Open Label Phase I hCT-MSC in Toddlers With Autism Spectrum Disorder

Inclusion Criteria: 1. Age ≥ 18 months to ≤ 48 months (48 months, 29 days) at the time of consent 2. Confirmed clinical DSM-5 diagnosis of Autism Spectrum Disorder using the DSM-5 Checklist as informed by the Autism Diagnostic Observation Schedule - 2. 3. Fragile X testing performed and negative; CMA and/or whole exome sequencing performed and results not linked to autism diagnosis 4. Stable on current psychoactive medication regimen (dose and dosing schedule) for at least 2 months prior to infusion of study product 5. Normal absolute lymphocyte count (≥1500/uL) 6. Participant and parent/guardian are English speaking 7. Able to travel to Duke University for two multi-day visits (baseline and six months) and parent/guardian is able to participate in interim surveys and interviews 8. Parental consent Exclusion Criteria: 1. General: 1. Review of medical records indicates ASD diagnosis not likely 2. Screening data suggests that participant would not be able to comply with the requirements of the study procedures as assessed by the study team 3. Family is unwilling or unable to commit to participation in all study-related assessments, including protocol follow up 4. Sibling is enrolled in this (Duke hCT-MSC) study 2. Genetic: 1. Records indicate that child has a known genetic syndrome such as (but not limited to) Fragile X syndrome, neurofibromatosis, Rett syndrome, tuberous sclerosis, PTEN mutation, cystic fibrosis, muscular dystrophy or a genetic mutation known to be associated with ASD 2. Known pathogenic mutation or copy number variation (CNV) associated with ASD (e.g., 16p11.2, 15q13.2, 2q13.3) 3. Infectious: 1. Known active CNS infection 2. Evidence of uncontrolled infection based on records or clinical assessment 3. Known HIV positivity 4. Medical: 1. Known metabolic disorder 2. Known mitochondrial dysfunction 3. History of unstable epilepsy or uncontrolled seizure disorder, infantile spasms, Lennox Gastaut syndrome, Dravet syndrome, or other similar chronic seizure disorder 4. Active malignancy or prior malignancy that was treated with chemotherapy 5. History of a primary immunodeficiency disorder 6. History of autoimmune cytopenias (i.e., ITP, AIHA) 7. Coexisting medical condition that would place the child at increased risk for complications of study procedures 8. Concurrent genetic or acquired disease or comorbidity(ies) that could require a future stem cell transplant 9. Significant sensory (e.g., blindness, deafness, uncorrected hearing impairment) or motor (e.g., cerebral palsy) impairment 10. Impaired renal or liver function as determined by serum creatinine \>1.5mg/dL or total bilirubin \>1.3mg/dL, except in patients with known Gilbert's disease 11. Significant hematologic abnormalities defined as: Hemoglobin \<10.0 g/dL, WBC \< 3,000 cells/mL, ALC \<1000/uL, Platelets \<150 x 10e9/uL 12. Known clinically relevant physical dysmorphology associated with neurodevelopmental conditions. 5. Current/Prior Therapy: a. History of prior cell therapy b. Current or prior use of IVIG or other anti-inflammatory medications with the exception of NSAIDs c. Current or prior immunosuppressive therapy i. No systemic steroid therapy that has lasted \>2 weeks, and no systemic steroids within 3 months prior to enrollment. Topical and inhaled steroids are permitted.