Intraventricular MSC administration appeared safe and feasible over 5 years in preterm infants with PVHI; however, baseline PVHI severity remained the strongest predictor of long-term neurodevelopmental outcomes.
Intraventricular administration of mesenchymal stromal cells in preterm infants with PVHI showed no significant short-term or long-term adverse events, including tumorigenicity, over 5 years of follow-up.
Infants with higher PVHI severity (score 3) showed more frequent adverse long-term neurodevelopmental outcomes compared to those with lower severity (score 2).
Lower intact brain volume ratio strongly correlates with the presence of cerebral palsy with GMFCS ≥3.
Baseline PVHI severity was the strongest predictor of long-term neurodevelopmental outcomes following intraventricular MSC administration.
The study supports feasibility of intraventricular MSC administration as a potential disease-modifying approach for PVHI, which currently has no established disease-modifying therapy.
This research describes a 5-year follow-up of nine premature babies who had a serious type of brain bleed called periventricular hemorrhagic infarction (PVHI, also known as grade 4 intraventricular hemorrhage) and who received stem cells (mesenchymal stromal cells) injected directly into the fluid-filled spaces of the brain as part of an early-phase clinical trial. The main question was whether this treatment was safe over the long term, and the answer appeared to be yes — no serious side effects, including no tumor formation, were detected over the 5-year follow-up period. However, the babies who had more severe brain bleeds at the start (PVHI score 3 versus score 2) tended to have worse outcomes at both 2 and 5 years of corrected age, including lower scores on developmental tests, more developmental impairments, and more severe cerebral palsy. This research suggests that while injecting stem cells into the brain ventricles of premature infants appears to be safe over a 5-year period, the original severity of the brain injury was the most important factor in predicting how children would develop — more so than the treatment itself. Babies with less severe bleeds generally did better, and a measure of how much healthy brain tissue remained was strongly linked to whether a child developed more severe cerebral palsy. The study also had no control group for comparison, which limits conclusions about whether the stem cell treatment itself improved outcomes. This research matters because PVHI is a devastating condition with no currently approved treatments that can change its course, and even small signals of safety open the door for larger studies. The findings suggest that future trials should include more patients and a control group to properly test whether stem cell therapy can actually improve outcomes, and that enrollment of infants with less severe injury may be important for detecting any potential benefit.
Yang M, Ahn S, Sung S, Chang Y, Park W. (2026). Five-year follow-up outcomes after phase 1 trial of mesenchymal stromal cells for periventricular hemorrhagic infarction in preterm infants.. Stem cells translational medicine. https://doi.org/10.1093/stcltm/szag030