An artificial womb filled with clear liquid, successfully tested on pre-natal lambs, could help extremely premature babies avoid death or life-long disability, researchers reported Tuesday.
"It is designed to continue what naturally occurs in the womb," said Alan Flake, a foetal surgeon at The Children's Hospital of Philadelphia and senior author of a study in Nature Communications that details the breakthrough.
"That's the beauty of it, and why I'm optimistic we will improve on what is currently done for extremely premature babies," he told journalists by phone.
Today, infants brought into the world after only 22 or 23 weeks of gestation rather than the full 40 have a 50/50 chance of living, and -- for those that survive -- a 90 percent change of severe and lasting health problems.
The new system mimics life in the uterus and could, if approved for human use, dramatically improve those odds.
The researchers are working with the US Food and Drug Administration to prepare human trials, which could start within three years.
The foetus -- breathing liquid, as it would in the womb -- lies in a clear-plastic sack filled with a synthetic amniotic fluid.
"A fluid environment is critical for foetal development," said Flake.
The umbilical cord is attached via tubes to a machine outside the bag, which removes CO2 and adds oxygen to blood passing through it.
There are no mechanical pumps -- it is the foetus's heart that keeps things moving.
Current treatment has pushed the boundary of survivability to 22 or 23 weeks, but comes at a high cost.
Beyond a high mortality rate, tiny lungs and hearts of preemies barely a half-a-kilo (a pound) in weight are ill-equipped to withstand the trauma of intubation, ventilators and artificial pumps.
- Normal in all respects -
Extremely premature infants who survive often have chronic lung infections and other crippling health problems.
"One of the major advantages of our system is the avoidance of heart failure, which comes from the imbalance of blood flows created with pump circuits," said co-author Marcus Davey, an investigator with the hospital's Center for Fetal Research and the project's lead engineer.
For the study, the researchers tested six preterm lambs transferred from their mothers' wombs to the device at 105 to 112 days of gestation -- the equivalent of 23 to 24 weeks in a human. They remained in the artificial wombs for up to 28 days.
In humans, the high-risk period for premature babies is 22 to 27 weeks. "At 28 weeks, you are at a point where the mortality and morbidity of prematurity is finished," said Flake.
Sheep have long been used in experiments for prenatal treatment, especially because lung development is highly similar.
While nestled in the devices, "the lambs showed normal breathing and swallowing, opened their eyes, grew wool, became more active, and had normal growth, neurological function and organ maturation," said Flake.
After the experiments, most of the animals were humanely put down so that their brains, lungs and other organs could be examined.
A few were bottle-fed and "appear to have normal development in all respects," said Flake. One has been retired to a farm in rural Pennsylvania.
If the Food and Drug Administration trials go ahead it could be another three to five years before the devices -- assuming they are proven safe and effective for newborns -- are in use, Flake said.
Colin Duncan, a professor of reproductive medicine at the University of Edinburgh, said: "This is a really attractive concept and this study is a very important step forward."
The devices, he added, "will require a lot of additional preclinical research and development."