Surgeons in California have completed the first trial of an idea that seemed too delicate to attempt: placing stem cells directly onto a baby's exposed spine while still in the womb. The results suggest it works. In all six cases treated, a brain abnormality that typically accompanies severe spina bifida—where part of the brain slips into the neck—reversed after birth. No tumors formed. The surgery healed normally. The babies' mobility improved.
This matters because spina bifida, which affects roughly one in every 1,000 pregnancies in the UK, has no cure. The best current option is fetal surgery to close the spinal defect before birth, a procedure that has already transformed outcomes for children born with the condition. But it doesn't stop all the damage. Adding stem cells to that surgery might.
How it works
The team at UC Davis extracted mesenchymal stem cells from the placenta—tissue the mother's body is about to discard anyway—and applied them to the baby's exposed spinal cord during surgical repair at 24 to 25 weeks of pregnancy. Dr Diana Farmer, who led the trial, describes the logic simply: the stem cells seem to help the spinal cord heal better and prevent some of the neurological damage that usually follows spina bifida.
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Start Your News DetoxThe trial, published in the Lancet this week, involved just six babies treated between 2021 and 2022. That's small enough that it raises an obvious question: could this have been luck. Possibly. But the consistency is striking. Every single baby showed the same reversal of hindbrain herniation on post-birth MRI scans. Researchers had worried about risks—tumors, infection, interference with wound healing—but found none.
Farmer said she believes this could become standard care if larger trials confirm the results. "If it makes more children able to walk who wouldn't have then it would become their standard of care," she said.
What comes next
Kate Steele, chief executive of the charity Shine, which supports people with spina bifida, noted that improvements in bladder and bowel function—two areas where spina bifida causes lifelong complications—would be "particularly welcome." Dr Magdalena Sanz Cortes, a fetal medicine expert in Texas, wrote in a linked commentary that if further studies confirm these results, they could "herald a new era in fetal surgery."
Between 8,100 and 11,900 people in England and Wales live with open spina bifida today. For families facing a diagnosis, the question now is whether this early promise will hold up in larger trials. The next phase will tell us whether six babies were the beginning of something bigger, or an encouraging signal that needs more evidence before it becomes routine.
