Stem cell therapy performed to babies in the womb could reverse brain abnormalities linked to a severe birth defect, experts have said.
Surgeons applied stem cells, derived from donated placentas, to the exposed spinal cord during foetal surgery.
Researchers are now optimistic the procedure could alter the lifelong health of those with the condition.
Spina bifida occurs when a baby’s spine fails to develop fully in the womb, typically diagnosed during pregnancy or shortly after birth.
There are two main types of the condition; open spina bifida and closed spina bifida.
Open spina bifida, known as myelomeningocele and meningocele, is less common but more serious, and causes the spinal cord to push out of a gap in the spine.
Symptoms can include problems with walking or paralysis, incontinence, a loss of feeling in the legs, a curved spine, and a build up of fluid in the brain which can cause learning difficulties.
In some cases, specialists can perform fetal surgery to close open spina bifida while the baby is still in the womb.
However, researchers say this “does not fully address” the problems with mobility that can happen when the lower motor neurons – which connect the brainstem and spinal cord to skeletal muscles – are damaged.
The trial, carried out in California, included six women between 24 and 25 weeks pregnant.
Each of their babies had been diagnosed with myelomeningocele and were shown to have hindbrain herniation, which are brain abnormalities associated with spina bifida.
All six patients had fetal surgery to correct their baby’s condition.
In an extra step, stem cells from donated placentas were also applied directly to the exposed spinal cord of the fetus.
The six babies were delivered between July 2021 and December 2022, and all were born with spinal repairs in tact and no signs of infection or abnormal tissue growth.
An MRI scan performed after the birth confirmed that the hindbrain herniation had been reversed.
Researchers said the study – published in The Lancet – “establishes a scalable and clinically feasible platform for the targeted delivery of biological therapeutics to the fetus”.
They added: “The successful integration of cell-based therapy into fetal surgery, under stringent regulatory oversight and within a standardised surgical workflow, shows the feasibility and safety of delivering rationally designed biologics during gestation.
“By intervening at early stages of development, this approach has the potential to alter lifelong health trajectories, reducing the burden of chronic disability and minimising the long-term social and economic impact of these conditions.”
The six children involved in the trial received routine care, but will also be followed-up at intervals until they are six to assess the long-term safety of the treatment.
The findings from the phase one trial have also allowed experts to proceed with the enrolment of 35 patients on another study.
Spina bifida affects about one in 1,000 births in the UK every year.
