The fate of heterotopically grafted neural precursor cells in the normal and dystrophic adult mouse retina

PURPOSE. To study the integration and differentiation of heterotopically transplanted neural precursor cells in the retina of adult mouse mutants displaying apoptotic degeneration of photoreceptor cells. METHODS. Neural precursor cells were isolated from the spinal cord of transgenic mouse embryos ubiquitously expressing enhanced green fluorescent protein. Cells were expanded in vitro and transplanted into the retina of adult wild-type and age-matched ␤2/␤1 knock-in mice. ␤2/␤1 knock-in mutants display apoptotic death of photoreceptor cells and were generated by placing the cDNA of the ␤1 subunit into the gene of the ␤2 subunit of Na,K-ATPase. The integration and differentiation of grafted cells in recipient retinas was studied 1 or 6 months after transplantation. RESULTS. Mutant retinas contained more donor-derived cells than wild-type hosts. Moreover, in mutants, donor cells integrated into deeper retinal layers. In both genotypes, grafted cells differentiated into astrocytes and oligodendrocytes. Only a few ganglion cell axons were myelinated by donor-derived oligodendrocytes 1 month after transplantation, whereas extensive myelination of the nerve fiber layer was observed 6 months after transplantation. Unequivocal evidence for differentiation of grafted cells into neurons was not obtained. CONCLUSIONS. Heterotopically transplanted neural precursor cells are capable of integrating, surviving, and differentiating into neural cell types in normal and dystrophic retinas of adult mice. The particular environment of a pathologically altered retina facilitates integration of transplanted precursor cells. In principle, neural precursors may thus be useful to substitute for or replace dysfunctional or degenerated cell types. Results of the present study also indicate that replacement of retinal cell types is likely to require more appropriate donor cells, such as retinal precursor cells. (Invest Ophthalmol Vis Sci. 2001;42:3311-3319) I nherited retinal dystrophies are a heterogeneous group of disorders characterized by progressive retinal degeneration. Effective therapeutic treatments of retinal dystrophies in humans are currently not available. However, animal experiments have shown beneficial effects of various therapeutic strategies, including gene therapy to substitute for the pathogenic gene, application of growth factors to minimize cell degeneration, or transplantation of committed cell types to replace dysfunctional or degenerated cells. 10 -12 Neural precursors have been isolated from the developing and adult brain and can be massively expanded in vitro, providing, in principle, unlimited amounts of cell material for transplantation (different from primary retinal cells). When transplanted into the developing or adult brain, they have been demonstrated to integrate extensively into the recipient tissue, to survive for extended periods, and to eventually differentiate into those cell types that are affected in the host. 22 These cells were expanded in vitro in the presence of mitogens and subsequently transplanted into the retina of adult wild-type mice and mouse mutants displaying apoptotic degeneration of photoreceptor cells. As a mutant host, we used ␤2/␤1 knock-in mice. 23 ␤1 and ␤2 are subunits of Na,K-ATPase, a heterodimeric ion pump additionally consisting of a catalytic ␣-subunit. 23,24 ␤-subunits play a pivotal role for the formation of functional Na,K-ATPases as exemplified, for instance, by the severe phenotype of ␤2-deficient mice. 25 Such mice display a variety of severe defects in the central nervous system (CNS), including massive apoptotic degeneration of photoreceptor cells, and die at the end of the third postnatal week. 23 To obtain information about the fate of heterotopically transplanted neural precursor cells in the normal and dystrophic mouse retina, we isolated such cells from the spinal cord of EGFP transgenic mice and transplanted them into the retinas of adult wild-type mice and ␤2/␤1 knock-in mutants. Heterotopically transplanted neural precursor cells integrated into the mutant retina without disrupting the histoarchitecture of the host tissue. Quantitative investigations revealed that donorderived cells were more numerous and more widely distributed in mutant retinas than in retinas of age-matched wild-type From th

Chassis organism from Corynebacterium glutamicum – a top-down approach to identify and delete irrelevant gene clusters

Unthan S, Baumgart M, Radek A, et al. Chassis organism from Corynebacterium glutamicum – a top-down approach to identify and delete irrelevant gene clusters. Biotechnology Journal. 2015;10(2):290-301

New hyperekplexia mutations provide insight into glycine receptor assembly, trafficking, and activation mechanisms

Background: Hyperekplexia mutations have provided much information about glycine receptor structure and function. Results: Weidentified and characterized nine new mutations. Dominant mutations resulted in spontaneous activation, whereas recessive mutations precluded surface expression. Conclusion: These data provide insight into glycine receptor activation mechanisms and surface expression determinants. Significance: The results enhance our understanding of hyperekplexia pathology and glycine receptor structure-function. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc. Published in the U.S.A

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

In vitro expanded stem cells from the developing retina fail to generate photoreceptors but differentiate into myelinating oligodendrocytes.

Cell transplantation to treat retinal degenerative diseases represents an option for the replacement of lost photoreceptor cells. In vitro expandable cells isolated from the developing mammalian retina have been suggested as a potential source for the generation of high numbers of donor photoreceptors. In this study we used standardized culture conditions based on the presence of the mitogens FGF-2 and EGF to generate high numbers of cells in vitro from the developing mouse retina. These presumptive 'retinal stem cells' ('RSCs') can be propagated as monolayer cultures over multiple passages, express markers of undifferentiated neural cells, and generate neuronal and glial cell types upon withdrawal of mitogens in vitro or following transplantation into the adult mouse retina. The proportion of neuronal differentiation can be significantly increased by stepwise removal of mitogens and inhibition of the notch signaling pathway. However, 'RSCs', by contrast to their primary counterparts in vivo, i.e. retinal progenitor cells, loose the expression of retina-specific progenitor markers like Rax and Chx10 after passaging and fail to differentiate into photoreceptors both in vitro or after intraretinal transplantation. Notably, 'RSCs' can be induced to differentiate into myelinating oligodendrocytes, a cell type not generated by primary retinal progenitor cells. Based on these findings we conclude that 'RSCs' expanded in high concentrations of FGF-2 and EGF loose their retinal identity and acquire features of in vitro expandable neural stem-like cells making them an inappropriate cell source for strategies aimed at replacing photoreceptor cells in the degenerated retina

Terminal differentiation of myelin-forming oligodendrocytes depends on the transcription factor Sox10

Sox10 is a high-mobility-group transcriptional regulator in early neural crest. Without Sox10, no glia develop throughout the peripheral nervous system. Here we show that Sox10 is restricted in the central nervous system to myelin-forming oligodendroglia. In Sox10-deficient mice progenitors develop, but terminal differentiation is disrupted. No myelin was generated upon transplantation of Sox10-deficient neural stem cells into wild-type hosts showing the permanent, cell-autonomous nature of the defect. Sox10 directly regulates myelin gene expression in oligodendrocytes, but does not control erbB3 expression as in peripheral glia. Sox10 thus functions in peripheral and central glia at different stages and through different mechanisms

<i>In vivo</i> myelin-formation by pre-differentiated ‘RSCs’ derived from peripheral regions of the developing retina.

<p>Analysis of wild-type retinas four weeks after transplantation of oligo-primed <i>actin-EGFP</i>-‘RSCs’ (green) from P3 into adult mice. Many GFP-expressing donor cells form MBP-positive elongated structures on the vitreal side of the retina (red; some are labeled by arrows in B; B is an enlarged view of the boxed area in A) showing MBP-positive fibers radiating towards the optic disc (white star). Scale bars: 100 µm (A), 50 µm (B).</p