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标题: Generation of Peripheral Sensory and Sympathetic Neurons and Neural Crest Cells [打印本页]

作者: 江边孤钓    时间: 2009-3-5 10:49     标题: Generation of Peripheral Sensory and Sympathetic Neurons and Neural Crest Cells

a Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel;5 o" I! U( _3 U: N8 Z5 N9 c

( ]8 G# u6 [' Fb The Hadassah Human Embryonic Stem Cell Research Center, Hadassah University Hospital, Jerusalem, Israel
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Key Words. Human embryonic stem cells ? Neural differentiation ? In vitro differentiation ? Neural induction9 x/ {8 w. Q4 g& {

) w% v+ o2 r: Y- zCorrespondence: Ronald S. Goldstein, Ph.D., Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel. Telephone: 972-3-531-8216; Fax: 972-3-736-0674; e-mail: goldst@mail.biu.ac.il
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1 M3 X, j* l, rABSTRACT" r- ~+ Z/ d: q0 |: N2 d. D
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Pluripotent human embryonic stem cells (hESCs) have been directed to differentiate into neuronal cells using many cell-culture techniques. Several central nervous system (CNS) cell types with potential clinical importance have been produced from hESCs, including dopaminergic and cortical pyramidal-like neurons (reviewed in ). However, for understanding of pathogenesis and drug discovery/treatment of peripheral neuropathies such as Familial Dysautonomia (FD), it will be necessary to produce peripheral neurons from hESCs. Availability of human peripheral sensory neurons (PSNs), for example, would permit the study of how the truncated protein product of the IKBKAP gene, the gene mutated in the vast majority of FD patients (reviewed in ), leads to specific degeneration of this type of neuron in this disease. In addition, normal human sensory neurons could be useful for screening of new and improved drugs for treating FD and other peripheral neuropathies . It is even possible that such neurons could eventually be used for cell-replacement therapy in patients who have significant sensory neuron loss.2 x8 e- r2 y* k& D& V6 G/ }' M' B) e

1 b2 }* `7 f9 T+ D1 _Sasai and his colleagues have shown that neurons are efficiently induced from ESCs of mice  and primates  when cocultured with the mouse stromal line PA6. This induction was named "stromal-derived inducing activity" (SDIA). Others have used this technique to enrich hESC cultures for neuronal precursors . Adding BMP4 to the culture medium after several days of coculture of SDIA-mouse ESC leads to the generation of a population of neurons coexpressing peripherin (a molecule characteristic of neurons with peripheral axons: sensory, autonomic, and motor ) and Brn3a, (a transcription factor characteristic of PSNs and a small population of CNS neurons ). Expression of this combination of markers is thought to be characteristic almost exclusively of PSNs . Rhesus monkey ESCs generated peripherin /Brn3a  sensory neurons spontaneously at low levels when cultured with PA6, and there was enrichment for this phenotype when low concentrations of BMP4 were added to the medium after several days of coculture. These cultures also included cells that were tyrosine hydroxylase (TH) /peripherin , a characteristic of peripheral sympathetic neurons.( b0 Q6 G; \/ N8 A) Y
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The peripheral nervous system (PNS) develops from a unique progenitor/stem cell population: the neural crest (NC) (reviewed in ). PA6 induction of peripheral sensory and sympathetic neurons from murine ESC was apparently preceded by the appearance of markers consistent with an NC intermediate because at early stages of the induction process, several molecules known to be expressed in the NC were detected by immunocytochemistry or polymerase chain reaction (PCR) . These include snail, Sox9, FoxD3, Msx-1, and p75NGFR . The development of the NC has been the topic of intense study in amphibians, avians, and rodents, but little is known about the NC of primates, including that of humans. To date, there have been no reports of the expression of these or other putative NC markers in the NC of primates, including that of humans.9 z* o& q9 _  C. r% ?
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In this study, we applied a modification of the SDIA induction method to two lines of human ESCs to produce cells with the characteristics of human peripheral neurons, both sensory and sympathetic. As was observed for rhesus ESCs, peripheral neurons are generated using SDIA without added BMP4. Similar to the mouse, but demonstrated here for the first time for primates, the peripheral ganglion-like neurons appear to pass through an NC-like stage. SDIA induction of peripheral neurons has great promise not only for study and drug discovery/testing for peripheral neuropathies, but for investigation of human NC development, which occurs at stages of embryonic development that are difficult to access.$ p6 j8 b7 V7 J
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MATERIALS AND METHODS: H1 ^3 }  P- Z& g9 w0 M; h; E
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SDIA Induction of Neuron-Like Cells from hESCs9 E, y2 j( w& H5 x; g- O+ C
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Cells with the molecular characteristics of neurons are induced from murine and primate ESCs when cocultured with the mouse stromal line PA6 . In this study, we repeated this experiment with modified conditions and cultured two lines of hESCs with PA6cells(SDIA). After 7 days of culturing hESCs with PA6, a distinct morphological change in the hESC colonies was observed. Undifferentiated hESCs cultured with mouse or human foreskin fibroblasts appeared as dense, round, or oval monolayer colonies. hESC colonies, by contrast, were irregular in outline after 7 days of SDIA treatment. At that time, the large majority of colonies differentiated into primarily NCAM  neural precursor cells (Figs. 1A–1C). Many colonies, primarily the larger ones, contained cells expressing the non-neural ectodermal marker E-cadherin  in their centers (Figs. 1B, 1C). Several colonies expressed a few ?-3-tubulin (Tuj-1)–staining cells (a universal and early marker for neurons), but most of these Tuj-1  cells did not extend axons (not shown). The results are consistent with other observations that PA6 induces neural differentiation from hESCs (i.e., ).
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. L# T* h; w: Z$ ?' h/ BFigure 1. Induction of ectodermal differentiation of hESCs by PA6 cells. A colony of hESCs induced by SDIA for 7 days immunostained for (A) NCAM (red) and (B) E-cadherin (green). (C): In the merge of (A) and (B), the E-cadherin putative epithelial cells are seen to occupy the center of the colony, a pattern that was commonly found in the cultures. (D): A colony from a 7-day coculture double-stained for NCAM (red) and AP2 (green), a combination thought to be indicative of neural crest cells . By 3 weeks of culture, massive neuronal differentiation is observed in a majority of the colonies, as shown by the neuron-specific tubulin immunostaining shown in panels (E) and (F) (green). In (E) and (F), nuclei are stained blue with Hoechst. Bars = 100 μm (A–E), 50 μm (F). Abbreviations: hESC, human embryonic stem cell; SDIA, stromal-derived inducing activity.: ?- Y* T5 ^; [% `6 \4 y
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Three weeks after seeding hESCs on PA6 cells, massive neuronal differentiation was observed using immunohistochemisty. More than 50% of the colonies were Tuj-1  with extensive networks of stained axons (Figs. 1E, 1F). When hESCs were grown with the same media but on gelatin or laminin without a PA6 cell feeder layer, very few cells survived after 2 weeks of coculture, and none expressed neural markers (not shown).
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9 H# L) _) F4 ], Z7 \5 nGeneration of Peripheral Neuron-Like Cells from hESCs
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6 e% R. e/ k+ ~& J$ z& Q# K: KPrevious studies have shown that SDIA could be used to generate both central and peripheral neurons from murine and primate ESCs. A study using SDIA on hESCs showed that it is neurogenic for hESCs as well, but the presence of peripheral neurons in the cultures was not investigated . To ascertain whether peripheral neurons are present in SDIA-induced cultures, we immunostained for the protein peripherin, which is present in neurons with axons outside the CNS . After 4 weeks of SDIA treatment, 51% of the colonies contained Tuj-1 /peri– CNS-like neurons, and 34.5% contained Tuj-1 /peripherin  PSN-like neurons (402 colonies, 3 independent experiments) (Figs. 2A, 2B). The number of peripherin /Tuj-1  cells was widely variable between the colonies. RT-PCR analysis confirmed that peripherin mRNA was expressed in 3-week cultures, but not 1-week cultures (see below).* {3 ]# f- o" }: I$ y, ^7 A

9 Z. }% l7 @2 ^/ I# MFigure 2. Induction of human peripheral neuron-like cells by PA6. A 4-week colony of SDIA-treated hESCs stained for general neuronal marker ?-III-tubulin (green) and peripheral neuron marker peripherin (red) is shown in (A). Arrows point to the processes of a bipolar cell double-stained for these markers. In other parts of the culture, large numbers of axons extending out of a colony were stained (red) for peripherin (B). SDIA treatment induced large numbers of cells to express TH, as seen in panel . (D, F): Some TH  neurons are CNS-like, and some are PSN-like. A pair of TH  cells (green) is shown in (D). Only one of these (arrow) was also stained for peripherin (E) red, and is a putative SG-like neuron. (F): A merge of (D) and (E). (G–I): Some peripherin  cells are not TH . Several TH  cells are shown by arrow heads in (G). These cells are SG-like, but the same field contains some peripherin  axons that are not TH  . (I): A merge of (G) and (H). Bars = 100 μm (A–C), 30 μm (D–I). Abbreviations: CNS, central nervous system; hESC, human embryonic stem cell; PSN, peripheral sensory neuron; SDIA, stromal-derived inducing activity; SG, sympathetic ganglion; TH, tyrosine hydroxylase.$ {* x0 U9 w( A- e9 c
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Most of the Tuj-1  colonies also contained cells and processes expressing TH (Fig. 2C). Several neuronal types express TH, including catecholaminergic CNS neurons and peripheral sympathetic ganglion neurons. To explore whether the TH  neurons in the SDIA cultures were CNS- or PNS-like, we double-stained colonies induced for 3 weeks with SDIA for peripherin and TH, a combination characteristic of sympathetic neurons. Of the 30% of the colonies that contained TH  cells, approximately half contained TH /peri  cells (Figs. 2D–2I). Less than 1% of the cells in these colonies displayed the TH /peri  PNS-like catecholaminergic phenotype.4 `$ S) S. P* b2 ?8 N# l
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Next, we tested the cultures for the presence of another peripheral neuron subpopulation, sensory ganglion neurons (PSNs). There is no single marker thought to be specific for PSNs. Therefore, in previous studies of PSN differentiation, double-staining with antibodies to Brn3a (a transcription factor characteristic of PSNs and a small population of CNS neurons ) and peripherin has been used as a criterion for PSN identity . When we used this combination of antibodies to stain cultures induced by SDIA for 4 weeks, cells positive for both Brn3a and peripherin were observed in some of the colonies (Fig. 3). Some of these putative sensory neurons migrated away from the colonies, and, as might be expected from neurons derived from the migratory NC, these migrated clusters sometimes comprised half the number of the cells in the neighboring dense colony. The percentage of colonies that contained cells expressing Brn3a, peripherin, and double-stained cells was determined in three separate experiments. Quantitative analysis revealed that double-stained cells were present in 16.5% ± 3.1% of the more than 400 colonies observed, approximately the same proportion of colonies that contained peripherin -only cells (18% ± 3.1%). Approximately half of the colonies contained Brn3a  cells (51.7% ± 4.2%), and some colonies did not contain cells staining for either marker (13.7% ± 2.2%, Fig. 4). Double-stained neurons were also observed at 3 weeks, but not at 2 weeks of coculture (not shown)./ V& b5 l8 q8 C1 s8 H! P
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Figure 3. SDIA treatment induces peripheral sensory-like neurons from hESCs. A field in a coculture of hESCs with PA6 cells with a large number of Brn3a  nuclei (green) and peripherin  axons (red) is shown at low magnification in (A). Nuclear staining (blue) of the same field (B) shows both the PA6 feeder cells and large colony of hESCs (asterisk). Note that the Brn3a  nuclei in (A) are outside and at the edges of the colony. A portion of a merge of panels (A) and (B) is shown in (C). (D): The edge of another colony (asterisk) that has a small mass of peripherin /Brn3a  neurons adjacent to it. (E): A triplet of sensory-like neurons is indicated by the arrow. The arrow in (F) shows a cell with the morphology of a dorsal root ganglion "intermediate neuroblast". ?-3-Tubulin stained cells with both bipolar (filled arrow) and pseudounipolar (open arrow) morphology are shown in (G). (H): A collection of drawings by His of Golgi-stained developing dorsal root ganglion neurons for comparison with the stained cells in (E–G). Bars = 100 μm (A), (B), 50 μm (C–H). Abbreviations: hESC, human embryonic stem cell; SDIA, stromal-derived inducing activity.
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Figure 4. Quantification of hESC colonies containing Brn3a and peripherin-immunoreactive cells after 4 weeks of SDIA induction. The percentage of colonies containing no peripherin  or Brn3a  cells (〞), singly stained Brn3a  cells or peripherin  cells, or double-stained peripherin /Brn3a  cells is depicted. Results are the average of three experiments, including a total of more than 300 colonies. Error bars = SEM. Abbreviations: hESC, human embryonic stem cell; SDIA, stromal-derived inducing activity.
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0 M9 Y- u6 i8 y, @Immature PSNs (like many other neurons) are bipolar, and the majority of the peri /brn3a  neurons we observed had this morphology (Figs. 3E, 3G). However, mature PSNs have a unique pseudounipolar structure, a morphology that arises from the fusion of the proximal segments of the two initial processes, as described by His around a century ago (Fig. 3H). We observed a few pseudounipolar peri /brn  cells and a number of double-stained cells with morphologies intermediate between immature and mature sensory neurons (Figs. 3E–3G). Peri /brn  cells with more than two processes exiting from the soma were never observed, in contrast to the frequent Tuj-1  and TH /peri  multipolar neurons.' i* }$ ~- ~8 z/ z7 j- D# N

7 ~* P0 F( [, E9 P( `% \PSNs express tyrosine-kinase receptors (Trks) that bind trophic factors of the neurotrophin family (reviewed in ). In the chick embryo, TrkC is initially expressed in migrating NC and in virtually all cells in the nascent dorsal root ganglia (DRG), and then is downregulated in most DRG cells, and only remains in large, proprioceptive neurons . By contrast, the low-affinity neurotrophin receptor p75 is expressed both in migrating neural crest cells  and many postmitotic neurons in DRG. RT-PCR analysis of SDIA-treated hESCs revealed that TrkC was induced in 1-week cocultures when compared with naive hESCs, but subsequently its expression was lower at 3 weeks of cocultures (Fig. 5). p75, by contrast, was expressed only at low levels in the 1-week cocultures, and was highly induced in the 3-week cultures. Although other cell types express these receptors, these results are consistent with the known pattern of expression of these receptors in developing PSNs in the chick embryo. Peripherin mRNA was first observed at 3 weeks of coculture, as was the case for the protein (Fig. 5).
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Figure 5. Temporal expression pattern of genes characteristic of peripheral sensory neurons in SDIA-induced hESC cultures. Neurotrophin receptor expression is characteristic of peripheral ganglion neurons. TrkC is expressed by many migrating neural crest cells and virtually all early DRG cells, and then is limited to a population of large, proprioceptive neurons as differentiation continues in chick embryos. Consistent with this, we observed a high level of TrkC expression at 1 week (neural crest/early precursor), and a much lower level at 3 weeks of SDIA treatment (neural differentiation stage). By contrast, in the chick embryo p75 is expressed in both migrating neural crest and mature DRG cells, and its mRNA increased over time from 1–3 weeks of coculture. Transcripts for the intermediate filament protein characteristic of peripheral neurons, peripherin, were detected only from 3 weeks of culture, consistent with our immunocytochemical evidence for the appearance of the protein at approximately this time. Abbreviations: DRG, dorsal root ganglion; hESC, human embryonic stem cell; SDIA, stromal-derived inducing activity.* {# p' M( s& T$ b
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SDIA Induces Differentiation of NC-Like Cells; {7 h) O+ Q" i' L: W  a

5 i( x/ p! O, D; |Most PSNs develop from the NC in vertebrate embryos (with the exception of those derived from ectodermal placodes in the head). To determine whether the differentiation of the PSN-like neurons we observed might be preceded by NC-like cells, we examined 7-day SDIA-induced hESCs for the presence of molecules expressed in murine NC. Unfortunately, there is no one specific marker indicative of NC identity, so we examined a number of different molecules used as NC markers in several species by immunostaining and RT-PCR.
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" p' P; C3 D2 oRT-PCR analysis was performed for a series of NC markers on undifferentiated hESCs and on hESCs after 1 and 3 weeks of SDIA treatment. High expression of the early mammalian  NC cell marker  SNAIL was observed after 1 week of SDIA induction and was dramatically reduced after 3 weeks of treatment (Fig. 6). Other transcripts associated with NC development in the mouse also induced by 1 week of SDIA treatment included Sox9, dHAND, and MSX1. The upregulation of these genes in the 1-week cultures, and the subsequent decrease in their expression by 3 weeks of culture, are consistent with the presence of NC-like cells in the 1-week cultures, and their subsequent differentiation into sensory-like and sympathetic-like neurons by the third week.
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Figure 6. Temporal expression pattern of genes characteristic of NC in SDIA-induced hESC cultures. Several genes that are used as markers of the NC phenotype in nonprimate species (see text) are observed to have a pattern of expression consistent with the generation of NC cells in SDIA-induced hESC cultures. The genes Snail, Sox9, Msx-1, and Dhand were all increased at 1 week as compared with naive hESCs, and then downregulated as cells further differentiated at 3 weeks. Another gene used as a marker for NC, Foxd3 was expressed at similar levels in naive hESCs and at 1 and 3 weeks of PA6 coculture. AP2 expression increased from 1–3 weeks of coculture, consistent with its expression in both epidermal precursors and NC cells. The expression pattern of AP2 is the same as was observed for the epithelial marker E-cadherin. Abbreviations: hESC, human embryonic stem cell; NC, neural crest; SDIA, stromal-derived inducing activity.
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A few genes considered to be NC markers did not show this pattern of early up- and later downregulation. FoxD3, expressed in the premigratory NC, was present in the 1-week cocultures. However, it was also expressed in naive hESCs (Fig. 6, ) as well as at 3 weeks of culture, so its detection was less informative than the aforementioned transcripts as to the presence of NC-like cells in the cultures. Immunocytochemistry showed that AP2 was expressed after 1 week of SDIA treatment, and this was confirmed by the presence of its mRNA. However, AP2 is expressed by epidermal cells as well as NC, and it is therefore not surprising that its mRNA expression continued to rise until 3 weeks, similarly to the increase in E-cadherin expression. It is therefore likely that our culture conditions are permissive for epidermal cells to differentiate and/or multiply. Pigmented cells were not observed in the cultures, and we did not stain for smooth muscle actin, because the SDIA method, coupled with the differentiation medium we used, has already been shown to inhibit the production of melanocytes and mesenchymal NC derivatives .3 W8 I( P; ?& t+ q+ R: \" t

6 m  I) g# E$ d4 z0 qImmunocytochemical evidence also supported the induction of NC from hESCs using SDIA. Cells expressing AP2 / NCAM, a combination thought to be characteristic of NC cells , were present in 42.3% ± 5.5% of the colonies after 1 week of coculture (163 colonies observed in two experiments) (Fig. 1D). Approximately 50% of the colonies also contained immunostained cells positive for the low-affinity neurotrophin receptor p75, which is expressed in migrating murine crest cells  (not shown).# O6 ~$ P, M2 W

9 T" ~) l/ z! \+ k5 ^  p. l' tWe designed the PCR primers in this study to be specific for human mRNAs. Control experiments showed that the (murine) PA6 cells grown alone did not express any of the mRNAs for human NC markers. The PA6 cells expressed murine, and not human, actin transcripts, as expected (not shown).
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DISCUSSION
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This work was supported by a very generous grant from the Familial Dysautonomia Foundation, Inc., New York. We thank Chaya Kalcheim (Hebrew University, Jerusalem) and Benny Motro (Bar-Ilan University, Ramat-Gan, Israel) for helpful discussions of these results. Chaya Morgenstern provided excellent logistical and technical support, and Natalie Nagorsky and Orel Pasder helped maintain the hESCs. Human foreskin fibroblasts were a gift of InterPharm Laboratories, Ness Ziona, Israel. The hESC line HUES-7 was provided by Doug Melton (Harvard University, Cambridge, MA). The AP2 antibody was developed by Trevor Williams and obtained from the Developmental Studies Hybridoma Bank, developed under the auspices of the NICHD and maintained by the Dept. of Biol. Sciences, University of Iowa, Iowa City, IA.; A* v8 v" ~, _/ m2 A, m" U
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作者: 大小年    时间: 2015-8-30 18:30

既然来了,就留个脚印  
作者: 命运的宠儿    时间: 2015-9-1 14:19

初来乍到,请多多关照。。。嘿嘿,回个贴表明我来过。  
作者: 昕昕    时间: 2015-10-8 09:35

感觉好像在哪里看过了,汗~  
作者: aakkaa    时间: 2015-10-18 14:34

我仅代表干细胞之家论坛前来支持,感谢楼主!  
作者: 红旗    时间: 2015-10-26 19:26

牛牛牛牛  
作者: 大小年    时间: 2015-11-12 12:34

又看了一次  
作者: nauticus    时间: 2015-11-13 07:50

努力,努力,再努力!!!!!!!!!!!  
作者: 石头111    时间: 2015-11-30 20:55

好帖,有才  
作者: 陈晴    时间: 2016-1-1 16:53

一定要回贴,因为我是文明人哦  
作者: 科研人    时间: 2016-1-11 20:43

今天没事来逛逛,看了一下,感觉相当的不错。  
作者: 兔兔    时间: 2016-1-15 07:54

帮你顶,人还是厚道点好  
作者: haha3245    时间: 2016-1-20 18:12

今天无聊来逛逛  
作者: tempo    时间: 2016-2-4 09:43

希望大家都有好运  
作者: sky蓝    时间: 2016-2-20 15:13

世界上那些最容易的事情中,拖延时间最不费力。  
作者: abc987    时间: 2016-3-2 09:18

干细胞行业  
作者: 兔兔    时间: 2016-3-4 14:01

胚胎干细胞
作者: 糊涂小蜗牛    时间: 2016-3-6 16:19

干细胞之家 我永远支持
作者: 咖啡功夫猫    时间: 2016-3-15 17:10

转基因动物
作者: 365wy    时间: 2016-3-22 10:43

楼主good  
作者: feixue66    时间: 2016-3-30 10:10

不要等到人人都说你丑时才发现自己真的丑。  
作者: syt7000    时间: 2016-4-9 10:18

这个贴好像之前没见过  
作者: 我学故我思    时间: 2016-5-2 18:10

…没我说话的余地…飘走  
作者: SCISCI    时间: 2016-5-4 21:51

发贴看看自己积分  
作者: 蚂蚁    时间: 2016-5-8 15:42

顶的就是你  
作者: 修复者    时间: 2016-6-19 22:23

支持~~  
作者: dmof    时间: 2016-6-23 17:01

自己知道了  
作者: beautylive    时间: 2016-6-30 14:35

神经干细胞
作者: feixue66    时间: 2016-8-10 14:01

干细胞分化技术
作者: 海小鱼    时间: 2016-8-29 10:43

干细胞研究非常有前途
作者: 考拉    时间: 2016-9-22 12:53

支持~~顶顶~~~  
作者: laoli1999    时间: 2016-9-24 13:35

帮你顶,人还是厚道点好  
作者: 干细胞2014    时间: 2016-10-15 04:13

顶也~  
作者: 舒思    时间: 2016-10-21 12:01

脂肪干细胞
作者: 追风    时间: 2016-11-16 18:09

哈哈 我支持你
作者: abc987    时间: 2016-12-6 07:50

不错不错.,..我喜欢  
作者: 安安    时间: 2016-12-10 18:52

…没我说话的余地…飘走  
作者: 红旗    时间: 2017-1-2 16:53

嘿...反了反了,,,,  
作者: tuting    时间: 2017-1-23 05:06

努力,努力,再努力!!!!!!!!!!!  
作者: dmof    时间: 2017-1-24 08:43

孜孜不倦, 吾等楷模 …………  
作者: 天蓝色    时间: 2017-2-3 14:43

角膜缘上皮干细胞
作者: syt7000    时间: 2017-2-13 08:43

小生对楼主之仰慕如滔滔江水连绵不绝,海枯石烂,天崩地裂,永不变心.  
作者: na602    时间: 2017-2-13 11:43

很好!很强大!  
作者: xiao2014    时间: 2017-2-14 01:31

一楼的位置好啊..  
作者: 小敏    时间: 2017-2-17 12:27

感觉好像在哪里看过了,汗~  
作者: chinagalaxy    时间: 2017-2-23 06:24

终于看完了~~~  
作者: xiao2014    时间: 2017-3-2 01:39

帮顶  
作者: sshang    时间: 2017-3-7 23:35

感谢党和人民的关爱~~~  
作者: bluesuns    时间: 2017-3-8 21:26

好困啊  
作者: ines    时间: 2017-3-29 19:24

支持一下  
作者: 快乐小郎    时间: 2017-4-24 00:00

我等你哟!  
作者: 旅美学者    时间: 2017-4-25 09:54

回贴赚学识,不错了  
作者: 大小年    时间: 2017-5-3 08:53

肿瘤干细胞
作者: 初夏洒脱    时间: 2017-5-5 00:42

不早了 各位晚安~~~~  
作者: 舒思    时间: 2017-5-22 05:06

支持你加分  
作者: biodj    时间: 2017-6-16 05:22

好贴坏贴,一眼就看出去  
作者: dataeook    时间: 2017-6-27 01:58

真是佩服得六体投地啊  
作者: 陈晴    时间: 2017-6-30 19:18

哈哈,看的人少,回一下  
作者: vsill    时间: 2017-7-2 08:35

看或者不看,贴子就在这里,不急不忙  
作者: 3344555    时间: 2017-7-13 11:10

厉害!强~~~~没的说了!  
作者: aakkaa    时间: 2017-7-14 04:09

感觉好像在哪里看过了,汗~  
作者: 坛中酒    时间: 2017-7-16 14:26

我帮你 喝喝  
作者: 橙味绿茶    时间: 2017-7-27 09:43

我来了~~~~~~~~~ 闪人~~~~~~~~~~~~~~~~  
作者: beautylive    时间: 2017-7-27 12:43

太棒了!  
作者: foxok    时间: 2017-8-8 04:43

我也来顶一下..  
作者: lalala    时间: 2017-8-10 02:49

不管你信不信,反正我信  
作者: 墨玉    时间: 2017-8-13 05:01

希望大家帮我把这个帖发给你身边的人,谢谢!  
作者: 依旧随遇而安    时间: 2017-8-18 02:14

原来这样也可以  
作者: 罗马星空    时间: 2017-9-3 11:54

造血干细胞
作者: 多来咪    时间: 2017-9-6 07:29

这样的贴子,不顶说不过去啊  
作者: dada    时间: 2017-9-27 18:23

干细胞疾病模型
作者: 生科院    时间: 2017-9-27 18:50

真是天底下好事多多  
作者: 杏花    时间: 2017-10-16 03:28

不错!  
作者: lab2010    时间: 2017-10-16 12:54

琴棋书画不会,洗衣做饭嫌累。  
作者: 求索迷茫    时间: 2017-10-16 23:01

青春就像卫生纸。看着挺多的,用着用着就不够了。  
作者: 某某人    时间: 2017-11-7 16:36

真的有么  
作者: aakkaa    时间: 2017-12-2 18:15

干细胞研究还要面向临床
作者: dreamenjoyer    时间: 2017-12-3 15:53

今天无聊来逛逛  
作者: 咕咚123    时间: 2017-12-8 18:05

我是来收集资料滴...  
作者: 修复者    时间: 2017-12-14 21:50

是楼主原创吗  
作者: frogsays    时间: 2017-12-26 03:43

风物长宜放眼量  
作者: feixue66    时间: 2018-2-3 11:39

我好想升级  
作者: 初夏洒脱    时间: 2018-2-14 08:26

鉴定完毕.!  
作者: xm19    时间: 2018-2-17 00:29

我的啦嘿嘿  
作者: 365wy    时间: 2018-2-17 10:18

每天到干细胞之家看看成了必做的事情
作者: 桦子    时间: 2018-3-11 18:24

哈哈 瞧你说的~~~  
作者: dogcat    时间: 2018-3-16 02:38

顶一个先  
作者: nosoho    时间: 2018-3-22 14:00

必须顶  
作者: 加菲猫    时间: 2018-3-24 03:33

好贴子好多啊  
作者: 蚂蚁    时间: 2018-5-28 02:53

支持一下  
作者: htc728    时间: 2018-6-10 22:08

我仅代表干细胞之家论坛前来支持,感谢楼主!  
作者: 安安    时间: 2018-6-16 08:01

好啊,谢楼主
作者: dypnr    时间: 2018-6-23 01:41

世界上那些最容易的事情中,拖延时间最不费力。  
作者: heart10    时间: 2018-7-22 10:42

我的啦嘿嘿  
作者: 分子工程师    时间: 2018-7-23 22:23

呵呵 大家好奇嘛 来观看下~~~~  




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