Prognostic relevance of circulating endothelial progenitor cells for severe traumatic brain injury

Objective: Traumatic brain injury (TBI) promotes the recruitment of endothelial progenitor cells (EPCs) into the injured tissue where EPCs play an important role in repairing injured vasculature. However, the repair mechanism and prognostic significance of EPCs after TBI remain poorly understood. Methods: Blood samples were collected from 21 patients with severe TBI and 20 healthy subjects. EPCs were quantified by flow cytometry and serum VEGF and MMP-9 level measured by ELISA on days 1, 4, 7, 14 and 21 after TBI. Results: EPCs in the patients decreased originally, then increased to the peak level at 7 days and was significantly correlated with GOS scores 6 months after TBI. VEGF and MMP-9 were significantly increased during the follow-up period after TBI. EPCs was also positively correlated with GCS score 1 day after TBI and with MMP-9 and VEGF 7 days and 14 days after TBI. Conclusion: The data demonstrate that TBI led to an increase of EPCs, VEGF and MMP-9, suggesting that increased VEGF and MMP-9 may mediate the recruitment of bone marrow-derived EPCs into the circulation. The association of EPCs with nerve functional recovery in patients provides evidence that EPCs may be a potential biomarker to monitor TBI angiogenesis and prognosis.