Injury-preconditioning secretome of umbilical cord mesenchymal stem cells amplified the neurogenesis and cognitive recovery after severe traumatic brain injury in rats.

Traumatic brain injury (TBI) is a dominant cause of death and permanent disability worldwide. Although TBI could significantly increase the proliferation of adult neural stem cells in the hippocampus, the survival and maturation of newborn cells is markedly low. Increasing evidence suggests that the secretome derived from mesenchymal stem cells (MSCs) would be an ideal alternative to MSC transplantation. The successive and microenvironmentally responsive secretion in MSCs may be critical for the functional benefits provided by transplanted MSCs after TBI. Therefore, it is reasonable to hypothesize that the signaling molecules secreted in response to local tissue damage can further facilitate the therapeutic effect of the MSC secretome. To simulate the complex microenvironment in the injured brain well, we used traumatically injured brain tissue extracts to pretreat umbilical cord mesenchymal stem cells (UCMSCs) in vitro and stereotaxically injected the secretome from traumatic injury-preconditioned UCMSCs into the dentate gyrus of the hippocampus in a rat severe TBI model. The results revealed that compared with the normal secretome, the traumatic injury-preconditioned secretome could significantly further promote the differentiation, migration, and maturation of newborn cells in the dentate gyrus and ultimately improve cognitive function after TBI. Cytokine antibody array suggested that the increased benefits of secretome administration were attributable to the newly produced proteins and up-regulated molecules from the MSC secretome preconditioned by a traumatically injured microenvironment. Our study utilized the traumatic injury-preconditioned secretome to amplify neurogenesis and improve cognitive recovery, suggesting this method may be a novel and safer candidate for nerve repair. Cover Image for this issue: doi: 10.1111/jnc.14741.

Diffusion tensor imaging predicting neurological repair of spinal cord injury with transplanting collagen/chitosan scaffold binding bFGF.

Prognosis and treatment evaluation of spinal cord injury (SCI) are still in the long-term research stage. Prognostic factors for SCI treatment need effective biomarker to assess therapeutic effect. Quantitative diffusion tensor imaging (DTI) may become a potential indicators for assessing SCI repair. However, its correlation with the results of locomotor function recovery and tissue repair has not been carefully studied. The aim of this study was to use quantitative DTI to predict neurological repair of SCI with transplanting collagen/chitosan scaffold binding basic fibroblast growth factor (bFGF). To achieve our research goals, T10 complete transection SCI model was established. Then collagen/chitosan mixture adsorbed with bFGF (CCS/bFGF) were implanted into rats with SCI. At 8 weeks after modeling, implanting CCS/bFGF demonstrated more significant improvements in locomotor function according to Basso-Beattie-Bresnahan (BBB) score, inclined-grid climbing test, and electrophysiological examinations. DTI was carried out to evaluate the repair of axons by diffusion tensor tractgraphy (DTT), fractional anisotropy (FA) and apparent diffusion coefficient (ADC), a numerical measure of relative white matter from the rostral to the caudal. Parallel to locomotor function recovery, the CCS/bFGF group could significantly promote the regeneration of nerve fibers tracts according to DTT, magnetic resonance imaging (MRI), Bielschowsky's silver staining and immunofluorescence staining. Positive correlations between imaging and locomotor function or histology were found at all locations from the rostral to the caudal (P < 0.0001). These results demonstrated that DTI might be used as an effective predictor for evaluating neurological repair after SCI in experimental trails and clinical cases.

Intravenously Infusing the Secretome of Adipose-Derived Mesenchymal Stem Cells Ameliorates Neuroinflammation and Neurological Functioning After Traumatic Brain Injury.

The secretome of mesenchymal stem cell (MSC) offers a series of immunoregulatory properties and is regarded as an effective method of mitigating secondary neuroinflammation induced by traumatic brain injury (TBI). The secretome of adipose-derived MSCs (ASC-ST) was collected under hypoxia conditions. Proteomics data were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and concentrations of major components were tested. After the TBI caused by an electric cortical contusion impactor, rats were injected ASC-ST through caudal veins for 7 days. The neurological functional prognosis of TBI rats was significantly improved, and the vasogenic edema of brain tissues that was measured 14 days after TBI was relieved by ASC-ST, corresponding to brain water content levels. ASC-ST ameliorated TBI-induced neuroinflammatory environments that caused the edema, the apoptosis of the neural cells, and the nerve fiber damage by increasing the number of M2 phenotypes present while reducing the number of M1 phenotype microglia present. Furthermore, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) levels were reduced, whereas transforming growth factor-beta (TGF-ß) and tumor necrosis factor-stimulated gene 6 protein (TSG-6) levels were increased after secretome treatment. Altogether, ASC-ST is capable of improving neural functioning by modulating TBI-induced neuroinflammation and its related secondary insults. ASC-ST may be one of the most promising candidates for regulating the secondary inflammatory reactions of central nervous systems for clinical use.

[The effects of optical genetic techniques on new neurons through the Wnt/ß-Catenin pathway].

OBJECTIVE: To investigate the effects of optical genetic techniques on new neurons through the Wnt/ß-Catenin pathway. METHODS: Neural stem cells (ESCs)were extracted from the cerebral cortex of fetal rat and transfected by lentivirus carrying DCX-ChR2-EGFP gene and the expression of DCX of newborn neurons differentiated from neural stem cells were observed. All cells were divided into 3 groups(n=9): control group, NSCs+EGFP and NSCs+ChR2 groups. The control group was normal cultured NSCs (NSCs group); the neural stem cells in NSCs+EGFP group were transfected with lentivirus carrying EGFP gene. The neural stem cells in NSCs+ChR2 group were infected with lentivirus carrying DCX-ChR2-EGFP gene. After 48 hours of lentivirus infection, 470 nm blue laser irradiation was performed for 3 consecutive days. NeuN+ positive cell density(the maturation of neural stem cells)and the ratio of NeuN+/Hoechst in each group were observed. Western blot was used to detect the expression levels of MAP2, NeuN, Neurog2, NeuroD1 and GluR2. Western blot was used to detect the expressions of ß-catenin and TCF4 associated with Wnt/ß-catenin signaling channel. Verapamil (100 µmol/L, L-type calcium channel blockers) and Dkk1 (50 µg/ml, ß-catenin inhibitor) were used to treat stem cells of the NSCs+ChR2 group and then the expressions of MAP2, NeuN, Neurog2, NeuroD1 and GluR were detected by Western blot. RESULTS: After 3 days of 470 nm blue laser irradiation, NeuN+ positive cell density(the maturation of neural stem cells)and the ratio of NeuN+/Hoechst, the expression levels of the protein MAP2, NeuN, Neurog2, NeuroD1, GluR and the protein ß-catenin and TCF4 associated with Wnt/ß-catenin signaling channel detected by Western blot were significantly increased in the group of NSCs+ChR2, compared with NSCs and NSCs+EGFP groups. The expressions of MAP2, NeuN, Neurog2, NeuroD1 and GluR were remarkably decreased after treated by verapamil and Dkk1 in the group of NSCs+ChR2. It was proved that the opening of ChR2 channel producing cationic influx promoted the maturation of neural stem cells and induced by the Wnt/ß-catenin signaling pathway. CONCLUSION: Optical genetic promoted the maturation of newborn neurons through the Wnt/ß-catenin signaling pathway.