "some serious bioengineering."

The idea of growing replacement organs may have been first espoused in a book, The Culture of Organs, authored by Nobel Laureate Alexis Carrel and aviator and futurist Charles Lindbergh back in 1937. But for years, the notion seemed like something better suited to science fiction.

Here's a 2007 TED lecture by regenerative medicine specialist Alan Russell, in which he discusses the future prospects for growing replacement organs. "If a newt can do this kind of thing, why can't we?" he asks.