Growth-associated protein 43 and neural cell adhesion molecule expression following bone marrow-derived mesenchymal stem cell transplantation in a rat model of ischemic brain injury

BACKGROUND： Transplantation of bone marrow-derived mesenchymal stem cells （BMSCs） improves motor functional recovery, but the mechanisms remain unclear. OBJECTIVE： To investigate expression of growth-associated protein 43 （GAP-43） and neural cell adhesion molecule following BMSC transplantation to the lateral ventricle in rats with acute focal cerebral ischemic brain damage. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment using immunohistochemistry was performed at the laboratories of Department of Neurology, Renmin Hospital of Wuhan University and Doctoral Scientific Research Work Station of C-BONS PHARMA, Hubei Province, China, from January 2007 to December 2008. MATERIALS： Monoclonal mouse anti-rat 5-bromo-2-deoxyuridine and neural cell adhesion molecule antibodies were purchased from Sigma, USA; monoclonal mouse anti-rat GAP-43 antibody was purchased from Wuhan Boster, China. METHODS： Rat models of right middle cerebral artery occlusion were established using the thread method. At 1 day after middle cerebral artery occlusion, 20μL culture solution, containing 5×10^5 BMSCs, was transplanted to the left lateral ventricle using micro-injection. MAIN OUTCOME MEASURES： Scores of neurological impairment were measured to assess neural function. Expression of GAP-43 and neural cell adhesion molecule at the lesion areas was examined by immunohistochemistry. RESULTS： GAP-43 and neural cell adhesion molecule expression was low in brain tissues of the sham-operated group, but expression increased at the ischemic boundary （P 〈 0.05）. Transplantation of BMSCs further enhanced expression of GAP-43 and neural cell adhesion molecule （P 〈 0.05） and remarkably improved neurological impairment of ischemic rats （P 〈 0.05）. CONCLUSION： BMSC transplantation promoted neurological recovery in rats by upregulating expression of GAP-43 and neural cell adhesion molecule.

Neural differentiation of human Wharton＇s jelly-derived mesenchymal stem cells improves the recovery of neurological function after transplantation in ischemic stroke rats

Human Wharton＇s jelly-derived mesenchymal stem cells（h WJ-MSCs）have excellent proliferative ability,differentiation ability,low immunogenicity,and can be easily obtained.However,there are few studies on their application in the treatment of ischemic stroke,therefore their therapeutic effect requires further verification.In this study,h WJ-MSCs were transplanted into an ischemic stroke rat model via the tail vein 48 hours after transient middle cerebral artery occlusion.After 4 weeks,neurological functions of the rats implanted with h WJ-MSCs were significantly recovered.Furthermore,many h WJ-MSCs homed to the ischemic frontal cortex whereby they differentiated into neuron-like cells at this region.These results confirm that h WJ-MSCs transplanted into the ischemic stroke rat can differentiate into neuron-like cells to improve rat neurological function and behavior.

Repair of spinal cord injury by neural stem cells transfected with brain-derived neurotrophic factor-green fluorescent protein in rats A double effect of stem cells and growth factors?

Brain-derived neurotrophic factor（BDNF）can significantly promote nerve regeneration and repair.High expression of the BDNF-green fluorescent protein（GFP）gene persists for a long time after transfection into neural stem cells.Nevertheless,little is known about the biological characteristics of BDNF-GFP modified nerve stem cells in vivo and their ability to induce BDNF expression or repair spinal cord injury.In the present study,we transplanted BDNF-GFP transgenic neural stem cells into a hemisection model of rats.Rats with BDNF-GFP stem cells exhibited significantly increased BDNF expression and better locomotor function compared with stem cells alone.Cellular therapy with BDNF-GFP transgenic stem cells can improve outcomes better than stem cells alone and may have therapeutic potential for spinal cord injury.

Bone morphogenetic protein 4 induces cholinergic differentiation of brain-derived neural stem cells in vivo and in vitro

In vitro studies have demonstrated that many factors of bone morphogenetic proteins （BMPs） induce cholinergic differentiation of neural stem cells. However, BMP retains the potential to induce increased numbers of cholinergic neurons in central nervous system regions that are rich in cholinergic cells, which is an important determinant of BMP. Therefore, BMP-4 was added to neural stem cell culture medium or the adult rat hippocampal dentate gyrus. Results demonstrated that BMP-4 induced cholinergic differentiation of neural stem cells in vitro and increased the number of cholinergic neurons in the adult rat hippocampal dentate gyrus.

Neural stem cells over-expressing brain-derived neurotrophic factor promote neuronal survival and cytoskeletal protein expression in traumatic brain injury sites

Cytoskeletal proteins are involved in neuronal survival.Brain-derived neurotrophic factor can increase expression of cytoskeletal proteins during regeneration after axonal injury.However,the effect of neural stem cells genetically modified by brain-derived neurotrophic factor transplantation on neuronal survival in the injury site still remains unclear.To examine this,we established a rat model of traumatic brain injury by controlled cortical impact.At 72 hours after injury,2 × 10~7 cells/m L neural stem cells overexpressing brain-derived neurotrophic factor or naive neural stem cells（3 m L） were injected into the injured cortex.At 1–3 weeks after transplantation,expression of neurofilament 200,microtubule-associated protein 2,actin,calmodulin,and beta-catenin were remarkably increased in the injury sites.These findings confirm that brain-derived neurotrophic factor-transfected neural stem cells contribute to neuronal survival,growth,and differentiation in the injury sites.The underlying mechanisms may be associated with increased expression of cytoskeletal proteins and the Wnt/β-catenin signaling pathway.

Ultrastructure of neuronal-like cells differentiated from adult adipose-derived stromal cells

β-mercaptoethanol induces in vitro adult adipose-derived stromal cells （ADSCs） to differentiate into neurons. However, the ultrastructural features of the differentiated neuronal-like cells remain unknown. In the present study, inverted phase contrast microscopy was utilized to observe β-mercaptoethanol-induced differentiation of neuronal-like cells from human ADSCs, and immunocytochemistry and real-time polymerase chain reaction were employed to detect expression of a neural stem cells marker （nestin）, a neuronal marker （neuron-specific enolase）, and a glial marker （glial fibrillary acidic protein）. In addition, ultrastructure of neuronal-like cells was observed by transmission election microscopy. Results revealed highest expression rate of nestin and neuron-specific enolase at 3 and 5 hours following induced differentiation; cells in the 5-hour induction group exhibited a neuronal-specific structure, i.e., Nissl bodies. However, when induction solution was replaced by complete culture medium after 8-hour induction, the differentiated cells reverted to the fibroblast-like morphology from day 1. These results demonstrate that β-mercaptoethanol-induced ADSCs induced differentiation into neural stem cells, followed by morphology of neuronal-like cells. However, this differentiation state was not stable.

Prolonged propagation of rat neural stem cells relies on inhibiting autocrine/paracrine bone morphogenetic protein and platelet derived growth factor signals

Continuous expansion of rat neural stem cell lines has not been achieved due to proliferation arrest and spontaneous differentiation in vitro. In the current study, neural precursor cells derived from the subventricular zone of adult rats spontaneously underwent astroglial and oligodendroglial differentiation after limited propagation. This differentiation was largely induced by autocrine or paracrine bone morphogenetic protein and platelet derived growth factor signals. The results showed that, by inhibiting bone morphogenetic protein and platelet derived growth factor signals, adult rat neural precursor cells could be extensively cultured in vitro as tripotent stem cell lines. In addition to adult rat neural stem cells, we found that bone morphogenetic protein antagonists can promote the proliferation of human neural stem cells. Therefore, the present findings illustrated the role of autocrine or paracrine bone morphogenetic protein and platelet derived growth factor signaling in determining neural stem cell self-renewal and differentiation. By antagonizing both signals, the long-term propagation of rat neural stem cell lines can be achieved.

Chondrogenic Differentiation of Mouse Bone Marrow Mesenchymal Stem Cells Induced by Cartilage-derived Morphogenetic Protein-2 In Vitro

To study the cartilage differentiation of mouse mesenchymal stem cells （MSCs） induced by cartilage-derived morphogenetic proteins-2 in vitro, the MSCs were isolated from mouse bone marrow and cultured in vitro. The cells in passage 3 were induced into chondrogenic differentiation with different concentrations of recombinant human cartilage-derived morphogenetic proteins-2 （0, 10, 20, 50 and 100 ng/mL）. After 14 days of induction, morphology of cells was observed under phase-contrast microscope. Collagen Ⅱ mRNA and protein were examined with RT-PCR, Western blotting and immunocytochemistry respectively and the sulfate glycosaminoglycan was measured by Alcian blue staining. RT-PCR showed that CDMP-2 could promote expression of collagen Ⅱ mRNA in an dose-dependant manner, especially at the concentration of 50 ng/mL and 100 ng/mL. Immunocytochemistry and Western blotting revealed a similar change. Alcian blue staining exhibited deposition of typical cartilage extracellular matrix. Our results suggest that mouse bone marrow mesencymal stem cells can differentiate into chondrogenic phonotype with the induction of CDMP-2 in vitro, which provides a basis for further research on the role of CDMP-2 in chondrogenesis.

Neurogenic Differentiation of Murine Adipose Derived Stem Cells Transfected with EGFP in vitro

Some studies indicate that adipose derived stem cells(ADSCs)can differentiate into adipogenic,chondrogenic,myogenic,and osteogenic cells in vitro.However,whether ADSCs can be induced to differentiate into neural cells in vitro has not been clearly demonstrated.In this study,the ADSCs isolated from the murine adipose tissue were cultured and transfected with the EGFP gene,and then the cells were induced for neural differentiation.The morphology of those ADSCs began to change within two days which developed i...

Correlation between receptor-interacting protein 140 expression and directed differentiation of human embryonic stem cells into neural stem cells

Overexpression of receptor-interacting protein 140（RIP140） promotes neuronal differentiation of N2 a cells via extracellular regulated kinase 1/2（ERK1/2） signaling.However,involvement of RIP140 in human neural differentiation remains unclear.We found both RIP140 and ERK1/2 expression increased during neural differentiation of H1 human embryonic stem cells.Moreover,RIP140 negatively correlated with stem cell markers Oct4 and Sox2 during early stages of neural differentiation,and positively correlated with the neural stem cell marker Nestin during later stages.Thus,ERK1/2 signaling may provide the molecular mechanism by which RIP140 takes part in neural differentiation to eventually affect the number of neurons produced.

Neural differentiation of human placenta-derived mesenchymal stem cells following neural cell co-culture

We induced human placenta-derived mesenchymal stem cells （hPMSCs） to differentiate into neural cells by adding chemical reagents, despite the fact that toxic chemicals induce cell shrinkage or cytoskeletal formation, which does not represent a proper cell differentiation process. The present study established a co-culture system with hPMSCs and neural cells and analyzed the influence of neural cells on hPMSC differentiation in a co-culture system, hPMSCs were isolated and purified from human full-term placenta using collagenase digestion. Fetal neural cells were co-cultured with hPMSCs for 48 hours using the Transwell co-culture system, hPMSCs co-cultured with neural cells exhibited a slender morphology with a filament. After 96 hours, hPMSCs expressed neuron-specific enolase, which suggested that co-culture of hPMSCs and neural cells induced neural differentiation of hPMSCs.

Distribution and differentiation of bone marrow-derived mesenchymal stem cells in vivo after intraperitoneal and tail vein injection into rats in the recovery phase of stroke: Which path is better?

BACKGROUND： Stereotactic injection （striatum or lateral ventricle） and vascular injection （ tail vein or carotid artery） are now often used in cellular therapy for cerebral infarction. Stereotactic injection can accurately deliver cells to the infarct area, but requires a stereotactic device and causes secondary trauma; vascular injection is easy and better for host neurological deficit recovery, but can cause thrombosis. OBJECTIVE： To compare the therapeutic potential of adult bone marrow-derived mesenchymal stem cells （BMSCs） transplantation by intraperitoneal versus intravenous administration to cerebral ischemic rats. DESIGN, TIME AND SE＇B＇ING： A randomized controlled animal experiment was performed at the Cell Room and Pathology Laboratory, Brain Hospital Affiliated to Nanjing Medical University from November 2007 to September 2008. MATERIALS： BMSCs were derived from 20 healthy Sprague-Dawley rats aged 4-6 weeks. METHODS： Forty-five adult middle cerebral artery occlusion （MCAO） rats were randomly divided into control, intravenous and intraperitoneal injection groups, with 15 rats in each group. At 21 days after modeling, rats in the control group received 1 mL of 0.01 mol/L phosphate buffered saline via tail vein injection and each experimental rat received 4 x 106 BMSCs labeled by bromodeoxyuridine （BrdU） via intravenous or intraperitoneal injection. MAIN OUTCOME MEASURES： Angiogenin expression and survival of transplanted cells were measured by immunohistochemical staining of brain tissue in infarction hemisphere at 7, 14 or 21 days after BMSC transplantation. Co-expression of BrdU/microtubule-associated protein 2 or BrdU/glial fibrillary acidic protein was observed by double-labeled immunofluorescence of cerebral cortex. Evaluation of nerve function adhesion-removal test was performed on the 14 or 21 days after BMSCs treatment. using the neurological injury severity score and the 1st and 21st day before and after MCAO, and at 3, 7 RESULTS： Angiogenin-positive new vessels were distributed in the bilateral striatum, hippocampus and cerebral cortex of each group of rats at each time point, most markedly in the intravenous injection group. There were significantly more BrdU-positive cells in the intravenous injection group than in the intraperitoneal injection group （P 〈 0.01）. Co-expression of BrdU/ microtubule-associated protein 2 or BrdU/glial fibrillary acidic protein were almost only seen in the intravenous group by fluorescence microscopy. After transplantation, BMSCs significantly restored nerve function in rats, particularly in the intravenous injection group. CONCLUSION： BMSCs were able to enter brain tissue via the tail vein or peritoneal injection and improve neurological function by promoting the regeneration of nerves and blood vessels in vivo, more effectively after intravenous than intraperitoneal injection.

MicroRNA changes of bone marrow-derived mesenchymal stem cells differentiated into neuronal-like cells by Schwann cell-conditioned medium

Bone marrow-derived mesenchymal stem cells differentiate into neurons under the induction of Schwann cells. However, key microRNAs and related pathways for differentiation remain unclear. This study screened and identified differentially expressed microRNAs in bone marrow- derived mesenchymal stem cells induced by Schwann cell-conditioned medium, and explored targets and related pathways involved in their differentiation into neuronal-like cells. Primary bone marrow-derived mesenchymal stem cells were isolated from femoral and tibial bones, while primary Schwann cells were isolated from bilateral saphenous nerves. Bone marrow-derived mesenchymal stem cells were cultured in unconditioned (control group) and Schwann cell-conditioned medium (bone marrow-derived mesenchymal stem cell + Schwann cell group). Neuronal differentiation of bone marrow-derived mesenchymal stem cells induced by Schwann cell-conditioned medium was observed by time-lapse imaging. Upon induction, the morphology of bone marrow-derived mesencaymal stem cells changed into a neural shape with neurites. Results of quantitative reverse transcription-polymerase chain reaction revealed that nestin mRNA expression was upregulated from 1 to 3 days and downregulated from 3 to 7 days in the bone marrow-derived mesenchymal stem cell + Schwann cell group. Compared with the control group, microtubule-associated protein 2 mRNA expression gradually increased from 1 to 7 days in the bone marrow-derived mesenchymal stem cell + Schwann cell group. After 7 days of induction, microRNA analysis iden:ified 83 significantly differentially expressed microRNAs between the two groups. Gene Ontology analysis indicated enrichment of microRNA target genes for neuronal projection development, regulation of axonogenesis, and positive regulation of cell proliferation. Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated that Hippo, Wnt, transforming growth factor-beta, and Hedgehog signaling pathv/ays were potentially associated with neural differentiation of bone marrow-derived mesenchymal stem cells. This study, which carried out successful microRNA analysis of neuronal-like cells differentiated from bone marrow-derived mesenchymal stem cells by Schwann cell induction, revealed key microRNAs and pathways involved in neural differentiation of bone marrow-derived mesenchymal stem cells. All protocols were approved by the Animal Ethics Committee of Institute of Radiation Medicine, Chinese Academy of Medical Sciences on March 12, 2017 (approval number: DWLI-20170311).

Transfection of the glial cell line-derived neurotrophic factor gene promotes neuronal differentiation

Glial cell line-derived neurotrophic factor recombinant adenovirus vector-transfected bone marrow mesenchymal stem cells were induced to differentiate into neuron-like cells using inductive medium containing retinoic acid and epidermal growth factor. Cell viability, micro- tubule-associated protein 2-positive cell ratio, and the expression levels of glial cell line-derived neurotrophic factor, nerve growth factor and growth-associated protein-43 protein in the su- pernatant were significantly higher in glial cell line-derived neurotrophic factor/bone marrow mesenchymal stem cells compared with empty virus plasmid-transfected bone marrow mes- enchymal stem cells. Furthermore, microtubule-associated protein 2, glial cell line-derived neurotrophic factor, nerve growth factor and growth-associated protein743 mRNA levels in cell pellets were statistically higher in glial cell line-derived neurotrophic factor/bone marrow mesen- chymal stem cells compared with empty virus plasmid-transfected bone marrow mesenchymal stem cells. These results suggest that glial cell line-derived neurotrophic factor/bone marrow mesenchymal stem cells have a higher rate of induction into neuron-like cells, and this enhanced differentiation into neuron-like cells may be associated with up-regulated expression of glial cell line-derived neurotrophic factor, nerve growth factor and growth-associated protein-43.

Protein hairy enhancer of split-1 expression during differentiation of muscle-derived stem cells into neuron-like cells

Muscle-derived stem cells were isolated from the skeletal muscle of Sprague-Dawley neonatal rats aged 3 days old. Cells at passage 5 were incubated in Dulbecco＇s modified Eagle＇s medium supplemented with 10% （v/v） fetal bovine serum, 20 IJg/L nerve growth factor, 20 pg/L basic fibroblast growth factor and 1% （v/v） penicillin for 6 days. Cells presented with long processes, similar to nerve cells. Connections were formed between cell processes. Immunocytochemical staining with neuron specific enolase verified that cells differentiated into neuron-like cells. Immunofluorescence cytochemistry and western blot results revealed that the expression of protein hairy enhancer of split-1 was significantly reduced. These results indicate that low expression of protein hairy enhancer of split-1 participates in the differentiation of muscle-derived stem cells into neuron-like cells.

Negative effects of Notch1 on the differentiation of muscle-derived stem cells into neuronal-like cells

We cultured rat muscle-derived stem cells in medium containing nerve growth factor and basic fi-broblast growth factor to induce neuronal-like cell differentiation.Immunocytochemical staining and reverse transcription-PCR showed that the differentiated muscle-derived stem cells exhibited processes similar to those of neuronal-like cells and neuron-specific enolase expression,but Notch1 mRNA and protein expression was decreased.Down-regulation of Notch1 expression may facilitate neuronal-like cell differentiation from muscle-derived stem cells.

Influence of hyperbaric oxygen on the differentiation of hypoxic/ischemic brainderived neural stem cells

BACKGROUND： It has been previously shown that hyperbaric oxygen may promote proliferation of neural stem cells and reduce death of endogenous neural stem cells （NSCs）. OBJECTIVE： To explore the effects of hyperbaric oxygen on the differentiation of hypoxic/ischemic brain-derived NSCs into neuron-like cells and compare with high-concentration oxygen and high pressure. DESIGN, TIME AND SETTING： An in vitro contrast study, performed at Laboratory of Neurology, Central South University between January and May 2006. MATERIALS： A hyperbaric oxygen chamber （YLC 0.5/1A） was provided by Wuhan Shipping Design Research Institute; mouse anti-rat microtubule-associated protein 2 monoclonal antibody by Jingmei Company, Beijing; mouse anti-rat glial fibrillary acidic protein monoclonal antibody by Neo Markers, USA; mouse anti-rat galactocerebroside monoclonal antibody by Santa Cruz Biotechnology Inc., USA; and goat anti-mouse fluorescein isothiocyanate-labeled secondary antibody by Wuhan Boster Bioengineering Co., Ltd., China. METHODS： Brain-derived NSCs isolated from brain tissues of neonatal Sprague Dawley rats were cloned and passaged, and assigned into five groups： normal control, model, high-concentration oxygen, high pressure, and hyperbaric oxygen groups. Cells in the four groups, excluding the normal control group, were incubated in serum-containing DMEM/F12 culture medium. Hypoxic/ischemic models of NSCs were established in an incubator comprising 93% N2, 5% 002, and 2% 02. Thereafter, cells were continuously cultured as follows： compressed air （0.2 MPa, 1 hour, once a day） in the high pressure group, compressed air ＋ a minimum of 80% 02 in the hyperbaric oxygen group, and a minimum of 80% Q2 in the high-concentration oxygen group. Cells in the normal control and model groups were cultured as normal. MAIN OUTCOME MEASURES： At day 7 after culture, glial fibrillary acidic protein, microtubule-associated protein 2, and galactocerebroside immunofluorescence staining were examined to observe differentiation and calculate the percentage of NSCs differentiating into neuron-like cells or neuroglia-like cells. RESULTS： Neuron-like cells or neuroglia-like cells were visualized in all five groups. There were no significant differences in the percentage of differentiating cells between the hyperbaric oxygen group and the normal control group （P 〉 0.05）. The percentage of NSCs differentiating into neuron-like cells in the hyperbaric oxygen group was significantly greater than model, high-concentration oxygen, and high pressure groups; however, the percentage differentiating into neuroglia-like cells was significantly lower （P 〈 0.01 ）. CONCLUSION： Hyperbaric oxygen promotes the differentiation of brain-derived neural stem cells into neuron-like cells but inhibits differentiation into neuroglia-like cells. Furthermore, the efficacy of hyperbaric oxygen is superior to high-concentration oxygen and high pressure.

Effects of brain-derived neurotrophic factor on induced differentiation of SH-SY5Y cells in vitro

BACKGROUND： Previous studies have demonstrated that brain-derived neurotrophic factor （BDNF） promotes neural differentiation. However, the mechanisms involved in cell cycle-related protein regulation, which highly correlates to neural proliferation and apoptosis, remain poorly understood. OBJECTIVE： To investigate the effects of various concentrations of BDNF on cycle-related protein mRNA expression in induce-differentiated SH-SY5Y cells in vitro prior to and following G2 phase, and to analyze the neuroprotective effects of BDNF. DESIGN, TIME AND SETTING： A comparison, observational study, based on cell biology, was performed at the Department of Biochemistry, Medical College of Tongji University, from March 2005 to October 2006. MATERIALS： SH-SY5Y cells were provided by Shanghai Institute of Cytology, Chinese Academy of Science; BDNF by Alomone Labs, Israel; all-trans retinoic acid （ATRA） by Sigma-Aldrich, USA. METHODS： SH-SY5Y cells were randomly divided into three groups： blank control [cells were treated in Insulin-Transferrin-Selenium （ITS） solution for 7 days], ATRA （cells were treated with ITS solution containing 10 μmol/L ATRA for 7 days）, and BDNF （cells were treated identical to the ATRA group for 5 days, and then respectively treated in ITS solution containing 1, 10, and 100 μg/L BDNF for 2 days）. The experiment was repeated three times for each group. MAIN OUTCOME MEASURES： mRNA expression levels of cyclin A1, B1, B2, cyclin-dependent kinase 1, and 5 were detected using quantitative real-time RT-PCR; percentage of cells in G1, S, and G2 phases were detected using fluorescence-activated cell sorting. RESULTS： mRNA expression levels of cyclin A1 in the high-dose BDNF group was significantly less than the ATRA group （P 〈 0.05）.mRNA expression levels of cyclin B1 was significantly less in the different BDNF concentration groups compared with the control and ATRA groups （P 〈 0.05 or P 〈 0.01）. mRNA expression levels of cyclin B2 and cyclin-dependent kinase 1 were significantly decreased in the high-dose BDNF group （P 〈 0.05 or P 〈 0.01）. Cyclin-dependent kinase 5 mRNA expression was significantly greater in the low-dose and moderate-dose BDNF groups compared with the ATRA group （P 〈 0.05）. The percentage of cells in G1 phase was significantly greater in the different BDNF concentration groups compared with the ATRA and control groups （P 〈 0.01）. Moreover, the percentage of cells in S phase was significantly less in the three BDNF groups compared with the ATRA group （P 〈 0.01）. However, the percentage of cells in S phase was significantly less in the low-dose and high-dose BDNF groups compared with the control group （P 〈 0.01）. CONCLUSION： BDNF enhanced the percentage of cells in G1 phase, but did not alter mRNA expression of cell cycle-related proteins prior to or following G2 phase. These results suggested that BDNF was not a risk factor for inducing apoptosis.

Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions

A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.

Soluble Nogo receptor 1 fusion protein protects neural progenitor cells in rats with ischemic stroke

Soluble Nogo66 receptor-Fc protein(sNgR-Fc)enhances axonal regeneration following central nervous system injury.However,the underlying mechanisms remain unclear.In this study,we investigated the effects of sNgR-Fc on the proliferation and differentiation of neural progenitor cells.The photothrombotic cortical injury model of ischemic stroke was produced in the parietal cortex of Sprague-Dawley rats.The rats with photothrombotic cortical injury were randomized to receive infusion of 400μg/kg sNgR-Fc(sNgR-Fc group)or an equal volume of phosphate-buffered saline(photothrombotic cortical injury group)into the lateral ventricle for 3 days.The effects of sNgR-Fc on the proliferation and differentiation of endogenous neural progenitor cells were examined using BrdU staining.Neurological function was evaluated with the Morris water maze test.To further examine the effects of sNgR-Fc treatment on neural progenitor cells,photothrombotic cortical injury was produced in another group of rats that received transplantation of neural progenitor cells from the hippocampus of embryonic Sprague-Dawley rats.The animals were then given an infusion of phosphate-buffered saline(neural progenitor cells group)or sNgR-Fc(sNgR-Fc+neural progenitor cells group)into the lateral ventricle for 3 days.sNgR-Fc enhanced the proliferation of cultured neural progenitor cells in vitro as well as that of endogenous neural progenitor cells in vivo,compared with phosphate-buffered saline,and it also induced the differentiation of neural progenitor cells into neurons.Compared with the photothrombotic cortical injury group,escape latency in the Morris water maze and neurological severity score were greatly reduced,and distance traveled in the target quadrant was considerably increased in the sNgR-Fc group,indicating a substantial improvement in neurological function.Furthermore,compared with phosphate-buffered saline infusion,sNgR-Fc infusion strikingly improved the survival and differentiation of grafted neural progenitor cells.Our findings show that sNgR-Fc regulates neural progenitor cell proliferation,migration and differentiation.Therefore,sNgR-Fc is a potential novel therapy for stroke and neurodegenerative diseases,The protocols were approved by the Committee on the Use of Live Animals in Teaching and Research of the University of Hong Kong(approval No.4560-17)in November,2015.