Bone marrow stem cells
used to repair damaged retina
University of Florida (UF)
researchers have programmed
bone marrow stem cells to
repair damaged retinas in
mice, suggesting a potential
treatment for one of the most
common causes of vision loss
in older people.
The success in repairing a
damaged layer of retinal cells in
mice implies that blood stem
cells taken from bone marrow
can be programmed to restore a
variety of cells and tissues,
including ones involved in
cardiovascular disorders such as
atherosclerosis and coronary
artery disease.
“To our knowledge, this is
the first report using targeted
gene manipulation to specifically programme an adult stem
cell to become a new cell type,”
said Dr Maria B. Grant, a
professor of pharmacology and
therapeutics at UF’s College of
Medicine. “Although we used
genes, we also suggest you can
do the same thing with drugs –
but ultimately you would not
give the drugs to the patient,
you would give the drugs to
their cells. Take the cells out,
activate certain chemical pathways,
and put the cells back
into the patient.”
In a paper which was due to
appear in the September 2009
issue of the journal Molecular
Therapy, scientists describe how
they used a virus carrying a gene
that gently changed cultured
adult stem cells from mice into
retinal cells. Only after the stem
cells were reintroduced into the
mice did they completely transform
into the desired type of
vision cells, apparently taking
environmental cues from the
damaged retinas.
After studying the celltransformation
process, scientists
were able to bypass the
gene manipulation step
entirely and instead use chemical
compounds that mirrored
environmental conditions in
the body, thus pointing the
stem cells toward their ultimate
identities as vision cells.
“First we were able to show
you can overexpress a protein
unique to a retinal cell type
and trick the stem cell into
thinking it is that kind of cell,”
said Grant, who collaborated
with Edward Scott, the
director of the Program in
Stem Cell Biology and
Regenerative Medicine at UF’s
McKnight Brain Institute.
“As we proceeded, we found
we could activate the stem
cells by mimicking the body’s
natural signalling channels
with chemicals. This implies a
whole new field of stem cell
research that uses drug manipulation
rather than genetic
manipulation to send these
immature cells along new
pathways,” Grant said.
Scientists chose to build
retinal pigment epithelial cells,
which form the outer barrier of
the retina. In addition to being
very specialised to identify,
RPE cells are faulty in many
retinal diseases, including agerelated
macular degeneration
and some forms of blindness
related to diabetes.
“This work applies to 85% of
patients who have age-related
macular degeneration,” Grant
said. “There are no therapies
for this devastating disease.”
The researchers removed
blood stem cells from the bone
marrow of mice, modified the
cells in cultures, and injected
them back into the animals’
circulatory systems. From
there, the stem cells were able
to home in on the eye injury
and become retinal cells.
At 28 days after receiving
the modified stem cells, mice
that had previously demonstrated
no retinal function
were no different than normal
mice in electrical measures of
their response to light.
Gene therapy for blindness
remains positive one year on
Three young adults who
received gene therapy for a
blinding eye condition
remained healthy and maintained
previous visual gains one
year later, according to an
August online report in Human
Gene Therapy. One patient also
noticed a visual improvement
that helped her perform daily
tasks, which scientists describe
in an 13 August letter to the
editor in the New England
Journal of Medicine.
These findings have emerged
from a phase I clinical trial
supported by the National Eye
Institute (NEI) at the US
National Institutes of Health,
and conducted by researchers
at the University of
Pennsylvania, Philadelphia,
and the University of Florida,
Gainesville. This is the first
study that reports the one-year
safety and effectiveness of
successful gene therapy for a
form of Leber congenital
amaurosis (LCA), a currently
untreatable hereditary condition
that causes severe vision
loss and blindness in infants
and children.
“These results are very significant
because they represent one
of the first steps toward the clinical
use of gene therapy for an
inherited form of blindness,”
said NEI director Paul A.
Sieving, MD, PhD.
The three patients in the
study-aged 22, 24 and 25-have
been legally blind since birth
due to a specific form of LCA
caused by mutations in the
RPE65 gene. The protein
made by this gene is a crucial
component of the visual cycle.
The RPE65 protein is necessary
for the production of a
retina-specific form of vitamin
A that is required for the lightsensitive
photoreceptor cells to
function. Mutations in the
RPE65 gene prevent this
production, which halts the
visual cycle and blocks vision.
The RPE65 disease offers an
opportunity for treatment in
that it leaves some photoreceptors
intact. In this study,
researchers pinpointed an area
of intact photoreceptors in the
retina of each patient. They
injected healthy copies of the
RPE65 gene under the retina
in this area in an attempt to
repair the visual cycle.
One year after the procedure,
the therapy had not provoked
an immune response in the eye
or in the body. Though the
patients' visual acuity, or ability
to read letters on an eye chart,
remained unchanged, all three
patients could detect very dim
lights that they were unable to
see prior to treatment. This
visual benefit provides evidence
that the newly introduced
RPE65 gene is functional and is
increasing the light sensitivity
of the retina.
● References
1. Cideciyan AV, et al. (2009)
Human RPE65 Gene Therapy for
Leber Congenital Amaurosis:
Persistence of Early Visual
Improvements and Safety at 1
Year. Human Gene Therapy, vol.
20, no. 9; published online
August 2009, ahead of print (doi:
10.1089/ hum.2009.086).
2. Cideciyan AV, et al. Vision 1 Year after Gene Therapy for
Leber's Congenital Amaurosis.
N Engl J Med 2009; 361:725-
727.
Researchers open new way
to reprogramme cells
A research team comprised of
faculty at Massachusetts, USbased
Worcester Polytechnic
Institute’s (WPI) Life Sciences
and Bioengineering Center
(LSBC) and investigators at
CellThera, a private company
also located at the LSBC, has
discovered a novel way to turn
on stem cell genes in human
fibroblasts (skin cells) without the
risks associated with inserting
extra genes or using viruses.
This discovery opens a new
avenue for reprogramming
cells that could eventually lead
to treatments for a range of
human diseases and traumatic
injuries by coaxing a patient’s
own cells to repair and regenerate
the damaged tissues.
The research team reported
its findings in the paper
“Induction of Stem Cell Gene
Expression in Adult Human
Fibroblasts without Transgenes,”
published online 21 July 2009
as a “fast track” paper from the
journal Cloning and Stem Cells.
“We show that by manipulating
culture conditions
alone, we can achieve changes
in fibroblasts that would be
beneficial in development of
patient-specific cell therapy
approaches,” the authors wrote
in the paper.
Early on, the emerging field
of regenerative medicine
focused on pluripotent embryonic
stem cells. In the pluripotent
state, several genes are
known to be active, helping to
control the stem cells. These
genes, including OCT4, SOX2
and NANOG, are accepted as
markers of pluripotency
because they are active in stem
cells, but become dormant once
the stem cells begin to differentiate
and head down the path to
developing into a specific kind
of cell type and tissue.
While the study of embryonic
stem cells continues to yield
important knowledge, research
teams around the world are also
working to change, or reprogramme,
fully-differentiated
cells like skin cells, back to a
more pluripotent state. Called
induced pluripotent stem cells
(iPS), these reprogrammed cells
could be used to regenerate
tissue without some of the problems
associated with embryonic
stem cells, including ethical
questions and the potential for
embryonic stem cells to be
rejected by a patient's immune
system or to grow out of control
and cause tumours.
The first induced pluripotent
stem cells were created in 2007
by Shinya Yamanaka's team at
Kyoto University in Japan,
which inserted extra copies of four known stem cell genes,
including OCT4 and SOX2,
into human skin cells. Those
genes began expressing proteins
that changed the skin cells back
to a more pluripotent state.
This technique, which has
since been repeated by other
labs and refined to the point
were fewer additional genes are
needed to achieve reprogramming,
was a major scientific
breakthrough. Its potential for
use in human therapies is
limited, however, because
inserting new genes into adult
cells, either directly or by using
viruses to carry the genetic
payload, can cause a host of
problems.
In the current study, the
team at WPI and CellThera
turned on the existing, yet
dormant, stem cell genes
OCT4, SOX2 and NANOG
already in the skin cells by
lowering the amount of atmospheric
oxygen the cells were
exposed to, and by adding a
protein called fibroblast
growth factor 2 (FGF2) to the
culture medium.
Furthermore, once the stem
cell genes were activated and
began expressing proteins, the
team found those proteins
migrated back into the nucleus
of the skin cells, precisely as
would occur in induced pluripotent
stem cells. “This was an
exciting observation,” said
Raymond Page, PhD, research
assistant professor of biology
and biotechnology at WPI and
lead author on the paper.
“Having these proteins localise
to the nucleus is the first step of
reprogramming these cells.”
Even more surprising, the
team found that the stem cell
genes OCT4, SOX2 and NANOG were not completely
dormant in untreated skins
cells, as was presumed. Those
genes were, in fact, sending out
messages, but those messages
were not being translated into
the proteins that do the work
of making cells pluripotent.
“This was quite unexpected,”
said Tanja Dominko, DVM,
PhD, associate professor of
biology and biotechnology at
WPI and president of
CellThera. “Not only does this
data force us to rethink what the
true markers of pluripotency
may be, it suggests there is a
natural mechanism at work in
these cells regulating the stem
cell gene expression. That opens
a whole new line of inquiry.”
DNA mutations linked
to diabetes
Genes that regulate the energy
consumption of cells have a
different structure and expression
in type II diabetics than
they do in healthy people,
according to a new study from
the Swedish medical university Karolinska Institutet published
in Cell Metabolism. The
researchers believe that these
‘epigenetic mutations’ might
have a key part to play in the
development of the disease.
Type II diabetes is characterised
by a lower sensitivity to
insulin in muscles and organs,
and a reduced ability to
consume energy in the form of
glucose. Heredity and environmental
factors (e.g. exercise)
are both involved in the
disease pathogenesis, but
scientists are still unclear as to
the mechanisms behind it.
A research group at Karolinska Institutet has now
shown that genes in the muscle
cells of diabetics are chemically
modified through what is
known as DNA methylation.
They found that in muscles cells
taken from patients with earlyonset
diabetes, a gene designated
as PGC-1 was modified
and had reduced expression.
PGC-1 controls other genes
that regulate the metabolism of
glucose by the cell.
The team has also demonstrated
that DNA methylation
occurs rapidly, when cells from
healthy people are exposed to
certain factors associated with
diabetes, such as raised levels
of free fatty acids and
cytokines. DNA methylation
is a form of epigenetic regulation,
a process involving
chemical modifications that
are imposed externally on
genes and that alter their
activity without any change to
the underlying DNA sequence.
“This type of epigenetic
modification might be the link
that explains how environmental
factors have a longterm
influence on the development
of type II diabetes,” says
Juleen Zierath, who led the
study. “It remains to be seen
whether the DNA methylation
of this gene can be affected by,
say, dietary factors.”
● Reference: “Non-CpG Methylation of the PGC-1
Promoter through DNMT3B
Controls Mitochondrial
Density”, Romain Barrès,
Megan E. Osler, Jie Yan, Anna
Rune, Tomas Fritz, Kenneth
Caidahl, Anna Krook and
Juleen R. Zierath, Cell
Metabolism, 2 September 2009.
Medsol partners with KFSH
for regional genetic testing
Medsol laboratories, a part of
Gulf Healthcare International,
is offering a new line of genetic
tests in the MENA via a partnership
with Saudi Arabiabased
King Faisal Specialist
Hospital and Research Centre
(KFSH&RC). The tests will be
available in association with
the CAP accredited Saudi
Diagnostics Limited (SDL),
owned by KFSH&RC. Medsol
provides pathology testing
services via a network of
branded laboratories, including
independent and hospital laboratories
across MENA and will
offer the genetic tests
throughout its 14 laboratories
across the region.
The availability of molecular
genetics testing is particularly
important in the Gulf region
with the widespread prevalence
of hereditary disease and
common practice of consanguinity.
Genetic tests being offered
at Medsol laboratories include:
● Cystic Fibrosis Single
Mutation
● Factor V Leiden
● Familial Mediterranean Fever
● Fragile X Syndrome (PCR
& Southern Blot Analysis)
● Hereditary Hemochromatosis
● Huntington Disease
● 5,10- Methylenetetrahydrofolate
Reductase (MTHFR)
Deficiency
● Mitochondrial Myopathy
Encephalopathy Lactic
Acidosis/Stroke-like
Episodes (MELAS)
● Multiple endocrine Neoplasa
(MEN 2)
● Myotonic Dystrophy
● Prothrombin 20210 G – A
Mutation
● Sickle Celll Anemia (HbS,
HbC)
Samples will be collected by Medsol and sent to SDL for
detailed analysis. The turnaround
time for tests in the
specialist area of genetics
ranges from several weeks to a
few months. 
