Gene Therapy Treats Baby Still In The Womb

A trial led by Dr Tippi MacKenzie, pediatrician and foetal surgeon at a children’s hospital in San Francisco, has cured a previously incurable blood disease. This was only possible because the patient, Elianna, was still in the womb.

In Elianna's case, successfully transplanted stem cells were crucial to keeping her alive and healthy until birth, but treating a foetus while inside its mother’s womb had long been thought to be impossible. However, groundbreaking research indicated that it was the mother’s immune system, not the foetus itself, that previously had rejected the injected cells.

Because half the DNA of the foetus comes from the father, it makes a portion of cells foreign to the mother. For co-existence during pregnancy to be possible, the mother's and the baby's cells learn to tolerate each other. The truce ends the minute the baby is born; the child’s immune system immediately closes. But cells from a healthy mother, injected when the foetus is still in its womb? It was a way around the problem.

Roughly 50 million of her mother’s cells were transferred into Elianna's bloodstream. And they weren’t rejected at all — after a few months, the baby girl was born. The next step is to see whether the mom’s cells permanently nest inside Elianna's bone marrow — generating healthy cells throughout her entire life. So far, phase one of this trial has been a success.

MacKenzie believes that the method could prevent children from developing similar diseases in the future, before they are even born. And her trial is just one illustration of how fast foetal medicine — once thought to be impossible — is progressing.