Hyperbaric oxygen therapy mobilized circulating stem cells and improved delayed encephalopathy after acute carbon monoxide poisoning with up-regulation of brain-derived neurotrophic factor.

Background Delayed encephalopathy (DE) is the most severe complication after acute carbon monoxide (CO) poisoning, which seriously affects the outcome of patients and leads to a high disability rate. Prior studies have shown that hyperbaric oxygen (HBO) therapy is therapeutic for DE due to reducing immune-mediated neuropathology and thus improving cognitive performance. Methods In our present perspective study, five DE patients were treated regularly with HBO therapy. The mini-mental state examination (MMSE) and Barthel index (BI) were intermittently collected during their hospitalization for mental and physical status evaluation, the peripheral bloods were serially sampled to determine the concentration changes of circulating stem cells, as well as corresponding BDNF and neural markers. Results MMSE and BI showed series of improvements after multiple HBO therapies. The CD34/CD90 and CD34/CD133 dual positive cells, which were categorized as circulating stem cells, were observed an overall up-regulation since the beginning of the DE onset upon the application of HBO therapy. Characteristic neurotrophin BDNF, neural markers such as nestin and synaptophysin (SYP) were also up-regulated after exposure of HBO. Conclusion The application of HBO therapy is of significance in improving the cognition of DE patients, along with mobilized circulating stem cells. We primarily infer that the CD34/CD90 and CD34/CD133 cells were mobilized by HBO exposure and have played a positive role in cognition improvement on DE patients by up-regulation of BDNF, nestin and SYP. The altering amount of circulating stem cells mobilized in peripheral blood could be a potential marker on predicting the outcome of DE.