Background and Purpose—The short time window required by neuroprotective strategies for successful treatment of patients with ischemic stroke precludes treatment for most. However, clinical therapies based on neuroregeneration might extend this therapeutic time window and thus address a significant unmet need. Human umbilical tissue-derived cells have shown great potential as neuroregenerative candidates for stroke treatment. Methods—The effectiveness of intravenous administration of human umbilical tissue-derived cells was tested in a rodent middle cerebral artery stroke model in a dose escalation study (doses tested: 3×105, 1×106, 3×x106, or 1×107 cells/injection) followed by a time-of-administration study (time after stroke: Day 1, Day 7, Day 30, and Day 90 at a dose of 5×106 cells/injection). Controls were phosphate-buffered saline injections and human bone marrow-derived mesenchymal stromal cell injections. Post-treatment outcome tools included the modified neurological severity score and the adhesiv...