We previously demonstrated pre-clinical efficacy of Human Central Nervous System Stem Cells (HuCNS-SC) in multiple rodent models of thoracic spinal cord injury (SCI). HuCNS-SC transplanted at 9, 30, and 60 days post-injury (dpi) engraft, survive, migrate, and exhibit predominant differentiation into oligodendrocytes and neurons. Critically, transplanted cells promoted recovery of locomotor function and showed no evidence of allodynia at each of these transplantation times. These data contributed to a Phase I/II SwissMedic trial targeting chronically injured individuals suffering from thoracic SCIs; the first patient received HuCNS-SC in September 2011 at the University of Zurich. Critically, 52% of clinical cases of SCIs occur at the cervical level. Targeting the chronic SCI population yields a much larger subject cohort and advantages for clinical safety and efficacy assessment (e.g. spontaneous recovery is a significant confound acutely). Discrimination of a therapy induced improvement for SCI is dependent, in part, on the spontaneous recovery rate. Spontaneous recovery is highest in acute thoracic subjects, and lowest in chronic cervical subjects. An acute thoracic SCI trial has been estimated to require as many as 225-250 ASIA A subjects and 1,100 ASIA B subjects to detect a moderate effect. In contrast, a chronic cervical SCI trial may require as few as 25 ASIA A subjects, and 50 ASIA B subjects. Further, a small gain of function in the cervical region affords a proportionally greater change in quality of life compared to a similar gain at the thoracic level. We have generated a unilateral cervical SCI model using immunodeficient Rag2g/c mice to optimize xeno-engraftment, and demonstrated that 9 dpi transplantation of HuCNS-SC promotes recovery of locomotor function with no adverse effects, establishing pre-clinical efficacy of HuCNS-SC. The UCI-StemCells Inc. team already has considerable experience in clinical translation using HuCNS-SC and has sought preliminary feedback from the FDA for a cervical SCI indication in the form of a pre-preIND consultation. This proposal is based on our FDA interactions and seeks to expand our current cervical SCI efficacy data to evaluate the intended clinical cell lot of HuCNS-SC for both efficacy and long-term safety/toxicology addressing the following Specific Aims: Aim 1: Establish efficacy and test cell delivery site for the HuCNS-SC CCL in a 9 dpi transplantation unilateral cervical SCI mouse model. Aim 2: Establish efficacy and test cell delivery site for the HuCNS-SC CCL in a 60 dpi transplantation unilateral cervical SCI mouse model. Aim 3: Assess the safety of the HuCNS-SC CCL in a rodent model of autonomic dysreflexia. Aim 4: Establish long-term safety/toxicology of the HuCNS-SC CCL in the established unilateral cervical SCI mouse model. Aim 5: If dictated by the FDA in a pre-IND meeting in Year 2, establish efficacy and safety/toxicology for the HuCNS-SC CCL in a second species (ATN rat), using a hybrid study design and cervical SCI rats receiving supplemental immunosuppression with anti-sialoGM1 antibody treatment. The aims of this project will enable IND application for the use of this HuCNS-SC clinical cell lot for cervical SCI as a therapeutic target.