| Objective:The previous research by our group has confirmed that circulating endothelial progenitor cells (EPCs) can improve the prognosis of traumatic brain injury (TBI). This study aims to identify correlations between circulating EPCs levels and outcomes in diffuse axonal injury (DAI) patients, then to explore the effects of progesterone on EPCs levels, lesion revascularization and neurological function recovery in rats with DAI.Methods:1) EPCs levels in15patients with DAI and26cases of traumatic intracerebral hemorrhage (TIH) brain injury were counted by FACS (Fluorescence Activating Cell Sorter) at Id,4d,7d,14d, and21d post-injury, and the patients prognosis were evaluated by Glasgow Outcome Scale (GOS) at6months after discharge.2) Male Wistar rats were randomly divided into4groups:sham operation group (SHAM), DAI alone group (DAI), DAI placebo group (placebo) and DAI progesterone treatment group (PROG). DAI rat models were established as Marmarou’s descripition. Rats in PROG group recieved16mg/kg progesterone intraperitoneally within1h post-insult, then subcutaneously after6h and24h and a once-daily dose for up to5d. Same amount of dimethyl sulfoxide (DMSO) were administered via same route and at same time points to placebo group. The circulating EPCs levels were enumerated by FACS after3h,6h,24h,3d,7d, and14d. Lesion angiogenesis were identified by immunofluorescence stained for CD34. At1d,7d,14d and21d after injury, changes of motor functions were evaluated by the Modified Neurological Severity Score (mNSS). From the14th day after injury, the Morris water maze (MWM) experiment was performed to assess the spatial learning and memory functions of the four groups. At day20after the-operation, the rats were subjected to long-term potentiation (LTP) recording in hippocampus to measure the percentage of slope and baseline of excitatory post-synaptic potential (EPSP).Results:1) Circulating EPCs levels in DAI patients showed an initial up-regulation and subsequent reduction. However, these dynamic changes were significantly more pronounced in TIH patients than DAI paitents (P<0.05) at7d,14d and21d post-injury. Regression analysis, linear correlation analysis and receiver operating characteristic curve (ROC) failed to establish significant correlation between the EPCs level and outcomes, while the placebo group and the DAI patients had comparable changes in EPCs levels.2) The EPCs level in progesterone-treated rats increased significantly compared to placebo rats (P<0.05), peaked after7days of treatmentand then gradually decreased, but remained higher than the placebo group through14d post-injury. Rats treated with progesterone for7d after injury had significantly increased numbers of CD34+cells in lesion and ipslateral hippocampus (P<0.05). The mNSS indicated significantly improved behavioral function in the progesterone-treated rats at7d post-injury, compared with the placebo group and DAI alone group (P<0.05). Progesterone-treated rats showed significantly less escape latencies, higher target quadrant time staying percentage and the number of times the original platform position was crossed after14d (P<0.05), and higher LTP at20d post-injury, than the placebo group and DAI alone group (P<0.05).Conclusion:The circulating EPCs levels in the DAI patients did not experience signifincantly fluctuations after injury or correlated with paitents outcome. And same changes were found in DAI rat model. Progesterone administration significantly enhanced mobilization of EPCs, promoted angiogenesis in lesion and hippocampus and thus improved behavioral function and learning and memory abilities. Therapies targeting to increase EPCs levels may provide a new efficient strategy for promoting vascular repair and nerve regeneration in DAI patients. |
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