An artificial womb successfully grew baby sheep — and humans could be next
Inside what look like oversized ziplock bags strewn with tubes of blood and fluid, eight fetal lambs continued to develop — much like they would have inside their mothers. Over four weeks, their lungs and brains grew, they sprouted wool, opened their eyes, wriggled around, and learned to swallow, according to a new study that takes the first step toward an artificial womb. One day, this device could help to bring premature human babies to term outside the uterus — but right now, it has only been tested on sheep.
Image: The Children’s Hospital of Philadelphia
“It’s “complete science fiction” to think you could do this without the mother”
“So parents have to make critical decisions about whether to use aggressive measures to keep these babies alive, or whether to allow for less painful, comfort care,” says neonatologist Elizabeth Rogers, co-director for the Intensive Care Nursery Follow-Up Program of UCSF Benioff Children’s Hospital, who was not involved in the study. “One of the unspoken things in extreme preterm birth is that there are families who say, ‘If I had known the outcome for my baby could be this bad, I wouldn’t have chosen to put her through everything.’”
That’s why for decades scientists have been trying to develop an artificial womb that would re-create a more natural environment for a premature baby to continue to develop in. One of the main challenges was re-creating the intricate circulatory system that connects mom to fetus: the mom’s blood flows to the baby and back, exchanging oxygen for carbon dioxide. The blood needs to flow with just enough pressure, but an external pump can damage the baby’s heart.
To solve this problem, Flake and his colleagues created a pumpless circulatory system. They connected the fetus’s umbilical blood vessels to a new kind of oxygenator, and the blood moved smoothly through the system. Smoothly enough, in fact, that the baby’s heartbeat was sufficient to power blood flow without another pump.
“For decades, scientists have been trying to develop an artificial womb”
Flake and his colleagues tested the setup for up to four weeks on eight fetal lambs that were 105 to 120 days into pregnancy — about equivalent to human infants at 22 to 24 weeks of gestation. After the four weeks were up, they were switched onto a regular ventilator like a premature baby in a NICU.
“Of course, lambs aren’t humans”
Of course, lambs aren’t humans — and their brains develop at a somewhat different pace. The authors acknowledge that it’s going to take more research into the science and safety of this device before it can be used on human babies. They’ve already started testing it on human-sized lambs that were put in the Biobags earlier in pregnancy. And they are monitoring the few lambs that survived after being taken off the ventilator to look for long-term problems. So far, the lambs seem pretty healthy. “I think it’s realistic to think about three years for first-in-human trials,” Flake says.
““I’m still blown away, whenever I’m down looking at our lambs.””
And Rogers worries about how hype surrounding the Biobag could impact parents coping with preterm infants. “I think many people have been affected by preterm birth and they think this is going to be some magic bullet. And I think that prematurity is just really complicated.” Preventing it in the first place should be a top priority, she says, but the Biobag could help drive that research forward.