Scientists have created an artificial uterus for lambs
American pediatricians presented an "artificial uterus" in which lambs at very short gestation periods developed normally for a month. The developers expect that their system will help to qualitatively change the practice of caring for premature babies.
The system developed by Alan Flake and his colleagues from the Children's Hospital in Philadelphia consists of a closed container filled with a constantly circulating artificial analogue of amniotic fluid, and an oxygenator with which the fetal circulatory system inside the device is connected via the umbilical cord. The idea of the scientists was, unlike similar developments, to bring their "artificial uterus" as close as possible to the real uterus in terms of the conditions and processes that occur in it.
In the article, the authors state that "lambs, from the point of view of the level of development, are equivalent to premature babies at 23-24 weeks (at this time, scientists estimate the chance of survival of the child at 30-50% – approx. "Attic"), can stay in such an artificial uterus for up to four weeks", developing normally. At a press briefing, Flake noted that the four-week period was limited not by the fundamental capabilities of the system, but by the protocol of the experiment. In total, scientists have successfully raised six lambs in prototypes of the system.
"All the development parameters that we measured for these lambs are normal, and this makes our development different from other similar systems," Flake said at a briefing.
Study co–author Emily Partridge explained that, first of all, premature babies suffer from underdevelopment of their lungs, which have to breathe air too early - in the womb, the baby's lungs are filled with fluid, and the "artificial uterus" developed by scientists simulates this condition. In addition, unlike conventional systems of care for premature babies, it maintains a closed sterile environment, protecting the fetus from pathogens of the external environment.
The system works without a pump by analogy with a real placenta: blood through an oxygenator, saturating it with oxygen and removing carbon dioxide, drives away the fetal heart. According to doctors, it will take only about a minute and a half to "switch" a premature baby born by caesarean section from the maternal placenta to the device, which the fetal body will completely cope with.
Some of the lambs were put to sleep after being in the "wombs" in order to study in detail how the artificial environment affected the development of their brain, lungs, nervous and circulatory systems, and so on. The remaining animals continued to develop normally even after the end of the experiment. "We have bottle-fed them, raised them, they are quite well developed and, in my opinion, quite intelligent… The oldest of them is about a year old now," Flake said. Partridge added that this young sheep now lives on a farm in Pennsylvania.
Image: The Children's Hospital of Philadelphia, translation: "Attic"
Lambs in the study were used as proven model organisms for intrauterine development studies. One fundamentally important difference for this study between sheep and humans is that in unborn lambs, the so-called germinal or germinal matrix matures earlier, a very important and vulnerable part of the brain in which neurons and glial cells are formed during its development. Hemorrhage in this part of the brain is one of the most common complications in severely premature babies.
Answering the question about how their system in connection with these circumstances can be applicable to people, Flake noted that one of the possible causes of such hemorrhages in infants is mechanical ventilation of the lungs, which is excluded in their system.
Another consequence associated with the use of artificial blood circulation systems is the formation of blood clots, and here the scientist stressed that they did not record any such cases, while using minimal doses of blood–thinning heparin. In the future, more advanced versions of such an "artificial uterus" will probably be able to do without heparin altogether, which will further reduce the risks of hemorrhages. In addition, scientists do not yet know how much the blood vessels in the umbilical cord of lambs are similar in their properties to human ones – this also remains to be found out in further research.
"Of course, we will need time and additional animal testing before we can talk about the effectiveness of such a system for humans. Now we are together with the FDA (FDA – approx. We are developing a plan for a preclinical study of animals, which we expect to conduct in the next two to three years," Flake said. According to his estimates, such devices can get into medical practice in 10 years.
Using this system for even more premature lambs or children, up to the equivalent of 22-23 weeks, most likely will not work – this will be associated with too great risks for an underdeveloped fetus. Scientists suggest that in their system premature babies will be able to develop up to 28 weeks, after which the prognosis improves significantly.
"We are not talking about premature babies hanging in rows in bags on the wall. We expect that in the future this device will be similar to an ordinary opaque incubator, possibly with cameras, so that parents can see how their child is breathing and developing, and he will be able to hear their voices. We will try to make this system more "friendly", including for parents, and the situation is less stressful than finding a child in the discomfort of a typical incubator," the scientist stressed.
The study is published in the journal Nature Communications (Partridge et al., An extra-uterine system to physiologically support the extreme premature lamb).
Lamb extracted from a live uterus on the 107th day of pregnancy, after 4 and 28 days
after being placed in an artificial uterus (from an article in Nature Communications) – VM.
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26.04.2017