The purpose of this study is to determine whether the plasticity of autologous intrathecal hematopoietic cells would improve the neurologic and the social skills of pediatric patients with autism spectrum disorders.

There is accumulating evidence that shows that the administration of hematopoietic cells into the brain in the patients with spectrum autism could help in the physiopathology of the illness.

It has been found that after introducing hematopoietic cells in the subarachnoid space of the spinal cord, these cells may be transported through the cerebrospinal fluid and can be delivered more efficiently to the injured area, when compared to the intravenous route.

Patients will be stimulated for 3 consecutive days with granulocyte colony stimulating factor (G-CSF) and then their bone marrow will be harvested according to their weight. Bone marrow will be processed in order to obtain CD34+ cells and minimize the amount of red blood cells. An inoculum of 5 to 10mL of stem cells will be infused intrathecally. Patients will be evaluated with two scales "CARS" and the "IDEA" also we will check the clinical history. On days 0, 30 and 180.

Inclusion Criteria: Children aged 5 to 15 years, Diagnosis of Autism Spectrum Disorder (ASD) confirmed by DSM-5 criteria, Ability to comply with study procedures, including assessments with CARS and IDEA scales, Written informed consent obtained from parents or legal guardians.

Exclusion Criteria: Presence of severe neurological disorders other than ASD, History of immunodeficiency or hematologic disorders, Active infection at the time of enrollment, Previous treatment with intrathecal stem cells, Any medical condition that, in the investigator's judgment, would make participation unsafe.