Co-grafting of neural stem cells with olfactory en sheathing cells promotes neuronal restoration in traumatic brain injury with an anti-inflammatory mechanism.

BACKGROUND: We sought to investigate the effects of co-grafting neural stem cells (NSCs) with olfactory ensheathing cells (OECs) on neurological behavior in rats subjected to traumatic brain injury (TBI) and explore underlying molecular mechanisms. METHODS: TBI was established by percussion device made through a weight drop (50 g) from a 30 cm height. Cultured NSCs and OECs isolated from rats were labeled by Hoechst 33342 (blue) and chloromethyl-benzamidodialkyl carbocyanine (CM-Dil) (red), respectively. Then, NSCs and/or OECs, separately or combined, were transplanted into the area surrounding the injury site. Fourteen days after transplantation, neurological severity score (NSS) were recorded. The brain tissue was harvested and processed for immunocytochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Significant neurological function improvement was observed in the three transplant groups, compared to the TBI group, and co-transplantation gave rise to the best improvement. Morphological evaluation showed that the number of neurons in cortex from combination implantation was more than for other groups (P <0.05); conversely, the number of apoptotic cells showed a significant decrease by TUNEL staining. Transplanted NSCs and OECs could survive and migrate in the brain, and the number of neurons differentiating from NSCs in the co-transplantation group was significantly greater than in the NSCs group. At the molecular level, the expressions of IL-6 and BAD in the co-graft group were found to be down regulated significantly, when compared to either the NSC or OEC alone groups. CONCLUSION: The present study demonstrates for the first time the optimal effects of co-grafting NSCs and OECs as a new strategy for the treatment of TBI via an anti-inflammation mechanism.

Transplantation of olfactory ensheathing cells promotes the recovery of neurological functions in rats with traumatic brain injury associated with downregulation of Bad.

BACKGROUND AIMS: The neuroprotective effects of olfactory ensheathing cells (OECs) after transplantation have largely been known in the injured nervous system. However, the underlying mechanisms still must be further elucidated. We explored the effects of OEC transplantation on the recovery of neurophysiologic function and the related anti-apoptosis mechanism in acute traumatic brain injury. METHODS: The OECs from neonatal Sprague-Dawley rats were isolated, identified and labeled and then were immediately transplanted into the regions surrounding the injured brain site that is resulted from free-weight drop injury. RESULTS: Nerve growth factor and it's recepor, p75 was expressed in cultured OECs. Transplanted OECs survived, migrated around the injury site and significantly improved the neurological severe scores compared with the control group (P < 0.05). OEC transplantation significantly increased the number of GAP-43-immunopositive fibers and synaptophysin-positive vesicles (P < 0.05) but significantly decreased the number of apoptotic cells (P < 0.05). On the molecular level, the expression of Bad in the OEC transplantation group was significantly downregulated (P < 0.05). CONCLUSIONS: OEC transplantation could effectively improve neurological deficits in TBI rats; the underlying mechanism may be related with their effects on neuroprotection and regeneration induction, which is associated with the downregulation of the apoptotic molecule Bad.

OECs transplantation results in neuropathic pain associated with BDNF regulating ERK activity in rats following cord hemisection.

BACKGROUND: The olfactory ensheathing cells (OECs) derived from olfactory bulb (OB) may improve motor function after transplantation in injured spinal cord. However, the effects of OEC transplantation on sensory function have not been reported yet. The purpose of this study is to investigate whether OEC transplantation could affect the sensory function and to analyze the underlying mechanism. RESULTS: OEC transplantation into the hemisected spinal cords can result in hyperalgesia, indicated by radiant and mechanical stimuli towards the plantar surface in rats. This could be associated with upregulation of Brain Derived Neurotrophic Factor (BDNF), indicated by RT-PCR. Immunofluorecent staining showed that BDNF was mainly located in the neurons of the laminas I and II of the dorsal horn. Moreover, a notable upregulation on the level of p-ERK (phosphorylation of extracellular signal-regulated kinase), the downstream molecule of BDNF, was detected by using Western Blot. These findings indicate that the increased BDNF level associated with the p-ERK was possibly involved in neuropathic pain in hemisected spinal cord subjected to OEC transplantation. CONCLUSIONS: The transplantation of OECs may induce the noticeable pain hypersensitivity in rats after hemisected spinal cord injury, and the possible mechanism may be associated with the phosphorylation of ERK and the activated BDNF overexpression.

Characteristics of olfactory ensheathing cells and microarray analysis in Tupaia belangeri (Wagner, 1841).

Tree shrews are most closely related to the primates and so possess a number of advantages in experimental studies; they have been used as an animal model in bacterial and virus infection, cancer, endocrine system disease, and certain nervous system diseases. Their olfactory ensheathing cells (OECs) are able to release several cytokines to promote neuronal survival, regeneration and remyelination. The present study used western blot analysis to identify antibody specificity in protein extracts from whole tree shrew brains to identify the specificity of p75 nerve growth factor receptor (NGFR) derived from rabbits (75 kDa). OECs were cultured and isolated, then stained and identified using the antibodies for p75NGFR. To investigate the capacity of OECs to express cytokines and growth factors, microarray technology was used, and the analysis revealed that OECs were able to express 9,821 genes. Of these genes, 44 genes were from the neurotrophic factor family, which may indicate their potential in transplantation in vivo. The present study considered the function of OECs as revealed by other studies, and may contribute to future research.

Propofol administration improves neurological function associated with inhibition of pro-inflammatory cytokines in adult rats after traumatic brain injury.

BACKGROUND: Neurological deficits following traumatic brain injury (TBI) result in dramatic impacts on the survivors, but the effect of propofol and associated mechanism are waiting to be determined. METHODS: Adult male Sprague-Dawley rats were randomly assigned into Sham, TBI, TBI+Intralipid and TBI+Propofol group. Modified Feeney method was adopted to generate TBI model from free hammer fall injury, and animals in TBI+Propofol group were immediately treated with propofol administration for 2hours after TBI, rats after TBI without propofol treatment was used as injury control, intralipid as vehicle in propofol was injected in TBI+intralipid group. Then, neurological severity scores (NSS) were evaluated at 1, 3, 7 and 14days. Moreover, the expressions of IL-1ß, IL-6 and TNF-α mRNA and protein were examined using quantitative real time-polymerase chain reaction and Western blot, immunohistochemical staining was used to localize cytokines. RESULTS: The NSS increased greatly in the rats induced by TBI, while propofol could effectively decreased NSS, confirming the neuroprotective effect of propofol. Moreover, the mRNA expressions of IL-1ß, IL-6 and TNF-α, at 1, 3, 7days after operation (dpo), were significantly augmented in the injured cortex, compared with sham one. But there was no difference between TBI and TBI+Intralipid group, but markedly decreased after propofol treatment. Additionally, the protein level of IL-1ß, IL-6 and TNF-α in four groups determined by Western blot and immunohistochemistry showed the similar change with mRNA expression. CONCLUSION: Propofol treatment could elicit a robust neuroprotective response, resulting in significant neurological function improvement for TBI rats, which was independent with intralipid. The underlying molecular mechanism may be partially associated with an inhibition of pro-inflammatory cytokines.

MicroRNAs: a novel promising therapeutic target for cerebral ischemia/reperfusion injury?

To determine the molecular mechanism of cerebral ischemia/reperfusion injury, we examined the microRNA (miRNA) expression profile in rat cortex after focal cerebral ischemia/reperfusion injury using miRNA microarrays and bioinformatic tools to systematically analyze Gene Ontology (GO) function classifications, as well as the signaling pathways of genes targeted by these differentially expressed miRNAs. Our results show significantly changed miRNA expression profiles in the reperfusion period after focal cerebral ischemia, with a total of 15 miRNAs up-regulated and 44 miRNAs down-regulated. Target genes of these differentially expressed miRNAs were mainly involved in metabolic and cellular processes, which were identified as hub nodes of a miRNA-GO-network. The most correlated pathways included D-glutamine and D-glutamate metabolism, the renin-angiotensin system, peroxisomes, the PPAR signaling pathway, SNARE interactions in vesicular transport, and the calcium signaling pathway. Our study suggests that miRNAs play an important role in the pathological process of cerebral ischemia/reperfusion injury. Understanding miRNA expression and function may shed light on the molecular mechanism of cerebral ischemia/reperfusion injury.