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所谓诱导多潜能干细胞疾病模型(disease-specific iPSCs)的潜在意义和动力是多方面的。生物医学和临床医学传统上采用动物模型来研究各种疾病的病理改变和疾病机制，但动物本身与人类之间存在
- O E+ a3 }& F, o的生物学差异使得很多疾病状态无法很好地用动物模型来模拟，换句话说，动物模拟的一些疾病状态结果无法直接用于人体临床。自有胚胎干细胞后，人们在设法利用胚胎干细胞的多潜能分化特性，来获得某种疾病的表型。但胚胎干细胞的来源有限以及疾病表型诱发是个难题。而iPSC技术提供了直接从患者获得所需的研究材料的手段，所获得的疾病多潜能干细胞及其终端分化细胞可以被用来研究疾病病理机制，药物筛选，药物安全性检验，以及个体化地选择治疗方案，甚至可能采用修复技术矫正疾病状态，获得所需的靶细胞用于治疗相关疾病。% O4 [9 S( E$ ~5 k" h
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从广义的角度来看，从患者获得的iPSC都具有潜在的疾病原型态，即使是无明显疾病的个体来源的iPSC，也可能受到机体特定状况如衰老程度和组织细胞状态（基因变异、表观遗传状态、端粒及端粒酶状况，甚至能量供应的--体的状态）的影响。因此，理论上可以把任何成体来源的iPSC当作某种“疾病特异性iPSC”。因此，除具有明确疾病表型的iPSC可用于疾病病理研究和药物筛选外，着眼于细胞移植的iPSC系都应该经过严格的“病检”或“健康检查”。至于体外技术如诱导手段和体外条件带来的负面变化，则属于外源性影响。例如，近来多项研究从不同角度发现“正常”iPSC系具有复杂的基因谱系和表观遗传改变，其原因除了体外诱导技术的作用外，也需要排除细胞源性因素。目前还做不到这一点。从这个意义上来说，诱导多潜能疾病干细胞是iPSC的最基本内容。iPSC细胞移植前景模糊，iPSC疾病模型不仅是个iPSC研究的必然转折，其实也是iPSC最终价值证明的必然途径。
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狭义上的疾病iPSC系是指从患有特定疾病的患者获得具有疾病表型的iPSC及其分化细胞，或者说从具有明确遗传基因异常原因的疾病患者体细胞获得的iPSC及其分化细胞，用于模拟该疾病的病理表现和过程。这个技术涉及特定疾病的遗传特性，细胞来源，iPSC本身的疾病表型，分化靶细胞的疾病表型，是否有外源性影响，分化效率，药物作用效应等方面。$ Q7 e1 x& j3 G* J( Y9 [
- g, v0 ?* a4 F. D$ n2 J从iPSC重编程研究的发展历程来看，除培养和诱导技术仍有很大发展和优化空间外，重编程的真正机制仍没有成型的轮廓，尤其是iPSC被证明带有自身的印记，与胚胎干细胞代表的真正naive状态仍有差距或者干脆属于两种不同的现象，尤其是从多种角度来看iPSC的成瘤性是一个巨大的障碍。因此，iPSC作为细胞治疗的来源广泛应用于临床的前景还很渺茫。在这种情况下，除了作为一种重编程的研究工具和平台外，最接近应用的方向就是所谓疾病iPSC了。这大概也是为什么去年至今iPSC最多的“突破”是在建立各种疾病多潜能干细胞系方面。% B3 H, p f6 Q
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从2008年始至今，关于疾病iPSC模型的发表的研究约有20多篇，涉及神经系统、血液系统、心血管、糖尿病、肝病等多种疾病类型，以及精神分裂症、多种遗传疾病。这些研究可以从一个基本研究框架上来分析各自的研究深度：疾病种类及病理、细胞来源、诱导技术（病毒整合，是否改变细胞表型或影响分化和疾病特征）、iPSC质量与是否带有疾病表型、是否分化为疾病组织细胞、分化细胞是否复制疾病表型、是否检验药物效应、是否解析疾病病理机制等。
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目前所发表的研究涉及的疾病种类以及研究手段比较多样，故就上述指标对每项研究结果做一简略的总结，以便对这个听起来简单而涵盖很广的方向能有一个轮廓的认识和初步的把握。方便起见，只列出了通讯作者及其单位，发表的期刊信息以及文章概述有关研究结果的部分信息。本文总结的一些信息取自原文，省略了一些遗传信息相关以及技术操作细节。
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$ C, J6 ^$ b6 T6 A2 |3 ~' ^（肌萎缩侧索硬化）Induced Pluripotent Stem Cells Generated from Patients with ALS Can Be Differentiated into Motor Neurons
9 i7 w# u" g0 s8 W29 AUGUST 2008 VOL 321 SCIENC Kevin Eggan，Harvard University: J+ O# ^ Z' C: |8 \0 `) q, k
...We have generated iPS cells from an 82-year-old woman diagnosed with a familial form of amyotrophic lateral sclerosis (ALS). These patient-specific iPS cells possess properties of embryonic stem cells and were successfully directed to differentiate into motor neurons, the cell type destroyed in ALS.
# O* h: d) F) aALS患者皮肤成纤维细胞诱导iPSC并分化为运动神经元，首次证明“高龄和疾病状态并不影响iPSC诱导和终端细胞分化”，“绕过了核移植和胚胎干细胞来源的疾病细胞系所面临的技术和伦理障碍”。没有报告iPSC或运动神经元的疾病表型。这是一篇发表最早的“疾病iPSC”文章。
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（多种遗传疾病）Disease-Specific Induced Pluripotent Stem Cells
- x5 }9 v3 L7 E* w4 mCell 134, 877–886, September 5, 2008；George Q. Daley，Children's Hospital Boston,Harvard Medical School
3 ?. _6 q; o- ^8 w% Z: ?/ X2 ~! x/ @...Here we describe the generation of induced pluripotent stem (iPS) cells from patients with a variety of genetic diseases with either Mendelian or complex inheritance;these diseases include adenosine deaminase deficiency-related severe combined immunodeficiency (ADA-SCID), Shwachman-Bodian-Diamond syndrome (SBDS), Gaucher disease (GD) type III,Duchenne (DMD) and Becker muscular dystrophy (BMD), Parkinson disease (PD), Huntington disease (HD), juvenile-onset, type 1 diabetes mellitus (JDM),Down syndrome (DS)/trisomy 21, and the carrier state of Lesch-Nyhan syndrome. Such disease-specific stem cells offer an unprecedented opportunity to recapitulate both normal and pathologic human tissue formation in vitro, thereby enabling disease investigation and drug development.( x8 W# M% @/ O
这篇研究包括了10种单基因显性遗传病和复杂遗传疾病的iPSC系（成纤维细胞或骨髓间充质干细胞），其中iPSC疾病表型鉴定结果有三：Down Syndrome来源的iPSC在数次传代中表现出异常核型；
& ]+ V* r/ a7 Y* Y3 k1 E* X" V9 gShwachman-Bodian-Diamond syndrome，ADA and GBA诱导iPSC具有与来源细胞相同的遗传疾病表型；Duchenne (DMD) or Becker type muscular dystrophy (BMD)以及Huntington disease (HD)诱导iPSC表现出某些遗传疾病表型。该作者说他们还获得了PD和糖尿病iPSC，但不合适用来分析。作者认为这个一堆疾病iPSC诱导研究的最大价值是证明Mendelian or complex inheritance疾病都可以产生iPSC。该研究没有将所获得的疾病iPSC分化为靶细胞进一步研究。( i. i2 d& [" J* \
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（脊髓性肌萎缩症）Induced pluripotent stem cells from a spinal muscular atrophy patient, M+ G( l3 l1 G$ l2 G a" t
Nature Vol 457| 15 January 2009，Clive N. Svendsen，The Stem Cell and Regenerative Medicine Center, University of Wisconsin-Madison' n+ ]- A# m% m; N: o z8 |
...Here we report the generation of induced pluripotent stem cells from skin fibroblast samples taken from a child with spinal muscular atrophy. These cells expanded robustly in culture, maintained the disease genotype and generated motor neurons that showed selective deficits compared to those derived from the child's unaffected mother. This is the first study to show that human induced pluripotent stem cells can be used to model the specific pathology seen in a genetically inherited disease. As such, it represents a promising resource to study disease mechanisms, screen new drug compounds and develop new therapies.& Q: D7 k9 f5 h6 ^# `
皮肤成纤维细胞诱导iPSC，初期可以分化为运动神经元，但后期呈现运动神经元退化。神经突触相关指标弱。源成纤维细胞以及诱导iPSC均缺乏nuclear gems，valproic acid and tobramycin可显著增
' \1 |/ g' j1 D5 `+ y& g1 G) v) T+ Z0 ~加nuclear gems，2-3倍的SMN蛋白水平提高。研究这正在（文章发表时）检测疾病iPSC分化运动神经元的nuclear gem 成型过程。SMA具有复杂的全身病理改变，导致运动神经元病变，iPS疾病模型可以用来研究这一过程。
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（帕金森病）Parkinson's Disease Patient-Derived Induced Pluripotent Stem Cells Free of Viral Reprogramming Factors+ F& U1 T$ M) w+ `
Cell 136, 964–977, March 6, 2009，Rudolf Jaenisch, The Whitehead Institute, Cambridge Center, MIT
) C6 F8 q7 D& j0 c...Here, we show that fibroblasts from five patients with idiopathic Parkinson's disease can be efficiently reprogrammed and subsequently differentiated into dopaminergic neurons. Moreover, we derived hiPSCs free of reprogramming factors using Cre-recombinase excisable viruses. Factor free hiPSCs maintain a pluripotent state and show a global gene expression profile, more closely related to hESCs than to hiPSCs carrying the transgenes. Our results indicate that residual transgene expression in virus-carrying hiPSCs can affect their molecular characteristics and that factor-free hiPSCs therefore represent a more suitable source of cells for modeling of human disease.
7 E( R& Z# [7 ~) n" f帕金森病人成纤维细胞诱导iPSC，采用Cre-recombinase excisable viruses，residual transgene expression in virus-carrying hiPSCs can affect their molecular characteristics+ T3 M+ b( }7 q) G
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（范可尼贫血）Disease-corrected haematopoietic progenitors from Fanconi anaemia induced pluripotent stem cells7 o; |0 V1 }% R+ X
Nature Published online 31 May 2009，Juan Carlos Izpisua Belmonte1, Gene Expression Laboratory, Salk Institute for Biological Studies
& L8 f6 D# I {8 K- L# O$ z...Here we show that, on correction of the genetic defect, somatic cells from Fanconi anaemia patients can be reprogrammed to pluripotency to generate patient-specific iPS cells. These cell lines appear indistinguishable from human embryonic stem cells and iPS cells from healthy individuals. Most importantly, we show that corrected Fanconi-anaemia-specific iPS cells can give rise to haematopoietic progenitors of the myeloid and erythroid lineages that are phenotypically normal, that is, disease-free. These data offer proof-of-concept that iPS cell technology can be used for the generation of disease-corrected, patient-specific cells with potential value for cell therapy applications.
, b" S5 Y, u$ Y& B! A# `' }+ O病人的皮肤细胞，基因矫正后诱导为iPSC，然后分化为造血前体细胞。无基因整合与oncogene(C-Myc)，效率有限，似乎与来源细胞的传代数有关。其潜在意义在于，临床目前的造血干细胞基因改造技术治疗FA的临床结果不好，体细胞基因矫正后诱导分化为造血干细胞移植可能开辟一条新路。4 i& |4 K1 I' ~
' ]$ p1 v4 z- ` c6 O. @0 G（家族性自主神经失调综合征）Modelling pathogenesis and treatment of familial dysautonomia using patient-specific iPSCs
' N- u4 d* l w9 U$ ?4 vNature Published online 19 August 2009. Lorenz Studer, Sloan-Kettering Institute, NY" \' e6 D; x6 A+ R3 I% {
...Here we report the derivation of patient-specific FD-iPSCs and the directed differentiation into cells of all three germ layers including peripheral neurons. Gene expression analysis in purified FD-iPSC-derived lineages demonstrates tissue specific mis-splicing of IKBKAP in vitro. Patient-specific neural crest precursors express particularly low levels of normal IKBKAP transcript, suggesting a mechanism for disease specificity. FD pathogenesis is further characterized by transcriptome analysis and cell-based assays revealing marked defects in neurogenic differentiation and migration behaviour. Furthermore, we use FDiPSCs for validating the potency of candidate drugs in reversing aberrant splicing and ameliorating neuronal differentiation and migration. Our study illustrates the promise of iPSC technology for gaining new insights into human disease pathogenesis and treatment./ a- k, l" f- t, A& r
患者成纤维细胞诱导iPSCs本身具有疾病表型，20种降低的transcripts与外周神经生长和神经细胞分化有关；疾病iPSC分化为神经crest前体细胞潜能降低；迁移率降低；早期iPS阶段连续给药显著提高
, p8 B* U9 ]6 V. [- O9 S+ M分化为神经元的比例，以及关键外周神经标记的表达水平。对疾病机制有所贡献。
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' n- X. [" C$ l# f) n j（I型糖尿病）Generation of pluripotent stem cells from patients with type 1 diabetes! c9 D& C& k& b$ Y9 L
PNAS September 15, 2009 vol.106 no. 37，Douglas A. Meltona, Harvard Stem Cell Institute, Harvard University) h, b% Y4 ?' U: S5 ]. \& h
...We show here that induced pluripotent stem (iPS) cells can be generated from patients with T1D by reprogramming their adult fibroblasts with three transcription factors (OCT4, SOX2, KLF4). T1D-specific iPS cells, termed DiPS cells, have the hallmarks of pluripotency and can be differentiated into insulin-producing cells. These results are a step toward using DiPS cells in T1D disease modeling, as well as for cell replacement therapy.
# h0 x1 Q2 F0 }/ p8 ?( z成纤维细胞诱导iPS，三因子，分化为胰岛素产生细胞，可分泌胰岛素，对血糖浓度有反应。下一步诱导免疫相关iPS，然后构建体外互动模型，研究病理机制。5 G+ @% J$ ]: s* N
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（获得性血液病）Human-induced pluripotent stem cells from blood cells of healthy donors and patients with acquired blood disorders
0 @" Q$ N; D( a( {+ V; U$ ], BBLOOD, 24 DECEMBER 2009 VOLUME 114, NUMBER 27，Linzhao Cheng，Johns Hopkins University School of Medicine' |! O: `/ v2 P6 e- x6 w' V
...Here we report derivation of iPS cells from postnatal human blood cells and the potential of these pluripotent cells for disease modeling. MultiplehumaniPS cell lines weregenerated from previously frozen cord blood or adult CD34+ cells of healthy donors, and could be redirected to hematopoietic differentiation. Multiple iPS cell lines were also generated from peripheral bloodCD34+ cells of 2 patients with myeloproliferative disorders (MPDs) who acquired the JAK2-V617F somatic mutation in their blood cells. The MPD-derived iPS cells containing the mutation appeared normal in phenotypes, karyotype, and pluripotency. After directed hematopoietic differentiation, the MPD-iPS cell-derived hematopoietic progenitor (CD34+CD45+) cells showed the increased erythropoiesis and gene expression of specific genes, recapitulating features of the primary CD34+cells of the corresponding patient from whom the iPS cells were derived. These iPS cells provide a renewable cell source and a prospective hematopoiesis model for investigating MPD pathogenesis.
( z7 z$ {1 f) l5 O8 d6 _5 u* D比较脐带血和成体血细胞、患者CD34+血细胞来源iPSCs形态、核型和多潜能正常，分化为造血前体细胞（CD34+和CD45+），表现出患者原CD34+ 细胞的特定基因表达以及红细胞增发性。局限，单基因对多表型疾病，需要不同细胞（带有和不带有JAK2-V617F变异的细胞）诱导iPS及分化细胞，与正常人比较。 4 N% `) f1 b7 n+ G- i' O1 X9 p* T
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（先天性角化不全症）Telomere elongation in induced pluripotent stem cells from dyskeratosis congenita patients
3 P% }7 N5 m& HNature Published online 17 February 2010，George Q. Daley，Children's Hospital Boston，Harvard Medical School+ M5 `. N5 m# s& m6 D3 S+ K
...We investigated whether defects in telomerase function would limit derivation and maintenance of iPS cells from patients with DC. Here we show that reprogrammed DC cells overcome a critical limitation in telomeraseRNAcomponent (TERC) levels to restore telomere maintenance and self-renewal. We discovered that TERC upregulation is a feature of the pluripotent state, that several telomerase components are targeted by pluripotencyassociated transcription factors, and that in autosomal dominant DC, transcriptional silencing accompanies a 39 deletion at the TERC locus. Our results demonstrate that reprogramming restores telomere elongation in DC cells despite genetic lesions affecting telomerase, and show that strategies to increase TERC expression may be therapeutically beneficial in DC patients.
: q5 D4 O- N; @2 @! c2 p, JDC患者DKC1 mutant fibroblast line诱导为iPS，效率降低，但具有多潜能性，带有del37L mutation，证明端粒缩短的细胞仍可以诱导为iPSC。初期iPSC端粒缩短，但可以长期传代，加 TERC and TERT可恢复端粒长度。表明重编程伴有内源性TERC水平上调，可能是iPSC诱导过程端粒延长和无限制自我更新的一个机制。这是第一次报导诱导多潜能性可延长端粒，并提示其复杂机制。$ q) I& b% C9 G$ p Z3 p
/ {9 D2 k% q6 y/ I2 z（豹皮综合征）Patient-specific induced pluripotent stem-cell-derived models of LEOPARD syndrome
, ~ ^4 j$ _& }: h$ A* pNature Vol 465，10 June 2010，Ihor R. Lemischka，Mount Sinai School of Medicine, New York3 ?; @5 Z# ]5 \) r+ s9 u
...We have generated iPSCs from patients with LEOPARD syndrome (an acronym formed from its main features; that is, lentigines, electrocardiographic abnormalities, ocular hypertelorism, pulmonary valve stenosis, abnormal genitalia, retardation of growth and deafness), an autosomal-dominant developmental disorder belonging to a relatively prevalent class of inherited RAS–mitogen-activated protein kinase signalling diseases, which also includes Noonan syndrome, with pleomorphic effects on several tissues and organ systems1,2. The patient-derived cells have a mutation in the PTPN11 gene, which encodes the SHP2 phosphatase. The iPSCs have been extensively characterized and produce multiple differentiated cell lineages. A major disease phenotype in patients with LEOPARD syndrome is hypertrophic cardiomyopathy. We show that in vitro-derived cardiomyocytes from LEOPARD syndrome iPSCs are larger, have a higher degree of sarcomeric organization and preferential localization of NFATC4 in the nucleus when compared with cardiomyocytes derived from human embryonic stem cells or wild-type iPSCs derived from a healthy brother of one of the LEOPARD syndrome patients. These features correlate with a potential hypertrophic state. We also provide molecular insights into signalling pathways that may promote the disease phenotype.# {: v& f7 z! Y8 R, _4 u
成纤维细胞诱导，经典四因子反转录病毒，iPSC具有PTPN11基因变异。疾病iPSC分化的心肌细胞呈现典型病理性增大，sarcomeric结构，以及被证明与心肌肥大病理相关的NFATC4倾向性核位置。病理机制探索，该研究发现MEK1是病理性上调的phosphoproteins之一，其下游是ERK1/2, 而心肌肥大相关疾病的ERK1/2基因有变异。6 a* K: n' R1 d: z
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（1型先天性QT间歇延长综合症）Patient-Specific Induced Pluripotent Stem- Cell Models for Long-QT Syndrome1 b8 o" \* Z( B( r0 U8 ?
July 21, 2010, N Engl J Med，Karl-Ludwig Laugwitz, Klinikum rechts der Isar, Technical University of Munich
) X" A6 N: |, K...We generated patient-specific pluripotent stem cells from members of a family affected by long-QT syndrome type 1 and induced them to differentiate into functional cardiac myocytes. The patient-derived cells recapitulated the electrophysiological features of the disorder. - }: f' B" v- N, i! `; R
患者注意力缺陷临床检查发现先天性QT间歇延长症基因变异，家族基因检测发现遗传变异，父亲和儿子无症状，其他成员有可能的相关症状。无症状的父亲和儿子皮肤成纤维细胞为来源，经典四因子诱导为iPSC，两个健康对照iPSC。患者皮肤成纤维细胞与诱导iPSC均表现出KCNQ1基因变异。分化为心肌细胞（心室、心房样）具有疾病表型，即延长的QT和延缓的重新极化。KCNQ1 protein表达类型分析，R190Q-KCNQ1主要表达于细胞内，呈现蛋白转移障碍，不能转运到细胞膜表面。单细胞电生理分析，钾离子浓度降低。channel阻断实验证明Iks current densities降低，以及其他电生理常，表明存在特定的genotype–phenotype 相关性。肾上腺激素刺激实验提示，疾病iPSC分化的心肌细胞对肾上腺刺激反应降低的缺陷的原因是上述Iks current异常，加重疾病病理并增加心律失常的风险。而beta阻断剂预处理，可以消除上述肾上腺激素刺激引起的疾病iPSC分化心肌细胞的心动过缓性心率失常。
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+ N/ R4 O+ G' i" B（肝脏代谢疾病）Modeling inherited metabolic disorders of the liver using human induced pluripotent stem cells* y3 v; L, Y( d& G, u' N& _
The Journal of Clinical Investigation Volume 120 Number 9 September 2010，Ludovic Vallier1，Cambridge Institute for Medical Research, University of Cambridge,+ l' K- k5 @! `! E
...Here, we examined the use of human iPS cells for modeling inherited metabolic disorders of the liver. Dermal fibroblasts from patients with various inherited metabolic diseases of the liver were used to generate a library of patient-specific human iPS cell lines. Each line was differentiated into hepatocytes using what we believe to be a novel 3-step differentiation protocol in chemically defined conditions. The resulting cells exhibited properties of mature hepatocytes, such as albumin secretion and cytochrome P450 metabolism. Moreover, cells generated from patients with 3 of the inherited metabolic conditions studied in further detail (α1-antitrypsin deficiency, familial hypercholesterolemia, and glycogen storage disease type 1a) were found to recapitulate key pathological features of the diseases affecting the patients from which they were derived, such as aggregation of misfolded α1-antitrypsin in the endoplasmic reticulum, deficient LDL receptor–mediated cholesterol uptake, and elevated lipid and glycogen accumulation.
, t/ b* ~" f P- c2 g+ a9 W五种肝脏疾病八名患者多个iPSC系，部分分化为肝细胞。其中，A1ATD具有特定细胞部位 α1-antitrypsin polymers堆积，并具有患者特异性（患者之间有差异），添加特定蛋白降解阻断剂可导致 α1
( @7 ^2 F1 v' m$ d-antitrypsin polymers升高，提示可作药物筛选模型；FH细胞系具有LDL receptor缺陷特征，即整合LDL的能力受损；GSD1a细胞系表现出细胞内glycogen堆积增高，lipid过度积累以及lactic acid产生
7 Q" p" }/ J( k! z z& E$ d1 F6 y3 J过多，glucagon刺激后具有3种canonical glucagon-responsive genes表达。证明某种疾病表型与疾病病理反应之间的联系。. Y: j, u8 d" W% u- Q5 w
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（肝脏疾病）Generation of Liver Disease-Specific Induced Pluripotent Stem Cells Along with Efficient Differentiation to Functional Hepatocyte-Like Cells
5 X' t5 f/ t6 }9 tStem Cell Rev and Rep 7 September 2010，Hossein Baharvand，University of Science and Culture, ACECR, Tehran, Iran
- k5 \" z4 h" \& V5 @...Here we report, for the first time, the derivation of iPSCs by the retroviral transduction of Yamanaka's factors in serum and feeder-free culture conditions from liver-specific patients with tyrosinemia, glycogen storage disease, progressive familial hereditary cholestasis, and two siblings with Crigler-Najjar syndrome. Furthermore, they were differentiated into functional hepatocyte-like cells efficiently. These iPSCs possessed properties of human embryonic stem cells (hESCs) and were successfully differentiated into three lineages that resembled hESC morphology, passaging, surface and pluripotency markers, normal karyotype, DNA methylation, and differentiation. The hepatic lineage-directed differentiation showed that the iPSC-derived hepatic cells expressed hepatocyte-specific markers. Their functionality was confirmed by glycogen and lipid storage activity, secretion of albumin, alphafetoprotein, and urea, CYP450 metabolic activity, as well as LDL and indocyanin green uptake.
& |6 h! ?" z7 o; k1 I y四种肝脏疾病五个患者的iPSC，经典四因子，分化为肝样细胞，具有一些肝功能指标。这篇伊朗科学家的期刊比上述The Journal of Clinical Investigation的肝病iPSC期刊早两天，号称第一。! @ C' z) A1 J7 m0 n
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（普拉德-威利综合征）Induced Pluripotent Stem Cells Can Be Used to Model the Genomic Imprinting Disorder Prader-Willi Syndrome
& W' i- K2 m) m$ ZJBC，Published on October 18, 2010，Duanqing Pei and Miguel A. Esteban1，Guangzhou Institutes of Biomedicine and Health, Chinese, Academy of Sciences, Guangzhou
: F# Z+ S# {# u& V7 y...Here we describe the generation of iPSCs from a patient with Prader-Willi syndrome bearing a partial translocation of paternally expressed chromosome 15q11-q13 region to chromosome. The resulting iPSCs match all standard criteria of bona fide reprogramming and could be readily differentiated into tissues derived from the 3 germ layers including neurons. Moreover, these iPSC retain high level of DNA methylation in the imprinting center of the maternal allele and show concomitant reduced expression of the disease-associated small nucleolar RNA HBII-85/SNORD116. These results indicate that iPSCs may be a useful tool to study Prader-Willi syndrome and perhaps other genetic imprinting diseases as well.
: l4 D7 V+ f% ?5 T4 F3 u- r: _2 T+ ]印记基因疾病是否可以iPSC手段模拟以前有争议。Prader-Willi Syndrome具有父系染色体15q11-q13 region在四号染色体上的部分易位。本研究购得病人成纤维细胞，诱导为iPSC，检查maternal DNA methylation pattern，提示与正常来源iPSC相似。疾病iPSC具有SNORD116（translocation 区域存在的snoRNA）不充分表达，并可以分化为该疾病主要受影响的神经细胞，证明PWS iPSC可以用于模拟该疾病，就是说证明印记基因疾病也可以用iPSC模拟。. ~0 E4 a$ x. O/ t& w V
5 R( \+ P- E$ _* Y3 N- e（亨廷顿舞蹈症）Characterization of Human Huntington's Disease Cell Model from Induced Pluripotent Stem Cells
' [! @# d/ |' [# e) L# I% ?/ X- dPLoS Curr. 2010 October 28，Lisa M. Ellerby，Buck Institute for Age Research and Stanford University Medical School
) e6 ?8 s& ?' @: T8 A4 Y3 C+ ~- J* N...We utilized the recently established human iPS cell line derived from HD patient fibroblasts to derive neuronal precursors and human striatal neurons. To achieve this goal, the differentiation of the HD-iPS cells into striatal fate required several steps. First, we generated nestin+/PAX6+/SOX1+/OCT4- neural stem cells (NSCs) from HD-iPS cells using the method of embryoid body formation. HD-NSCs were then subjected to a differentiation condition combining morphogens and neurotrophins to induce striatal lineage commitment. Striatal neuronal precursors/immature neurons stained with β-III tubulin, calbindin and GABA but not DARPP-32 (dopamine- and cyclic AMP-regulated phosphoprotein, Mr = 32,000) were produced in this step. Finally, maturation and terminal differentiation of the striatal neuronal precursors/immature neurons resulted in striatal neurons expressing markers like DARPP-32. The HD-iPS cells derived striatal neurons and neuronal precursors contain the same CAG expansion as the mutation in the HD patient from whom the iPS cell line was established. Moreover, the HD-NSCs showed enhanced caspase activity upon growth factor deprivation compared to normal NSCs (from iPS or H9 NSCs).
1 ]3 [. q! K. C4 Y* I$ j前述2008年Daley的研究其中已有Huntington iPSC诱导成功报道，据说具有疾病表型（未发表资料）。本研究利用了Daley的Huntington病iPSC系分化为神经干细胞，将神经干细胞再分化为纹状体神经元。疾病iPSC，分化神经干细胞以及再分化纹状体神经元均具有 72 CAG repeats，与患者成纤维细胞相同。生长因子去除导致疾病神经干细胞caspase-3/7 activity活跃，意味着细胞毒性增大。这个研究可以看作是Deley诱导HD-iPS结果的进一步再分化及部分疾病表型验证。
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（弗里德赖希氏共济失调）Friedreich's Ataxia Induced Pluripotent Stem Cells Model Intergenerational GAA,TTC Triplet Repeat Instability+ J& A s5 L& D( l4 o
Cell Stem Cell 7, 631–637, November 5, 2010，Joel M. Gottesfeld1，The Scripps Research Institute, La Jolla, CA& J1 R7 M) z; ^$ F1 K
...We report the derivation of induced pluripotent stem cells (iPSCs) from FRDA patient fibroblasts by transcription factor reprogramming. FXN gene repression is maintained in the iPSCs, as are the global gene expression signatures reflecting the human disease. GAA,TTC repeats uniquely in FXN in the iPSCs exhibit repeat instability similar to patient families, where they expand and/or contract with discrete changes in length between generations. The mismatch repair enzyme MSH2, implicated in repeat instability in other triplet repeat diseases, is highly expressed in pluripotent cells and" a& ~) y+ ~' z' n" b
occupies FXN intron 1, and shRNA silencing of MSH2 impedes repeat expansion, providing a possible molecular explanation for repeat expansion in FRDA.5 e: j+ ?: x, L9 ^8 T5 d. i
Friedreich’s ataxia患者成纤维细胞经典因子重编程为iPSC，global mRNA表达分析提示与疾病特征有关的一些基因谱系特点。FXN GAA,TTC repeats showed repeat instability in the iPSC lines，implicate the involvement of MSH2 in GAA,TTC repeat instability.一个例外，临床家族遗传表型只有母系pathogenic allele经历代际扩展，而父系不变。然而iPSC观察到母系和父系allele都扩展了，一个解释是双亲allele在体外重编程过程发生了同样的细胞水平变化，而在正常配子发育过程则是选择性的母系allele变化。提示iPSC重编程与正常发育过程的可能区别。
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（蕾特氏症）A Model for Neural Development and Treatment of Rett Syndrome Using Human Induced Pluripotent Stem Cells8 @3 [3 k& y0 F0 F0 m0 E
Cell 143, 527–539, November 12, 2010，Alysson R. Muotri2，University of California San Diego, School of Medicine
/ r3 Y- j. b7 E6 i+ c8 I% Q( t...Using Rett syndrome (RTT) as an ASD genetic model, we developed a culture system using induced pluripotent stem cells (iPSCs) from RTT patients' fibroblasts. RTT patients' iPSCs are able to undergo X-inactivation and generate functional neurons. Neurons derived from RTT-iPSCs had fewer synapses, reduced spine density, smaller soma size, altered calcium signaling and electrophysiological defects when compared to controls. Our data uncovered early alterations in developing human RTT neurons. Finally, we used RTT neurons to test the effects of drugs in rescuing synaptic defects. Our data provide evidence of an unexplored developmental window, before disease onset, in RTT syndrome where potential therapies could be successfully employed. Our model recapitulates early stages of a human neurodevelopmental disease and represents a promising cellular tool for drug screening, diagnosis and personalized treatment.) d8 e+ }; s% m3 _* K
作者认为本模型重现了RTT神经元早期发育过程，即X-inactivation在RTT-iPSC克隆重编程过程中被抹去，随后在神经元分化中恢复。并且，the recapitulation of X-inactivation produces mosaic
% M$ _3 d8 S x8 T* j; wneuronal cultures with different ratios of cells expressing normal MeCP2 levels, mimicking what is observed in RTT patients' brains。蕾特氏病有可能在个体发育早期发病之前存在神经突触兴奋强度异常，因此，在这个模型上的rescue努力，即提升MeCP2水平，增加神经突触等手段，有可能用于临床矫治早期无症状的蕾特氏病。蕾特氏病仍被认为属于自闭症谱系障碍类，因此作者认为本模式有可能在其他相关神经发育障碍疾病机理研究与药物筛选。! _7 s! Q- ?9 \% v/ f
, p: h! F0 ~% X" z（精神分裂症）Integration-free induced pluripotent stem cells derived from schizophrenia patients with a DISC1 mutation
$ x* r- j- p+ ?% GMolecular Psychiatry (2011), 1–3 G-I Ming，Johns Hopkins University School of Medicine
& O `' a% I1 z% [! D...this study presents the first iPSC lines derived from schizophrenia patients. In addition, it presents the first cases of generation of integration free iPSCs from adult patients using the episomal vector approach....These established iPSC lines from schizophrenia patients with a defined DISC1 mutation will provide a useful resource for investigating the function of DISC1 in human neurodevelopment...8 E6 ^/ Q8 T/ U' |% V
DISC1（Disrupted-in-Schizophrenia 1）基因变异家系精神分裂症患者皮肤成纤维细胞诱导为iPSC，具有与来源细胞同样的DISC1基因变异。该基因变异与精神分裂症、躁郁症及反复性严重抑郁症有关，被列为这些疾病的危险因素，然而机理不清。episomal vector approach曾被用于胎儿皮肤成纤维细胞诱导iPSC，本研究宣称该方法第一次用于成人病人iPS诱导成功。* @2 P2 E( h( [
" Q$ ?3 L @9 [% |( Z; _, u（早年衰老综合症）A Human iPSC Model of Hutchinson Gilford Progeria Reveals Vascular Smooth Muscle and Mesenchymal Stem Cell Defects
# k) X. ^1 c7 c' ~9 B* | p2 r. ACell Stem Cell 7 January 2011，Alan Colman，Stem Cell Disease Models, A*STAR Institute of Medical Biology, Singapore9 f( U8 m' T ? k
...To understand the underlying molecular pathology of HGPS, we derived induced pluripotent stem cells (iPSCs) from HGPS dermal fibroblasts. The iPSCs were differentiated into neural progenitors, endothelial cells, fibroblasts, VSMCs, and mesenchymal stem cells (MSCs). Progerin levels were highest in MSCs, VSMCs, and fibroblasts, in that order, with these lineages displaying increased DNA damage, nuclear abnormalities, and HGPS-VSMC accumulating numerous calponinstaining inclusion bodies. Both HGPS-MSC and-VSMC viability was compromised by stress and hypoxia in vitro and in vivo (MSC). Because MSCs reside in low oxygen niches in vivo, we propose that, in HGPS, this causes additional depletion of the MSC pool responsible for replacing differentiated cells lost to progerin toxicity.) X4 D' f- @0 q0 H8 L6 v
HGPS的死因之一为早熟性动脉硬化伴随血管平滑肌丧失，可能的病理机制是LMNA变异产生mutant lamin A, progerin，后者引发nuclear lamina结构、功能及完整性的破坏。临床患者尸检发现progerin
5 v+ H# r* b3 m) |存在于角质化细胞，血管平滑肌，皮肤成纤维细胞以及内皮细胞。本研究采用具有基因变异的患者皮肤成纤维细胞诱导为iPSC，表现出C-T mutation of the LMNA gene，证明progerin不影响细胞重编程。但iPSC中LaminA/C and Progerin Expression被沉默。分化过程伴随progerin表达，以间充质细胞最高，依次为血管平滑肌细胞，成纤维细胞，内皮细胞，神经前体细胞表达最低。与过去的研究和病理资料相符。培养条件下，分化成纤维细胞与原成纤维细胞具有类似表型和功能，分化的神经前体细胞与内皮细胞基本没有疾病表型和细胞病理功能表现。分化的间充质进一步分化为成骨细胞，成软骨细胞和成脂肪细胞，均显示核变形以及其他基因损害。间充质分化得来的血管平滑肌细胞表现类似的核变形以及其他相关病理特征。诱导分化的间充质、血管平滑肌细胞以及成纤维细胞在正常培养条件下呈现渐进性病理变化如progerin累积。将血管平滑肌细胞放在三种外源性应激（stress）条件下观察其进一步病理变化：低氧加去除培养基、低氧、反复电刺激（模拟体内收缩环境），均表现出相对高于非病理来源分化细胞的病理改变。采用间充质细胞移植于小鼠肢体缺血模型，正常对照间充质（父母来源）细胞可以大规模恢复供血，而疾病iPSC分化的间充质细胞几乎没有作用，原因似乎是疾病间充质细胞对缺氧加营养缺乏条件更敏感，消失更快。shRNAs拮抗方法降低progerin水平可恢复疾病iPSC分化的间充质细胞对缺氧和营养匮乏的抵抗力。提示间充质细胞在一定条件下作为治疗手段的价值。
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( e) Q1 X3 m' |1 D2 O7 p* Y（早年衰老综合症）Recapitulation of premature ageing with iPSCs from Hutchinson–Gilford progeria syndrome; c2 a4 c! X, R: a
Nature Published online 23 February 2011，Juan Carlos Izpisua Belmonte，Salk Institute for Biological Studies and Center for Regenerative Medicine in Barcelona
' Q) F9 X( n$ J+ E% B- N...Here we report the generationof inducedpluripotent stemcells (iPSCs) from fibroblasts obtained from patients with HGPS. HGPS-iPSCs show absence of progerin, and more importantly, lack the nuclear envelope and epigenetic alterations normally associated with premature ageing. Upon differentiation of HGPS-iPSCs, progerin and its ageingassociated phenotypic consequences are restored.Specifically,directed differentiation of HGPS-iPSCs to SMCs leads to the appearance of premature senescence phenotypes associated with vascular ageing. Additionally, our studies identify DNA-dependent protein kinase catalytic subunit (DNAPKcs, also known as PRKDC) as a downstream target of progerin. The absence of nuclear DNAPK holoenzyme correlates with premature as well as physiological ageing. Because progerin also accumulates during physiological ageing6,12,13, our results provide an in vitro iPSC-based model to study the pathogenesis of human premature and physiological vascular ageing.7 R, Z- J4 k: j- f, m
早老症患者成纤维细胞诱导iPSC，iPSC没有疾病表型即progerin，神经鞘以及表观遗传改变。iPSC分化为血管平滑肌内皮细胞后，出现progerin及其病理后果。各种progerin操控实验证明其作为各种疾病iPSC分化细胞早衰表型的关键因素。可以获得progerin改造后的iPSC，其progerin表达显著降低，分化为血管平滑肌内皮细胞后增殖潜能显著改善，下调细胞早衰相关的transcripts，分化为成纤维细胞后恢复正常核型和表观遗传特征。下游机制分析揭示deficiency of the DNAPK holoenzymemay 构成早衰以及生理性衰老的新指标。作者认为本研究结果对早衰疾病和正常生理性血管衰老均具有意义，并提示逆转的可能。: \4 D. _ ^' a% E" _
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（帕金森氏病）LRRK2 Mutant iPSC-Derived DA Neurons Demonstrate Increased Susceptibility to Oxidative Stress
2 Q8 Q7 @* |) wCell Stem Cell 8, 267–280, March 4, 2011，Theo D. Palmer and Renee Reijo Pera，Institute for Stem Cell Biology and Regenerative Medicine,Stanford University
|* m& h" g5 L" e...Here, we report generation of induced pluripotent stem cells that carry the p.G2019S mutation (G2019S-iPSCs) in the Leucine- Rich Repeat Kinase-2 (LRRK2) gene, the most common PD-related mutation, and their differentiation into DA neurons. The high penetrance of the LRRK2 mutation and its clinical resemblance to sporadic PD suggest that these cells could provide a valuable platform for disease analysis and drug development. We found that DA neurons derived from G2019S-iPSCs showed increased expression of key oxidative stress-response genes and a-synuclein protein. The mutant neurons were also more sensitive to caspase-3 activation and cell death caused by exposure to stress agents, such as hydrogen peroxide, MG-132, and 6-hydroxydopamine,than control DA neurons. This enhanced stress sensitivity is consistent with existing understanding of early PD phenotypes and represents a potential therapeutic target.' l7 }; c0 V4 H2 D
病人皮肤成纤维细胞诱导iPSC，保留了the missense homozygous G2019S mutation。疾病iPSC分化为中脑神经元，不同分化阶段表现出与正常情况不同的基因表达，其中一些与稳定态氧化stress有关。G2019S-iPSCs以及分化为多巴胺神经元后仍保留了一部分PD疾病表型，如氧化应激反应增高，a-synuclein 累积。相应地，hydrogen peroxide (H2O2)处理后对氧化应激反应增强，对6-Hydroxydopamine（损害线粒体）更敏感，对蛋白降解障碍因子更敏感等。本研究的几个局限：单一细胞系难以排除偶然因素；难以获得大量纯化神经元；缺乏明确的位置的有关神经元标记及其内在机制；缺乏对基因和环境因素单独以及整合致病作用的理解。这些其实也是多因素疾病模拟的相对普遍问题。
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（2型先天性QT间歇延长综合症）Modelling the long QT syndrome with induced pluripotent stem cells
2 F0 t/ }7 F7 m* ~- u& y10 March 2011 Vol 471, Nature，Lior Gepstein，Technion—Israel Institute of Technology5 S2 }: j+ f3 y7 k+ {0 d
...Here we report the development of a patient/disease specific human iPSC line from a patient with type-2 LQTS (which is due to the A614V missense mutation in the KCNH2 gene). The generated iPSCs were coaxed to differentiate into the cardiac lineage. Detailed whole-cell patch-clamp and extracellular multielectrode recordings revealed significant prolongation of the action potential duration in LQTS human iPSC-derived cardiomyocytes (the characteristic LQTS phenotype) when compared to healthy control cells. Voltage-clamp studies confirmed that this action potential- duration prolongation stems from a significant reduction of the cardiac potassium current IKr. Importantly, LQTS-derived cells also showed marked arrhythmogenicity, characterized by early-after depolarizations and triggered arrhythmias. We then used the LQTS human iPSC-derived cardiac-tissue model to evaluate the potency of existing and novel pharmacological agents that may either aggravate (potassium-channel blockers) or ameliorate (calcium-channel blockers, KATP-channel openers and late sodiumchannel blockers) the disease phenotype. Our study illustrates the ability of human iPSC technology to model the abnormal functional phenotype of an inherited cardiac disorder and to identify potential new therapeutic agents. As such, it represents a promising paradigm to study disease mechanisms, optimize patient care (personalized medicine), and aid in the development of new therapies./ m5 C. r; c+ c. v$ [7 k
先天性QT间歇延长综合症是一组基因变异引起的疾病，依据变异基因的不同分为十三种，其中LQT1-3常见，LQT-8导致Timothy Syndrome。2010年《新英格兰医学杂志》发表的iPS模型是第一型，本研究是第二型。本期《自然》杂志的另一篇文章是Timothy Syndrome的iPS疾病模型。LQT1的研究用的是无症状的带病基因被试，本研究是确诊病人皮肤成纤维细胞诱导iPS，具有特异基因变异。分化为心脏细胞，其中心室样和心房样细胞表现出QT延长及相关病理，窦房结样细胞无病理表现。固定频率电刺激、单细胞Ikr电压测定、心肌细胞心电图均发现疾病iPS分化的心肌细胞具有相应病理表型。尤其是在单细胞层面以及细胞群体层面表现出心律失常。临床上导致心律失常的阻断剂可以引发疾病iPS分化心肌细胞动作电位期延长以及心律失常，与前述Ikr电压结果一起提示变异基因的影响的幅度，这一平台可应用于药物安全实验。钙离子内流通道阻断剂可以有效改善疾病心肌细胞的动作电位延长并控制心律失常现象。另一个角度是加速钾离子外流来平衡钙离子内流，钾离子通道促进剂具有与钙离子通道阻断剂类似的作用。另一个最近被用于QT-3型的钠离子通道阻断剂对疾病iPS分化心肌细胞动作电位没有影响，但表现出明显的抗心律失常效应。
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/ D+ A! b9 i8 S# S7 f+ J# Y（提摩西综合症）Using induced pluripotent stem cells to investigate cardiac phenotypes in Timothy syndrome
0 q) J8 J, o" r2 pNature Vol 471, 10 March 2011, Ricardo E. Dolmetsch，Department of Neurobiology, Stanford University School of Medicine, Stanford
: G1 T6 V% s( u" I9 A...To explore the effect of the Timothy syndrome mutation on the electrical activity and contraction of human cardiomyocytes, we reprogrammed human skin cells from Timothy syndrome patients to generate induced pluripotent stem cells, and differentiated these cells into cardiomyocytes. Electrophysiological recording and calcium (Ca21) imaging studies of these cells revealed irregular contraction, excess Ca21 influx, prolonged action potentials, irregular electrical activity and abnormal calciumtransients in ventricular-like cells. We found that roscovitine, a compound that increases the voltage-dependent inactivation of CaV1.2 (refs 6–8), restored the electrical and Ca21 signalling properties of cardiomyocytes from Timothy syndrome patients. This study provides new opportunities for studying the molecular and cellular mechanisms of cardiac arrhythmias in humans, and provides a robust assay for developing new drugs to treat these diseases.
$ E" @9 {. c+ x4 ~患者皮肤成纤维细胞，证实疾病基因表型。四因子诱导iPS，具有疾病基因表型。分化为心肌细胞（分化效率无差异），EB收缩频率显著降低，表现为延长的收缩间歇。单细胞分析reduced voltage-dependent inactivation，心室样细胞动作电位长度三倍于正常细胞。疾病iPS诱导心肌细胞在收缩期表现出更不规律的、延长的、更大幅度的钙离子浓度升高。三种不同剂量的钙离子通道干扰剂检验，中度剂量有效减弱钙离子浓度升高的不规律性幅度，该药物具有相应的提高钙离子通道电压条件控制的抑制，缩短动作电压潜伏期长度以及减弱不规律去极化的效用。两个病人的五个iPS细胞系结果一致。Timothy与QT1-2型的不同，前者仅有心室动作电位延长，而后者心室心房均有；前者有EB自发跳动的心律失常和延迟的去极化，后者只有在药物刺激下才有。
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3 s+ Z C8 i( Q, n7 c从已发表的研究轨迹来看，其中一部分只是显示可以将患者成体细胞诱导为iPSC，基本证明一些疾病状态（基因异常）并不妨碍重编程。近期的一些研究开始深化，在疾病病理机制上通过体外细胞模型深入探索，并有一部分采用已知药物检验细胞疾病表型，少数有基因改造的尝试。大致可以列出iPSC诱导、靶细胞分化、病理表型证明、机制探索、干预试验几大模块。疾病表型的复制前提是相对明确的疾病基因变异，单基因显性遗传特异组织病编最适宜模拟，多基因疾病比较复杂，而基因与环境因素互相作用的疾病则很难以单一细胞模型来完全模拟。这是以后的问题。
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另一个普遍的局限是多数研究还只是少数患者、组织得来的少数iPSC细胞系，无法排除个体间差异和偶然性以及特定个体内单一细胞系的偶然性，大多数的模型需要群体大样本以及个体多细胞系研究以获得更具代表性的模型。需要指出的是一部分研究结果具有与正常组织细胞模型的对照，对照的意义可能是因疾病类型和研究目的而异的。疾病iPSC诱导及分化、检验方法应该会随着iPSC重编程技术的进步而更新。
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7 k* _; m6 D9 t0 M与现有疾病病理机制以及病程的理解相接洽，需要多学科尤其是临床的结合，以及与现有动物模型和胚胎干细胞疾病模型的结合。与发育有关的和渐进性疾病，还需要解决体外iPSC疾病模型如何复制疾病进程的问题。操控培养皿中的分子机制以通过仿制发育过程来推断病理发展，还需要与动物模型或临床病理来验证。多表型综合征也需要不同疾病表型细胞模型来加以鉴别。有些疾病可能需要建立疾病病理相关组织细胞的iPSC系列模型，研究复杂的动态过程。3 p" c$ f* l) }" y! U# {1 b
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利用疾病iPSC模型的药物筛选，需要有大批量，内在齐整性的细胞资源，这方面的数据比较少，大概进入这个阶段的研究基本上属于转化阶段，成了商业运作了。在iPSC细胞模型层面上结合药物，可以用于鉴别可能的病理机制，寻找药物的靶点，研究药理机制，验证药物安全性与剂量，甚至未来用于个体化医疗，即通过特定病人的特定iPSC细胞模型筛选药物种类、组合、剂量、途径等。也有人认为这个前景效价比不高，不容易scale up，另一个更现实的应用模式是大规模、大批量、多个体、同疾病表型的特定疾病iPSC细胞模型库，通过具有足够广泛代表性的库来寻找个体差异所代表的个体化解决方案。孰优孰劣还都是推想，有待观察。
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基因改造用于疾病iPSC模型有两个方案，一是改造来源细胞的基因异常，以获得健康的iPSC及其分化产品；或者改造iPSC的基因异常，或通过特定重编程分子手段消除分化产品的基因异常。这些手段一方面可以结合病理机制探索和药物筛选，另一方面也为未来实现吹嘘了这么久的细胞移植治疗提供一个路径。/ i' @5 A% e6 |
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如前所述，一些罕见的特异性遗传疾病似乎相对比较好模拟，而很多常见病、高发病都具有复杂的病理机制，遗传与环境的复杂相互作用病因，长期、多样（潜伏期）的病理进程等，要在体外通过疾病iPSC细胞水平模型来模拟，可能是不够的，或者将来能够发展出复杂的体外组织甚至器官水平模型，就好像人们期待未来通过干细胞组织工程体外制造复杂的组织器官一样。* A8 y( k$ F0 B- C
' a0 f3 |8 I4 \! U% u, N7 Z最后，大规模制备的知识产权要求可能会带出疾病iPSC细胞的伦理问题，比如提供细胞来源的患者权益等。
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总体上来说，重编程是否能真正“返回”到“原始”状态，可能还是问题，也可能只能是一种“模拟”。那就意味着未来iPSC必定呈现三个层次：一，所有非疾病iPSCs都具有某种“非正常”性质，比如衰老、潜在基因异常和病理形态，线粒体及其遗传基因特性，端粒状态，内源性成瘤性，以及外源性操作影响等；二、特定疾病表型的iPSCs及其分化细胞；三、基因改造后的iPSCs及其分化细胞产品。在这三个层次中，特定疾病表型iPSC模型也许起着枢纽作用。这是疾病iPSC模型的广义定义吧。 ?% ^2 @8 n l3 ^( P, P# o/ _2 w
1 W# k1 l4 H9 v3 U（有限的理解，仅供参考，请勿他用，请勿转贴）。) @2 r M5 f; T" o' W/ V$ b. a# a
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（一些文章原文取自本版网友linlicau的“iPS与疾病模型的12篇文章！”，另一些文献来自网友的文献互助及期刊提供者，共23篇）
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发表于 2011-4-3 20:53
发表于 2011-4-4 20:06
