All human life is sacred. This is what young women contemplating abortion should know!
or your mother, child, or lover...)
SCIENCE NEWS
New Stem Cell Lines Spare
Embryo
Human embryonic stem cells offer
great medical hope, because of their ability to develop into almost any kind of
adult cell. But harvesting the pluripotent cells from
stored embryos has raised ethical concerns, due to the necessity of destroying
potential humans to derive these cells. Now new research has shown that stem
cells can be cultivated from cells split off from developing embryos without
impacting the embryo itself.
In previous research, Robert Lanza and his colleagues at Advanced Cell Technology had
shown that single-cell biopsies done on mouse embryos--similar to those used
for genetic diagnosis prior to a human embryo's implantation--might allow for
the cultivation of stem cell lines without discernible impact. The team thawed
16 human embryos that had gone unused by parents pursuing in vitro
fertilization. The scientists separated single cells, known as blastomeres,
from the embryos and cultivated them separately.
More than half of the
blastomeres continued to divide and the researchers were able to cultivate
specific target cells, such as endothelial cells. The shape, growth and
abilities of these cells closely matched those of stem cells derived from other
techniques. Overall, in 10 separate experiments, they created 19 embryonic stem
cell-like growths as well as two cell lines capable of continuous production.
"We believe the success rate can be further increased by optimizing
conditions at the earliest stages of blastomere outgrowth," the
researchers write in the paper presenting the finding, published online by
Nature today.
If confirmed, the new technique
would allow researchers to create and experiment with stem cells while avoiding
ethical concerns as individual blastomeres, or their multicellular derivatives,
have never been shown to be capable of generating a complete organism. And
numerous studies have shown that this genetic testing technique has little
impact on the survival rate of embryos. In fact, the single cells used in such
testing routinely today could, in the future, grow stem cells for the resulting
children, and humanity. --David Biello
*****************************************************************************
News
Studies Provide Additional
Insight into Abilities of Stem Cells
E-mail
Print Link RSS
del.icio.us Digg
The controversy surrounding stem
cell research—in particular whether the cells should come from embryonic
sources or adult ones—hinges on what, exactly, cells from the two sources are
capable of. Embryonic stem cells, which are more politically contentious
because they must be harvested from human embryos, can differentiate into any
tissue in the human body. Adult stem cells, although available from less
controversial sources, have so far shown less plasticity than their embryonic
counterparts. Now the results of two studies published online by the journal
Nature provide additional insight into the abilities of both classes of stem cells.
The findings further suggest that only by investigating the two kinds of stem
cells will it be possible to determine which source will prove most useful in
treating a particular disease.
Catherine Verfaillie and of the
University of Minnesota Stem Cell Institute and her colleagues report that a particular kind of adult stem cell, derived from bone marrow and
dubbed a multipotent adult progenitor cell (MAPC), can differentiate into
nearly all types of mouse tissue. The
scientists injected MAPCs into mice blastocysts (embryos comprised of
approximately 100 cells), which were then transferred to foster mothers for
gestation. The resultant animals exhibited multiple tissue types, including brain, lung, retina, spleen and skin, attributable to the MAPCs. "Some of the animals are
40 percent derived from the bone marrow stem cells, suggesting that the cells
contribute functionally to a number of organs," Verfaillie notes.
"This is similar to what one would expect of [embryonic stem] cells."
The team next injected MAPCs into a living animal and found that the cells
still differentiated into liver, intestine and lung tissue, but overall MAPCs
were detected in fewer tissue types than in the blastocyst-injected mice.
ADVERTISEMENT (article continues
below)
Contrary to some recent study
results that indicate adult stem cells may merely be fusing with cells already
present in the body instead of fully differentiating, the researchers report
that they did not co-culture the bone marrow cells with other cell types,
thereby ruling out fusion in vitro. Verfaille cautions, however, that the in
vivo experiments are not conclusive with regard to the fusion problem. But so
far the MAPCs also have not demonstrated a potential problem of embryonic stem
cells: growth of tumors known as teratomas, which contain multiple tissue
types.
In the second published paper,
Ronald McKay of the National Institute of Neurological Disorders and Stroke and
his colleagues report having successfully cultured embryonic stem cells into
dopamine-producing neurons, the type lost in Parkinson's disease. By adding a gene called Nurr1 to stem cells from mice, the
scientists made an abundance of dopamine neurons, nearly 80 percent of the
cells produced the neurotransmitter. When implanted into rats missing
dopamine-producing cells on one side of their brains, the stem cell-derived
neurons made functional connections with surrounding cells. And animals that
received neurons containing Nurr1 showed more improvement in their Parkinsonian
symptoms than did animals that received embryonic stem cells lacking the gene.
Although some Parkinson's patients have shown improvements after receiving
experimental transplants of fetal tissue cells into their brains, McKay
suggests that treatments based on the new findings could hold even greater
promise. Because this technique enables routine access to
dopamine-producing neurons, researchers will be able to investigate in a
systematic way new ways to make using them safe for future patients, he says.
Both groups advise that
potential applications of their recent work remain a long way off and that
research studies involving the two stem cell types are not mutually exclusive.
According to Verfaille, studies of adult and embryonic stem cells should
proceed in parallel because what is learned about one cell type can help
advance research into the other. Natalie DeWitt, a senior editor at Nature,
concurs. "While the two papers will no doubt rekindle the debate on the
relative merits of embryonic versus adult stem cells," she says,
"together they emphasize the outstanding potential of stem cells and the
need for continued research in all areas of stem biology." --Sarah Graham
****************************************************************************************
Scientists Coax Neurons from
Bone Marrow Stem Cells
E-mail
Print Link RSS
del.icio.us Digg
As part of their continuing
effort to skip over the ethical and political hurdles surrounding embryonic
stem cells, researchers have unlocked even more potential from the adult kind.
New findings suggest that a biochemical cocktail
can coax adult bone marrow stem cells to become neurons, according to a report
presented yesterday at the annual meeting of the Society for Neuroscience in
San Diego. But although the ability to effect such a
metamorphosis may someday hold promise for treating neurodegenerative ailments
such as Parkinson's disease, the transformed cells currently revert back to
their primordial state within two to three days.
Stem cells from adult bone
marrow normally generate bone, muscle, cartilage and fat cells—a limited set
compared with embryonic stem cells, which can spawn the full spectrum of adult
tissues. Prior research with cultured tissue had shown that a mix of chemicals
could change bone marrow stem cells from mice to those resembling brain cells,
but when a team led by neurologist Lorraine Iacovitti of Thomas Jefferson
University in
She doesn't know yet whether
they will act like neurons, but the changed cells seem to produce the
neurotransmitter known as GABA. Cells that make GABA deteriorate in
Huntington's disease, Iacovitti notes. She hopes to find dopamine-producing
neurons to replace those lost in Parkinson's disease. Generating neurons from adult stem cells "would be a huge leap
forward and put to rest a lot of the ethical issues we've been grappling with
for years," she explains. People are also less likely to reject
transplanted cells from their own bodies. Iacovitti
says she has to tackle the problem of keeping the cells differentiated before
she can do anything else, however. "We're a long way off from thinking
about the clinic. But the fact that we can get it to happen is still extremely
hopeful." --JR Minkel
*************************************************************************
News
Researchers Find Adult Stem
Cells in Skin
E-mail
Print Link RSS del.icio.us Digg
In the wake of the federal
government’s recent decision to limit embryonic stem cell research to existing
cell lines, Canadian scientists announced they have discovered a new, noncontroversial source of stem cells. Researchers at
The researchers isolated cells
from the deeper layers of skin, or dermis, of juvenile and adult mice. When
cultured, the cells—termed SKPs, for skin-derived precursors—generated a variety of different cell types, including neurons,
muscle cells and fat cells. "We believe our
discovery is important as we have identified an exciting new stem cell from a
noncontroversial source that holds considerable promise for scientific and
therapeutic research," says co-author Freda Miller.
ADVERTISEMENT (article continues
below)
The newly discovered cells are
distinct from other adult-derived stem cells, such as those originating from
bone marrow, and retain their ability to morph into diverse cell types for up
to a year, the scientists report. The team tested human skin to determine if it
could generate SKPs and concluded that "similar precursors may be present
within adult human skin." If human cells can be exploited for therapeutic
treatments, Miller says, "complications seen in donor transplantations are
avoided as the patient's own cells are being transplanted." --Sarah Graham
*******************************************************************
Titre du document / Document title
Isolation and characterization
of multipotent skin-derived precursors from human skin
Auteur(s) / Author(s)
TOMA Jean G. ; MCKENZIE Ian A. ;
BAGLI Darius ; MILLER Freda D. ;
Résumé / Abstract
We have previously isolated,
expanded, and characterized a multipotent precursor
cell from mammalian dermis (termed skin-derived
precursors [SKPs]) that can
differentiate into both neural and mesodermal
progeny. In this study, we report the isolation, expansion, and
characterization of a similar precursor cell from neonatal human foreskin tissue. Like their
rodent counterparts, human SKPs grew in suspension as
spheres in the presence of the mitogens fibroblast
growth factor 2 and epidermal growth factor and expressed nestin, fibronectin, vimentin, and
characteristic embryonic transcription factors. Human SKPs
could be maintained in culture for long periods of time and would still
differentiate into neurons, glia, and smooth muscle cells, including cells with
the phenotype of peripheral neurons and Schwann cells. Clonal analysis
indicated that single SKP cells were multipotent and could give rise to all of
these progeny. Moreover, human SKPs apparently derive from an endogenous
precursor within human foreskin; a subpopulation of dissociated primary
foreskin cells could differentiate into neurons, a cell
type never seen in skin, and the initial spheres to develop from skin expressed
the same markers and had the same potential as do passaged SKPs. Together,
these data indicate that SKPs are an endogenous multipotent precursor cell
present in human skin that can be isolated and expanded and differentiate into
both neural and mesodermal cell types.
Revue / Journal Title
Stem cells (Stem cells)
ISSN 1066-5099 CODEN STCEEJ
Source / Source
2005, vol. 23, no6, pp. 727-737
[11 page(s) (article)]
Langue / Language
Anglais
Editeur / Publisher
AlphaMed,
Mots-clés d'auteur / Author
Keywords
Neural stem cells ; Neural crest
; Neurons ; Schwann cells Smooth muscle cells ; Foreskin ; Stem cells ; Dermis
;
Localisation / Location
INIST-CNRS,
Copyright 2006 INIST-CNRS. All
rights reserved
Toute reproduction ou diffusion
même partielle, par quelque procédé ou sur tout support que ce soit, ne pourra
être faite sans l'accord préalable écrit de l'INIST-CNRS.
No part of these records may be
reproduced of distributed, in any form or by any means, without the prior
written permission of INIST-CNRS.
Nº notice refdoc (ud4) :
16869208
*******************************************************
Nature Cell Biology 6, 1082 - 1093 (2004)
doi:10.1038/ncb1181
There is an Addendum (May 2005)
associated with this Article.
A dermal niche for multipotent
adult skin-derived precursor cells
Karl J. L. Fernandes1, 2, 8, Ian
A. McKenzie2, 5, 8, Pleasantine Mill2, 3, Kristen M. Smith1, 2, Mahnaz
Akhavan2, Fanie Barnabé-Heider2, 5, Jeff Biernaskie2, Adrienne Junek7, Nao R.
Kobayashi2, Jean G. Toma2, David R. Kaplan1, 2, 3, Patricia A. Labosky6, Victor
Rafuse7, Chi-Chung Hui2, 3 & Freda D. Miller2, 3, 4
1 Department of Cancer Research,
2 Department of Developmental
Biology, Hospital For Sick Children Research Institute,
3 Departments of Medical and
Molecular Genetics,
4 Department of Physiology,
5 Department of Neurology and
Neurosurgery,
6 Department of Cell and
Developmental Biology,
7 Department of Anatomy and
Neurobiology,
8 These authors contributed
equally to this work.
Correspondence should be
addressed to Freda D. Miller [email protected]
A fundamental question in stem
cell research is whether cultured multipotent adult
stem cells represent endogenous multipotent precursor
cells. Here we address this question, focusing on SKPs,
a cultured adult stem cell from the dermis that generates both neural and
mesodermal progeny. We show that SKPs derive from
endogenous adult dermal precursors that exhibit properties similar to embryonic
neural-crest stem cells. We demonstrate that these endogenous SKPs can first be
isolated from skin during embryogenesis and that they persist into adulthood,
with a niche in the papillae of hair and whisker follicles. Furthermore,
lineage analysis indicates that both hair and whisker follicle dermal papillae
contain neural-crest-derived cells, and that SKPs from the whisker pad are of
neural-crest origin. We propose that SKPs represent an endogenous embryonic
precursor cell that arises in peripheral tissues such as skin during
development and maintains multipotency into adulthood.
Although adult mammalian stem
cells were previously thought to differentiate solely into cells of their
tissue of origin, a number of recent reports have identified cultured adult
stem cells that show a surprisingly diverse differentiation repertoire1.
Although some reported cases of multipotency are due
to unanticipated cellular fusion events2, 3, 4, compelling evidence still
exists for the multipotency of a number of cultured
adult stem cell populations. For example, blastocyst
injection studies show that both multipotent adult
progenitor cells (MAPC) bone marrow cells5 and neural stem cells from the
central nervous system (CNS)6 contribute to many different developing tissues.
One caveat to these studies is that multipotency was
demonstrated only after these stem cells were expanded in culture, raising the
possibility that it was a consequence of culture-induced de-differentiation
and/or reprogramming1.
We have previously described a multipotent precursor cell population from adult mammalian
dermis7. These cells — termed SKPs, for skin-derived
precursors — were isolated and expanded from rodent and human skin and
differentiated into both neural and mesodermal
progeny, including cell types never found in skin, such as neurons7, 8. One
endogenous embryonic stem cell population that contributes to dermis and has a
similar broad differentiation potential is neural-crest
stem cells (NCSCs)9. We
therefore proposed that SKPs represent a multipotent neural-crest-like precursor that arises in embryonic mammalian tissues, and is maintained into
adulthood. Here we provide evidence supporting this hypothesis
and identify a dermal niche for these precursors.
Results
SKPs share characteristics with, and have multipotentiality
similar to, embryonic NCSCs
To characterize the origin of SKPs, we first compared them to stem cell populations that
generate neural and/or mesodermal progeny. Because we
previously demonstrated that SKPs are distinct from
mesenchymal stem cells7, we focused on CNS neural stem cells and embryonic
NCSCs. Immunocytochemical comparison of SKPs and embryonic CNS neurospheres revealed that the two populations were
distinct: both expressed nestin and vimentin, but only SKPs expressed
fibronectin and the precursor cell marker Sca-1 (refs
10,11), whereas only neurospheres contained cells
expressing p75NTR (see Supplementary Information, Fig. S1a). We then analysed SKPs for expression of
genes associated with embryonic NCSCs. RT-PCR analysis
(Fig. 1a) showed that SKPs expressed the
transcription factor genes slug12, snail13, twist14, Pax3 (ref. 15) and Sox9 (ref. 16), expressed in various populations of embryonic NCSCs17
in vivo. Except for Sox9, all of these genes were expressed at lower or
undetectable levels in embryonic CNS neurospheres (Fig. 1a). SKPs also express
the transcription factors Dermo-1 (ref. 18) and SHOX2 (ref. 19; see
Supplementary Information, Fig. S1b), which are expressed in embryonic dermis
and craniofacial regions. A similar pattern of gene expression was observed in
embryonic, neonatal and adult SKPs passaged from 1-15 times. Thus, SKPs express
genes characteristic of embryonic NCSCs and/or their embryonic derivatives.
Figure 1. SKPs express markers
of embryonic neural crest and differentiate into peripheral neurons and Schwann
cells.
(a) RT-PCR for genes involved in embryonic neural crest determination and migration in total RNA isolated from SKP spheres compared with embryonic telencephalic neurospheres (CNS), both of which were cultured in the presence of FGF2 and EGF. RNA from an E12 neural tube functioned as a positive control (+), RT-PCR for GAPDH was used as a loading control and reaction with no input nucleic acid was run in the last lane as a negative control (-). (b) RT-PCR for two markers of peripheral catecholaminergic neurons, dopamine--hydroxylase (DH) and peripherin, in murine SKPs differentiated for one week in 10% serum (Diff. SKPs). SKP spheres and dissociated SKPs plated in proliferation medium (PM) do not express these mRNAs. (c) Western blot analysis for tyrosine hydroxylase (TH) in murine SKP spheres compared with SKPs differentiated for 14 days in 10% serum supplemented with neurotrophins. The positive control was protein isolated from cultured sympathetic neurons of the superior cervical ganglion (SCGs). (d) RT-PCR for three markers of peripheral Schwann cells, p75NTR, myelin basic protein (MBP) and P0 peripheral myelin protein (P0), in total RNA from undifferentiated and differentiated rat SKPs. (e) Immunocytochemical analysis of differentiated murine SKPs for markers of peripheral neurons. Left, morphologically complex differentiated cells co-express the neuronal markers III-tubulin and NFM (yellow cells in the merged image). Right, differentiated cells co-express III-tubulin (red; bottom inset) and p75NTR (green; top inset), proteins expressed by virtually all peripheral neurons. (f) Immunocytochemical analysis of differentiated SKPs, showing that a subset of bipolar cells co-express: left, S100 (red) and M
