Safety and Efficacy of Angiotensin (1-7) in Persons With Moderate to Severe Traumatic Brain Injury

Inclusion Criteria: * Participant or representative willing to provide informed consent. * Age 18 years or older at time of enrollment. * Traumatically induced head injury resulting from insult to head from an external force. * Clinical diagnosis of acute intracranial lesion based on neuroradiologist report. CT scan and report must be available. * Moderate or severe traumatic brain injury (TBI) defined as Glasgow Coma Scale (GCS) score on trauma presentation of 12 or less. In general: Moderate TBI will be defined as loss of consciousness between 30 minutes and 24 hours and GCS between 9 and 12. Severe TBI will be defined as loss of consciousness \> 24 hours and GCS ≤ 9. * Enrollment within 48 hours of TBI. Exclusion Criteria: * Time of injury cannot be determined. * Neurosurgery within the last 30 days. * History of neurodegenerative disease or disorder including dementia, Parkinson's disease, multiple sclerosis, seizure disorder, or brain tumors that would impact cognitive testing. * Contraindication to having an MRI. * Pregnant or lactating female. * Female of childbearing potential or sexually active male who is not willing to use an acceptable method of birth control for the treatment period and 7 days after the last dose of the study drug. * Participation in another clinical study involving investigational product within 30 days prior to study enrollment. * If in the opinion of the investigator, candidate is unsuitable for participation in the study.