The following is general information introducing research findings. Results reported in studies do not mean the same outcome for any individual, and most of these studies are small or early-stage.
Summary — Research on stem cells for autism produced two human clinical results in summer 2026. A team at Tehran University of Medical Sciences gave umbilical cord-derived mesenchymal stromal cells into the spinal canal three times, one month apart, to five children with autism spectrum disorder (ASD) in a phase I trial; there were no serious adverse events and the CARS score improved in all five children. A team at the Chinese PLA General Hospital randomized 36 autistic children with immune dysregulation in a double-blind trial and reported a greater improvement in social responsiveness scores (SRS-2) with umbilical cord blood mononuclear cells than with placebo. This article walks through both studies and what they mean.
Autism spectrum disorder and current support
Autism spectrum disorder (Japanese: 自閉スペクトラム症) is a neurodevelopmental condition marked by differences in social communication and by repetitive behaviors and interests. Support today centers on behavioral interventions such as applied behavior analysis, speech therapy, occupational therapy and special education, with medication added when accompanying symptoms such as irritability or attention problems are significant. These approaches are important for building everyday skills, and families have also shown interest in approaches that act on biological changes such as inflammation and immune responses in the brain.
Recent studies have reported elevated inflammatory cytokines in the blood and cerebrospinal fluid of some autistic children. Mesenchymal stem cells (MSCs) and cord blood cells release substances that calm inflammation and protect nerves, so stem cell trials for autism based on this neuroinflammation hypothesis are under way in several countries. An overview of the field is on the autism spectrum disorder stem cell page.
Phase I trial in Iran: stem cells for autism given into the spinal canal three times
Published in Stem Cell Research & Therapy on 30 July 2026, this study was carried out by the Psychiatric Research Center at Roozbeh Hospital, Tehran University of Medical Sciences, together with the Royan Institute. Five children aged 3 to 7 with autism diagnosed by DSM-5 criteria took part, all on stable behavioral and drug treatment for at least two months. The team gave 20 million donor umbilical cord-derived MSCs (UC-MSCs) intrathecally through the lower back three times, one month apart, and followed the children for six months.
There were no serious adverse events. All five children had at least one mild-to-moderate, transient reaction: fever in five and nausea in four, all of which passed. The team monitored the children before and after each injection to manage these reactions.
The exploratory results were encouraging. The CARS score, which reflects the degree of autism symptoms, improved in all five children; two moved from the mild-to-moderate range into the non-autistic range and three moved from the severe range into the mild-to-moderate range. Other measures, including the parent-rated ATEC, also improved, and the inflammatory markers TNF-α and IL-6 in cerebrospinal fluid fell consistently across participants. In one child, the EEG shifted toward a more typical pattern.
Randomized double-blind trial in China: cord blood cells and social responsiveness
The second study appeared in the same journal on 19 June 2026 (volume 17, article 301). Researchers at the First Medical Center of the Chinese PLA General Hospital and Nankai University enrolled autistic children aged 3 to 8 whose blood inflammatory cytokines (such as IL-6 or TNF-α) exceeded 1.5 times the reference limit, which they defined as immune dysregulation. Thirty-six children were randomized: one group received 300 million donor umbilical cord blood mononuclear cells (UCB-MNCs) and the other an equal volume of saline, intravenously four times at weekly intervals. Children and assessors did not know the group assignment, and both groups continued their usual rehabilitation.
In the week-13 analysis (17 children per group), the primary endpoint, SRS-2 total score, decreased by 6.03 points more in the cord blood group than in the placebo group (P = 0.045); lower SRS-2 scores mean fewer social difficulties. The difference was larger in the social cognition domain, at 9.95 points (P = 0.002). At week 4, the cell group was also ahead on play and leisure and on attention-related scores.
Adverse events were similar in both groups: four cases of transient excitement and one of low-grade fever in the cell group, and two cases of transient excitement, one mild infiltration at the infusion site and three of low-grade fever in the placebo group, with no major transplantation-related events reported. Reading this alongside our article on the Duke cord blood trials highlights the value of a design that narrows the target group.
What the two studies show about the stage of autism stem cell research
The Iranian study is a small phase I trial focused on safety and feasibility, without a control group, so the team presented the behavioral and inflammatory improvements as preliminary and plans larger controlled trials. The Chinese study, with placebo control and double blinding, showed a statistically significant difference on its primary endpoint, which is a major step forward. The Vineland-3 adaptive behavior composite did not differ clearly between groups and follow-up was 13 weeks, so the team named longer multicenter trials as the next step.
Both studies focus on inflammation. One confirmed a decrease in inflammatory substances in cerebrospinal fluid, and the other selected children with high blood inflammation from the start. Criteria that identify which children are most likely to respond to cell therapy are likely to become central to future research.
How is stem cell therapy for autism handled in Japan?
In Japan, treatments and research using stem cells are governed by the Act on the Safety of Regenerative Medicine. Medical institutions must submit their plans to the Ministry of Health, Labour and Welfare after review by a certified committee, and submitted plans can be viewed in a public system. The framework is covered in our Japan regenerative medicine timeline, and Japanese pediatric research with baby-tooth stem cells is covered in the cerebral palsy SHED article.
Frequently asked questions
Which cells are used in stem cell therapy for autism?
These two studies used mesenchymal stromal cells from umbilical cord tissue (UC-MSCs) and mononuclear cells from cord blood (UCB-MNCs). Studies using bone marrow stem cells, stem cell conditioned medium and exosomes are also registered and running overseas.
How does intrathecal delivery differ from intravenous delivery?
Intrathecal delivery places cells directly into the cerebrospinal fluid space through the lower back, aiming to bring them closer to the brain. Intravenous delivery uses an arm vein and is less demanding as a procedure. The Iranian study used intrathecal delivery and the Chinese study used intravenous delivery.
Which children can take part?
Each study sets its own criteria for age, symptom severity and blood inflammation levels; the Chinese trial, for example, enrolled only children with immune dysregulation. Whether a given child is suitable is decided by the treating physicians who examine the child.
Conclusion
The two studies published in summer 2026 show that autism stem cell research has moved beyond safety checks to controlled trials reporting improvements in social function. In the phase I intrathecal umbilical cord MSC study, the CARS score improved in all five children, and in the randomized double-blind trial the cord blood group improved more on SRS-2 than the placebo group. These reported effects come from small studies, and trials with more children are continuing. Suitability and risks of treatment are judged by the treating physicians.
Autism, Developmental Disorders & Cerebral Palsy →
References
- Khodadoust E, Zarafshan H, Nouri M, Majmaa A, Khaleghi A, Zamani F, et al. Three repeated intrathecal injections of allogenic umbilical cord-derived mesenchymal stromal cells in autism spectrum disorder: a Phase I clinical trial. Stem Cell Res Ther. 2026 (published online 2026-07-30). doi:10.1186/s13287-026-05122-1 https://link.springer.com/article/10.1186/s13287-026-05122-1
- Zhang Z, Wang G, Han F, Zhou H, Liang Y, Zhang L, 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;17:301 (published 2026-06-19). doi:10.1186/s13287-026-05091-5 https://link.springer.com/article/10.1186/s13287-026-05091-5
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