| A kind of undifferentiated cells has been found existing widely in the mammalian central nervous system (CNS) since 1990s. The cells that are thought as the neural stem cells (NSCs) have some characters such as self-renewing capacity and multipotency. At present the techniques of isolation, expansion and culture in vitro for the NSCs's are ripe. Induced by some factors, NSCs could differentiate into several phenotypes such as neuron, astrocyte and oligodendrocyte. However, the normal cultured cells (including NSCs) generally stop dividing at their 50-60 propagated numbers, which is named replicative senescence. And the telomere,the specialized DNA structures that stabilize the ends of chromosomes,become gradually short during cell division. The NSCs derived from human cortex still have their disadvantages due to either their slow expansion or their polyclonal origin for basic research and clinic application. The concept of the immortalized neural stem cells has been prompted, which is to halt the progression of a developmental program by controlling the cells to remain in continuous cell cycle. Cells can be rendered immortal by a number of manipulations, although the most common is the introduction of neural stem cells with retroviral vectors encoding the oncogene. There are many different isoforms of oncogenes such as myc, neu, p53, SV40 large T-antigen (T-ag), and v-myc and the large-T antigen are the more extensively choiced among them. The immortalized neural stem cells have advantageous characteristics as follows: (1) They are self-renewing and can be expanded to large numbers in culture; (2) They express stable reporter and therapeutic genes and providing human NSCs that divide more rapidly in vitro will clearly enhance the efficiency of transgenesis procedures for generating numerous stable transduced cells in culture rather easily; (3) They can have been isolated as single clones; (4) The in vivo multipotent properties of the cells indicate that the immortalization process has not substantially altered their stem-cell or progenitor-like properties. In the present study, human neural stem cells from aborted human embryo cortex from 10 to12 weeks gestational age were isolated, identified and expanded in vitro. Furthermore, we produced and established a cell lineage of the continuous immortalizedneural stem cells by transfecting the neural stem cells with the viral supernatant containing retroviral constructed with v-myc gene which was generated by LXSNv-myc cell lineage. The main methods and results are as follows: 1 Isolated, identified and expanded the neural stem cells from 10 weeks gestational age, aborted human embryo cortex in vitro.2 The viral supernatant (contain retroviral constructed with v-myc gene) which was produced by LXSNv-myc cell could transfect the neural stem cells effective.3 The immortalized neural stem cells remain kept undifferentiated feature and had self-renewing capacity and multipotency. The speed of growth of the immortalized neural stem cells was obviously faster than the neural stem cells, and the division capacity was obviously strengthened.4 The immortalized neural stem cells of human embryo which were transfected with v-myc gene could cause tumor. So the cells were not suitable for the further research and use of transplantation.In the our study, we isolated, identified and expanded the neural stem cells from 10 to12 weeks gestational age, aborted human embryo cortex in vitro successfully, and transfected the neural stem cells with retroviral which was constructed with v-myc gene. We confirmed the immortalized neural stem cells remain kept undifferentiated feature and had self-renewing capacity and multipotency. The speed of growth of the immortalized neural stem cells was obviously faster than the neural stem cells, and the division capacity was obviously strengthened. But we need to research and overcome the tumorigenicity which was caused by some unknown factors in the course of preparating the immortalized neural stem cells through transfect...
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