Hematopoietic Cell Transplantation in Children with Sickle Cell Disease: A Single-Center Experience and Exploration of an Age Threshold for Post-Transplant Complications

Background/Objectives: Hematopoietic cell transplantation (HCT) is the only established curative option for sickle cell disease (SCD), yet the optimal timing in pediatric cohorts remains incompletely defined. Methods: We retrospectively analyzed all patients under 20 years with SCD who underwent HCT at the University Hospital of Strasbourg between 2006 and 2024 and explored whether an age threshold exists for post-HCT complications. Results: Regarding the MSD-HCT (n = 30), median age at HCT was 8.4 years (3.7–16.7). All received myeloablative conditioning with thymoglobulin. Median follow-up was 4.1 years. Five-year overall and event-free survival were 93%. The single death was accidental; therefore, there was no transplant-related mortality. Grade II-IV acute GVHD occurred in two patients (7%) and chronic GVHD in one (3%). GVHD-free rejection-free survival was 87%. No graft failure occurred, and 70% achieved complete donor chimerism. No statistically significant age threshold for post-transplant complications was identified, although PRES tended to be more frequent from 8 years. Cerebral vasculopathy was stable or improved in all evaluated patients. In the haploidentical group, one primary graft failure occurred despite thiotepa and post-transplant cyclophosphamide. Conclusions: This cohort demonstrates excellent survival and low morbidity following MSD-HCT in children with SCD and justifies a larger registry-based analysis of age and complications. The growing role of haploidentical HCT warrants evaluation in larger prospective cohorts, with particular attention to conditioning strategies.