Intrathecal Administration of Expanded Wharton's Jelly Mesenchymal Stem Cells in Chronic Traumatic Spinal Cord Injury

Inclusion Criteria: 1. Single spinal cord injury lesion caused by trauma 2. Affected cord segments between T2 and T11, confirmed by magnetic resonance 3. Complete paraplegia (ASIA A) 4. Chronic disease state (between 12 months and 5 years after the injury) 5. Patients from 18 to 65 years of age, both sexes 6. Life expectancy \> 2 years 7. Confidence that the patient will attend the follow-up visits. 8. Given informed consent in writing 9. Patient is able to understand the study and its procedures Exclusion Criteria: 1. Mechanic ventilation 2. Lesion affecting multiple levels 3. Lesion length superior to 3 spinal cord segments, assessed by magnetic resonance 4. Penetrating trauma affecting the spinal cord 5. Positive serology to HIV, HBV, HCV and or syphilis 6. Pregnant woman or without proper anticonceptive measures according to the investigator, or breath feeding 7. Use of metal implants that complicates the MRI interpretation 8. Planned spinal surgery within subsequent 24 month after entering the trial 9. Intrathecal medication or immunosuppressive drugs the previous 60 days. 10. Neurodegenerative diseases 11. Significant abnormal laboratory tests that contraindicates patient's participation in the study. 12. Neoplasia within the previous 5 years, or without complete remission 13. Patient with difficulty for communicating 14. Participation in another clinical trial or treated with an investigational medicinal product the previous 60 days 15. Contraindication for lumbar punction 16. Other pathologic conditions or circumstances that could complicate the participation of the patient in the study according to medical criteria 17. The patient does not accept to be followed-up for a period that could exceed the clinical trial length