Prospective Clinical Study on Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes for the Treatment of Childhood Autism

Inclusion Criteria: * Diagnosis meets the ICD-11 ASD criteria or DSM-5 ASD clinical diagnostic standards. * No significant improvement in core symptoms was observed after ≥3 months of standardized behavioral intervention. * Score ≥30 on the CARS2, indicating mild-to-moderate or more severe autism. * Aged 3 (inclusive) to 7 (inclusive) years, regardless of gender * Voluntary participation in this clinical study, with written informed consent provided by the patient's legal guardian, and willingness to undergo examinations, treatment, and cooperate with follow-up visits. * In the investigator's judgment, the patient is capable of understanding and complying with study requirements. Exclusion Criteria: * History of severe allergic reactions. * Any severe mental disorder or other types of autism spectrum disorders. * History of epileptic seizures within the past six months. * Autism secondary to epilepsy, cerebrovascular disease, or traumatic brain injury. * Disease severity rated as normal, borderline mental disorder, or mild mental disorder on the Clinical Global Impression scale. * Moderate or severe extrapyramidal symptoms or tardive dyskinesia. * Severe self-injurious behavior. * Active systemic or severe localized infections, including human immunodeficiency virus, syphilis, and hepatitis. * Autoimmune diseases. * Major organ impairment. * Severe pulmonary or hematological diseases, malignancies, or immunodeficiency. * Concurrent treatments that may interfere with the safety and efficacy evaluation of stem cell therapy. * Participation in other clinical trials within the past three months. * Other clinical conditions deemed by investigators as unsuitable for study inclusion.