Developing Therapies for Traumatic Brain Injury

Traumatic brain injury (TBI) is the leading cause of death and disability in people under age 45 in industrialized countries, but there is no specific treatment available for TBI. Circulating endothelial progenitor cells (EPC) are markers of vascular injury that are mobilized after signaling with cytokines, interleukins, MMP9 and other biomarkers (BM) that may be detected in blood. However, the relation of EPC and these BM to TBI severity has not been quantified. MRI measurements of lesion volume provide an objective method for TBI severity assessment and outcome prediction. Moreover, diffusion tensor imaging (DTI) is sensitive to detect TBI-related axonal injury, and PET (positron emission tomography) is useful in functional interpretation of image findings. This cross-sectional study aims to determine whether EPC and other BM are associated with MRI, DTI and PET findings, and with functional outcomes in TBI patients.

OBJECTIVES:

The primary objective of the study is to evaluate levels of EPC and other BMs participating in EPC mobilization in TBI patients in comparison to the healthy volunteers and to the non-TBI trauma controls. The second objective is to relate EPC and BM levels to TBI severity quantified by functional and radiological evaluations (MRI, DTI and PET). The third objective is to determine, if there is a relationship between the level of EPC and other BM and functional outcomes.

POPULATION:

100 male or female participants between 18 and 70 years of age will be enrolled within 30 days of a moderate TBI (classified as Glasgow Coma Scale (GCS) of 9-12) or mild TBI (GCS 13-15). If participants had post-traumatic amnesia (PTA) it must have lasted less than 7 days and any loss of consciousness (LOC) must have lasted less than 24 hours. Fifty healthy volunteers and 50 persons with non-TBI injuries (such as broken bones, orthopedic injuries or surgery) will be enrolled.

RESEARCH DESIGN:

Before participating in this protocol, TBI and non-TBI injured participants must have received routine clinical evaluations for their injuries in hospitals, doctors offices or other medical facilities. They may be referred to the NIH Clinical Center after discharge or they may be self-referred. They must be willing to have their medical records sent to the NIH to assure that their injuries fit the protocol inclusion criteria. Healthy volunteers may be recruited from families of other participants but most will be recruited through the NIH Patient Recruitment and Public Liaison Office (PRPL).

This is an outpatient, observational study. Eligible participants will come to the NIH for two 1 1/2 day outpatient visits separated by 30 days. Persons with TBI will have the same tests at each of their two visits: a history and physical exam, electrocardiogram, research blood draws (no more than 75 ml each visit), pregnancy and HIV testing, neuropsychological testing, head magnetic resonance imaging (MRI) scan, and positron emission tomography scan (PET scan). Healthy controls and persons with non-TBI injuries will have the same tests at visit 1 as listed above. At visit 2, they will have all the same tests except they will not have brain MRIs or PETs.

IMPORTANCE:

This study will provide novel data regarding the association of levels of EPC and the blood BMs with severity of imaging-positive TBI. This study will provide a foundation for the development of interventional trials aiming to improve neovascularization in TBI patients.