Artificial womb

C&I Issue 4, 2017

An artificial womb could transform care for extremely premature babies by giving them a few invaluable weeks to develop their lungs and other organs. Its developers say that a decade from now these devices could take the place of incubators attached to ventilators.

Babies born younger than 26 weeks are classified as extremely premature. Neonatal care practices can support babies from 22 to 23 weeks of gestation, but these babies have a 30-50% chance of survival.

‘These infants have an urgent need for a bridge between the mother’s womb and the outside world,’ explains team leader Alan Flake of the Children’s Hospital of Philadelphia. ‘If we can develop an extra-uterine system to support growth and organ maturation for only a few weeks, we can dramatically improve outcomes for extremely premature babies.’

As foetal lungs are designed to function in fluid, Flake’s team has designed a container or bag to hold the baby while laboratory-produced amniotic fluid passes in and out. This fluid allows the lungs and other organs to develop, while supplying nutrients and growth factors (Nature Communications, doi:10.1038/ncomms15112).

The container is attached to custom-designed machines that provide physiological support.  There is no external pump to drive circulation, because even gentle artificial pressure can fatally overload an underdeveloped heart, and there is no ventilator, because the immature lungs are not ready to breath in atmospheric oxygen. Instead, the baby’s heart pumps blood via the umbilical cord into the system’s low-resistance external oxygenator that substitutes for the mother’s placenta in exchanging oxygen and carbon dioxide. The sealed, sterile environment inside the system is insulated from variations in temperature, pressure and light, and particularly from hazardous infections.

‘Our system could prevent the severe morbidity suffered by extremely premature infants by potentially offering a medical technology that does not currently exist,’ Flake says, adding that the goal is to support infants from 23 to 28 weeks.

The team tested the system on six preterm lambs, equivalent to a 23- or 24-week-gestation babies. It operated for up to 28 days with some animals. The lambs showed normal breathing and swallowing, opened their eyes, grew wool, became more active, and had normal growth, neurological function and organ maturation, the team reports. The researchers will need to downsize the system for human infants, who are one-third the size of the infant lambs used in this study.

Colin Duncan, professor of reproductive medicine and science at the University of Edinburgh, comments: ‘This is a really attractive concept and this study is a very important step forward. However, there are still huge challenges to refine the technique. This will require is a lot of additional preclinical research and development, and this treatment will not enter the clinic anytime soon.’

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