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ObjectiveTo construct a neural network-like tissue with the potential of synaptic formation in vitro by seeding human induced pluripotent stem cell-derived neural precursor cells （hiPSC-NPCs） on decellularized optic nerve （DON）， so as to provide a promising approach for repair of nerve tissue injury. MethodsThrough directional induction and tissue engineering technology， human induced pluripotent stem cells （hiPSCs） and 3D DON scaffolds were combined to construct neural network-like tissues. Then the hiPSCs were directionally induced into human neural precursor cells （hNPCs） and neurons. Immunofluorescence staining was used to identify cell differentiation efficiency. 3D DON scaffolds were prepared. Morphology and cytocompatibility of scaffolds were identified by scanning electron microscopy and Tunnel staining. Induced hiPSC-NPCs were seeded on DON scaffolds. Immunofluorescence staining， scanning electron microscopy， transmission electron microscopy and patch clamp were used to observe the morphology and functional identification of constructed neural network tissues. Results①The results of immunofluorescence staining suggested that most of hiPSC-NPCs differentiated into neurons in vitro. We had successfully constructed a neural network dominated by neurons. ② The results of scanning electron microscopy and immunohistochemistry suggested that a neural network-like tissue with predominating excitatory neurons in vitro was successfully constructed. ③The results of immunohistochemical staining， transmission electron microscopy and patch clamp indicated that the neural network-like tissue had synaptic transmission function. ConclusionA neural network-like tissue mainly composed of excitatory neurons has been constructed by the combination of natural uniform-channel DON scaffold and hiPSC-NPCs， which has the function of synaptic transmission. This neural network plays a significant role in stem cell derived replacement therapy， and offers a promising prospect for repair of spinal cord injury （SCI） and other neural tissue injuries.
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ObjectiveDirected differentiation of human induced pluripotent stem cells （hiPSCs） into spinal cord γ-aminobutyric acid （GABA）-ergic progenitor cells were implanted into an decellularized optical nerve （DON） bioscaffold to construct a hiPSC-derived inhibitory neural network tissue with synaptic activities. This study aimed to provide a novel stem cell-based tissue engineering product for the study and the repair of central nervous system injury. MethodsThe combination of stepwise directional induction and tissue engineering technology was applied in this study. After hiPSCs were directionally induced into human neural progenitor cells （hNPCs） in vitro， they were seeded into a DON for three-dimensional culture， allowing further differentiation into inhibitory GABAergic neurons under the specific neuronal induction environment. Transmission electron microscopy and whole cell patch clamp technique were used to detect whether the hiPSCs differentiated neurons could form synapse-like structures and whether these neurons had spontaneous inhibitory postsynaptic currents， respectively， in order to validate that the hiPSC-derived neurons would form neural networks with synaptic transmission potentials from a structural and functional perspective. ResultsThe inhibitory neurons of GABAergic phenotype were successfully induced from hiPSCs in vitro， and maintained good viability after 28 days of culture. With the transmission electron microscopy， it was observed that many cell junctions were formed between hiPSC-derived neural cells in the three-dimensional materials， some of which presented a synapse- like structure， manifested as the slight thickness of cell membrane and a small number of vesicles within one side of the cell junctions， the typical structure of a presynatic component， and focal thickness of the membrane of the other side of the cell junctions， a typical structure of a postsynaptic component. According to whole-cell patch-clamp recording， the hiPSC-derived neurons had the capability to generate action potentials and spontaneous inhibitory postsynaptic currents were recorded in this biotissue. ConclusionsThe results of this study indicated that hiPSCs can be induced to differentiate into GABAergic progenitor cells in vitro and can successfully construct iPSC-derived inhibitory neural network tissue with synaptic transmission after implanted into a DON for three-dimensional culture. This study would provide a novel neural network tissue for future research and treatment of central nervous system injury by stem cell tissue engineering technology.
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Objective To investigate the scientific research ability and training needs of the new posts of medical undergraduates for better training them.Methods A total of 62 new posts of medical undergraduates from a level-two general hospital in China were recruited by questionnaire survey.Resuits the scientific research ability of the new posts of medical undergraduates is poor,so it is very necessary for their in-service training,93.5~ of them have interest in scientific research and hope to get the training,especially want to take part in the practical activity.Conclusions It is not better that the scientific research ability of the new posts of medical undergraduates,so as early as possible to give the scientific research skill training to them.
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<p><b>OBJECTIVE</b>To investigate the current smoking regulations and their impacts on the environmental tobacco smoke (ETS) levels inside restaurants and bars in Beijing.</p><p><b>METHODS</b>Telephone survey was used to investigate the smoking regulations. TSI Sidepak AM510 was used to measure the level of fine particles less than 2.5 microns in diameter (PM2.5) in restaurants and bars. Analysis of variance and non-parametric rank tests were used to examine the association between indoor and outdoor PM2.5 levels and (1) smoking regulations; and (2) types of restaurants and bars.</p><p><b>RESULTS</b>Of the 305 restaurants and bars surveyed, 27.9% had complete or partial smoking prohibiting rules. The average indoor PM2.5, level of the 92 restaurants and bars was 253.08 microg/m3 , 102.37% higher than the outdoor level. The average indoor and outdoor PM2.5 levels in the restaurants and bars with smoking ban regulations were 93.10 microg/m3 and 110.33 microg/m3 whole 289.34 microg/m3 and 128.40 microg/m3 in those without, respectively. The average indoor and outdoor PM2.5 levels of bars were 413.46 microg/m3 and 190.62 microg/m3, respectively, while in the western fast-food restaurants, they were 83.86 microg/m3 and 104.77 microg/m3, respectively. The outdoor PM2.5 levels were higher than the indoor levels in different classes of restaurants and bars. Furthermore, there was a significant positive correlation between PM2.5 levels and the number of smokers per cube meters (r = 0.47, P < 0.001).</p><p><b>CONCLUSION</b>Smoking regulations could effectively reduce the ETS level in restaurants and bars.</p>