This clinical trial aims to evaluate the safety and preliminary efficacy of intravenous administration of human bone marrow-derived mesenchymal stem cells (hBMMSCs) in patients with autism spectrum disorder (ASD).

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized primarily by impaired social communication, restricted interests, and repetitive, stereotyped behaviors. Currently, there are no effective therapeutic drugs, and main interventions consist of educational rehabilitation and behavioral management.The purpose of this study is to evaluate the safety and preliminary efficacy of hBMMSC intravenous treatment in patients with ASD. The clinical trial intends to involve 42 participants. The trial is expected to last approximately 2 years.

Inclusion Criteria:

• Male or female ≥6 years old
• Body weight ≥ 17 kg
• Meets the diagnostic criteria for Autism Spectrum Disorder (ASD) as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), and confirmed by the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule-2 (ADOS-2)
• Has either not received any psychotropic medication in the three months prior to enrollment or has been on a stable regimen of psychotropic medication for at least three months
• The subject and/or their legal guardian(s) agree to participate in the trial and provide signed informed consent.

Exclusion Criteria:

• Inability of the subject or their guardian to sufficiently understand instructions in Chinese
• Active infection (viral, bacterial, fungal, or mycobacterial)
• A confirmed diagnosis of Rett syndrome, childhood disintegrative disorder, fragile X syndrome, or other genetic/metabolic diseases that may impact cognitive development
• History of epileptic seizures within 6 months prior to enrollment
• History of suicide attempts/self-harm, presentation of suicidal ideation, or being judged as the risk of suicidal by the investigator
• Severe hematologic diseases or active malignancy
• Severe hepatic or renal disease
• Participation in a drug clinical trial within 3 months prior to enrollment (unless beyond the protocol-defined wash-out period) or participation in any other stem cell study within the past year
• A positive skin test result
• Any other condition which, in the opinion of the investigator, would make the subject unsuitable for participation in this study