Cord-Derived Stem Cells for Pediatric Autism Spectrum Disorder: Biological Rationale and Source-Specific Trial Design

Autism spectrum disorder (ASD) affects approximately 1 in 31 children, yet no pharmacological agent targets its core symptoms, leaving a substantial therapeutic gap. Umbilical cord-derived mesenchymal stem/stromal cells (UC-MSCs) have emerged as a biologically rational candidate, because their immunomodulatory, anti-inflammatory, and neurotrophic properties align with the chronic neuroinflammation, peripheral immune dysregulation, and microglial overactivation that characterize ASD pathophysiology. This review synthesizes the mechanistic rationale, tissue-source biology, manufacturing and characterization standards, preclinical evidence, and clinical trial landscape for cord-derived cell therapy in pediatric ASD, and examines administration routes, post-treatment monitoring, and long-term safety. Across five published clinical trials employing cord blood mononuclear cells, autologous and allogeneic umbilical cord blood, UC-MSCs, bone marrow-derived MSCs, and Wharton's jelly-derived MSCs, short-term safety is the most consistent finding, whereas efficacy remains unresolved owing to small sample sizes, single-arm designs, and heterogeneous outcome measures; a completed randomized Phase II trial of a cord tissue MSC product, reported to date only in the trial registry, did not meet its primary endpoint. The central argument advanced here is that the proposed active component of cord-derived therapy is the purified MSC population rather than the heterogeneous mononuclear cell fraction; this proposition is supported by the CD14⁺ monocyte mechanism and by the one pediatric trial in which purified UC-MSC was added to a mononuclear preparation, but it has not been confirmed in any clinical study and remains a hypothesis. Advancing the field requires dedicated source-specific randomized controlled trials integrating product standardization, patient stratification, and dose-route-timing optimization.