The New York Stem Cell Foundation: Fifth Annual Translational Stem Cell Research Conference

Ann. N.Y. Acad. Sci. ISSN 0077-8923

ANNALS OF THE NEW YORK ACADEMY OF SCIENCESIssue: Annals Meeting Reports

The New York Stem Cell Foundation: Fifth AnnualTranslational Stem Cell Research Conference

Caroline Marshall,1 George Kai Wang,2 Elisa Cimetta,2 Chutima Talchai,2 Dieter Egli,1

Jae-won Shim,3 Ian Martin,4 Faizzan Ahmad,1 Andrew Sproul,1 Ting Chen,5 Valentina Fossati,1

David McKeon,1 Kristin Smith,1 and Susan L. Solomon1

1The New York Stem Cell Foundation, New York, New York. 2Columbia University, New York, New York. 3MemorialSloan-Kettering Cancer Center, New York, New York. 4Johns Hopkins University, Baltimore, Maryland. 5The RockefellerUniversity, New York, New York.

Address for correspondence: Caroline Marshall, The New York Stem Cell Foundation, 163 Amsterdam Avenue, Box 309, NewYork, NY 10023.

The New York Stem Cell Foundation’s “Fifth Annual Translational Stem Cell Research Conference” convened onOctober 12–13, 2010 at the Rockefeller University in New York City. The conference attracted over 400 scientists, pa-tient advocates, and stem cell research supporters from 16 countries. In addition to poster and platform presentations,the conference featured panels entitled “Road to the Clinic” and “Regulatory Roadblocks.”

Keywords: translational medicine; regulatory; human embryonic stem cells; stem cells

Introduction

Since the “Fourth Annual Translational Stem CellConference” was held in October 2009,1 progresshas continued to move research closer to the clinic.Techniques for deriving disease-specific pluripotentstem cell lines translatable to therapeutic uses havecontinued to improve,2 and more efficient, accuratedifferentiation protocols are being developed thatwill provide in vitro models for disease pathology.In the clinic, Geron’s halted trial3 to investigate theuse of human embryonic stem cells (hESCs) to safelytreat patients with early stage spinal cord injury wasrestarted. With these and other developments thereis enormous optimism that stem cell research willprovide insights into a range of incurable diseasesand eventually to cures, either by the identificationof safe, efficient therapeutics or by cellular therapies.

In sharp contrast, progress for federal supportof stem cell research over the last nine months hasbeen stagnated by a recent legal battle. On August23, 2010, a federal judge issued an order block-ing all federally funded stem cell research. The un-expected decision was so far reaching that it notonly overturned President Obama’s 2009 ExecutiveOrder4 authorizing stem cell research, it even halted

research on lines approved during the Bush ad-ministration.5 The judge ruled that the Obama ad-ministration’s policy was illegal on the basis of hisinterpretation of the Dickey-Wicker Amendment.A temporary stay on the injunction was issued onSeptember 9, 2010, and oral arguments for the casewere heard on December 6th before a three-judgepanel of the United States Court of Appeals for theDistrict of Columbia Circuit. On April 29, 2011, theCourt of Appeals voted 2-1 to vacate the preliminaryinjunction, ruling that the Dickey-Wicker Amend-ment should not prohibit funding research usingembryonic stem cells. It is possible that the plain-tiffs will appeal this decision to be heard before thefull Court of Appeals or the Supreme Court. Whilethis is a victory for scientists across the country, thebureaucracy has not gone away and philanthropyand state funding programs remain key drivers ofstem cell research.

As in previous years, the New York Stem CellFoundation’s (NYSCF) annual translational stemcell conference opened with two panels of ex-perts discussing topics that affect the translationalprogress of stem cell research. In the first panel,“Road to the Clinic,” moderated by Lee Rubin,director of translational medicine at the Harvard

doi: 10.1111/j.1749-6632.2011.06038.xAnn. N.Y. Acad. Sci. 1226 (2011) 1–13 c© 2011 New York Academy of Sciences. 1

The New York Stem Cell Foundation Marshall et al.

Stem Cell Institute and the NYSCF scientific ad-visor, leading experts from the pharmaceutical,biotechnology, and healthcare industries werejoined by representatives from venture capital andgrant-awarding foundations to explore what isneeded to accelerate research from the laboratoryto the bedside. Panelists included Max Wallace (Ac-celerate Brain Cancer Cure), Ian Ratcliffe (Stem-gent), Anthony Envin (Venrock), and Robi Blumen-stein (Cure Huntington’s Disease Initiative (CHDI)Foundation). The panel discussed how scientistsshould navigate the scientifically challenging andexpensive path toward clinical trials. The secondpanel, “Regulatory Roadblocks,” composed of lead-ing stem cell researchers and policy makers, dis-cussed the regulatory challenges facing researcherson the road to the clinic from their differing perspec-tives. Moderator Michael Werner (Alliance for Re-generative Medicine) and panelists Arlene Chiu (Of-fice of New Research Initiatives, Beckman ResearchInstitute at City of Hope), Kevin Eggan (NYSCFand Harvard Stem Cell Institute), Donald Fink, Jr.(U.S. Food and Drug Administration), and Mahen-dra Rao (Life Technologies; Johns Hopkins Univer-sity, Buck Institute of Aging) examined the changesin policy that will be needed to advance the devel-opment, evaluation, and approval of emerging stemcell treatments and regenerative medicine.

During the second day of the conference, an in-ternational panel of researchers at the forefront ofthe stem cell field presented their work in sessionson diabetes, heart and muscles, cancer and blooddisease, neurodegeneration and spinal cord injury,and programming/reprogramming. This year’s con-ference included two keynote addresses. The firstwas by John E. Dick (University of Toronto), whodiscussed the role of stem cells in cancer; the sec-ond was by Fiona Watt (Cambridge Research In-stitute, UK), who presented her seminal work onstem cell niche interactions in the mammalian epi-dermis. The NYSCF, in collaboration with Annals ofNew York Academy of Sciences, is delighted to presentthis report; compiled by young stem cell scientists, itsummarizes the excellent, groundbreaking progressin stem cell research.

Diabetes

Camillo Ricordi (University of Miami, Florida) aninventor of the Ricordi chamber, an effective de-vice to isolate and purify islets from a donated pan-

creas for human islet transplantation, presented re-cent data on long-term insulin independence ratesfrom post-transplantation patients.6 Recently, thismethod was able to achieve up to 70% successfulinsulin independence after seven years’ follow-up.However, the availability of donated organs andthe requirement of long-term immunosuppressivedrugs limit this approach to patients with extremelysevere hypoglycemia unawareness, a very small frac-tion of insulin-requiring diabetic patients. To cir-cumvent this roadblock, Ricordi aims to developautologous insulin-producing cells from an expand-able source and make insulin-producing cells avail-able for all of those who are in need. Ricordi’s groupinvestigates adipose-derived stem cells as a poten-tial source in aiding differentiation into functionalinsulin-producing cells.

Matthias Hebrok (University of California, SanFrancisco) pointed out that researchers in thisfield have not yet generated fully mature insulin-producing cells either from hESCs or from theprocess of trans-differentiation of pancreatic aci-nar cells.7 To tackle this problem, Hebrok’s grouphas studied the roles of mesenchymal signals thatdirect insulin-producing differentiation and acinarcell de-differentiation. In his unpublished data, He-brok showed that B cells and T cells of the adap-tive immune system regulated the regeneration ofinsulin-producing cells in an animal model of aci-nar cell injury.

Douglas Melton (Harvard University) discussedthe steps and necessary components for generat-ing a model of type 1 diabetes (T1D) using stemcells.8 These components are the insulin-producing� cells, the hematopoietic stem cells (HSCs) giv-ing rise to immune cells, and the thymic epitheliumrequired to “educate” the developing T cells. In prin-ciple, all these components can be generated fromstem cells of a diabetic patient, combined, and thenintroduced into immunocompromised mice. If themice become diabetic, containing the immune sys-tem and � cells of a T1D patient, fundamental ques-tions can then be addressed, such as, What are theprimary antigens that trigger the onset of diabetes?or How many ways are there to develop diabetes?

The first step toward such a model is to gener-ate a sufficient number of � cells from stem cells.Melton’s laboratory is using a stepwise and system-atic approach to generate � cells. They have re-cently described compounds that induce definitive

2 Ann. N.Y. Acad. Sci. 1226 (2011) 1–13 c© 2011 New York Academy of Sciences.

Marshall et al. The New York Stem Cell Foundation

endoderm from stem cells9 and, using indolac-tam, Pdx1+ pancreatic precursors from definitiveendoderm.10 Doug Melton presented novel andunpublished data on a chemical screen that uses4,000 chemical compounds to induce Pdx1+ pan-creatic progenitors to differentiate into ngn3+ en-docrine precursor cells. They found 27 hits, someof which increase the number of ngn3+ cells from3% to more than 50%. These ngn3+ cells are alsoable to further differentiate into insulin-producingcells. However, the yield of � cells per stem cell usedas starting material is still low. Therefore, Meltonasked the question of whether endocrine cells couldbe induced to expand and self-renew in culture. Toaddress this question, Melton’s laboratory tested theability of several primary cell lines, including en-dothelial lines, mesenchymal cell lines, and of vari-ous extracellular matrix components, to induce self-renewal of definitive endoderm. He recounted thatsome mesenchymal cell lines promote the expansionof Sox17+ cells for up to six passages—or as much as1,500-fold expansion—without a loss in differenti-ation potential. Such fold-expansion is a significantstep toward the production of a sufficient numberof � cells for experimentation.

Repairing our heart and muscles

Thomas Rando (Stanford University) discussed thenature and regulation of quiescence and activationof muscle stem cells. Satellite cells—muscle-specificstem cells—reside in a quiescent state beneath thebasal lamina of muscle fibers. Specific signals inducetheir activation, proliferation, and terminal differ-entiation into myogenic precursors. One of the mostrelevant findings of Rando’s group is the elucidationof the different behavior of stem cells in young ver-sus old organisms. In particular, they demonstratedhow aging of the local and systemic environment,rather than aging of the stem cells themselves, in-duced increased differentiation in fibroblasts insteadof myoblast precursors, which results in fibrosis andreduced regeneration of injured muscle. In parabi-otic pairing experiments (in which the circulatorysystems of two mice are physically connected), thecells of young mice exposed to cells of old mice in-duced the young cells to “behave” as old cells, whichthen partially transformed into fibroblasts; impor-tantly, they also showed that old cells could be madeto behave like young cells if the exposure were theother way round.11 In addition, Rando’s group more

recently demonstrated that systemic inhibition ofWnt signaling can change the aging process12 byreducing the percentage of fibrogenic, versus myo-genic, cells.

Reprogramming cells to the quiescent state—especially with regard to the phenomenon of old-to-young transformation and the increasingly agingworld population and aging-related diseases—has apotentially profound therapeutic potential. In dys-trophic muscles, for example, the extensive fibrosisseen may be due to premature aging of the localmuscle environment, in which satellite cells “ac-quire” similar characteristics of aged muscle.13 Thecapacity to use autologous cells “corrected” back toa young state by in vitro reprogramming would ob-viously be a beneficial source of functional healthymyoblasts that could be retransplanted into the pa-tient and, we would hope, help restore normal tissue.

Rando’s group follows a “reprogramming alongthe lineage” approach by starting from differentiatedmyoblasts that can be reprogrammed to the state ofactivated pluripotent stem cells, which are then dif-ferentiated into myoblasts and myofibers, therebyshortening the differentiation path that would oth-erwise have to lead all the way back to inducedpluripotent stem cells (iPSCs).

Kenneth Chien (Harvard University) next pre-sented their advances in deriving optimal cellsources for regenerative cardiovascular medicine,with the focus on driving pluripotent cells towarda mature ventricular cell fate. Chien’s group hasidentified previously in mouse,14 and recently inhuman,15 a set of cardiac progenitor cells markedby expression of Islet-1 that is both multipotentand capable of self-renewal and expansion beforedifferentiation into cardiomyocyte, smooth muscle,and endothelial cell lineages—the three major celltypes in the heart. Importantly, Chien’s group suc-cessfully isolated a subset of Nkx2.5+ cells in themouse Islet-1 lineage as committed ventricular pro-genitors (CVPs) that can differentiate and organizeinto functional ventricular muscle tissue in vitro.16

Although the isolation of human CVPs remains tobe demonstrated, their findings open a door to ter-minal differentiation of pluripotent stem cells intoa mature ventricular myocardium. Because under-standing the intrinsic checkpoints that limit theproliferative capacity of CVPs is critical for theirclinical use, Chien’s group is focusing on themolecular switches that trigger cardiac ventricular

Ann. N.Y. Acad. Sci. 1226 (2011) 1–13 c© 2011 New York Academy of Sciences. 3


myogenesis in the Islet-1 lineage pathway. Throughchemical screening and study of iPSCs carryingTGF-� receptor-mutations that cause Loeys–Dietzsyndrome, they have identified Tbx5, Tbx1, andTGF-� as key cytokines that can expand the pop-ulation size of CVPs such that cardiomyocytes insufficient numbers can be obtained. Another po-tentially valuable cell source for cardiac regenerationderived by Chien’s group is the ventricular-inducedpluripotent stem cells. Preliminary results indicatedthat this secondary type of iPSCs, which are gener-ated from mature heart cells by genetic engineering,showed earlier and greater induction of Islet-1 anddownstream cardiac/ventricular-restricted gene ex-pression (e.g., of the genes expressing Nkx2.5, cTNT,and MLC2V) than primary iPSCs. Chien’s work hasresulted in a step-wise cardiogenic cell fate map thatwill lead to a better understanding and developmentof human heart stem cell models and therapeutics.

The last speaker of the session, Christine Mum-mery (Leiden University Medical Center, theNetherlands), discussed the application of cardio-vascular derivatives of both hESCs and iPSCs indisease and drug discovery. Mummery discussedthe current challenges of using stem cells for car-diac repair, including requirements for optimizingthe timing, number, type, and method of cell de-livery into the heart. As an example, Mummery’slab demonstrated that hESC-derived cardiomyoc-tyes (hESC-CMs) can survive and integrate in thelong term (>6 months) in an infarcted mouseheart but do not align, integrate with host tissue,or give long-term improvement in cardiac func-tion.17 By contrast, more immediate applicationsof hESCs and iPSC-derived cardiomyoctyes haveemerged in drug discovery and disease modeling asa scalable and reproducible cell source due to the re-cent advances in cardiac differentiation and patient-specific iPSC derivation.18 One of the greatest ad-vantages of cardiomyocytes derived from humanstem cells (over widely used mouse models) is theclose similarity of the electrophysiological proper-ties to hESC-CMs adult human cardiomyoctyes. Asa proof of concept, Mummery’s group used hESC-CMs to test the effect of a wide range of cardiacand noncardiac drugs associated with QT prolon-gation and/or torsade de pointes (French term thatliterally means “twisting of the points”) during clin-ical use in humans on extracellular field potentials(FP) recorded by microelectrode arrays.19 Interest-

ingly, all 12 drugs tested nonblindly and 19 of 20drugs tested blindly showed the predicted relation-ship between FP duration (FPD) prolongation andarrhythmias, strongly suggesting FPD prolongationof hESC-CMs could accurately serve as a cardiacsafety criterion for preclinical evaluation of newdrugs. As for human-induced pluripotent stem cellcardiomyoctyes, Mummery’s group has begun workon iPSCs generated from patients with the long QTsyndrome, a life-threatening arrhythmia caused bymutations in cardiac ion channels such as sodiumchannel (SCN5A),20 which, it is hoped, will lead to abetter understanding of the mechanisms of diseasepathogenesis and help to develop potential patient-specific treatment.

Cancer and blood

HSCs sustain mature blood cell production and self-renew to maintain the HSC pool throughout life.In 1978, Schofield21 introduced the HSC niche asthe microenvironment in which HSCs reside andself-renew, and outside of which the HSCs begindifferentiating to generate mature blood cells. Al-though many different studies have been performedsince then to identify the cell types that constitutethe HSC niche, the question remains unanswered.Both osteoblasts and endothelial cells in the bonemarrow have been proposed as cellular componentsof the true HSC niche.

In the first talk of this session, Paul Frenette(Albert Einstein College of Medicine) tried to rec-oncile the existing hypotheses by proposing a newmodel of the HSC niche. Frenette et al. previ-ously made important contributions to the un-derstanding of HSC mobilization, by uncoveringthe role of the sympathetic nervous system in therelease of HSCs.22,23 They also showed that no-radrenergic signals, secreted with circadian oscil-lation by nerves in the bone marrow, generate acyclical release of HSCs in antiphase with the ex-pression of Cxcl12 in the bone marrow.24 Frenettewent on to identify the cells targeted by the sympa-thetic fibers and found a population of perivascularmesenchymal stem cells (MSCs) characterized bynestin expression.25 Nestin+ MSCs can be propa-gated as “mesospheres” and they self-renew in vivo,as shown by serial transplantation in mice. Underdifferentiation conditions nestin+ MSCs differenti-ated into osteogenic, adipogenic, and chondrogeniclineages. Further experiments strongly indicated



Douglas A. Melton (Harvard University and NYSCF medical advisory board member) presents his work, “Degeneration andregeneration in type I diabetes.”

that MSCs constitute the HSC niche; for example,Frenette showed that nestin+ MSCs are strategicallylocalized adjacent to HSCs and have a direct rolein HSC maintenance in the bone marrow. Frenetteet al. demonstrated the latter by showing that in vivodepletion of nestin+ MSCs rapidly reduces the num-ber of HSCs by ∼50%.25 This study offers novel in-sights into the controversial field of the HSC niche,presenting an alternative cellular constituent thatencompasses all features associated with osteoblas-tic and endothelial niches.

Keynote 1

John E. Dick (University of Toronto, Canada) de-scribed a study by his group that compared nor-mal and leukemic stem cells in order to predictpatient survival outcomes and effective treatmentof the (leukemia) disease. Solid evidence supportsthe conclusion that human acute myeloid leukemia(AML) follows the cancer stem cell (CSC) model(i.e., that for many cancers, cells within a tumor areorganized in a hierarchical lineage relationship anddisplay different tumorigenic potential). However,the clinical relevance of the CSC model has beenchallenged by recent reports that some tumors mayactually not follow this model in circumstances ofheightened use of xenografts.

Dick et al. set out to address this issue bydetermining whether the molecular properties of

leukemia stem cells (LSCs) are more predictiveof patient survival than parallel assessments ofbulk cancer cells. Their long-term goal is to deter-mine whether (therapeutically) targeting LSCs re-sults in more durable disease control/eradication.First, they carried out a comprehensive study ofthe normal human HSCs and their progenitors26

by using immunodeficient female NOD/SCID/IL-2Rg(c)-null mice that, according to their work, aresuperior xenograft recipients (compared to malemice) for detecting human HSCs.27 After screen-ing for eight established markers of HSCs, Dicket al. were able to isolate HSCs to near homogene-ity as the CD49f+CD90+rhodaminelow population.They then carried out global mRNA gene expressionprofiling of FACS-sorted subpopulations of cells en-riched either for the CD49f+CD90+rhodaminelow

HSCs, for other progenitor cells, or for mature cellsfrom normal cord blood. An mRNA array signaturebased on these analyses was generated that corre-lated with the stem cell state. Dick et al. then carriedout a similar comparative study of the LSCs. Ofthe established marker of LSCs, they found that theCD38CD34 profile varies dramatically from patientto patient. While CD38−CD34+ population con-tains LSCs, the CD38+CD34+ population does aswell, albeit at different percentages. They then car-ried out a similar analysis as above and discoveredthat the LSCs share few similarities with ESCs or



Shahin Rafii (Weill Cornell Medical College and NYSCF medical advisory board member) chairs the session on Cancer and BloodDisease.

progenitor cells, and possess a “core transcriptionalprogram” similar to HSCs. Remarkably, both LSCand HSC signatures, when evaluated in a large groupof cytogenetically normal AML samples, showedstriking prognostic significance. These data supportthe hypothesis that the biological determinants thatunderlie “stemness” in both normal and leukemiccells influence survival outcomes and are potentialtargets for therapy.

Neurodegeneration and spinal cord injury

In the first talk of this session, Thomas Jessell(Columbia University Medical Center) discussedmotor neuron differentiation, beginning with thedevelopmental programs of motor neuron diver-sification and how different subtypes assemble intocircuits that permit the activation of individual mus-cles that control movement in limbed animals. Dur-ing development, the emergence of specialized celltypes is orchestrated by signaling events that pro-gressively restrict the fates of progenitor cells. Spinalmotor neurons also experience multiple stages ofneuronal subtype specification. Initially, the emer-gence of motor pool identity is distinguished fromother interneuron and sensory neuron fates by agradient of sonic hedgehog expression. Subtypesare then determined by sequential hox gene expres-sion, which is itself controlled by gradients of fi-

broblast growth factor and retinoic acid (RA);28 theintrinsic regulatory hox gene network establishesmotor neuron pool identity and target muscle con-nectivity.29 Jessell’s explanation of the strategy formotor neuron generation from ESCs is based onthe understanding of the mechanism of acquisitionof motor neuron subtype specificity. Use of sim-ple small molecules, such as RA and hedgehog ag-onist, is a key point of direct differentiation fromESCs to spinal motor neurons.30 This differentia-tion protocol provides a good model study for mo-tor neuron development and diversification in vivoand provides insight into directing stem cell dif-ferentiation along defined motor neuron fates invitro. Through inductive programming, using nor-mal embryonic inductive signals to coax cells alongparticular pathways, it is now possible to converta naive ES cell through neuroprogenitor and spinalprogenitor stages to a specific motor neuron in a waythat faithfully recapitulates the normal developmen-tal program. This system generates motor neuronpools without addition of exogenous factors by us-ing growth conditions in which cells within the em-bryoid bodies themselves supply inductive factorsand therefore can potentially be adapted to gener-ate any class of neuronal cell in the CNS for whichnormal embryonic patterning mechanisms areknown.



Paul S. Frenette (Albert Einstein College of Medicine and NYSCF medical advisory board member) speaks to the audience on newinsights into the hematopoietic stem cell niche.

Lastly, Jessell discussed recent studies on motorneurons derived from human ESCs that bring to-gether an understanding of normal developmentalmechanisms and how this can be used in a moreapplied context. Since not all motor neurons die indiseases such as amyotrophic lateral sclerosis (ALS)and spinal muscular atrophy (SMA), the ability togenerate subtypes that are vulnerable or resistantto disease will provide insight into the molecularmechanisms that underlie disease vulnerability. Ifthese properties can be recapitulated in disease-specific iPSCs, this will permit direct comparisonwith human ESC-derived neuronal cohorts. Thesesystems can then be used to design assays for chem-ical screens to establish the relevance of preventingneuronal death in diseases such as ALS and SMA.

Next, Hongjun Song (Johns Hopkins UniversitySchool of Medicine) discussed his group’s studieson neurogenesis within the adult hippocampus thatmodel neuronal development in vivo, and to iden-tify susceptibility genes associated with neurode-velopmental disorders that contribute to psychi-atric diseases, such as schizophrenia. One recentfocus of investigation has been on the gene dis-rupted in schizophrenia-1 (DISC1), a schizophrenia-susceptibility gene shown to be an importantregulator of embryonic and adult neurogenesis.31

Importantly, the Song lab recently showed that

DISC1 regulates the development of neurons inthe adult brain by modulating the AKT/mTOR sig-naling pathway.32 DISC1 knock-down in the adulthippocampus leads to aberrant neurogenesis in thedentate gyrus, hypertrophy of cell somas and den-drites, and impaired neuronal positioning. DISC1knock-down also affects neuronal function, leadingto more rapid synapse formation and augmentedneuronal excitability. A hypothesis based on theobservation that PTEN knock-out leads to simi-lar hypertrophic cell phenotypes33 was postulatedthat DISC1 might exert its effects by acting on theAKT/mTOR pathway. By studying the interactionsof DISC1, the Song lab demonstrated that DISC1interacts with AKT-binding partner KIAA1212 toregulate AKT signaling in developing neurons;KIAA1212 interacts with AKT, leading to increasedAKT signaling to downstream effectors.34 SinceDISC1 normally binds to KIAA1212 and blocksKIAA1212’s interaction with AKT, DISC1 suppres-sion results in elevated levels of KIAA1212 and,therefore, enhanced AKT activation. The cell over-growth phenotypes observed upon DISC1 knock-down are consistent with excessive activation ofAKT, which has an established role in mediatingprotein synthesis and a range of neuronal develop-mental processes. A role for enhanced AKT signal-ing in neuronal phenotypes associated with DISC1



John E. Dick (University of Toronto, Canada) delivered a special keynote address during the conference on the role of stem cells incancer.

deficits was also supported by the finding that eithergenetic suppression of PTEN or overexpression ofAKT, both of which lead to increased AKT/mTORpathway activation, results in similar overgrowthphenotypes in developing neurons. Importantly,suppression of AKT/mTOR signaling via eitherrapamycin treatment or Rheb1 deletion rescuesthe developmental defects associated with DISC1knock-down, further supporting the involvement ofthis signaling pathway in the aberrant phenotypesobserved.

To further investigate the link between DISC1and schizophrenia, Song’s group went on to ex-amine patient populations to determine whethersingle-nucleotide polymorphisms (SNPs) in DISC1are associated with an increased risk for devel-oping schizophrenia. Interestingly, they discoveredthat SNPs in DISC1 alone were not associatedwith schizophrenia risk, although SNPs in DISC1and NKCC1 (a Na+-K+-2Cl– cotransporter) com-bined resulted in significantly increased risk. More-over, they used fMRI to show that patients withboth DISC1 and NKCC1 SNPs exhibit reduced hip-pocampal function in a test of recognition mem-ory. Collectively, the data strongly support a rolefor DISC1 in regulating neurogenesis and neuronaldevelopment.

Programming and reprogramming

Dieter Egli (NYSCF and a NYSCF-DruckenmillerFellow) presented progress on human nuclear trans-fer. He began by reviewing the process of nucleartransfer, which is achieved by removing the oocytegenome, an unfertilized egg, and transferring thesomatic nucleus labeled by green fluorescent pro-tein (GFP) into the oocyte and then using artificialactivation to induce development.

Therapeutic nuclear transfer is taking a nucleusand transferring it to a stem cell line to make patient-specific cell lines; this concept was born duringthe birth of Dolly the sheep.35 Ten years later welearned that a similar fate can be achieved usinggenes rather than eggs. Egli posed the question ofwhether theurapuetic cloning is dead.

Researchers in the field are now trying to ad-dress whether iPSCs are equivalent to cells obtainedfrom the embryo. Although these cells are similar,some problems do persist; for instance, abnormalimprinting in mouse iPSCs,36 memory of tissue ori-gin in mouse,37,38 and differences in gene expres-sion.39 However, these issues do not apply to mousenuclear transfer ESCs.40

Egli conducted work in the field of nuclear trans-fer as a postdoctoral fellow in the laboratory of



Kevin Eggan at Harvard. Egli pointed out the issuesin recruiting patients to donate embryos in Mas-sachusetts, mainly due to the fact that the lab wascomplacent with state law, which did not allow forcompensation. Most women were concerned aboutcompensation, the time commitment, and the med-ications and injections required for the procedure.After obtaining a one oocyte donation and con-ducting the experiment, Egli found that the em-bryos arrested at the 6- to 8-cell stage. Egli et al.demonstrated that in the mouse, fertilized eggs canreprogram a somatic cell nucleus to an embryonicstate,41 which prompted the use of human zygotesand perhaps human embryonic blastomeres in or-der to supplement human oocytes for the creationof patient-derived hESCs. Thus, a method for nu-clear transfer into human fertilized eggs (zygotes)was initiated using nocadozole to inhibit cytokine-sis, and then replaced with a somatic cell genomemarked by H2B:GFP in order to track the donorcell nucleus, which developmentally arrested at themorula stage. They next asked, What is the defectleading to this developmental arrest?

Gene expression analysis in nuclear transfer em-bryos and zygotes at day one shows clustering andsuggests that there is a global defect in transcrip-tion. In order to show that transcriptional inhibi-tion in normal zygotes leads to the same develop-mental arrest, Egli et al. administered amanitin andconcluded that embryos with transcriptional inhi-bition and nuclear transfer embryos have similardevelopmental potential. These sets of experimentsprovide evidence that there is a profound defect intranscription that could explain this developmentalarrest. In order to conduct experiments with fertil-ized zygotes, it is interesting to note that the ethicallandscape regarding hESCs is a delicate one to ne-gotiate. Egli states “We were fortunate to receivesurplus embryos from couples who had completedthe in vitro fertilization program,” thus, in essence,using those embryos that would have only beendiscarded.

Egli also demonstrated that karyotypic abnor-malities do not explain the transcriptional defectsseen in the arresting embryos, as they clustered withnormal in vitro fertilization embryos, indicating thatthe karyotypic abnormalites alone do not explaintranscriptional defects; rather, the primary cause ofdevelopmental arrest can be explained by the tran-scriptional defect. It could be that the epigenetic

state of the somatic nucleus is not compatible withpreimplantation development.

One of the highlights from the “programmingand reprogramming” section of this year’s NYSCFconference was a talk by the new NYSCF-Robertsoninvestigator, Marius Wernig. Wernig has recentlystarted his own lab at Stanford University and pre-sented two lines of research from his group. Thefirst story involves his lab’s efforts to model a rarechild-onset disease dystrophic epidermolysis bul-losa (DEB) via generation of iPSCs from patientswith recessive forms of the disease. DEB is causedby mutations in type VII collagen, a critical com-ponent of connective tissue that anchors skin toits function.42 Children with DEB can have sheetsof skin that literally fall off, as Wernig showed ingraphic pictures to underscore the seriousness andtragedy of this disorder. Other symptoms can in-clude mitten hands and the onset of squamous cellcarcinomas. Wernig’s group has successfully gener-ated multiple well-characterized lines of iPSCs fromfour patients, using an excisable lentiviral cassette tointroduce reprogramming factors. The next step hislab is pursuing is the use of zinc finger gene target-ing technology to correct the mutation in the DEBiPSCs.

Wernig’s second story described his work thatwas recently published in Nature, in which mousefibroblasts were directly converted into neurons.43

This approach opens an exciting additional possi-bility for generating patient-specific nerve cells forcell replacement therapy to treat neurodegenerativediseases. The theoretical approach was similar tothat of the first iPSC paper by Shinya Yamanaka’sgroup, which included a description of a large panelof proneural transcription factors added to fibrob-lasts in the hope of reprogramming them to a neuralfate. As we now know, of course, this worked, and bytrial and error Yamanaka’s group was able to reducethe number to three factors for efficient reprogram-ming. Wernig spent the rest of his talk describinghis lab’s new efforts to better characterize the mousefibroblast-derived neurons, and to extend this workinto human cells.

Keynote address 2

Fiona Watt (Cambridge Research Institute, UK)gave the second keynote address of the conference.Watt explained that stem cell behavior in vivo is acomposite response to the different environmental



Fiona Watt (Cambridge Research Institute, UK) closed the conference speaking about her work on stem cell niche interactions inthe mammalian epidermis.

signals that the cell is exposed to, including signalsfrom extracellular matrix (ECM) proteins, secretedfactors, and from physical factors, such as oxygentension and the interaction between stem cells andtheir niche.

The adult epidermis is maintained by prolif-eration of stem cells and differentiation of theirprogeny. In the undamaged epidermis, stem cellsin a particular location only give rise to lineagesappropriate to that location. However, followingwounding or genetic manipulation, any epidermalstem cell is capable of repopulating all epidermal lin-eages, revealing remarkable plasticity. Watt’s groupis using a range of in vitro and in vivo approachesto define the environmental signals that regulateepidermal stem cell fate under normal adult home-ostatic conditions and how these mechanisms arealtered in tumors. She presented evidence that ac-tivation of the factors Wnt and Notch, which areaberrantly expressed in many tumors, cause changesin the dermal stroma and ECM that underlie thebasal membrane and to which epidermal stem cellsadhere.44,45

Watt’s group, based on their observation someyears ago that human epidermal cells in culture ex-press the Notch ligand �1, demonstrated that �1expression by stem cells causes neighboring cells todifferentiate. Activation of the Notch pathway in theepidermis results in increased proliferation and ac-

cumulation of differentiated cells, thickening of theepidermis, and blistering. In addition, greatly in-creased numbers of melanocytes accumulate in thedermis. Notch activation in the epidermis also up-regulates expression of the Notch ligand Jagged1 inboth dermis and epidermis. Deletion of Jagged1 re-moves these effects, suggesting that Notch activationleads to induction of Jagged1; this, in turn, leads toaccumulation of dermal cells.

Next, Watt discussed work that involves the Wntsignaling pathway. In the absence of Wnt activation,the hair follicles in the epidermis are in resting phase.Upon activation of the Wnt pathway in the dermis,ectopic hair follicles and genes associated with pro-liferation are induced in the epidermis. Over time,activation of the Wnt pathway in the epidermis re-sults in a complete remodeling of the ECM in thedermis to a mature matrix and simultaneous pro-liferation in the epidermis. Therefore, in tumors,including breast cancer, where there is abnormalactivation of these pathways, there may also be non-cell autonomous changes in the underlying stromaand ECM. Tumors may be initiated by changes innondividing, differentiating cells through commu-nication with underlying cells.

Watt also discussed a long-term project to studythe part communication between cell layers withinthe epidermis plays in driving tumor formation. Notevery cell that sustains an oncogenic change will



Susan L. Solomon (CEO, NYSCF), Elaine Fuchs (The Rockefeller University and NYSCF medical advisory board member), KevinEggan (CSO, NYSCF; and Harvard University), Ruth Lehmann (New York University and NYSCF medical advisory board member),and Derrick Rossi (Immune Disease Institute of Harvard University and NYSCF-Robertson investigator) gather at the conclusionof NYSCF’s Fifth Annual Translational Stem Cell Research Conference.

form a tumor, suggesting that differentiated cellsgive out signals that either “encourage” the expan-sion of oncogenic cells with mutations, or that, con-versely, hold mutant cells in check.

In the epidermis, cells in the basal layer prolif-erate and migrate away. Normally, ECM integrinsare expressed in the basal layer, where they anchorcells, and are downregulated as the cells migrate up-ward and start to differentiate. However, when theepidermis is hyperproliferative or in squamous cellcarcinomas, integrins are frequently aberrantly ex-pressed in suprabasal layers. Induced expression ofspecific integrins in epidermal suprabasal layers intransgenic mice does not lead to tumor formationbut, in some cases, does predispose the epidermis totumor formation in response to chemical carcino-genesis.46 Watt’s group found that in a transgenicmouse model aberrant expression of �1 integrinsin suprabasal layers induced sporadic hyperprolif-eration, inflammation, and abnormal activation ofthe ERK pathway associated with upregulation ofthe cytokine IL-1�. Surprisingly, they also foundthat these mice developed tumors, specifically atwound sites, and the proliferating cells were in thebasal layer attached to the basement membrane,not in the transgene-positive compartment, sug-

gesting that transgene-positive cells were either de-differentiating and proliferating, or were instructingunderlying cells to proliferate and form the tumormass. To test this, they generated chimeric mice inwhich GFP+ cells would be transgene negative andfound that the tumors contained substantial num-bers of GFP+ cells. Both basal cells and neighboringcells were proliferating, suggesting that this was not acell-autonomous effect. There was also a significantincreased IL-1 expression in the tumors, suggest-ing that inflammation was driving tumor forma-tion. Moreover, inhibition of IL-1, released duringwounding, resulted in a significant delay in induc-tion and a reduced number of tumors. Watt’s groupis now investigating the role of bone marrow cells inthis model.

The results of Watt’s group to date suggest thatcommunication between the epidermis and cells ofthe immune system is also important for tumorformation. Differentiated cells within the epidermiscontribute to tumor formation through communi-cation with underlying basal cells and with bonemarrow cells to produce soluble factors. This is es-sential for normal epidermal homeostasis but couldalso be more significant in tumor formation thanpreviously thought.



Conclusion

The meeting convened leaders in stem cell research,both senior and innovative young scientists, pro-viding attendees with novel scientific presenta-tions that focused on a wide variety of dis-eases. The speakers, including two scientists fromNYSCF’s inaugural class of NYSCF-Robertson in-vestigators, gave conference participants a first-handlook at unpublished and recently published pio-neering research. The “Sixth Annual TranslationalStem Cell Research Conference” will take place onOctober 11–12, 2011 and will build upon the successof this year’s conference.

Conflicts of interest

The authors declare no conflicts of interest.

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Appendix

New York Stem Cell FoundationFifth Annual Translational Stem Cell ResearchConference

Co-chairs:Lee Goldman, M.D., M.P.H., Columbia University

Medical CenterAntonio M. Gotto, Jr., M.D., D.Phil., Weill Cornell

Medical CollegeDouglas A. Melton, Ph.D., Harvard UniversityPaul Nurse, Ph.D., The Rockefeller UniversityAllen M. Spiegel, M.D., Albert Einstein College of

Medicine

Scientific Co-chairs:Zach W. Hall, Ph.D., The New York Stem Cell

FoundationIhor Lemischka, Ph.D., The Mount Sinai School of

MedicineDan R. Littman, M.D., Ph.D., Skirball Institute of

Biomedicine

Principal Sponsor:The Robertson Foundation

Co-sponsoring institutions:Albert Einstein College of MedicineColumbia University Medical CenterHelen and Martin Kimmel Center for Stem Cell

Biology, New York University School of MedicineMount Sinai School of Medicine

Tri-Institutional Stem Cell Initiative:Memorial Sloan-Kettering Cancer Center,The Rockefeller University, Weill Cornell Medical

College


Documents

The New York Stem Cell Foundation: Fifth Annual Translational Stem Cell Research Conference