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标题: Temporal Expression Patterns and Corresponding Protein Inductions of Early Respo [打印本页]

作者: 江边孤钓    时间: 2009-3-5 10:49     标题: Temporal Expression Patterns and Corresponding Protein Inductions of Early Respo

Research Service and Geriatrics Research, Education, and Clinical Center, Veterans Affairs Medical Center, Miami, Florida, USA; Department of Biomedical Engineering, University of Miami, Coral Gables, Florida, USA$ J! L6 T& v' g6 N( ~$ V

7 K8 q5 J+ ^6 W9 a- C3 `' o: a5 B; M6 XKey Words. Chondrogenesis ? Adult bone marrow stem cells ? TGF-? receptor ? TGF-?1 ? Gene expression ? Mesenchymal stem cell
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9 G8 E: B* b& _" H+ F- QCorrespondence: Herman S. Cheung, Ph.D., Research Service, Miami VA Medical Center, 1201 NW 16th Street, Miami, Florida 33125, USA. Telephone: 305-575-3388; Fax: 305-575-3365; e-mail: hcheung@med.miami.edu  U; d" G1 o8 T

7 v* _; y- Y5 E' s5 ?8 HABSTRACT& ~2 w  ~5 @( Z" Q1 ~

8 G3 P; C# ]! C" V# }When damage on articular cartilage extends into the subchondral bone, mesenchymal stem cells (MSCs) migrate from bone marrow (BM) to the injured area and form a new cartilage-like reparative tissue . This clinical finding indicates that local stimuli at the injured site of articular cartilage can induce chondrogenic differentiation of MSCs. It has been demonstrated that continuous passive motion enhanced the repair of full-thickness defects of articular cartilage with autogenous periosteal grafts containing MSCs . A recent study repaired large, full-thickness cartilage defects of rabbit keen joints by transplanting BM-derived MSCs (BM-MSCs) and showed that 6 months after the implantation, different local mechanical environments resulted in substantial differences in mechanical properties of reparative tissues on the posterior and anterior aspects of the repair area . These cartilage repair studies suggest that mechanical stimuli may affect chondrogenic differentiation of MSCs and/or cartilage-specific matrix formation of differentiated cells (i.e., chondrocyte).  b4 W  Z' J/ l4 Y+ M  J

, `. E: r% k# g( P9 NIt has been well documented that compressive loading modulated the cartilage-specific macromolecule biosynthesis of mature chondrocytes , whereas compressive loading was shown to stimulate chondrogenic differentiation of chick and mouse embryonic mesenchymal cells . Recently, Angele et al. showed that cyclic hydrostatic pressure enhanced the extracellular matrix deposition of human BM-MSCs, which underwent chondrogenesis in pellet cultures . Our recent study found that cyclic compressive loading promoted gene expressions of chondrogenic markers (collagen type II and aggrecan) and transforming growth factor-?1 (TGF-?1) in rabbit BM-MSCs in a serum-free media, suggesting that the TGF-? signal pathway may be involved in BM-MSC chondrogenic differentiation stimulated by dynamic compressive loading .% q" N( a  K6 b. d6 k2 H% J
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In vitro studies have demonstrated that TGF-? can induce chondrogenesis of BM-MSCs . TGF-? regulates a variety of cellular functions by signaling through a heteromeric receptor complex of two transmembrane serinethreonine kinases (receptor types I and II). The intracellular TGF-? signal transduction is initiated by type I receptor (T?R-I) after its phosphorylation by ligand-bound type II receptor (T?R-II) . Mizuta et al. found that the gene expressions of both receptors and TGF-?1 ligand were upregulated during periosteal chondrogenesis induced by exogenous TGF-?1 treatment wherein the temporal and spatial gene expression patterns of both receptors were consistent with those of the ligand itself , suggesting that TGF-?1 regulated periosteal chondrogenesis. Therefore, the presence of both receptors is essential for chondrogenesis of BM-MSCs when TGF-? signaling is involved.( j+ X! v9 ^' J8 j# v0 w

6 s2 i" d) V' Z3 FActivating protein 1 (AP-1), a transcription factor complex of the Jun and Fos nuclear oncoproteins, is one of the downstream targets for mitogen-activated protein kinase (MAPK) signaling pathway. It has been shown that MAPKs regulated chondrogenesis of chick embryo limb bud cells at postprecartilage condensation stages , whereas overexpression of c-Fos gene inhibited chondrocyte differentiation of ATDC5 chondrogenic cells . Recent studies demonstrated that AP-1 binding activity is a requisite for promoting chondrogenesis of C3H10T1/2 mesenchymal cells . In addition, Kim et al. showed that induction of endogenous TGF-?1 gene expression by TGF-?1 treatment was mediated by binding of the AP-1 complex to the promoter region of TGF-?1 gene, whereas both components (c-Fos and c-Jun) of the AP-1 complex were required for TGF-?1 autoinduction . Therefore, it is possible that activity of AP-1 may regulate BM-MSC chondrogenesis induced by TGF-?.4 J% z" ?6 a% m8 u+ A

# v( T* l1 S5 jSox9, a member of Sry-type high-mobility-group box (Sox) genes, is identified as an essential transcription factor for chondrogenesis of mesenchymal cells and expressed in precartilaginous mesenchymal condensation and maturing cartilage . It has been indicated that Sox9 can regulate expression of chondrocyte-specific collagen (i.e., type II, IX, and XI collagens) and aggrecan genes. Sox9 was able to promote type II collagen gene expression by binding directly to an enhancer element in the first intron of the collagen II gene  while it could bind to the promoter of type IX and XI collagen genes . Sox9 also enhanced the gene promoter activity of aggrecan in the TC6 chondrocytic cell line . Recently, it has been demonstrated that overexpression of Sox9 gene in mouse BM-MSCs promoted chondrogenesis in in vitro micromass culture and in vivo transplantation . Because of its capability to regulate chondrogenic gene expressions, Sox9 may play an important role in regulation of chondrocyte differentiation of BM-MSCs.
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Our recent study suggested that dynamic compressive loading might promote chondrogenesis of rabbit BM-MSCs through the TGF-? signaling pathway . To advance our understanding of the mechanism behind this finding, our first step was to examine expressions of the early responsive genes that may regulate chondrogenesis and TGF-? signal transduction. Therefore, the objective of this study was to examine the temporal expression patterns of c-Fos, c-Jun, Sox9, TGF-?1, and TGF-? receptors and induction of their corresponding proteins in agarose cultures of rabbit BM-MSCs under cyclic compressive loading.! K4 W0 Z; e2 G# V6 B( o# }& r% C/ S

* e( K3 a1 r& K) G0 O; y1 yMATERIALS AND METHODS
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Typical Gene Expressions
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In general, the gene expressions of c-Fos, c-Jun, Sox9, type II collagen, TGF-?1, and T?R-I and T?R-II were upregulated in the samples under dynamic compression, whereas the temporal expressions of those genes, except c-Fos, were different between the first and second days of testing (Figs. 1, 2).% w" D' c& E( q  T
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Figure 1. RT-PCR analysis of gene expressions of rabbit BM-MSCs on the first day of testing. Gene expressions of the loading group were analyzed after being subjected to 1 (L1), 2 (L2), and 4 (L4) hours of dynamic compressive loading and after 4 (R4), 8 (R8), and 20 (R20) hours of rest following 4-hour dynamic compressive loading. Gene expressions of the control group were analyzed at the beginning of the compression test. Total RNA was isolated and RT-PCR was performed on 1 μg of each sample using primers for c-Fos, c-Jun, Sox9, T?R-I, T?R-II, TGF-?1, collagen II, and GAPDH as shown on the left. Bands shown are representatives of five independent experiments. Abbreviations: BM-MSC, bone-marrow mesenchymal stem cell; RT-PCR, reverse transcription–polymerase chain reaction.4 [2 ?9 X; w; R
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Figure 2. RT-PCR analysis of gene expressions of rabbit BM-MSCs on the second day of testing. Gene expressions of the loading group were analyzed after being subjected to 1 (L1), 2 (L2), and 4 (L4) hours of dynamic compressive loading and after 4 (R4), 8 (R8), and 20 (R20) hours of rest following 4-hour dynamic compressive loading. Gene expressions of the control group were analyzed at the beginning of the compression test. Total RNA was isolated and RT-PCR was performed on 1 μg of each sample using primers for c-Fos, c-Jun, Sox9, T?R-I, T?R-II, TGF-?1, collagen II, and GAPDH as shown on the left. Bands shown are representatives of five independent experiments. Abbreviations: BM-MSC, bone-marrow mesenchymal stem cell; RT-PCR, reverse transcription–polymerase chain reaction.
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' N7 f" A0 @/ }Day 1 of Testing ? During the 4-hour compression test, gene expressions of c-Jun, Sox9, type II collagen, TGF-?1, T?R-I, and T?R-II for the loading group gradually increased and reached the peak after 2 hours of loading and then decreased from that peak after 4 hours of loading. Only the loading group exhibited a weak expression of c-Fos gene after 1 hour of loading (Fig. 1). After the 4-hour compression test, all gene expressions of the loading group decreased to a level similar to (i.e., c-Jun, type II collagen, TGF-?1, and T?R-II) or slightly higher than (i.e., Sox9) those of the control group except that the expression of the T?R-I gene exhibited another peak after 8 hours of rest (Fig. 1).* S' ~4 ^& R0 j# U
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Day 2 of Testing ? During the 4-hour compression test, all gene expressions of the loading group were upregulated. The gene expressions of c-Jun, Sox9, type II collagen, T?R-I, and T?R-II for the loading group gradually increased and reached the peak after 4 hours of loading, whereas the gene expression of TGF-?1 quickly reached the highest level after 1 hour of loading (Fig. 2). Similar to the first day of testing, only weak expression of c-Fos gene was seen for the loading group after 1 hour of loading (Fig. 2). After the 4-hour compression test, gene expressions of c-Jun, Sox9, type II collagen, TGF-?1, and T?R-I for the loading group gradually decreased to a level slightly higher than those of the control group, whereas T?R-I gene expression was similar to those of the control group (Fig. 2).! g( J8 E. a) W* @- b9 `  E/ d

  V% d8 Y, s% p# ?# M5 UStatistical Analysis of Gene Expressions# j% s* c) s) |1 ^( M  ]0 g
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Day 1 of Testing ? Significant differences were found in all gene expressions between two experimental groups with the samples subjected to 2-hour dynamic compression having a higher level of expression than the control group (Figs. 3–5). After 4-hour dynamic compression, the loading group still exhibited significantly greater expression of type II collagen than the control (Fig. 5). Compared with the control group, the loading group also exhibited significantly higher levels of T?R-I and T?R-II gene expressions after 1-hour dynamic compression as well as higher expression of T?R-I gene after 8 hours of rest following 4 hours of dynamic compression (Fig. 3).5 u' l; G; U# X& w. J, @+ Y- ?
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Figure 3. Statistical analysis of gene expressions of TGF-? type I and type II receptors. The relative gene expressions of TGF-? type I and type II receptors among six time points of 2 days of testing, as presented in Figures 1 and 2, were statistically analyzed using a one-way analysis of variance with Student-Newman-Keuls comparison test (n = 10 for control group; n = 5 for loading group). Gene expressions of the loading group were analyzed after being subjected to 1 (L1), 2 (L2), and 4 (L4) hours of dynamic compressive loading and after 4 (R4), 8 (R8), and 20 (R20) hours of rest following 4-hour dynamic compressive loading on each day of testing. Gene expressions of the control group were analyzed at the beginning of the compression test and the recovery period on each day of testing.
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$ J4 H4 ]1 O$ |' Q% t5 V" ?Figure 4. Statistical analysis of gene expressions of TGF–?1 and c-Jun. The relative gene expressions of TGF–?1 and c-Jun among six time points of 2 days of testing, as presented in Figures 1 and 2, were statistically analyzed using a one-way analysis of variance with Student-Newman-Keuls comparison test (n = 10 for control group; n = 5 for loading group). Gene expressions of the loading group were analyzed after being subjected to 1 (L1), 2 (L2), and 4 (L4) hours of dynamic compressive loading and after 4 (R4), 8 (R8), and 20 (R20) hours of rest following 4-hour dynamic compressive loading on each day of testing. Gene expressions of the control group were analyzed at the beginning of the compression test and the recovery period on each day of testing.
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( b2 s; U0 s3 _2 ]/ e+ uFigure 5. Statistical analysis of gene expressions of Sox9 and type II collagen. The relative gene expressions of Sox9 and type II collagen among six time points of 2 days of testing, as presented in Figures 1 and 2, were statistically analyzed using a one-way analysis of variance with Student-Newman-Keuls comparison test (n = 10 for control group; n = 5 for loading group). Gene expressions of the loading group were analyzed after being subjected to 1 (L1), 2 (L2), and 4 (L4) hours of dynamic compressive loading and after 4 (R4), 8 (R8), and 20 (R20) hours of rest following 4-hour dynamic compressive loading on each day of testing. Gene expressions of the control group were analyzed at the beginning of the compression test and the recovery period on each day of testing.
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7 R3 J( p5 g& FDay 2 of Testing ? Significant differences were found in all gene expressions between two experimental groups with the samples subjected to 4-hour dynamic compression having higher levels of expression than those of the control group (Figs. 3–5). For the gene expression of TGF-?1, the samples subjected to 1- and 2-hour dynamic compression exhibited significantly higher levels of expression than the control group (Fig.4). In addition, samples subjected to 2-hour dynamic compression also exhibited a significantly greater expression of T?R-II gene than the control group (Fig. 3). However, no significant differences were found in all gene expressions between two experimental groups during the recovery period./ `4 Z; }' Z* O3 k8 r& J3 h' [
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Typical Protein Induction
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  U! [9 @) A/ X0 v1 b' a+ `In general, the protein inductions of c-Jun, Sox9, TGF-?1, T?R-I, and T?R-II were seen in the samples subjected to 2- and 4-hour dynamic compression (Fig. 6). The protein inductions of c-Jun, Sox9, T?R-I, and T?R-II reached the highest levels in the loading group after 4 hours of loading and then decreased to a level similar to the control group after 4 hours of rest (Fig. 6). However, after the protein induction of TGF-?1 in the loading group by the 2-hour dynamic compression, the protein level of TGF-?1 was maintained at the similar level after 4-hour loading and during the 4-hour recovery period (Fig. 6).
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! }' ?" m0 s7 kFigure 6. Western blot analysis of corresponding protein inductions of c-Jun, Sox9, TGF-?1, and TGF-? receptors on the first day of testing. Protein inductions of the loading group were analyzed after being subjected to 2 (L2) and 4 (L4) hours of dynamic compressive loading and after 2 (R2) and 4 (R4) hours of rest following 4-hour dynamic compressive loading. Protein inductions of the control group were analyzed at the beginning of the compression test. Nuclear extract of NIH/3T3 mouse fibroblasts treated with phorbol, cell lysate of rabbit chondrocytes, recombinant protein of mouse T?R-I, fusion protein of human T?R-II, and cell lysate of human normal fibroblasts were used as positive controls ( ) for c-Jun, Sox9, T?R-I, T?R-II, and TGF-?1, respectively. Bands shown are representative of four independent experiments.
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DISCUSSION
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, n4 z$ Z2 Y8 A* q; JThis work was supported by a National Institutes of Health grant (AR 38421) and a VA Merit Review Grant. The authors would like to thank Ms. Kristen Hagar for her technical assistance with RT-PCR and cell culture.% [1 S1 I8 k! ^+ t" ~
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Takahashi I, Nuckolls GH, Takahashi K et al. Compressive force promotes sox9, type II collagen and aggrecan and inhibits IL-1beta expression resulting in chondrogenesis in mouse embryonic limb bud mesenchymal cells. J Cell Sci 1998;111:2067–2076.) a1 d! ~) w+ r6 n! G. {- B

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Wong C, Rougier-Chapman EM, Frederick JP et al. Smad3-Smad4 and AP-1 complexes synergize in transcriptional activation of the c-Jun promoter by transforming growth factor beta. Mol Cell Biol 1999;19:1821–1830.' A$ A1 }) h$ T1 S5 u' R8 `$ I& R
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+ f" Y' W4 n% {: V5 IOkazaki R, Ikeda K, Sakamoto A et al. Transcriptional activation of c-fos and c-jun protooncogenes by serum growth factors in osteoblast-like MC3T3-E1 cells. J Bone Miner Res 1992;7:1149–1155.
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Karin M. The regulation of AP-1 activity by mitogen-activated protein kinases. J Biol Chem 1995;270:16483–16486.
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作者: aakkaa    时间: 2015-6-8 20:26

我帮你 喝喝  
作者: bluesuns    时间: 2015-6-26 12:08

呵呵,明白了  
作者: 杏花    时间: 2015-7-28 08:46

楼主good  
作者: 123456zsz    时间: 2015-8-18 15:01

真是佩服得六体投地啊  
作者: 科研人    时间: 2015-8-30 13:54

淋巴细胞
作者: 石头111    时间: 2015-10-6 17:59

(*^__^*) 嘻嘻……   
作者: aakkaa    时间: 2015-10-13 21:27

加油啊!!!!顶哦!!!!!  
作者: immail    时间: 2015-10-19 13:54

哎 怎么说那~~  
作者: 剑啸寒    时间: 2015-10-21 15:54

顶顶更健康,越顶吃的越香。  
作者: aakkaa    时间: 2015-11-1 20:01

昨晚多几分钟的准备,今天少几小时的麻烦。  
作者: haha3245    时间: 2015-11-15 19:12

不错 不错  比我强多了  
作者: 剑啸寒    时间: 2016-1-9 18:36

加油啊!偶一定会追随你左右,偶坚定此贴必然会起到抛砖引玉的作用~  
作者: 昕昕    时间: 2016-1-21 09:35

谢谢分享了!  
作者: bluesuns    时间: 2016-1-28 17:17

支持一下吧  
作者: 干细胞2014    时间: 2016-2-16 08:35

鉴定完毕.!  
作者: Whole    时间: 2016-2-21 15:35

不对,就是碗是铁的,里边没饭你吃啥去?  
作者: abc987    时间: 2016-3-4 08:43

今天没事来逛逛  
作者: tuting    时间: 2016-3-15 11:43

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: yunshu    时间: 2016-4-22 12:09

给我一个女人,我可以创造一个民族;给我一瓶酒,我可以带领他们征服全世界 。。。。。。。。。  
作者: 龙水生    时间: 2016-5-1 12:18

水至清则无鱼,人至贱则无敌!  
作者: qibaobao    时间: 2016-5-10 20:18

你还想说什么啊....  
作者: pengzy    时间: 2016-5-25 17:43

希望大家帮我把这个帖发给你身边的人,谢谢!  
作者: wq90    时间: 2016-5-30 18:47

好啊,谢楼主
作者: xiao2014    时间: 2016-6-11 20:54

干细胞之家是国内最好的干细胞网站了
作者: 三星    时间: 2016-6-20 13:35

初来乍到,请多多关照。。。  
作者: ringsing    时间: 2016-6-22 10:27

我该不会是最后一个顶的吧  
作者: ringsing    时间: 2016-6-26 00:51

我的啦嘿嘿  
作者: 黄山    时间: 2016-7-30 10:26

病毒转染干细胞
作者: 知足常乐    时间: 2016-8-3 10:54

心脏干细胞
作者: vsill    时间: 2016-8-3 15:34

挤在北京,给首都添麻烦了……  
作者: 苹果天堂    时间: 2016-8-7 13:06

免疫细胞治疗  
作者: 昕昕    时间: 2016-8-10 23:35

写得好啊  
作者: 安安    时间: 2016-8-18 16:10

干细胞我这辈子就是看好你
作者: 小倔驴    时间: 2016-9-27 14:10

帮你顶,人还是厚道点好  
作者: 甘泉    时间: 2016-12-7 14:27

转基因动物
作者: happyboy    时间: 2017-1-15 11:17

勤奋真能造就财富吗?  
作者: 坛中酒    时间: 2017-1-26 16:01

我喜欢这个贴子  
作者: foxok    时间: 2017-2-3 20:33

强人,佩服死了。呵呵,不错啊  
作者: dglove    时间: 2017-2-23 12:43

每天早上起床都要看一遍“福布斯”富翁排行榜,如果上面没有我的名字,我就去上班……  
作者: chongchong    时间: 2017-3-3 09:02

真是汗啊  我的家财好少啊  加油  
作者: 石头111    时间: 2017-3-20 11:18

看或者不看,贴子就在这里,不急不忙  
作者: yunshu    时间: 2017-3-30 10:27

不错不错.,..我喜欢  
作者: immail    时间: 2017-4-26 00:16

做对的事情比把事情做对重要。  
作者: vsill    时间: 2017-5-4 04:26

干细胞之家
作者: xm19    时间: 2017-6-2 10:27

干细胞研究非常有前途
作者: 生科院    时间: 2017-6-16 05:00

间充质干细胞
作者: 老农爱科学    时间: 2017-6-20 23:18

文笔流畅,修辞得体,深得魏晋诸朝遗风,更将唐风宋骨发扬得入木三分,能在有生之年看见楼主的这个帖子。实在是我三生之幸啊。  
作者: 知足常乐    时间: 2017-6-25 15:10

不错不错,我喜欢看  
作者: biobio    时间: 2017-6-26 15:27

几头雾水…  
作者: dd赤焰    时间: 2017-6-29 23:41

在线等在线等  
作者: Kuo    时间: 2017-7-24 04:22

干细胞与基因技术
作者: foxok    时间: 2017-7-26 02:26

其实回帖算是一种没德德,所以我快成圣人了  
作者: 小敏    时间: 2017-8-2 20:11

不错不错,我喜欢看  
作者: 修复者    时间: 2017-8-3 05:41

人气还要再提高  
作者: qibaobao    时间: 2017-8-5 08:01

怎么就没人拜我为偶像那?? ~  
作者: marysyq    时间: 2017-8-6 02:54

顶顶更健康,越顶吃的越香。  
作者: 20130827    时间: 2017-8-24 23:59

不错,感谢楼主
作者: 龙水生    时间: 2017-8-25 07:54

强人,佩服死了。呵呵,不错啊  
作者: tuting    时间: 2017-8-25 19:01

不错啊! 一个字牛啊!  
作者: cjms    时间: 2017-9-2 23:27

楼上的话等于没说~~~  
作者: 黄山    时间: 2017-9-5 16:18

造血干细胞
作者: bioprotein    时间: 2017-9-20 19:35

我的妈呀,爱死你了  
作者: 小丑的哭泣    时间: 2017-9-21 13:18

又看了一次  
作者: keanuc    时间: 2017-10-13 09:27

好帖,有才  
作者: IPS干细胞    时间: 2017-10-14 23:00

羊水干细胞
作者: mk990    时间: 2017-10-25 20:01

要不我崇拜你?行吗?  
作者: mk990    时间: 2017-11-7 07:31

好 好帖 很好帖 确实好帖 少见的好帖  
作者: 水木清华    时间: 2017-11-8 21:12

21世纪,什么最重要——我!  
作者: xuguofeng    时间: 2017-11-18 06:52

先看看怎么样!  
作者: alwaysniu    时间: 2017-11-27 15:35

这贴子你会收藏吗  
作者: Kuo    时间: 2017-12-2 16:27

站个位在说  
作者: 陈晴    时间: 2017-12-28 10:54

只有一条路不能选择——那就是放弃的路;只有一条路不能拒绝——那就是成长的路。  
作者: aliyun    时间: 2017-12-29 14:43

青春就像卫生纸。看着挺多的,用着用着就不够了。  
作者: foxok    时间: 2017-12-29 23:35

我是来收集资料滴...  
作者: mk990    时间: 2018-1-6 19:18

赚点分不容易啊  
作者: nosoho    时间: 2018-1-13 06:07

ding   支持  
作者: 狂奔的蜗牛    时间: 2018-1-13 07:49

不错不错.,..我喜欢  
作者: 老农爱科学    时间: 2018-1-15 17:36

好人一个  
作者: 安安    时间: 2018-1-17 18:14

貌似我真的很笨????哎  
作者: dr_ji    时间: 2018-1-28 02:59

说的不错  
作者: pengzy    时间: 2018-2-3 12:41

站个位在说  
作者: 小丑的哭泣    时间: 2018-2-12 17:33

几头雾水…  
作者: 咖啡功夫猫    时间: 2018-2-18 03:55

感謝樓主 干细胞之家真的不错  
作者: 加菲猫    时间: 2018-2-21 22:48

厉害!强~~~~没的说了!  
作者: frogsays    时间: 2018-3-7 23:40

神经干细胞
作者: frogsays    时间: 2018-3-12 01:34

dc-cik nk  
作者: 蚂蚁    时间: 2018-3-20 19:39

感觉好像在哪里看过了,汗~  
作者: nauticus    时间: 2018-3-27 12:01

心脏干细胞
作者: beautylive    时间: 2018-4-11 20:29

不错啊! 一个字牛啊!  
作者: abc987    时间: 2018-4-16 13:18

加油啊!!!!顶哦!!!!!  
作者: 生物小菜鸟    时间: 2018-4-22 19:53

说嘛1~~~想说什么就说什么嘛~~  
作者: sshang    时间: 2018-4-25 06:37

初来乍到,请多多关照。。。  
作者: 旅美学者    时间: 2018-5-1 03:20

严重支持!
作者: tian2006    时间: 2018-5-7 11:54

呵呵 哪天得看看 `~~~~  
作者: 苹果天堂    时间: 2018-5-17 06:44

原来是这样  
作者: 榴榴莲    时间: 2018-5-27 18:53

真的有么  
作者: 3344555    时间: 2018-5-29 08:11

肌源性干细胞
作者: 8666sea    时间: 2018-6-6 22:30

回贴赚学识,不错了  
作者: 锦锦乐道    时间: 2018-6-14 09:18

神经干细胞




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