Safety and Efficacy of Autologous Human Schwann Cell (ahSC) Augmentation in Severe Peripheral Nerve Injury (PNI)

Inclusion Criteria: 1. Persons with severe sciatic nerve injury, brachial plexus injury, and/or major nerve injury at the upper or lower extremity within previous year; 2. Between the ages of 18 and 65 at last birthday Exclusion Criteria: 1. Persons unable to safely undergo an MRI; 2. Persons with pre-existing conditions that would preclude satisfactory sural nerve harvest; 3. Persons with severe peripheral nerve injury gap length \> 10 cm; 4. Persons with history of radiation or local cancer in area of nerve injury, including primary tumors of the nerve; 5. Pregnant women or a positive pregnancy test in those women with reproductive potential prior to enrollment; 6. Presence of disease that might interfere with participant safety, compliance, or evaluation of the condition under study; 7. History of active substance abuse; 8. Persons allergic to gentamicin; 9. Persons who test positive for HIV or Hepatitis B or C virus. 10. Persons unable to provide consent independently due to cognitive impairment