WASHINGTON -- Researchers are creating an artificial womb to improve care for extremely premature babies - and remarkable animal testing suggests the first-of-its-kind watery incubation so closely mimics mum that it just might work.
Today, premature infants weighing as little as 500 grammes are connected to ventilators and other machines inside incubators. The Children's Hospital of Philadelphia (CHOP) is aiming for a gentler solution, to give the tiniest premies a few more weeks cocooned in a womb-like environment - treating them more like foetuses than newborns - in hopes of giving them a better chance of healthy survival.
A handout photo released on April 25, 2017 by Nature Communications and made available by Children's Hospital of Philadelphia showing a lamb (left) at 107 days of gestation, on the 4th day of support inside a Biobag, and the same lamb on the 28th day of support, illustrating growth and maturation (right) in Philadelphia. (Photo via EPA)
The researchers created a fluid-filled transparent container to simulate how foetuses float in amniotic fluid inside the mother's uterus, and attached it to a mechanical placenta that keeps blood oxygenated.
In early-stage animal testing, extremely premature lambs grew, apparently normally, inside the system for three to four weeks, the team reported on Tuesday.
"We start with a tiny foetus that is pretty inert and spends most of its time sleeping. Over four weeks we see that foetus open its eyes, grow wool, breathe, swim,'' said Dr Emily Partridge, a CHOP research fellow and first author of the study published in Nature Communications.
"It's hard to describe actually how uniquely awe-inspiring it is to see,'' she added in an interview.
Human testing still is three to five years away, although the team already is in discussions with the Food and Drug Administration.
"We're trying to extend normal gestation,'' said Dr Alan Flake, a foetal surgeon at CHOP who is leading the project and considers it a temporary bridge between the mother's womb and the outside world.
Increasingly, hospitals attempt to save the most critically premature infants, those born before 26 weeks gestation and even those right at the limits of viability - 22 to 23 weeks. Extreme prematurity is a leading cause of infant mortality, and those who do survive frequently have serious disabilities such as cerebral palsy.
Dr Alan Flake, a foetal surgeon at Children’s Hospital of Philadelphia who is leading the research to develop a fluid-filled incubation system that mimics a mother’s womb for extremely premature infants. (Children's Hospital Photo via AP)
The idea of treating premies in fluid-filled incubators may sound strange, but physiologically it makes sense, said Dr Catherine Spong, a foetal medicine specialist at the National Institutes of Health.
"This is really an innovative, promising first step,'' said Spong, who was not involved with the research.
One of the biggest risks for very young premies is that their lungs are not ready to breathe air, she explained. Before birth, amniotic fluid flows into their lungs, bringing growth factors crucial for proper lung development. When they are born too soon, doctors hook premature babies to ventilators to keep them alive, but at risk of lifelong lung damage.
Flake's goal is for the womb-like system to support the very youngest premies just for a few weeks, until their organs are mature enough to better handle regular hospital care like older premature babies who have less risk of death or disability.
The device is simpler than previous attempts at creating an artificial womb, which have not yet panned out.
How the "Biobag'' system works:
- The premature lambs were delivered by C-section and immediately placed into a temperature-controlled bag filled with a substitute for amniotic fluid that they swallow and take into their lungs.
"We make gallons of this stuff a day,'' said foetal physiologist Marcus Davey. It is currently an electrolyte solution. He is working to add other factors to make it more like real amniotic fluid.
- Then the researchers attach the umbilical cord to a machine that exchanges carbon dioxide in blood with oxygen, like a placenta normally does.
- The lamb's heart circulates the blood, without the need for any other pump.
The researchers tested five lambs whose biological age was equivalent to 23-week human premies, and three others a bit older. All appeared to grow normally, with blood pressure and other key health measures stable and few complications during the weeks they were inside the womb-like device.
The study did not address long-term development. Most of the lambs were euthanized for further study that found normal organ development for their gestational age. One was bottle-weaned and is now more than a year old, apparently healthy and living on a farm in Pennsylvania.
Flake stressed that the womb-like system is not intended to support premies any younger than today's limits of viability -- not what he calls the more "sensationalistic'' idea of artificially growing embryos.
He acknowledged that parents might question the approach, but notes that the premies always could be whisked into standard care if they fared poorly in the new system. And while further adaptation of the device is needed before it can begin human testing, he envisioned parents being able to see the baby and even piping in the sound of the mother's heartbeat.