From teratomas to embryonic stem cells:
discovering pluripotencyPeter W. Andrews and Paul J. Gokhale
The term ‘teratoma’ denotes the weird manifestations of benign or malignant
tumours that possess the hallmarks of abnormal embryogenesis. They containan array of tissues found in developing embryos, and malignant teratomas
contain the archetypal cancer stem cell, the embryonic carcinoma (EC) cell.
The resemblance of these tumours to abnormal embryos, and the discovery

Supplement to Nature Publishing GroupMOLECULAR
CELL BIOLOGY
Teratoma orteratocarcinoma?
The term teratomadescribes a tumour
containing differentiatedelements of all threeembryonic germ layers.
The term teratocarcinoma
describes malignant
tumours that contain
EC cells, the presumed
malignant stem cells, inaddition to these threelayers38. It is valuable todistinguish benign
teratomas from malignant
teratocarcinomas39.

Characterization of teratomas

Characterization of EC cells in culture

The discovery that 129 strain mice develop testicular
teratocarcinomas2 allowed the experimental studyof these cancers, which are GCTs arising from thePG cells in the embryo40; an example of teratoma
histology is shown (right). A strong genetic component
contributes to a predisposition to GCT development.
Lewis Kleinsmith and Barry Pierce showed that a single
EC cell from a teratocarcinoma can generate a
differentiated tumour when transplanted to a hostmouse — a demonstration of a cancer stem cell4.
EC cells in the tumour are malignant and capableof self-renewal and differentiation.

Beginning with work by Boris Ephrussi and Brenda
Finch in 1967 (REF. 5), mouse EC cells cultured
in vitro were studied through the 1970’s12,41–45.
Their capacity for differentiation and expressionof common markers suggested equivalence to thepluripotent ICM cells of the early embryo. Indeed, chimeric mice could
develop following blastocyst injection11,46,47 (above). In one report,
the EC cells populated the germline46. This work, especially thedevelopment of EC culture conditions using feeder cells12,43 and thediscovery of F9 antigen10 and, later, of the monoclonal antibodydefined antigen SSEA1 (REF. 14) as cell surface antigens of EC cells, paved
the way for the isolation of ES cell lines directly from the ICM17,18.

EC cells are identified as cancer stem cells, owing
to the fact that single EC cells can generate thecomplex histology of teratocarcinomas4

Richard Gardner demonstrates
that chimeric mice can beproduced following blastocyst
injection of ICM cells6

Leroy Stevens discovers
that testicular teratomas
occur frequently in the129 mouse strain2

Human
Monstrous tumours
have been a sourceof fascination since
the dawn of time1

4
195

1957

Karen Artzt and colleagues
show that the F9 cell surface
antigen links EC cells andICM cells of the early embryo101964

4197

196
71879

Barry Pierce reports passaging humanteratocarcinomas as xenografts3

19 6 81 97 0

Clinical pathology of teratomas
Teratomas occur most commonly as benign ovarian tumours,
dermoid cysts, and rarely as tumours of newborns.
The description on the clay cuneiform tablet with omens from
Nineveh (left) is almost certainly of a newborn’s sacrococcygeal
teratoma1. Teratomas also occur in the testis, where they arealways malignant and are described as teratocarcinomas.
They belong to a group of GCTs that includes seminomas,
which resemble PG cells. As in the mouse, testicular
GCTs are most likely to originate from defects ingerm cell development in utero9. They are the mostcommon, but most curable, cancers in young men.

www.abcam.com

nrmposter_oct12-print.indd 1

ES cells transformed the field of mouse
genetics, and they can be used to form
germ line chimaeras (right; the embryo
derived from ES cells is shown in blue,
the host placenta in green) after altering almost any locus by genetargeting22,27,28. Analysis of the signalling pathways that regulate
ES cell self-renewal and differentiation48 is providing important
insights into early embryonic development, cancer and the potential
application of ES cells in regenerative medicine. The International
Mouse Knockout Consortium intends to mutate every protein-coding
gene in the mouse.
Martin Evans and Gail Martin isolate mouse
ES cells17,18

Sid Strickland shows thatdifferentiation of EC cells in culture
can be induced by retinoic acid15

5197

1978

1979

198
0

3

It is demonstrated thatmouse ES cells can form
germ line chimaeras22

198
119 8

2SSEA3 is found tobe expressed byhuman EC cells20,2119 8 4#FWNV$NCUVQE[UV%QPXGTUKQP%+52)EGNNU
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OCT4 (POU5F1) is identified as apluripotency factor29)GTOEGNNU

NANOG is identified asa pluripotency factor33,34

SOX2 is identified as apluripotency factor30

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Jamie Thomson andcolleagues isolate
human ES cells32

Jamie Thomson andcolleagues isolate rhesus
monkey ES cells31

The first iPS cells are derived frommouse somatic cells by Shinya
Yamanaka and colleagues35

2006

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The groups of Shinya Yamanaka andJamie Thomson separately reportthat iPS cells can also be derived
from human somatic cells36,37
The first clinical trial of human ES cell-derived cells inregenerative medicine is started, for spinal cord injury

TRA-1-60 and TRA-1-81 surface antigensof human EC cells are defined26

The relationship of mouse EC cells to the early embryo suggested
a use for human EC cells in studying human development53,54.
However, developmental differences and differences in surface
antigen expression indicated that human and mouse EC cells
correspond to different embryonic cells, or that equivalent cells
differ between species16. Nevertheless, pluripotent human
EC cells23,26,55 (below) contributed to our understanding ofdevelopment, including the realization that retinoic acid acts
through HOX genes in the embryo56. The transplantation of NTERA2
EC cell-derived neurons into stroke patients was the first attempt touse pluripotent cells in regenerative medicine57.

Surface antigens have played a key part in dissecting
complex developmental systems since they were first usedin the immune system by Edward Boyse and Lloyd Old in the1960’s58. Subsequently, the identification of F9 antigen by asyngeneic anti-EC cell serum10 and, later, of its counterpart
SSEA1 by a monoclonal antibody14 were central
to relating mouse EC and ICM cells. SSEA1,
EC and ES cell phenotypes
SSEA3 and SSEA4 are glycolipids with
Human
Mouse
–differential expression in mouse and human
SSEA1
SSEA1+
19,59,60
embryos and EC cells. An extensive panel
SSEA3+
SSEA3–of surface antigen markers of human EC cells
SSEA4+
SSEA4–
61,62
has subsequently been defined(right) and isTRA-1-60+ TRA-1-60–
in use in human ES cell and iPS cell studies.
GCTM2+
GCTM2–63,64
Other markers, such as ALP
and, notably,
THY1+
THY1–+
the transcription factors OCT4, SOX2 andMHC
MHC–
NANOG, which have a key role in maintaining
ALP+
ALP+
pluripotency, are commonly expressed between
OCT4+
OCT4+
mouse and human EC and ES cells29,30,33,34.
NANOG+NANOG+

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Our Abpromise guarantees full technical support
from our experienced team. If an antibody doesn’t
work as it says on our datasheet we will give you afull refund or replacement, if you tell us within sixmonths. We publish everything we know about
every product on our datasheets and our catalogue
is web-based. This allows daily updates and far more
information than in any printed catalogue, including
customer reviews, technical enquiries and links topublication references.

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Human EC TERA2 cells arefound to be pluripotent23,24,25

Surface antigens and other markers

We have over 60,000 antibodies in our catalogue.
Our stem cell markers range includes over14,000 antibodies to:• Embryonic stem cells• Germ cells• Hematopoietic stem cells• Mesenchymal stem cells• Neural stem cells• Ectoderm, mesoderm and endoderm lineages• Wnt, TGF-β, Hedgehog and Notch signaling
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SSEA3 is found on cleavage stage mouseembryos but absent from mouse EC cells19

TERA1 and TERA2 cell lines are establishedfrom human teratocarcinomas13
Peter Andrews and colleagues suggestthat human EC cells differ from mouse
EC cells and do not express SSEA1 (REF 16)

Pluripotent cells have the capacity to differentiate
to all somatic cell types and germ cells. EC cells andK25EGNNU
teratocarcinomas probably arise from a short-circuit innormal germ cell development (right). In humans, an*WOCP'5CPF
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intermediate stage of CIS and seminoma, representing
malignant PG cells, is also found, but mouse PG cells
convert directly to a pluripotent state; in vitro they cangive rise to EG cells49,50. EC cells are ‘degenerate’ ES cells
that have adapted to tumour growth. EpiS cells,'%EGNNU
derived from the epiblast stage51,52, are primed fordifferentiation, whereas ES cells correspond to a
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more primitive, naive state of the ICM48. Human
ES cells resemble mouse EpiS cells51,52. Somatic)COGVGU
cells can be reprogrammed to iPS cells by theexpression of key pluripotency factors35–37.

Homologous recombination is used toalter the genotype of mouse ES cells27,28

Development of human EC cell lines“When a woman gives birth to an infant thathas three feet, two in their normal positions
attached to the body, and the third between
them, there will be great prosperity in the land.”Abcam supplies antibodies and reagents to researchers
worldwide. We ship directly to over 115 countries with officesin the UK, US, Japan and Hong Kong and offer customer support
in English, French, German, Spanish, Japanese and Chinese.
We are rapidly developing and expanding our range, looking for
new targets and improving our existing antibodies. To help withthis we actively attend, support and help organize conferenceson stem cell research. Find out more on our website:

1972

1 97

Pluripotent stem cells, germ cells and somatic cells

ES cells in culture andtheir use in gene targeting

Barbara Knowles and Davor Solter define theEC cell surface marker SSEA1, a counterpart of
the F9 antigen, using a monoclonal antibody14

Niels Skakkebaek identifies abnormal intratubular
germ cells (CIS) as the likely precursor of invasive
testicular teratocarcinomas9

Rudolf Virchow
coins the term
‘teratoma’Abcam Stem Cell antibodies you can rely on!

Gail Martin and Martin Evans show differentiationof EC cells in embryoid bodies in vitro12

Ralph Brinster reports that EC cells
are able to chimerise the developingembryo, indicating their functional
equivalence to ICM cells11

Pluripotent mouse
EC cells arecultured in vitro5

Mouse
600 BC

Leroy Stevens7, and Davor Solter, Nikola Skreb
and Ivan Damjanov8, find that teratomas canbe derived from ectopic embryosthat EC cells are pluripotent, like the ICM of the early embryo, suggested an
opening to experimental mammalian developmental biology before the toolsthat we now use became available. The study of EC cells led to the isolation,
30 years ago, of mouse embryonic stem (ES) cells. ES cells now provide tools
for experimental embryology and regenerative medicine.

Human ES cells and regenerative medicine
The surgical replacement of diseased or damaged tissues withcells differentiated from ES cells (for example, RPE cells (below,stained for the tight junction protein ZO1)) is a real possibility.
The first clinical trialof ES cell-derived
oligodendrocytes forspinal cord injury isunderway, and trials forother diseases are near,including those for eye
diseases, such as maculardegeneration. Many otheropportunities remain forusing ES cells in drug
discovery and toxicology.

Pluripotent stem cells and disease models
The production of human iPS cells36,37, now a rapidly developing
field, offers the possibility of circumventing the problems ofimmune rejection in regenerative medicine applications (below).
The production of iPS cells from patients with a specific genetic
disease presents a new opportunity to create disease models withwhich to search for new treatments65–68.

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Abbreviations

Image credits

Further reading

ALP, alkaline phosphatase; CIS, carcinoma
in situ; EG, embryonic germ; EpiS, epiblast
stem; GCT, germ cell tumour; ICM, innercell mass; iPS, induced pluripotent stem;
KLF4, Krüppel-like factor 4; MHC, major
histocompatibility complex; PG, primordial
germ; PS-iPS, patient-specific iPS;RPE, retinal pigment epithelium;
SSEA, stage-specific embryonic antigen;
THY1, thymocyte differentiation antigen 1;
ZO1, zonula occludens 1.

Photograph of L. Stevens courtesy of The Jackson Laboratory, USA | Photographs of B. Pierce andof teratoma histology courtesy of I. Damjanov, University of Kansas, USA | Image of chimeric mouseis reproduced, with permission, from © (1974) The Rockefeller University Press | Photograph ofM. Evans courtesy of M. Evans, Cardiff University, UK | Photograph of G. Martin courtesy ofG. Martin, University of California, San Francisco, USA | Photograph of J. Thompson courtesy ofJ. Thompson, Morgridge Institute for Research, USA | Image of gene-targeted embryo is reproduced,with permission, from © (2002) BioMed Central | Photograph of S. Yamanaka courtesy of the Center
for iPS cell Research and Application, Kyoto University, Japan | Image of Cuneiform tablet withomens © The Trustees of the British Museum. All rights reserved | Photograph of RPE cells derived
from human ES cells courtesy of P. Coffey, University College London, UK | Disease models
schematic is modified, with permission, from © (2010) American Society for Clinical Investigation.

Damjanov, I. & Solter, D. Experimental teratoma. Curr. Top.
Pathol. 59, 69–130 (1974) | Stevens, L. C. The biology ofteratomas. Adv. Morphog. 6, 1–31 (1967) | Andrews, P. W.
From teratocarcinomas to embryonic stem cells.
Phil. Trans. R. Soc. B 357, 405–417 (2002) | Solter D. Fromteratocarcinomas to embryonic stem cells and beyond:a history of embryonic stem cell research. Nature Rev
Genet. 7, 319–327 (2006) | Evans, M. Discovering
pluripotency: 30 years of mouse embryonic stem cells.
Nature Rev. Mol. Cell Biol. http://dx.doi.org/10.1039/
nrm3190 (2011).

For the reference list please see:
http://www.nature.com/nrm/posters/
discoveringpluripotency

Contact information

p.w.andrews@sheffield.ac.uk
p.gokhale@sheffield.ac.uk
Edited by Katharine H. Wrighton;
copy-edited by Antony Bickenson;
designed by Vicky Summersby.
 2011 Nature Publishing Group.
http://www.nature.com/nrm/posters/
discoveringpluripotency

23/08/2011 11:08