Effect of hyperbaric oxygen on the protection of nerve system and the expression of mesenchymal stem cells homing factor in rats with traumatic brain injury

Abstract

Objective To observe the effects of hyperbaric oxygen (HBO) on the expressions of stromal derived factor-1(SDF-1)and CXC chemokine receptor 4(CXCR4)in rats with traumatic brain injury and also to discuss potential mechanism of HBO in the protection of the nerve system of the rats with TBI. Methods The experimental models of traumatic brain injury were developed by modified Feeney free-falling method. Seventy-two SD male rats were randomly divided into 3 groups: the sham surgery group, the model group and the HBO group, each consisting of 24 rats. Then, in accordance with HBO intervention time, the HBO group was subdivided into the 3-day and 10-day subgroups. The rats in the HBO group received HBO therapy 24 hours after development of the model, one session a day. Recovery of the nerve system, 24 hours after development of the model, 3 and 10 days after therapy, was assessed by using Neurological Severity Scores (NSS), and neurological function recovery was compared between the groups. At the same time, samples of damaged brain tissues were taken for the detection of expression levels of SDF-1 and CXCR4 by using Western blotting. Results (1)Neurological function deficiency was not noted in the sham surgery group. There were no significant differences in neurological function deficiency scores detected 24 hours after the development of the model, when comparisons were made between the model group and the HBO group(P>0.05). Three and 10 days after therapy, neural function recovered gradually, with the neural function deficiency scores of the HBO group being(8.7±0.4)and(4.7±0.6)respectively, which were obviously lower than those of the model group(10.5±0.6 and 6.4±0.6 respectively)(P 0.05). Three days after therapy, the expression levels of SDF-1 and CXCR4 for the model group were all significantly increased, as compared with those of the sham surgery group(P>0.05). Ten days after therapy, the expression level of SDF-1 for the model group was decreased, which tended to be the identical level of the sham surgery group(P>0.05). Though the expression level of CXCR4 was also decreased, it was obviously higher than that of the sham surgery group(P>0.01). Three and 10 days after therapy, the expression levels of SDF-1 and CXCR4 for the HBO group were significantly increased, as compared with those of the model group(P>0.01). Conclusions HBO therapy could accelerate neurological function recovery of the rats with TBI and promote homing of endogenous mesenchymal stem cells to the injured brain tissues by up-regulating SDF-1/CXCR4 axis. Key words: Hyperbaric oxygen; Traumatic brain injury; Neurological function scores; Stromal derived factor-1; SDF-1; CXC chemokine receptor 4; Homing; Rat