Developmental Brain Research 134 (2002) A12–A18www.bres-interactive.com

Abstracts of oral presentationsPresenting authors are underlined

O1-1 that can give rise to multiple peripheral neuron cell types, glia (SchwannRegulation and function of neurogenesis in the adult hippocampus cells) and smooth muscle cells. Cells with similar properties can beFred H. Gage prospectively isolated from uncultured neural tissue by fluorescenceThe Salk Institute, La Jolla, CA, USA activated cell sorting using specific cell surface antibody markers. These

cells self-renew in vivo as well as in vitro. I will discuss current studies ofthe control of cell fate decisions in these stem cells by extracellularMost neurons in the adult central nervous system (CNS) are terminallysignals and by transcription factors.differentiated and are not replaced when they die. Evidence now exists

that small populations of neurons are formed in the adult olfactory bulband hippocampus. In the adult hippocampus, newly born neurons Keywords: Neural crest; Stem cell; Peripheral neuronoriginate from putative stem cells that exist in the subgranular zone of thedentate gyrus. Progeny of these putative stem cells differentiate into

O1-4neurons in the granular layer within a month of the cells’ birth, and thisIs there more than one type of stem cell in the nervous system?late neurogenesis continues throughout the adult life of all mammals.Derek Van der KooyStems cells can be harvested from a variety of brain and spinal cordDept. of Anatomy, University of Toronto, 1 Kings College Circle,regions genetically modified and transplanted back to the brain and spinalToronto, ON M5S 1A8, Canadacord where they can differentiate into mature glia and neurons depending

on the local environment. In addition, environmental stimulation candifferentially effect the proliferation, migration and differentiation of Perhaps the most conservative definition of a neural (or indeed any) stemthese cells in vivo. These environmentally induced changes in the cell is that it is a single cell that (from the time it is formed) lasts thestructural organization of the hippocampus, result in changes in electro- lifetime of the organism and can give rise to all of the differentiated typesphysiological responses in the hippocampus as well as in hippocampal of cells present in its tissue of origin. By this definition, neither therelate behaviors. We are studying the cellular, molecular as well as pluripotent embryonic stem cell (which is transient in vivo) nor theenvironmental influences that regulate neurogenesis in the adult brain and primitive neural stem cell (derived from the embryonic stem cell as aspinal cord. These adult stem cells from the brain can be genetically default state once the inhibitory effects of TGFb signaling have beenmodified and transplanted to the adult intact and damaged brain, thus can removed, and also transient in vivo) are stem cells. However, once thebe a delivery system therapeutic genes. In addition these cells can be FGF2 dependent neural stem cell arises in the mouse neural plate bytargeted with retroviruses that to express factors that may be important in embryonic day 8, then this ‘‘true’’ neural stem cell persists unchanged inthe repair process following injury. The potential of these cells, in vitro vivo until the mouse dies. Nevertheless, this true neural stem cell alsoand in vivo will be discussed shows regional specification at different levels of the neuraxis in both the

embryo and adult. Thus, neural stem cells isolated from the cortex,striatum, midbrain, hind brain and retina express homeobox genes that areKeywords: Neurogenesis; Hippocampus; Stem cell; Brain; Spinal cordspecific to their region of origin, even through repeated passaging in vitro.However, a neural stem cell is not irreversibly committed to its regional

O1-2 specification, and after exposure to other neuraxis environments, a neuralFrom embryonic stem cell to neuron stem cell can change its region specific homeobox gene expressionRon McKay pattern. Thus, there may be one true neural stem cell with the ability toNational Institute of Neurological Disorders and Stroke, NIH, Bethesda, adopt different neuraxis regional identities.MD, USA

Keywords: Neural stem cell; Embryonic stem cell; Regionalization;[No abstract received] Specification

O1-3 O2-1Neural crest stem cells Neurogenesis and migration in the anterior subventricular zoneDavid J. Anderson Marla LuskinDept. of Biology 216-76, Howard Hughes Medical Institute, Caltech, Dept. of Cell Biology, Emory University School of Medicine, Atlanta,1200 E California Blvd, Pasadena, CA 91125, USA GA, USA

Neural crest stem cells are self-renewing, multipotent neural stem cells [No abstract received]

0165-3806/02/$ – see front matter 2002 Elsevier Science B.V. All rights reserved.PI I : S0165-3806( 02 )00327-9

Abstracts BRI ’01 Symposium: Stem Cells in the Mammalian Brain A13

O3-1O2-2Neurosphere cultures from human brain tissue: characterization andRetinal regeneration: stem cells, progenitor cells, and Muller gliaexpansionT.A. Reh, A. Fischer, J. Close, A. Moshiri, J. Freidman-Little and B.

]]Clive SvendsenDierksThe Waisman Center, University of Madison-Wisconsin, Madison, WI,Dept. of Biological Structures, University of Washington, Box 357420,USASeattle, WA 98195, USA

[No abstract received]Regeneration of the retina has long been known to occur in cold-bloodedvertebrates, but thought not to be possible in homeothermic vertebrates,such as birds and mammals. In the past year, we have found thatposthatch chickens possess the ability to regenerate several types of O3-2neurons, including retinal ganglion cells and other inner retinal neurons Isolation of human neural stem cells from fetal brainafter neurotoxic lesions. Stem cells at the retinal margin, as well as 1 1N. Uchida , S.J. Tamaki , D. He, M. Dohse, K. Eckert, G. Jain, M.J.

]]]Muller glia, appear to contribute to this regenerative response. The fate of 1 1 2 3Reitsma , D.W. Buck, A.S. Tsukamoto , F.H. Gage and I.L. Weissmanthe progeny of the retinal stem cells can be influenced by the same factors 1 2StemCells Inc., Palo Alto, CA 94304, Salk Institute, La Jolla, CAthat control cell fate decisions in the developing retina. More recent 392037, and Stanford University School of Medicine, Stanford, CAevidence indicates that at least some of the key steps in the process of 94035, USAretinal regeneration can be restored in certain strains of mice. Therefore,our evidence indicates that it may be possible to develop strategies for

Neurogenesis and gliogeneisis proceed from clonogeneic neural stemretinal repair by stimulating regeneration from resident retinal stem cells.cells with self-renewal and multilineage differentiation properties. Wereported direct isolation of human central nervous system stem cells

Keywords: Neurogenesis; Retina; Regeneration; Stem cell; Glia; Trans- (CNS-SC) from fetal brain by flow cytometry based on the cell surface1 1 2 2 2 / lodifferentiation markers; they are CD133 . 5E12 . CD34 , CD45 and CD24 [1].

1 2 2 1CD133 CD34 CD45 (CD133 ) represent about 1–5% of enzymati-cally processed fetal brain cells (16–21 gestational weeks). These non-

1genetically modified sorted CD133 cells continue to expand exponen-tially and maintain their multi-differentiation capacity for over 20

1O2-3 passages, including to tyrosine hydroxylase dopaminergic neurons.1Building brains: neural chimeras in the study of stem cell differentia- Single-sorted CD133 cells initiated neurosphere cultures and the

tion progeny of these cells could differentiated into both neurons and glia.1 1 1 2 1

1¨ ¨O. Brustle , B. Scheffler , J. Steffel , C. Steinhauser , K. Karram , S.C. Single cells re-isolated from sorted /expanded CD133 cells also re-]]]3 3 1Zhang , J.A. Thomson and M. Wernig initiated neurosphere cultures, demonstrating the self-renewal potential of1 2

2 2Depts. of Neuropathology and Neurosurgery, University of Bonn this highly enriched stem cell population. In contrast, CD133 CD343

2Medical Center, Bonn, Germany; Dept. of Medical Sciences, University CD45 sorted cells, which represent 95% of fetal brain cells, fail to1of Wisconsin, Madison, WI, USA initiate neurosphere cultures. When these sorted /expanded CD133

neurosphere cells were transplanted into immunodeficient NOD-SCIDmice, some of the grafted human cells continued to proliferate in theIn vitro differentiation of embryonic stem (ES) cells and transdifferentia-neurogenic sites, the subventricular zone of the lateral ventricle and thetion of adult stem cells have opened new avenues for cell replacementdentate gyrus of the hippocampus. In long-term engraftment (.6strategies. Appropriate animal models are needed to probe the propertiesmonths), the progeny of the human cells migrate and differentiate intoof these stem cell populations in vivo. Transplantation into the ventricleneurons in the olfactory bulb, hippocampous and, in some cases, in theof embryonic and neonatal rodents permits widespread integration ofcerebral cortex with extensive dendrite extension. Human-deriveddonor cells throughout the host brain. Bypassing immunological prob-oligodendrocytes are detected in the fimbria of the hippocampus and thelems, this approach can also be applied to human cells. Followingcorpus callosum. These human CNS-SC from fetal brain can expand inintraventricular transplantation, murine and human ES cell-derived neuralvitro and give widespread long-term (life-long) engraftment with self-precursors incorporate into a variety of host brain regions where theyrenewal, migration and multilineage differentiation in the host brainsdifferentiate into neurons and glia. With respect to glial cells, this strategyunder site specific regulated fashion.can be exploited for widespread myelin repair in neonatal dysmyelinating

diseases.Since the grafted cells are directly exposed to the embryonic ventricu- [1] N. Uchida et al., Proc. Natl. Acad. Sci. 97 (2000) 14720–14725.

lar zone, intrauterine transplantation may also be used to study the effectof local instructive cues on non-neural stem cells. Myogenic precursors

Keywords: Central nervous system stem cell; Neural stem cell; Neuro-grafted into embryonic hosts populate large areas of the fore- and

genesis; Site-specific differentiation; Self-renewal; Neurosphere-initiatingmidbrain. In contrast to neural precursors, myogenic cells exhibit a close

cellassociation to endogenous blood vessels and show partial expression ofendothelial marker antigens.

Transplantation into hippocampal slice cultures can be employed tostudy migration, differentiation and function of GFP-positive cells in O3-3more detail. In this system, individual murine ES cell-derived astrocytes Isolation and induction of adult neural progenitor cellswere found to establish gap junction-mediated coupling to as many as 50 Steve Goldmanhost cells. Glial network integration of ES cell-derived precursors may Dept. of Neurology, Cornell University Medical College, New York, NYdevelop into a new approach for the widespread delivery of small 10021, USAmolecules and transglial modification of neuronal function.

Neuronal precursor cells remain ubiquitous in the adult vertebrate brain,including that of humans. These cells persist within both the ventricularKeywords: Embryonic stem cell; Neural precursor; Cell transplantation;subependyma and the dentate gyrus of the human forebrain, and includeSlice culture; Myelin repair

A14 Abstracts BRI ’01 Symposium: Stem Cells in the Mammalian Brain

distinct populations of neuronal progenitors and uncommitted precursors. cells in the olfactory bulb and dentate gyrus, each structure was found toIn addition, a distinct population of nominally glial progenitor cells acquire its neurons during a specific developmental time window.remains dispersed throughout the subcortical white matter. Each of these Importantly, the duration of this time window is not related to the finalcell types may be identified, specifically extracted and enriched from the quantity of neurons in a given structure (e.g., 1.2 million retinal ganglionadult brain, based upon their expression of fluorescent transgenes driven cells are generated during 40 days (E30–E70) whereas 1.5 millionby cell-specific promoters. At first glance, these appear to represent geniculate neurons are produced in less than 8 days (E36–43). Todistinct cell populations. However, once removed from the tissue environ- understand the regulation of neuronal production during development asment, each may generate multiple cell types, suggesting that each of these well as the inhibitory mechanisms in adulthood, we have also usedprogenitor phenotypes may be plastic in its autonomous lineage potential, retroviral gene transfer methods and the application of various transcrip-and directed to its in vivo fate by virtue of local environmental signals. tion factors both in vivo and in vitro to analyze genetic and epigeneticOur ability to specifically harvest these cells has allowed us to assess their factors that regulate the kinetics of neuronal stem cell proliferation andlineage potential, functional capacity, and engraftment efficacy upon their allocation. Altogether, these studies indicate that a species-specifictransplantation. In addition, it has allowed us to rationally design size of a given structure is determined early in the proliferative zone bystrategies for inducing resident progenitor cells in vivo. On this basis, we genes controlling cell production (i.e. onset, cycle length, symmetric /have found that each adult progenitor phenotype can mature to functional asymmetric mode of division, the rate of programmed cell death) and thecompetence ex vivo, can successfully integrate upon xenograft, and can allocation of postmitotic cells regulated by gradients of attractive andbe induced in vivo by exogenous delivery of cognate neurotrophic repulsive molecules. The absence of neurogenesis in most regions of adultcytokines. As such, neural progenitor cells may provide a cellular brain indicates that overcoming the brain’s resistance to the acquisition ofsubstrate for neuronal and oligodendrocytic replacement in the damaged functionally competent new neurons will require an understanding of whyadult brain and spinal cord. neurogenesis ceases at the end of specific developmental time windows

and why there are regional variations in this phenomenon.

O4-1The biology of neuronal replacement in juvenile and adult birds

O4-3Fernando NottebohmStem cell neurogenesis in the adult mammalian forebrainRockefeller University, Research Center, 495 Tyrrel Road, Millbrook, NYSamuel Weiss12545, USADept. of Anatomy /Pharmacol. Therapy, University of Calgary, 3330Hospital Drive, NW, Calgary, AB T2N 4N1, Canada

Studies of the recruitment of new neurons in the developing and adultsong system of songbirds have yielded insights that may apply to this

Our laboratory studies epidermal growth factor (EGF) — responsivephenomenon in general. For example: (1) new neuron recruitment is oftenneural stem cells (NSCs) in the adult mammalian forebrain. In culturepart of a replacement process, in which serial events induce the death ofthese NSCs proliferate, self-renew and produce neurons, astrocytes andsome neurons and survival of others; (2) this replacement process isoligodendrocytes. In vivo, these NSCs participate in repopulation of theregulated by hormones and pathway use, which in turn regulate theadult subventricular zone. Recently, we have focused on asking how theseproduction of neurotrophins, whose ups and downs seem to determineNSCs produce restricted progenitors and whether this contributes to adultwhich cells die and which survive; (3) experience can influence neuronalneurogenesis in the olfactory bulb. We have found that the CNTFR/replacement even when the total number of neurons in a particular part ofLIFR/gp130 signaling system maintains NSCs in an undifferentiated statethe brain remains unchanged. As a result, two birds with the sameby preventing their restriction to a glial lineage. Forebrain intraventricularneuronal count may have significantly different neuronal profiles, much asinfusion of CNTF increases the numbers of NSCs in the adult, whiletwo pictures with the same number of pixels can show very differentdisruption of LIFR signaling results in a reduction in the number oflandscapes; (4) in the natural in vivo situation, vacancies created by cellNSCs, an associated reduction in proliferation in the subventricular zonedeath can promote new cell survival, but normally only a few types ofand a decreased number of interneurons in the olfactory bulb. We havecells are recruited and replaced in this manner. Though most of the detailsalso found that erythropoietin signaling directs the restriction of NSCs toof the above choreography remain unknown, the four observations offereda neuronal lineage. Infusion of erythropoietin into the adult lateralprovide a new scaffolding for the study of plasticity in the developing andventricles results in a 50% reduction in the number of NSCs, aadult brain. Replaceable neurons and the stems cells and conditions thatconcomitant doubling in neuronal progenitors, and an increase in newgive rise to them will remain an intellectual gem for many years to come.neurons in the olfactory bulb. Immunoneutralization of erythropoietinresults in an increase in NSC numbers. These findings suggest that

Keywords: Neuronal replacement; Hormone; Neurotrophins; Pathway EGF-responsive NSCs may turn over continuously in vivo, a subpopula-use; Learning; Songbird tion of which spontaneously differentiates into restricted glial progenitors,

while another subpopulation is directed to the neuronal restricted lineageby erythropoietin. Our findings also suggest that the numbers of NSCs

O4-2 directly determine the magnitude of forebrain neurogenesis. A model forControl of neuronal production forebrain neurogenesis by NSCs will be presented.Pasco Rakic Supported by the Canadian Institutes of Health Research.Dept. of Neurobiology, Yale University School of Medicine, New Haven,CT, USA

Keywords: Neural stem cells; Differentiation; Neuronal progenitors;Erythropoietin; Glial progenitors; Ciliary neurotropic factor

The number of neurons in a given brain structure is determined in theproliferative centers during specific developmental periods, by cell deathoccurring during a period of regression, and by the limits of productionand/or turnover of neurons in adulthood. To gain insight into these O4-4

3events, we have used H-TdR autoradiography and BrdU immuno- Generation of neurons from stem cells in the adult brain´histochemistry to examine more than 100 classes of neurons in 35 regions Jonas Frisen

of in the macaque monkey brain ranging in age from 30 days post- Dept. of Cell and Molecular Biology, Medical Nobel Institute, Karolinskaconception (E25) to 17 years postnatal. With the exception of granule Institute, S-17177 Stockholm, Sweden

Abstracts BRI ’01 Symposium: Stem Cells in the Mammalian Brain A15

primary brain tumors, including gliomas which can form neurospheresNeurons are continuously generated in certain regions of the adultunder the same culture conditions used for cloning normal multipotentmammalian brain. These neurons derive from multipotent, self-renewingastrocytes. Whether or not glial or other stem/progenitor cells we haveneural stem cells. Such stem cells can be cultured from the walls of theshown to exhibit stem cell-like behaviors are directly involved inventricular system of the adult rodent and human brain. Under certaingliomagenesis, the generation of neurospheres from clonogenic gliomaconditions, adult neural stem cells can generate a large number ofcells with distinct gene expression profiles suggests a potential linkdifferent non-neural cell types. We have found, by in vivo labelingbetween normal and hyperplastic neurogenesis.experiments, cell sorting and in vitro cultures, that ependymal cells have

Finally, transplant studies using different stem/progenitor cell popula-neural stem cell properties in the rodent. Ependymal cells divide rarely totions reveal the ability of certain populations to integrate and migrategive rise to subventricular zone progenitor cells which generate neuro-within the SEZ/RMS. The molecular cell biology of stem cell popula-blasts that migrate to the olfactory bulb. In response to a spinal cordtions, with the discovery of new factors and conditions that favor theinjury, ependymal cells lining the central canal are induced to proliferategrowth and expansion of particular populations from different tissuesand generate migratory progeny which differentiate to astrocytes andincluding the adult human brain, should provide insights into the controlcontribute to scar formation. Further studies on the regulation of stem cellof proliferation, fate and integration of these clinically important cells.differentiation may allow the development of strategies to stimulate

Supported by NIH/NINDS Grant NS37556.neurogenesis in the adult brain.

Keywords: Human neuropoiesis; Gene expression profiling; Stem cellKeywords: Neurogenesis; Stem cell; Ependymal cell; Synapsebioassay; Tumorigenesis

O4-5O5-1Multipotent astrocytic and other stem cells in mature, post-mortemGenes and environment in the regulation of adult hippocampaland tumorigenic brainsneurogenesisDennis A. SteindlerGerd Kempermann

Depts. of Neuroscience and Neurosurgery, The McKnight Brain Institute,¨ ¨Max Delbruck Center for Molecular Medicine (MDC), Robert-Rossle-Str.

Shands Cancer Center, and Stem Cell Biology Program of the University´10, D-13125 Berlin-Buch, and Dept. of Neurology, Charite, Schumannstr.

of Florida, Gainesville, FL 32610, USA20/21, D-10117 Berlin, Germany

Cells that exhibit stem cell-like behaviors have been isolated from theTo some degree, brain development never ceases. Much like neurogenesis

adult mammalian forebrain, including the subependymal zone (SEZ) andduring embryonic development, neurogenesis in the adult hippocampus is

the hippocampus. We have isolated clonogenic stem/progenitor cells fromshaped by an interaction of inheritable traits and experience. Regulation

the adult rodent and human brain, even with surprisingly long post-of adult hippocampal neurogenesis is complex in that control occurs on

mortem intervals (e.g. up to 5 days). The periventricular SEZ has manyseveral levels of neuronal development. This development starts from a

attributes in common with hematopoietic structures, e.g. bone marrow,neural stem cell in the subgranular zone and leads to a functioning neuron

including the presence of a dense extracellular matrix, and support cellsin the granule cell layer. Individual steps and their regulatory response to

surrounding a population of growth factor and cytokine-receptive prolifer-external stimuli are influenced differentially by inheritable traits. When

ating cells. Recent studies have established additional links between cellexposed to an enriched environment, the genetic background, age,

proliferation in hematopoietic and neuropoietic structures, including thetimepoint and duration of the exposure influence the effect on adult

potential for trans-differentiation and de-differentiation of different stemhippocampal neurogenesis. These findings can be seen in relation to data

cell populations.from behavioral tests, particularly tasks assessing hippocampal learning.

Using novel cell culture paradigms, including neurosphere-generatingThere is increasing evidence that adult hippocampal neurogenesis is

assays, we have found that the adult brain stem/progenitor cell populationinvolved at least in certain aspects of hippocampal function. Studying

is heterogeneous, i.e., different clonogenic cells give rise to diverseadult hippocampal neurogenesis provides a useful model system to

populations of progeny that express a variety of distinct phenotypic andinvestigate how neuronal development from neural stem cells is possible

developmental genes. Cells in neurospheres undergo proliferation andin the adult brain. While this has implications for research with the goal to

differentiation through a variety of stages that mirror, to an extent, celluse neural stem cells for therapy, knowledge on adult hippocampal

growth and differentiation as seen in the germinal matrix of theneurogenesis will also give new insight into the mechanisms underlying

developing brain. RT-PCR studies and the generation of cDNA librarieslearning and memory and neuroplasticity.

from individual neurosphere clones, used in subtractive and microarrayhybridization studies, reveal differences in clusters of gene expression

Keywords: Hippocampus; BrdU; Progenitor cell; Stem Cell; Mouseacross stem/progenitor cell-derived clones, including members of thenotch /delta and IAP, and other signaling pathways, as well as a variety ofdifferentiation- and apoptosis / survival-related genes.

Amongst the population of heterogeneous neurosphere-forming cells,O5-2

cells exhibiting characteristics of differentiated astrocytes also have beenThe role of voluntary exercise in adult neurogenesis

found to behave as multipotent stem cells — giving rise to both neuronsHenriette van Praag

and glia — under particular tissue culture conditions. These cells haveLaboratory of Genetics, The Salk Institute for Biological Studies, La

been identified from diverse CNS regions in addition to the SEZ,Jolla, CA 92037, USA

including the cerebral cortex and spinal cord, during a critical period inpostnatal development when astrocytes are known to support reactive

Most neurons in the adult central nervous system (CNS) are terminallyregeneration. It is interesting that astrocytes within the SEZ/rostraldifferentiated and cannot be replaced when they die. However, evidencemigratory stream (RMS) exhibit multipotency and reactivity throughoutnow exists that small populations of new neurons are generated in thelife, coincidental with the expression of developmentally regulatedadult olfactory bulb and hippocampus. In the adult hippocampus, newlyextracellular matrix molecules believed to be involved in tissue growthborn neurons originate from putative stem cells that exist in theand plasticity.subgranular zone of the dentate gyrus. Recently, it has been shown thatThe adult brain neural stem cell population may also be involved in

A16 Abstracts BRI ’01 Symposium: Stem Cells in the Mammalian Brain

environmental stimulation affects the proliferation and differentiation of crucial determinant for the structural development of individual brainthese cells in vivo. Specifically, exposure to an enriched environment regions. In the adult brain, new neurons are generated from proliferatingincreases dentate gyrus neurogenesis. Subsequent studies indicated that neural stem cells of the ventricle wall and the hippocampus. Because cellphysical activity is a critical component of enrichment. Initial research death appears to be a prominent feature in regions with neural stem cellsuggested that voluntary exercise in a running wheel results in the same activity, we assume that a neuronal turnover takes place in the adultincrease in neurogenesis as enrichment. However, when the running mammalian brain. The final number of newly generated neurons in thewheel was taken out of the enriched environment, there were twice as adult brain is dependent on the coordinated interplay of several cellularmany new neurons in the running as compared to the enriched condition. events: proliferation of stem cells, differentiation of neuroblasts andInvestigation of the consequences of running and enrichment for behavior apoptotic elimination of progenitor cells and neurons. The aim of theshowed that the improvement in spatial learning was the same in both study is to determine how neuronal turnover in the brain is coordinatedgroups. Our further research of consequences of running for hippocampal and which molecular signals are involved.function showed that exercise increases long-term potentiation (LTP, an We demonstrate that mice deficient of the cyclin-dependent kinaseelectrophysiological model of memory function) in vitro and in vivo. (CDK) inhibitors p27Kip1 generate higher numbers of neurons in theInterestingly, the amount of running has a positive correlation with the adult brain. Since the transgenic expression of the anti-apoptotic genenumber of new neurons. These findings suggest that exercise is correlated Bcl-2 under a neuronal promoter also increases the amount of neuro-with enhanced learning, synaptic plasticity and neurogenesis. Whether the genesis, we assume that proliferative as well as apoptotic events regulatenew neurons play a unique role in these effects on hippocampal function the final number of neurons generated in the adult brain. Animalsremains to be determined. deficient for the transcription factor E2F1, which induces cell cycle entry,

show a significant reduction in stem cell proliferation. Because E2F1 isable to induce cell cycle progression in proliferation-competent cells, butKeywords: Exercise; Neurogenesis; Dentate gyrus; Spatial memorycell death in postmitotic differentiated cells, it is conceivable that anintegration of proliferative and apoptotic signals during neuronal turnovercould take place at level of cell cycle control.

O5-3Keywords: Cell cycle regulation; Transcription factor; Programmed cellRegulation of adult neurogenesis by antidepressant treatmentdeathRonald S. Duman

Abraham Ribicoff Research Facilities, Dept. of Psychiatry, Yale Uni-versity School of Medicine, New Haven, CT 06508, USA

O5-5Basic research studies demonstrate that social or physical stress decreasesRole of IGF in hippocampal neurogenesisneurogenesis in the hippocampus of adult rodent and non-human pri-Peter Erikssonmates. Down-regulation of neurogenesis could contribute to the decreasedInstitute of Clinical Neuroscience, Sahlgrenska University Hospital,volume of hippocampus observed in patients with stress-related psychiat-

¨ ¨Goteborg University, Goteborg, Swedenric disorders, including depression and post-traumatic stress disorder. Incontrast, we have found that chronic administration of an antidepressant,including a serotonin or norepinephrine selective reuptake inhibitor, [No abstract received]increases neurogenesis in hippocampus of adult rodent. Up-regulation ofneurogenesis is dependent on repeated treatment, consistent with the timecourse for the therapeutic action of antidepressants. Using a combinationof pharmacological and transgenic approaches we have found thatactivation of the cAMP-CREB cascade increases adult neurogenesis.Moreover, we have found that phosphorylated CREB is colocalized with O5-6markers of maturing neurons and BrdU 2–3 weeks after administration of Neurogenesis in hippocampus: what is the role of the vasculature?the thymidine analogue. In summary, up-regulation of neurogenesis could Theo Palmeroppose the atrophy of hippocampus caused by stress and could contribute Dept. of Neurosurgery, Stanford University, Stanford, CA, USAto the therapeutic action of antidepressant treatment. Up-regulation ofneurogenesis could occur via activation of the cAMP-CREB pathway, The adult brain is limited in its ability to repair after injury but somewhich also appears to play a role in the differentiation and function of areas display slow but continuous neuronal replacement. The hippocam-new neurons in hippocampus. pus is one such structure where neural precursors proliferate within a

discrete zone underlying the dentate granule cell layer. Daughter cellsKeywords: Stress; Depression; Hippocampus; Srotonin; Nrepinphrine; then migrate into the granule cell layer where they differentiate intocAMP response element binding protein granule cell neurons. This process starts within a unique vascular

microenvironment where endothelial and neural precursors proliferatewithin tightly packed clusters. This co-localization suggests that endo-thelium and/or angiogenic signaling may influence neurogenesis. Initialanalysis of these clusters in vivo shows that the vascular endothelialO5-4growth factor (VEGF) receptor, Flk-1, is expressed. In addtion,VEGF canNeuronal turnover in the adult brain: a balance of stem celldirectly stimulate the proliferation of neural precursors cultured from theproliferation and cell deathadult hippocampus. The role of vascular microenvironment in adult¨H. Georg Kuhn, Christiana M. Cooper-Kuhn, Manfred Biebl and Jurgen

]]]] neurogenesis and the potential utility of induced angiogenesis as aWinklerframework for modulating neurogenesis are under investigation.Dept. of Neurology, University of Regensburg, D-93053 Regensburg,

Germany

During nervous system development the fate decision of neural stem cells Keywords: Neurogenesis; Hippocampus; Vascular endothelial growth— whether to undergo proliferation, differentiation or apoptosis — is a factor; Endothelium; Angiogenic signaling

Abstracts BRI ’01 Symposium: Stem Cells in the Mammalian Brain A17

cortex, via BrdU and immunocytochemical markers of progressiveO6-1neuronal differentiation. We found that precursors can be induced in situUse of stem cells for dopamine neuron replacement in Parkinson’sto differentiate into mature neurons in a layer- and region-specificdisease

1manner. BrdU newborn cells express NeuN, a mature neuronal marker,¨Anders Bjorklundexclusively in regions of cortex undergoing targeted neuronal death; theWallenberg Neuroscience Center, Lund University, S-22184 Lund,newborn neurons survived at least 28 weeks. We observed 97669 newSweden 3neurons /mm in experimental cortex, vs. 0 in controls. Early on, subsets

1of BrdU precursors expressed Doublecortin, a protein exclusivelyCell replacement therapy for Parkinson’s disease (PD) is based on the expressed in migrating neurons, and Hu, an early neuronal marker. Theidea that implanted dopamine neurons may be able to substitute for the retrograde label FluoroGold, injected into thalamus, labeled newborn,

1lost nigrostriatal neurons. In rodent models of PD, embryonic dopamine BrdU neurons, showing that newborn neurons can form long-distanceneurons can reinnervate the striatum and restore dopaminergic neuro- corticothalamic connections. Other experiments from our lab suggest thattransmission in the area surrounding the transplant. Clinical trials have these results are generalizable to other populations of projection neurons.shown that dopamine neuroblasts obtained from fetal human mesence- Together, these results demonstrate that endogenous precursors can bephalon can survive and function also in the brains of PD patients, restore induced in situ to differentiate into cortical neurons, survive for manystriatal dopamine release, and ameliorate impairments in motor behavior. months, and form appropriate long-distance connections in the adultThe main limitations of this approach are the problems associated with mammalian brain. This suggests the possibility of neuronal replacement

therapies that do not require transplantation of exogenous cells. Ongoingthe use of tissue derived from aborted human fetuses, and the largeexperiments are investigating the molecular mechanisms underlying thisnumbers of donors needed to obtain good therapeutic effects. Until now,induced neurogenesis; whether this induced cortical neurogenesis can betransplantation of dopamine neurons has focused primarily on differen-modulated to increased levels; whether the new neurons differentiatetiated neuroblasts and young postmitotic neurons, at the stage of neuronalprecisely into the mature neuronal phenotype they are replacing; anddevelopment that is optimal for survival and growth of the grafted cells.whether newborn neurons join or form functional circuitry in the adultHowever, progenitors taken at earlier stages of development might provebrain.more effective. Efforts are now made to expand multipotent neural stem-

or progenitor cells in vitro, and control their phenotypic differentiationinto a dopaminergic neuronal fate. Initial results suggest that in vitro Keywords: Neurogenesis; Neocortex; Mouse brainexpanded cells can survive and function after transplantation to thestriatum in the rat PD model, but the overall yield of surviving dopamineneurons has been very low. With further development, expanded

O6-4progenitors or dopamine neuron precursors, possibly in combination withNeurogenesis in strokecell engineering techniques, may offer new sources of cells for replace-

1 2Frank R Sharp and Jialing Liument therapy in PD. This approach would have the additional advantage ]]]]1Dept of Neurology and Neuroscience Program, University of Cincinnatithat the cells can be standardized, screened and modified, by cell sorting2Vontz Center, Cincinnati, OH 45267-0536, and Dept. of Neurosurgery,or gene transduction, in ways that would never be possible with the

University of California-San Francisco, San Francisco, CA, USAlimited quantities of cells that are available from fresh tissue.

Recent studies have shown that acute brain injury, including that causedKeywords: Cell transplantation; Dopamine; Motor behaviorby ischemia, seizures and trauma can stimulate neurogenesis in the adultmammalian brain. Following global ischemia produced by temporarybilateral carotid occlusions in adult gerbils, there is no change in the

O6-2 numbers of BrdU-labeled cells for the first week. There is then aCell therapy in models of CNS disease 5–10-fold increase in the numbers of BrdU-labeled cells that peaks atEvan Snyder 11–13 days and returns to normal levels within a few weeks [1]. Over theDept. of Neurology & Pediatrics, Harvard Medical School, Children’s next 40 days about 60% of the newborn cells migrate into the dentateHospital, Boston, MA, USA granule cell layer and 40% go to the dentate hilus. Roughly two-thirds of

the cells in the granule cell layer become NeuN stained neurons and lessthan one-third of the cells in the hilus become GFAP stained astrocytes.[No abstract received]This neurogenesis can be stimulated in ischemia tolerance models wherethere is no CA1 neuronal cell death. Ischemia-induced neurogenesis canbe blocked by administering NMDA or AMPA antagonists, eitherO6-3systemically or into the hippocampus just prior to the ischemia [2]. FocalInduction of neurogenesis in the neocortex of adult micecerebral ischemia also stimulates neurogenesis [3]. Following middleJeffrey D. Mackliscerebral artery occlusions in adult rats, there is increased BrdU incorpora-Division of Neuroscience, Children’s Hospital, Dept. of Neurology andtion into cells at 1 week in the subgranular zone of the dentate gyrusProgram in Neuroscience, Harvard Medical School, Boston, MA 02115,(DG), and at 2 weeks in the subventricular zone (SVZ). The increase wasUSAgreater in the ipsilateral DG. BrdU-labeled cells expressed Doublecortinand PCNA but not Hu or NeuN, suggesting the cells were immature

Neurogenesis does not normally occur in postnatal mouse cortex. Is this neurons. These newborn cells likely contribute to functional recoverydue to limitations of endogenous precursors’ potential, or lack of signals following global and focal ischemia, though how they do this needs to befor neuronal differentiation /survival? Prior results from our lab show that elucidated.in regions of adult mouse cortex undergoing synchronous apoptosis ofprojection neurons, nearby cells upregulate genes that guide transplanted

[1] J. Liu et al., J. Neurosci. 18 (1998) 7768.neuroblasts or precursors to undergo directed migration, differentiation,[2] Bernabeu and F.R. Sharp, J. Cereb. Blood Flow Metab. 20 (2000)synaptic integration, and re-formation of long-distance projections.

1669.To ask whether we can direct the fate of endogenous precursors in mature[3] Jin et al., Proc. Natl. Acad. Sci. 98 (2001) 4710.cortex, we examined their differentiation when exposed in situ to these

signals, without transplantation. We induced degeneration of cor-ticothalamic neurons in layer VI and examined fates of dividing cells in Keywords: Neurogenesis; Gliogenesis; Ischemia; Hippocampus; Memory

A18 Abstracts BRI ’01 Symposium: Stem Cells in the Mammalian Brain

that this modulatory effect may be mediated through the changes in theO6-5levels of several growth factors which occur after stroke. In agreement,Neurogenesis in ischemic and epileptic insultsstroke-induced DG neurogenesis was recently demonstrated to be stronglyZaal Kokaia and Olle Lindvall

]]]impaired in mice with deletion of the FGF-2 gene. The involvement ofSection of Restorative Neurology, Wallenberg Neuroscience Center,neurotrophic factors is also supported by our preliminary data showingUniversity of Lund, S-22362 Lund, Swedenthat increased levels of BDNF, induced by transduction of hippocampalneurons by a viral vector carrying the BDNF gene, significantly at-

In the adult mammalian brain, the generation of new neurons occurstenuated ischemia-induced neurogenesis. In contrast, proliferation or

mainly in two regions, the dentate gyrus (DG) of the hippocampalsurvival of newly generated cells was not affected. Caspases are probably

formation and the subventricular zone (SVZ) in the wall of the lateralinvolved in marked apoptotic death of the newly born cells following

ventricle. Mechanical, epileptic and ischemic lesions in the hippocampalstatus epilepticus, because this cell death can be mitigated by administra-

formation lead to increased neurogenesis in the DG. However, enhancedtion of caspase inhibitors. The functional consequences of insult-induced

neurogenesis is also caused by seizure activity, mild global forebrainneurogenesis are still unclear. Hypothetically, the increased neurogenesis

ischemia and stroke not associated with neuronal death in the hippocam-might lead to abnormal excitability and contribute to epileptogenesis, or

pus. Thus, cell death is not necessary for insult-induced neurogenesis.be a compensatory mechanism to replace lost neurons and counteract

Stroke has also been reported to increase neurogenesis in the SVZ. Thefunctional impairments.

increased neurogenesis in the DG following stroke is triggered byglutamatergic mechanisms acting on NMDA receptors. We hypothesize