Stem Cell Research & Therapy, 19/06/2026
Abstract
This randomized, double-blind, placebo-controlled clinical trial evaluated the safety and efficacy of allogeneic umbilical cord blood mononuclear cells (UCB-MNCs) in children with autism spectrum disorder (ASD) and peripheral immune dysregulation.
A total of 34 children aged 3-8 years received either four intravenous infusions of UCB-MNCs or placebo over four weeks while continuing their standard rehabilitation programs. After 13 weeks of follow-up, children treated with UCB-MNCs showed significantly greater improvements in overall social responsiveness and social cognition compared with the placebo group. Importantly, no serious treatment-related adverse events were observed.
These findings suggest that allogeneic UCB-MNC therapy is safe and may offer therapeutic benefits for improving specific social and cognitive symptoms in children with ASD associated with immune dysregulation. Further large-scale studies are needed to confirm these preliminary results.
Introduction
Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterized by persistent difficulties in social communication and interaction, accompanied by restricted and repetitive behaviors. The prevalence of ASD has increased steadily worldwide, making it an increasingly important public health concern.
Although the exact causes of ASD remain unclear, growing evidence suggests that immune dysregulation and neuroinflammation play important roles in its development. Elevated levels of inflammatory cytokines and abnormal activation of immune cells have been consistently observed in individuals with ASD. These findings have led researchers to explore immunomodulatory therapies as potential treatment strategies.
Currently, ASD management relies primarily on behavioral and educational interventions, while no approved medications effectively address the core symptoms of the disorder. This unmet medical need has encouraged the investigation of stem cell-based therapies.
Among various cell therapy approaches, umbilical cord blood mononuclear cells (UCB-MNCs) have attracted attention because of their immunomodulatory, anti-inflammatory, and neuroprotective properties. Compared with autologous cord blood cells, allogeneic UCB-MNCs offer greater accessibility and may provide stronger immunomodulatory effects due to their origin from healthy donors.
Previous clinical studies have suggested potential benefits of stem cell therapy for ASD; however, most were limited by small sample sizes, open-label designs, or lack of placebo controls. Therefore, this randomized, double-blind, placebo-controlled trial was conducted to evaluate the safety and efficacy of repeated intravenous infusions of allogeneic UCB-MNCs in children with ASD and peripheral immune dysregulation.
Methods
This study was a prospective, single-center, randomized, double-blind, placebo-controlled clinical trial conducted at the First Medical Center of the Chinese PLA General Hospital in Beijing, China. The study was approved by the institutional ethics committee and registered on the Chinese Clinical Trial Registry (ChiCTR2400082762). Written informed consent was obtained from all participants’ legal guardians.
A total of 55 children with Autism Spectrum Disorder (ASD) were screened for eligibility. After applying inclusion and exclusion criteria, 36 children were enrolled and randomly assigned to either the allogeneic umbilical cord blood mononuclear cell (UCB-MNCs) group or the placebo group. All participants received four intravenous infusions, and 34 children completed the study and were included in the final efficacy analysis.
Eligible participants were children aged 3-8 years with a confirmed diagnosis of ASD and laboratory evidence of peripheral immune dysregulation, defined by elevated inflammatory cytokine levels. Children with active infections, immunodeficiency, tumors, severe organ dysfunction, significant allergies to blood products, or other neurological and psychiatric disorders were excluded.
Participants were free to withdraw from the study at any time without affecting their medical care.
UCB-MNCs Preparation
The allogeneic umbilical cord blood mononuclear cells (UCB-MNCs) used in this study were supplied by the Shandong Provincial Cord Blood Hematopoietic Stem Cell Bank and obtained from multiple healthy donors. All cell products were manufactured according to Good Manufacturing Practice (GMP) standards.
Before clinical use, each batch underwent strict quality control, including cell viability testing (≥90% viable cells), pathogen screening (negative for bacterial endotoxins, bacteria, fungi, and mycoplasma), and flow cytometric analysis confirming a CD34+ cell proportion of at least 0.05%.
Participants in the treatment group received 3×108 UCB-MNCs per infusion, administered once weekly for four consecutive weeks. The placebo group received saline infusions of the same volume.
UCB-MNCs Infusion
Intravenous infusion was selected as the route of administration because it is minimally invasive, allows repeated dosing, and enables systemic distribution of cells. Although intravenously infused cells may have limited penetration across the blood–brain barrier, previous studies suggest that they may exert therapeutic effects through the secretion of bioactive factors that modulate inflammation and support neural function.
All infusions were performed under physician supervision. The infusion rate was initially maintained at 20-30 drops per minute for 10 minutes and then increased to 60-70 drops per minute if no adverse reactions occurred. Each infusion was completed within approximately 30 minutes. Participants remained under medical observation for two hours after treatment, while continuing their routine rehabilitation and behavioral interventions throughout the study.
Outcome Measures and Safety Assessment
The primary efficacy endpoint was the Social Responsiveness Scale, Second Edition (SRS-2), a validated instrument used to quantify autism-related social impairments across five domains: Social Awareness, Social Cognition, Social Communication, Social Motivation, and Restricted Interests/Repetitive Behaviors.
Secondary outcome measures included the Vineland Adaptive Behavior Scales (Vineland-3), Childhood Autism Rating Scale (CARS), Autism Behavior Checklist (ABC), SNAP-IV, and Self-Rating Anxiety Scale (SAS). Together, these instruments assessed adaptive functioning, autism severity, behavioral symptoms, attention deficits, hyperactivity, and anxiety.
Safety was evaluated through adverse event monitoring, physical examinations, vital signs, complete blood counts, liver and kidney function tests, and laboratory assessments conducted throughout the study and follow-up period.
Results
Baseline Characteristics
Among the 34 children included in the final analysis, 29 were male (85.3%) and 5 were female (14.7%). Baseline demographic characteristics and clinical assessment scores were comparable between the UCB-MNCs and placebo groups. No statistically significant differences were observed in SRS-2, Vineland-3, CARS, ABC, SAS, SNAP-IV scores, or serum cytokine levels before treatment, indicating good baseline homogeneity.
Laboratory Safety Outcomes
At Week 13, no significant changes were observed in liver function, blood counts, or most biochemical parameters compared with baseline. In the UCB-MNCs group, serum creatinine levels showed a statistically significant decrease, while the placebo group demonstrated a significant reduction in blood urea nitrogen. No clinically meaningful abnormalities were identified.
Clinical Efficacy Outcomes
The primary outcome analysis demonstrated a significantly greater reduction in total SRS-2 scores in the UCB-MNCs group compared with the placebo group (LS Mean Difference = -6.03; 95% CI: -11.93 to -0.14; P = 0.045), indicating improvement in overall social responsiveness.
Among the secondary outcomes, the Social Cognition domain of the SRS-2 showed significant improvement in the UCB-MNCs group (LS Mean Difference = -9.95; 95% CI: -15.90 to -4.00; P = 0.002).
No significant differences were observed in the overall Vineland-3 adaptive behavior scores. However, at Week 4, children receiving UCB-MNCs demonstrated significant improvement in the Play and Leisure subdomain compared with the placebo group.
In addition, SNAP-IV assessments showed a significant improvement in attention deficit and hyperactivity symptoms at Week 4 in the UCB-MNCs group compared with controls.
Safety and Adverse Events
No serious adverse events (SAEs) related to allogeneic UCB-MNC infusion were reported during the study.
In the UCB-MNCs group, four children (23.5%) experienced transient excitement and one child developed a transient low-grade fever. In the placebo group, two children experienced transient excitement, one developed mild infusion-site infiltration, and three developed transient low-grade fever.
All adverse events were mild, temporary, and resolved without long-term consequences.
Discussion
Compared with previous studies, this trial specifically enrolled children with evidence of peripheral immune-inflammatory abnormalities and employed a repeated infusion strategy (four infusions at one-week intervals) to enhance potential immunomodulatory effects. The results demonstrated that allogeneic UCB-MNC therapy was generally safe and was associated with improvements in overall social responsiveness and social cognition.
Safety Profile
UCB-MNCs offer several practical advantages:
- Readily available from donated umbilical cord blood.
- Manufactured under standardized quality-controlled conditions.
- Lower risk of immune rejection and graft-versus-host disease (GVHD) compared with many other allogeneic cell sources.
- Can be administered intravenously without invasive procedures.
No serious treatment-related adverse events were observed in this study. Reported side effects were mild, transient, and self-limiting, including temporary excitement and low-grade fever.
These findings are consistent with previous clinical studies showing favorable safety outcomes for both autologous and allogeneic umbilical cord blood therapies in children with ASD.
Potential Clinical Benefits
The study demonstrated significant improvements in:
- Overall social responsiveness (SRS-2 Total Score)
- Social cognition
- Play and leisure activities
- Symptoms related to attention deficit and hyperactivity
These findings suggest that UCB-MNC therapy may positively influence several core domains affected in ASD, particularly social functioning and attention-related behaviors.
Possible Mechanism of Action
Growing evidence suggests that immune dysregulation and chronic neuroinflammation play an important role in ASD. Previous studies have reported elevated levels of inflammatory cytokines in individuals with ASD such as IL-1β, IL-6, IL-8, IL-17, TNF-α. UCB-MNCs possess immunomodulatory and anti-inflammatory properties that may help restore immune balance and reduce neuroinflammation. Although the exact mechanism remains unclear, the therapeutic effects observed in this study may be related to modulation of immune pathways and inflammatory responses.
Future research involving proteomics and metabolomics analyses may help clarify these biological mechanisms.
Limitations
Several limitations should be considered:
- Small sample size.
- Single-center study design.
- Relatively short follow-up period (13 weeks).
- Reliance on caregiver- and clinician-reported assessment scales.
- Lack of objective biological efficacy markers.
- Limited ability to evaluate long-term safety and durability of treatment effects.
Therefore, larger multicenter studies with longer follow-up periods are needed to confirm these preliminary findings.
Conclusion
Repeated intravenous infusions of allogeneic UCB-MNCs demonstrated good short-term safety and showed potential benefits in improving social responsiveness and social cognition in children with ASD and immune dysregulation. Larger, multicenter studies with longer follow-up are needed to further confirm efficacy, safety, and underlying mechanisms.
References:
Zhang, Z., Wang, G., Han, F. et al. Efficacy and safety of allogeneic umbilical cord blood mononuclear cells therapy in children with autism spectrum disorder and immune dysregulation: a single-center, double-blinded, randomized, placebo-controlled trial. Stem Cell Res Ther (2026). https://doi.org/10.1186/s13287-026-05091-5
Source: Stem Cell Research & Therapy
Link: https://link.springer.com/article/10.1186/s13287-026-05091-5
