Unrelated cord blood transplantation for pediatric patients with inborn error of immunity and inborn error of metabolism in Vietnam: early single-center experience

Introduction Umbilical cord blood (CB) contains hematopoietic stem and progenitor cells and is an established alternative donor source for hematopoietic stem cell transplantation (HSCT) in both malignant and non-malignant disorders, particularly in children. Patients and methods We retrospectively studied 12 consecutive pediatric patients with genetically distinct inborn error disorders who underwent single-unit unrelated cord blood transplantation (UCBT) at Vietnam National Children’s hospital between October 2020 and February 2026. Outcomes were analyzed descriptively, with emphasis on engraftment, graft failure or rejection, graft-versus-host disease (GVHD), infectious complications, donor chimerism, and immune reconstitution. Result The median age at transplantation was 19 months (range, 7–42 months), and the median interval from diagnosis to transplantation was 10 months (range, 3–39 months). The study cohort included patients with Wiskott–Aldrich syndrome, very early-onset inflammatory bowel disease caused by an IL10R mutation, severe combined immunodeficiency, major histocompatibility complex class II deficiency, and mucopolysaccharidosis type II. With a median follow-up of 26 months, neutrophil engraftment occurred in nine patients (75%). The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) was 41.6%, and no patient developed chronic GVHD. Five patients discontinued immunosuppressive therapy. One patient died due to multiorgan failure within the first month after UCBT. Two patients underwent successful haploidentical transplantation because of graft failure, and one patient developed graft rejection after initial engraftment. No additional deaths occurred during follow-up, resulting in an overall survival rate of 91.1% (11/12), whereas the UCBT success rate was 66.7%. The small sample size and relatively short follow-up for some patients restrict the strength of the study. Conclusion UCBT was feasible for children who required stem cell transplantation but lacked a suitable donor, providing sustained donor engraftment and immune recovery in most long-term survivors.