Overexpression of microRNA-124 promotes the neuronal differentiation of bone marrow-derived mesenchymal stem cells

microRNAs （miRNAs） play an important regulatory role in the self-renewal and differentiation of stem cells. In this study, we examined the effects of miRNA-124 （miR-124） overexpression in bone marrow-derived mesenchymal stem cells. In particular, we focused on the effect of overexpression on the differentiation of bone marrow-derived mesenchymal stem cells into neurons. First, we used GeneChip technology to analyze the expression of miRNAs in bone marrow-derived mesen- chymal stem cells, neural stem cells and neurons, miR-124 expression was substantially reduced in bone marrow-derived mesenchymal stem cells compared with the other cell types. We con- structed a lentiviral vector overexpressing miR-124 and transfected it into bone marrow-derived mesenchymal stem cells. Intracellular expression levels of the neuronal early markers [3-III tu- bulin and microtubule-associated protein-2 were significantly increased, and apoptosis induced by oxygen and glucose deprivation was reduced in transfected cells. After miR-124-transfected bone marrow-derived mesenchymal stem cells were transplanted into the injured rat spinal cord, a large number of cells positive for the neuronal marker neurofilament-200 were observed in the transplanted region. The Basso-Beattie-Bresnahan locomotion scores showed that the motor function of the hind limb of rats with spinal cord injury was substantially improved. These re- sults suggest that miR-124 plays an important role in the differentiation of bone marrow-derived mesenchymal stem cells into neurons. Our findings should facilitate the development of novel strategies for enhancing the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for spinal cord injury.

Transplantation of placenta-derived mesenchymal stem cell-induced neural stem cells to treat spinal cord injury

Because of their strong proliferative capacity and multi-potency, placenta-derived mesenchymal stem cells have gained interest as a cell source in the field of nerve damage repair. In the present study, human placenta-derived mesenchymal stem ceils were induced to differentiate into neural stem cells, which were then transplanted into the spinal cord after local spinal cord injury in rats. The motor functional recovery and pathological changes in the injured spinal cord were observed for 3 successive weeks. The results showed that human placenta-derived mesenchymal stem cells can differentiate into neuron-like cells and that induced neural stem cells contribute to the restoration of injured spinal cord without causing transplant rejection. Thus, these cells promote the recovery of motor and sensory functions in a rat model of spinal cord injury. Therefore, human placenta-derived mesenchymal stem cells may be useful as seed cells during the repair of spinal cord injury.

In vivo tracking of neuronal-like cells by magnetic resonance in rabbit models of spinal cord injury

In vitro experiments have demonstrated that neuronal-like cells derived from bone marrow mesen- chymal stem cells can survive, migrate, integrate and help to restore the function and behaviors of spinal cord injury models, and that they may serve as a suitable approach to treating spinal cord injury. However, it is very difficult to track transplanted cells in vivo. In this study, we injected su- perparamagnetic iron oxide-labeled neuronal-like cells into the subarachnoid space in a rabbit model of spinal cord injury. At 7 days after cell transplantation, a small number of dot-shaped low signal intensity shadows were observed in the spinal cord injury region, and at 14 days, the number of these shadows increased on T2-weighted imaging. Perl＇s Prussian blue staining detected dot-shaped low signal intensity shadows in the spinal cord injury region, indicative of superpara- magnetic iron oxide nanoparticle-labeled cells. These findings suggest that transplanted neu- ronal-like cells derived from bone marrow mesenchymal stem cells can migrate to the spinal cord injury region and can be tracked by magnetic resonance in vivo. Magnetic resonance imaging represents an efficient noninvasive technique for visually tracking transplanted cells in vivo.

Similarity on neural stem cells and brain tumor stem cells in transgenic brain tumor mouse models

Although it is believed that glioma is derived from brain tumor stem cells, the source and molecular signal pathways of these cells are still unclear. In this study, we used stable doxycycline-inducible transgenic mouse brain tumor models （c-myc/SV40Tag＋/Tet-on＋） to explore the malignant trans- formation potential of neural stem cells by observing the differences of neural stem cells and brain tumor stem cells in the tumor models. Results showed that chromosome instability occurred in brain tumor stem cells. The numbers of cytolysosomes and autophagosomes in brain tumor stem cells and induced neural stem cells were lower and the proliferative activity was obviously stronger than that in normal neural stem cells. Normal neural stem cells could differentiate into glial fibrillary acidic protein-positive and microtubule associated protein-2-positive cells, which were also negative for nestin. However, glial fibrillary acidic protein/nestin, microtubule associated protein-2/nestin, and glial fibrillary acidic protein/microtubule associated protein-2 double-positive cells were found in induced neural stem cells and brain tumor stem cells. Results indicate that induced neural stem cells are similar to brain tumor stem cells, and are possibly the source of brain tumor stem cells.

Effect of VEGF on Neural Differentiation of Human Embryonic Stem Cells in vitro

The effects of vascular endothelial growth factor （VEGF） on neural differentiation of human embryonic stem cells （hESCs） in vitro and the possible mechanism were observed. The hESCs lines, TJMU1 and TJMU2, were established and stored by our laboratory, hESCs differentiated into neuronal cells through embryonic body formation. In this induction process, hESCs were divided into three groups： group A, routine induction; group B, routine induction＋10 ng/mL VEGF; group C, routine in- duction＋10 ng/mL VEGF＋10 ng/mL VEGFR2/Fc. OCT4, Nestin and GFAP in each group were de- tected by RT-PCR, and the cells expressing Nestin and GFAP were counted by immunofluorescence. The percentage of Nestin positive cells in group B was significantly higher than in groups A and C, while the percentage of GFAP positive cells in group B was significantly lower than in groups A and C （P〈0.01）. There was no significant difference between groups A and C （P〉0.05）. It was concluded that VEGF, via VEGFR2, stimulated the neural differentiation of hESCs in vitro.

Are human dental papilla-derived stem cell and human brain-derived neural stem cell transplantations suitable for treatment of Parkinson’s disease?

Transplantation of neural stem cells has been reported as a possible approach for replacing impaired dopaminergic neurons. In this study, we tested the efficacy of early-stage human dental papilla-derived stem cells and human brain-derived neural stem cells in rat models of 6-hydroxydopamine-induced Parkinson＇s disease. Rats received a unilateral injection of 6-hydroxydopamine into right medial forebrain bundle, followed 3 weeks later by injections of PBS, early-stage human dental papilla-derived stem cells, or human brain-derived neural stem cells into the ipsilateral striatum. All of the rats in the human dental papilla-derived stem cell group died from tumor formation at around 2 weeks following cell transplantation. Postmortem examinations revealed homogeneous malignant tumors in the striatum of the human dental papilla-derived stem cell group. Stepping tests revealed that human brain-derived neural stem cell transplantation did not improve motor dysfunction. In apomorphine-induced rotation tests, neither the human brain-derived neural stem cell group nor the control groups （PBS injection） demonstrated significant changes. Glucose metabolism in the lesioned side of striatum was reduced by human brain-derived neural stem cell transplantation. [18F]-FP-CIT PET scans in the striatum did not demonstrate a significant increase in the human brain-derived neural stem cell group. Tyrosine hydroxylase （dopaminergic neuronal marker） staining and G protein-activated inward rectifier potassium channel 2 （A9 dopaminergic neuronal marker） were positive in the lesioned side of striatum in the human brain-derived neural stem cell group. The use of early-stage human dental papilla-derived stern cells confirmed its tendency to form tumors. Human brain-derived neural stem cells could be partially differentiated into dopaminergic neurons, but they did not secrete dopamine.

Nutritional assessment with different tools in leukemia patients after hematopoietic stem cell transplantation

Objective： Correct nutritional assessment is essential for leukemia patients after hematopoietic stem cell transplantation （HSCT）. This study aimed to investigate the best nutritional assessment method for leukemia patients after HSCT, and find the possible nutritional risk of the patients during the transplantation process in order to intervene in the patients with nutritional risks and undernourished patients timely, so that the entire transplantation process could be successfully completed. Methods： A prospective study was performed in 108 leukemia patients after HSCT, and different nutritional assessment methods, including nutritional risk screening 2002 （NRS2002）, mini nutritional assessment （MNA）, subjective globe assessment （SGA） and malnutritional universal screening tools （MUST）, were used. The associations between nutritional status of these patients and nutritional assessment methods were analyzed. Results： A total of 108 patients completed SGA, and 99 patients completed NRS2002, MNA and MUST. During the treatment process, 85.2% of the patients lost weight, wherein, 50% lost weight greater than 5%, and 42.6% had significantly reduced food intake. For nutritional risk assessment, the positive rates of NRS2002, MNA and MUST were 100%, 74.7% and 63.6%, respectively. There was a significant difference （P〈0.05） among the positive rates of NRS2002, MNA and MUST. In undernutrition assessment, the positive rate of SGA （83.3%） was significantly higher than that of MNA （17.2%） （P〈0.05）, and the incidence rate of nutritional risk among leukemia patients _〈30 years old was greater than that of patients 〉30 years old （P〈0.05）. Conclusions： Patients with leukemia were in poor nutritional status during and after HSCT. The leukemia patients 〈30 years old had a greater incidence rate of nutritional risk. As nutritional risk screening tool, the specificity of NRS2002 is not high, but it can be used for evaluating nutritional deficiencies. MNA is a good nutritional risk screening tool, but not an adequate tool for nutritional assessment. If assessment of undernutrition is necessary, the combination of all these screening tools and clinical laboratory indicators should he applied to improve accuracy.

SoxC transcription factors in retinal development and regeneration

Glaucoma and other optic neuropathies result in optic nerve degeneration and the loss of retinal ganglion cells（RGCs）through complex signaling pathways.Although the mechanisms that regulate RGC development remain unclear,uncovering novel developmental pathways may support new strategies to regenerate the optic nerve or replace RGCs.Here we review recent studies that provide strong evidence that the Sry-related high-mobility-group C（SoxC）subfamily of transcription factors（TFs）are necessary and sufficient for axon guidance and RGC fate specification.These findings also uncover novel SoxC-dependent mechanisms that serve as master regulators during important steps of RGC development.For example,we review work showing that SoxC TFs regulate RGC axon guidance and direction through the optic chiasm towards their appropriate targets in the brain.We also review work demonstrating that Sox11 subcellular localization is,in part,controlled through small ubiquitin-like post-translational modifier（SUMO）and suggest compensatory cross-talk between Sox4 and Sox11.Furthermore,Sox4 overexpression is shown to positively drive RGC differentiation in human induced pluripotent stem cells（hi PSCs）.Finally,we discuss how these findings may contribute to the advancement of regenerative and cell-based therapies to treat glaucoma and other optic nerve neuropathies.

A brief review of recent advances in stem cell biology

Stem cells have the remarkable potential to develop into many different cell types, essentially with- out limit to replenish other cells as long as the person or animal is still alive, offering immense hope of curing Alzheimer＇s disease, repairing damaged spinal cords, treating kidney, liver and lung diseases and making damaged hearts whole. Until recently, scientists primarily worked with two kinds of stem cells from animals and humans： embryonic stem cells and non-embryonic ＂somatic＂ or ＂adult＂ stem cells. Recent breakthrough make it possible to convert or ＂reprogram＂ specialized adult cells to assume a stem stem-like cells with different technologies. The review will briefly dis- cuss the recent progresses in this area.

Expansive effects of aorta-gonad-mesonephros-derived stromal cells on hematopoietic stem cells from embryonic stem cells

Background Hematopoietic stem cells （HSCs） give rise to all blood and immune cells and are used in clinical transplantation protocols to treat a wide variety of refractory diseases, but the amplification of HSCs has been difficult to achieve in vitro. In the present study, the expansive effects of aorta-gonad-mesonephros （AGM） region derived stromal cells on HSCs were explored, attempting to improve the efficiency of HSC transplantation in clinical practice.Methods The murine stromal cells were isolated from the AGM region of 12 days postcoitum （dpc） murine embryos and bone marrow（BM） of 6 weeks old mice, respectively. After identification with flow cytometry and immunocytochemistry, the stromal cells were co-cultured with ESCs-derived, cytokines-induced HSCs. The maintenance and expansion of ESCs-derived HSCs were evaluated by detecting the population of CD34^＋ and CD34^＋ Sca-1^＋ cells with flow cytometry and the blast colony-forming cells （BL-CFCs）, high proliferative potential colony-forming cells （HPP-CFCs） by using semi-solid medium colonial culture. Finally, the homing and hematopoietic reconstruction abilities of HSCs were evaluated using a murine model of HSC transplantation in vivo.Results AGM and BM-derived stromal cells were morphologically and phenotypically similar, and had the features of stromal cells. When co-cultured with AGM or BM stromal cells, more primitive progenitor cells （ HPP-CFCs ） could be detected in ESCs derived hematopoietic precursor cells, but BL-CFC＇ s expansion could be detected only when co-cultured with AGM-derived stromal cells. The population of CD34^＋ hematopoietic stem/ progenitor cells were expanded 3 times, but no significant expansion in the population of CD34^＋ Sca-1^＋ cells was noted when co-cultured with BM stromal cells. While both CD34^＋ hematopoietic stem/progenitor cells and CD34^＋ Sca-1^＋ cells were expanded 4 to 5 times respectively derived stromal cells, like BM-derived stromal cells, homing to BM in vivo. when co-cultured with AGM stromal cells. AGM regioncould promote hematopoietic reconstruction and HSCs＇homing to BM in vivo.Conclusions AGM-derived stromal cells in comparison with the BM-derived stromal cells could not only support the expansion of HSCs but also maintain the self-renewal and multi-lineage differentiation more effectively. They are promising in HSC transplantation.

Subcutaneous administration of granulocyte colony stimulating factor and stem cell factor ameliorates the outcome of acute myocardial infarction

Orlic et al treated mice （splenectomized two weeks ago） with granulocyte colony stimulating factor （G-CSF） and stem cell factor （SCF） for five days before acute myocardium infarction （AMI） and three days after AMI. They found that those treatments could repair infarcted hearts, improve heart performance and decrease mortality. However, from the clinical standpoint, the work of Orlic and his co-workers has an obvious limitation.