Could Stem Cells Help Babies With Birth-Related Brain Injury? An Early Answer

A plain-language look at a Japanese study (Wada et al., 2025) that added stem cells to standard cooling treatment for newborns deprived of oxygen at birth

A small clinical trial in Japan tested whether giving stem cells on top of the usual "cooling" treatment could improve recovery for newborns with brain injury caused by a lack of oxygen around the time of birth. Fourteen babies took part, and the researchers found that adding the stem cells appeared safe but did not clearly improve outcomes compared with cooling alone — largely because cooling by itself already helped most of the babies do well. The study is an important first step rather than a final answer, and its clearest message is that today's standard cooling treatment remains the proven option while stem cell therapy is still being studied.

Why This Research Matters

When a baby's brain is deprived of oxygen and blood flow during pregnancy or delivery, the result can be a serious condition called hypoxic ischemic encephalopathy, or HIE [1]. It is one of the situations that neonatal teams take most seriously, because the injury can lead to lifelong difficulties with movement, learning, and thinking, and in the most severe cases can be fatal. For families, few moments are more frightening than being told that their newborn's brain may have been harmed at birth. Understanding what treatments actually help — and which promising ideas have not yet proven themselves — matters enormously to the parents living through it.

How Doctors Used to Face This Problem

For most of medical history, there was no treatment that could change the course of this brain injury. Doctors could support a sick newborn — helping the baby breathe, controlling seizures, keeping the body stable — but they had no way to protect the brain itself. That changed in the 2000s with a discovery that reshaped newborn care: cooling the baby's body to about 33–34 °C (a few degrees below normal) for three days, started within six hours of birth, reduced death and disability in babies with moderate or severe injury [2]. Cooling works by slowing the brain's chemistry at the crucial moment, giving injured cells a better chance to survive the hours after oxygen is restored [3]. To decide who needs cooling, doctors grade how severe the injury appears using a system developed decades ago that is still used at the cotside today [4]. Cooling is now standard care in newborn intensive-care units around the world.

But cooling is not a cure. Even with the best cooling treatment, a significant number of babies still die or grow up with disabilities [5], and even babies with milder injury who are not cooled can have subtle difficulties by the time they are toddlers [6]. That gap — the babies cooling cannot fully help — is what has driven researchers to look for something to add to cooling. For about fifteen years, the most exciting possibility has been cell therapy. An earlier US study showed it was practical to collect and give a baby's own umbilical-cord-blood cells alongside cooling [7], building on years of laboratory work suggesting that such cells help mainly by calming harmful inflammation and releasing protective substances, rather than by physically rebuilding the brain [8], [9].

What the Researchers Did

The Japanese team tested a specific, ready-made stem cell product called Temcell, made from adult bone-marrow cells [1]. One advantage of this product is that it is kept ready "off the shelf" and can be given to any baby without needing to match donor and recipient — unlike a baby's own cord blood, which must be collected and prepared at birth. Temcell has been approved and used in Japan since 2015 for a serious complication of bone-marrow transplants, so doctors already had experience with its safety in other patients [10], [11].

In the trial, fourteen newborns who were already receiving cooling were randomly split into two groups of seven. One group received cooling plus Temcell, given through a vein twice a week for four weeks; the other group received cooling alone [1]. "Randomly" means a chance process, like a coin toss, decided which treatment each baby received — the fairest way to compare two options. The researchers then followed the children to age 18 months and measured their development, checking whether each child reached a developmental score in the normal range. Independent experts who did not know which treatment each baby had received reviewed the results, which helps keep the assessment unbiased.

What They Found

Among the babies who could be fully assessed, about two-thirds in the stem cell group reached a good developmental score, compared with a similar proportion in the cooling-alone group [1]. After the independent expert review, the numbers were 4 out of 6 in the stem cell group and 5 out of 7 in the cooling-alone group. In plain terms: adding the stem cells did not produce noticeably better results than cooling by itself. Brain scans and movement assessments at 18 months were also broadly similar between the two groups, with most children in both groups doing well.

Importantly, the stem cell treatment appeared safe. Both groups had the many minor medical events that are normal for very sick newborns, but none were severe, and no babies died [1]. A few mild, temporary reactions occurred in the stem cell group and resolved on their own. Because this was an early-stage study designed mainly to check safety, showing that the treatment could be given without serious harm is itself a meaningful result.

What This Means for Families

The most useful thing for families to understand is what this study does and does not show. It does not mean stem cells are a proven treatment for birth-related brain injury, and it is not a reason to seek out stem cell treatment outside of a research study. If you read online about "stem cells for birth injury," this trial is a good example of why caution matters: a careful, fair test found no clear added benefit, mostly because cooling on its own already helped most babies do well [12]. What the study does support is continued confidence in cooling as the standard treatment — the one therapy shown, in large trials, to protect the newborn brain. Whole-body cooling, the kind used here, works at least as well as older methods that cooled only the head [13].

It also helps to understand what taking part in a study like this actually involves for a baby and family. The stem cells were not a single dose but a course of eight infusions given through a vein over four weeks, which meant the babies stayed in hospital longer and needed extra monitoring for reactions [1]. For families weighing whether to join a future trial, that commitment is real, and it is one reason researchers want to be sure any benefit is large enough to justify the extra treatment. The children were then followed to 18 months and given careful developmental testing and brain scans [13] — the only way to tell whether a therapy truly helped, since a newborn's eventual abilities cannot be judged in the first days of life.

It is also fair to be honest about the study's limits, and the researchers are. With only a handful of babies in each group, the trial was simply too small to detect anything but a very large difference; a real benefit from stem cells could exist and still be missed in a study this size. One group of babies also received a steroid medicine before their infusions and the other did not, which makes the two groups harder to compare directly. These are reasons to see the study as an encouraging first step, not the last word.

What Researchers Are Working On Next

The scientists behind this trial are clear that a bigger, more rigorous study is needed — one with more babies, a "dummy" infusion for the comparison group so that neither families nor doctors know who got the cells, and careful brain scans and developmental testing at 18 to 24 months [14]. Researchers also want to work out the best dose and timing, since the schedule used here was borrowed from a different disease and may not be ideal for protecting the brain [7]. The broader field of cell therapy continues to advance in adults too, where similar stem cells have been given safely to stroke patients with early signs of benefit [15]. For now, the reassuring bottom line for any family facing this diagnosis is that the proven treatment — prompt, carefully delivered cooling, started within the first hours after birth — is available today in newborn intensive-care units, and that dedicated scientists are actively working to make recovery even better for future babies in the years to come.

References

  1. Wada K, Takeuchi A, Katayama Y, et al. Combined treatment with mesenchymal stem cells and therapeutic hypothermia for neonatal hypoxic ischemic encephalopathy: a phase 1/2 randomized trial. Scientific Reports. 2025;15:16302. doi:10.1038/s41598-025-98504-z ↩
  2. Azzopardi DV, Strohm B, Edwards AD, et al. Moderate hypothermia to treat perinatal asphyxial encephalopathy. New England Journal of Medicine. 2009;361(14):1349–1358. doi:10.1056/NEJMoa0900854 ↩
  3. Silveira RC, Procianoy RS. Hypothermia therapy for newborns with hypoxic ischemic encephalopathy. Jornal de Pediatria (Rio J). 2015;91(6 Suppl 1):S78–S83. doi:10.1016/j.jped.2015.07.004 ↩
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  10. Muroi K, Miyamura K, Okada M, et al. Bone marrow-derived mesenchymal stem cells (JR-031) for steroid-refractory grade III or IV acute graft-versus-host disease: a phase II/III study. International Journal of Hematology. 2016;103(2):243–250. doi:10.1007/s12185-015-1915-9 ↩
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  13. Goenka A, Yozawitz E, Gomes WA, Nafday SM. Selective head versus whole body cooling treatment of hypoxic-ischemic encephalopathy: comparison of electroencephalogram and magnetic resonance imaging findings. American Journal of Perinatology. 2020;37(12):1264–1270. doi:10.1055/s-0039-1693466 ↩
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