By Rob Stein, The Washington Post
Embryonic stem cells have numerous pitfalls in addition to the ethical dilemmas. While the concept of a “blank slate” cell is extremely attractive in terms of generating new tissues for transplantation and organ replacement, the problem is that these cells are so young that they do not properly “know” how to integrate with existing tissues. This causes the problem of possible dysfunction of the cellular products made from the cells, but also causes the issue of cancer formation. Many studies have demonstrated that administration of embryonic stem cells, or products made from them form cancers when injected into mice that lack an immune system.
Because of the risks associated with embryonic stem cells, the FDA has been historically reluctant to allow initiation of clinical trials with them. The leader of the field of embryonic stem cells is Geron, the company that funded the research that lead to the discovery of human embryonic stem cells, as well as the company that has the exclusive license for their commercial use. The business of embryonic stem cells is associated with large financial investments. Specifically, patents are not only associated with the cells themselves but one methods of growing the cells and methods of selecting the cells to reduce the possibility of cancer formation. In some ways people believe that embryonic stem cells are an exercise in science because adult stem cells have been demonstrated to elicit numerous therapeutic effects without the risks.
Last year a monumental study was initiated in that the FDA allowed for the first human use of an embryonic stem cell product. The company Geron was granted approval to treat patients with spinal cord injury using embryonic stem cell derived oligodendrocytes, the cells that generate the myelin that lines the nerves.
Today, information was released on the first patient that was treated with these cells. The patient was a partially paralyzed young man, Timothy J. Atchison, 21, known to family and friends as T.J.
T.J. was a student at the University of Alabama College of Nursing when he was partially paralyzed in a Sept. 25 car accident, his aunt and father said. He agreed to let doctors infuse more than 2 million cells made from stem cells into his spine 13 days later at the Shepherd Center in Atlanta, according to his aunt and a family friend.
While the primary endpoint of the trial is to demonstrate safety, doctors are also testing whether the cells restore sensation and movement. It was too soon to tell whether the cells were helping T.J., Angela Atchison said. “They said it would be about a year before they’ll know if there’s any difference — if it takes,” she said. “We’re just hoping and praying that it works.”
T.J.’s father, Timothy Atchison of Millry, said his son had maintained a positive attitude, beginning when he was in the emergency room after the accident. and understood how seriously he was injured.
“He said, whatever the Lord leaves him with, he’ll do the best he can with it,” the father said in a phone interview Monday. He would not directly acknowledge that his son was in the stem cell study, but confirmed details including his Shepherd Center treatment. “I’ll put it this way, they tested a lot of folks, and only one made the cut,” he said during another interview Tuesday. “You can read between the lines.”
First patient to get stem cell therapy identified
Blood Vessels Made from Embryonic Stem Cells are Different than Naturally Occurring Blood Vessels
Glaser et al. J Vasc Res. 2011 May 31;48(5):415-428.
In addition to ethical dilemmas associated with embryonic stem cells, there are ample data demonstrating at administration of these cells causes formation of aggressive tumors called teratomas. One way in which scientists are trying to “tame” these cells is to reprogram them in the test tube. Conceptually if you can develop a stable population of cells in vitro, then these can be expanded and used clinically. Still the issue comes up whether the embryonic stem cell derived cells have a higher predisposition to cancer. This indeed may be the case because it takes many years for an embryonic stem cell to become an adult cell naturally, whereas in vitro generated cells are “hyperaccelerated” to maturity. The possibility that in vitro generated cell products from embryonic stem cells have abnormalities is supported by research showing that cells derived from embryonic stem cells actually have a lower potential to stimulate the immune system as compared to equivalent tissue. In other words, cardiac cells generated from embryonic stem cells are less visible to the immune system compared to cardiac cells from an adult.
In a recent study Glaser et al. Functional Characterization of Embryonic Stem Cell-Derived Endothelial Cells. J Vasc Res. 2011 May 31;48(5):415-428, scientists from the University of California Merced have used embryonic stem cells to generate blood vessel cells called endothelial cells. Endothelial cells are very important from a therapeutic point of view because they can be used to treat diseases of poor circulation. These include angina, limb ischemia and some types of heart failure.
The scientists compared the biological activities of endothelial cells generated from embryonic stem cells with those of naturally occurring cultured mouse aortic endothelial cells. They showed that the embryonic stem cell generated endothelial cells produce less NO on a per cell basis, increased angiogenic sprouting and are more resistant to inflammatory signals. They also found that the embryonic stem cell derived endothelial cells possessed a higher propensity towards the venous endothelial lineage as compared to aortic endothelium. These studies suggest that it is still difficult to replicate generation of adult cells from embryonic stem cells.
Killing of the iPS Field?
Zhao et al. Nature.
Embryonic stem cells are associated with numerous ethical dilemmas. The creation of equivalents of ES cells through retrodifferentiation led to a new area of research that does not require destruction of life. Specifically, it was discovered that any adult cell can be transfected with several genes, which results in the cell taking the phenotype and function of cells that appear to be very similar to embryonic stem cells. These cells can give rise to any tissue that embryonic stem cells give rise to, and unfortunately, like embryonic stem cells for teratomas (tumors). We made a video to explain this http://www.youtube.com/watch?v=_RLlUdJLy74.
One of the most exciting medical properties of iPS cells is that they can be made from a donor and theoretically the cells and their differentiated offspring should not be rejected by the donor. This would allow for generation of compatible cells, without the need for immune suppression. However, a recent study suggests that this may not be the case.
In the study (Zhao et al. Immunogenicity of induced pluripotent stem cells. Nature. 2011 May 13) investigators assessed the ability of embryonic stem cells and induced pluripotent stem cells (iPS) to stimulate immune responses using inbred, genetically identical mice. They found that embryonic stem cells (ESCs) derived from C57BL/6 (B6) mice can efficiently form teratomas (an aggressive type of tumor) in B6 mice (syngeneic) without any evident immune rejection. However, when allogeneic ESCs from 129/SvJ mice where transplanted into B6 mice, they were rapidly rejected by the B6 immune system. This by itself is interesting because transplantation of adult stem cells, mesenchymal stem cells, does not lead to rejection when transplanted between mouse strains.
When B6 mouse embryonic fibroblasts (MEFs) were reprogrammed into iPSCs by either retroviral approach (ViPSCs) or a novel episomal approach (EiPSCs) that causes no genomic integration and transplanted into B6 mice rejection was observed. Specifically, the retrovirally-generated iPS cells were more immunogenic than those generated by the novel episomal method. Rejection of both types of iPS cells was characterized by T cell infiltration.
Global gene expression analysis of teratomas formed by B6 ESCs and EiPSCs demonstrated that several iPS genes were expressed that contributed to immunogenicity. According to the authors “these findings indicate that, in contrast to derivatives of ESCs, abnormal gene expression in some cells differentiated from iPSCs can induce T-cell-dependent immune response in syngeneic recipients.”
Time to end stem cell institute CIRM
Wesley J. Smith , San Francisco Chronicle
The California Institute for Regenerative Medicine (CIRM) was created in 2004 as a result of the California Proposition 71, which called for a new bond issue to generate 3 billion dollars in order to support stem cell research in the State. In part, the institute was created as a response to President George W. Bush’s order restricting federal funding of embryonic stem cell research. The hope behind this enormous influx of cash to stem cell research was based on the popular belief that the State would have reduced medical costs, as well as treatments for many of the debilitating diseases that could benefit from stem cell therapy.
According to the author of the article, who is a senior fellow at the Discovery Institute’s Center on Human Exceptionalism and a consultant to the Center for Bioethics and Culture. “The CIRM hasn’t come close to fulfilling those promises. Here’s why California voters should reject the bond issue and shut the agency down in 2014…”
His rationale is that a) CIRM was created primarily to fund human cloning for research and embryonic stem cell research. So far, cloning has failed and embryonic stem cell cures, if they ever come, are a very long way off; b) Questionable uses of taxpayer’s funds. Specifically, $300 million went to help pay for plush research facilities, particularly those associated with board members of CIRM; c) Members of CIRM are paid exorbitant salaries. For example, the head of CIRM makes just under $500,000 a year, Art Torres, a board member and former chairman of the California Democratic Party, works four days a week – for a whopping $225,000 a year.
It is our opinion that basic research is critical for development of new therapies and for advancement of medicine. Therefore, conceptually, there is nothing wrong with supporting the use of taxpayer’s dollars for stem cell research. The issue that we have revolves around what research gets funded and how those projects are in line with the goals for which the funds were donated.
In the “drug development cycle” the first step is basic research and discovery of a biological mechanism of action associated with the disease. The second step is understanding how to manipulate the interaction. The third step is developing an intervention that may theoretically be useful and testing it in animal models of diseases. The fourth step, which is considerably more difficult, is to test the putative therapy in humans either at a low dose in healthy volunteers, or in terminal patients. This usually involves 10-40 patients and is formally called a Phase I clinical trial. Phase II clinical trials are the fifth step of developing a therapeutic. This involves 30-100 patients and assesses efficacy of the therapy in patients with disease. The last step of developing a drug involves conducting Phase III clinical trials, whose aim is to see whether the putative therapy induces therapeutic effects in a double blind, placebo controlled manner.
The majority of research funded by CIRM covers projects that are at the first to third steps, that is, from identifying new biological pathways, to trying to treat mice. Very few CIRM funded projects supported adult stem cell companies that are using their cells to treat patients. We anticipate that with more articles such as the one published by Wesley Smith, CIRM will become more cognizant of the reason why taxpayers supported the Institute: to develop cures faster. Indeed, one can see this increasing support in CIRM for adult stem cell companies in that in October of this year only 5 of 19 grants were for embryonic stem cell research.
International Stem Cell Corporation Expands Sales of Skin Care Product
North County Times – McClatchy-Tribune Information Services via COMTEX
The Oceanside California company International Stem Cell Corporation, (ISCO.OB) announced increased sales of its skin care product, the Lifetime Skin Care Line, which was associated with a 19% rise in stock price. In a press release, International Stem Cell Corporation stated “products are now being sold to subscribers of the investment newsletter of John Mauldin, founder of Millennium Wave Investments. The products were earlier offered to investors and others associated with International Stem Cell.”
The company has been developing a novel type of stem cell, called “parthenogenic derived” stem cells that has no ethical issues, yet appears to possess many of the properties associated with embryonic stem cells. Specifically, parthenogenic derived stem cells are generated by “activating” a human egg cell in absence of sperm. These cells multiply like embryonic stem cells, and possess the same ability as embryonic stem cells to generate all tissues of the body. The main therapeutic goals of the company are to develop islet cells for patients with diabetes, hepatocytes for patients with liver failure, and artificial corneas. However, given that approval from the FDA and other regulatory agencies is a long-term process, International Stem Cell Corporation has decided to leverage existing technologies into generating a product that can produce revenue without long-term research and development expenses.
By concentrating extracts that are produced by the parthogenic derived stem cells, the company has created stem cell-based products that are believed to be useful in skin care and restoration. On December 1st 2010, International Stem Cell Corporation announced the launch of its skin care product line which consists of a defensive Day Moisture Serum, and Recovery Night Moisture Serum.
“Because the quality products Lifeline Skin Care offers are experiencing strong demand and the human stem cell extracts require innovative manufacturing processes, we chose to develop our sales channels gradually and incrementally,” said Lifeline Skin Care CEO, Dr. Ruslan Semechkin.
International Stem Cell Corporation has historically been keen to develop products to market in order to generate ongoing revenue while its flagship products are under development. An example of this is the LifeLine research reagents company, which was developed by International Stem Cell Corporation as a means of selling products to researchers that are created as part of the company’s ongoing research and development program.
Stem cells approved to treat ‘orphan’ disease
Stargardt’s Macular Dystrophy is the most common form of
genetic juvenile macular degeneration. Manifestation of the condition begins in
late childhood, leading to legal blindness. It is symptomatically similar to
age-related macular degeneration, and it affects approximately one in 10,000
children. Olympic and Paralympic skier Brian McKeever is the best-known victim
of the disease, which has no treatment. Today the company Advanced Cell
Technology obtained "Orphan Drug Status" of use of its embryonic stem cell
derived product MA09-hRPE as a treatment for Stargardt’s disease.
Orphan Drug Status is a mechanism the government uses to
promote interest of pharmaceutical in disease for which a small market exists.
Typically to obtain this the target market must be less than 200,000 people in
the United States. Orphan Drug Status allows a company to retain market
exclusivity for seven years, as well as allows for various clinical trial tax
incentives.
Human embryonic stem cells have been demonstrated to be
capable of giving rise to the cells that make up practically every tissue in the
body. The ability of these cells to make anything from liver, to lung, to nerve
cells makes them attractive as sources of replacement tissues to biomedical
researchers. Last year the Obama Administration opened federal funding to
more-recent generations of such stem cells, and in January allowed research
funding to cells such as ACT’s, grown from a single cell clipped from an
early-stage embryo.
Designation of Orphan Drug Status is not approval of the
embryonic stem cell based product for sale, but only classifies the cells as a
product in development. Approval of a drug, whether it is a chemical, a
biologic, or a cell, requires clinical trials in which safety and efficacy is
demonstrated. The initial hurdle companies must pass is to obtain
Investigational New Drug status. This was only granted to one embryonic stem
cell company, Geron, for use of their embryonic stem cell derived
oligodendrocytes for treatment of spinal cord injury. The approval, however,
was rapidly retracted after additional preclinical data demonstrated development
of abnormal growths in treated animals. Subsequent to IND approval companies
have to demonstrate safety in Phase I studies, efficacy in Phase II studies, and
double blinded efficacy in Phase III studies which usually involve numerous
clinical trial sites.
The major problem with embryonic stem cell derived products
is the risk of tumor formation. In general embryonic stem cells are defined by
the ability to form a type of cancer called teratoma. These tumors are highly
aggressive and comprise numerous cells of the body. When Advanced Cell
Technologies or Geron are differentiating retinal epithelia cells, or
oligodendrocytes, respective, they must demonstrate to the FDA that no
contaminating stem cells are present in the injection mixture that could
possibly lead to tumor formation. Another drawback of embryonic stem cell
technology is that it is extremely difficult to selectively add new cells to the
area of injury. Specifically, the de novo created functional body cells must be
capable of integrating into the existing cells and taking over their function.
Optimization of these approaches requires understand the molecular cues involved
in natural stem cell differentiation into cells of the body. Yet another
drawback is that embryonic stem cell lines are not patient-specific. This
requires the use of immune suppression, which often comes with numerous side
effects.
Contract’s end means changes for stem cell scene
In 2005 WiCell, a nonprofit organization affiliated with
the University of Wisconsin was charged with creating and maintaining a national
embryonic stem cell bank supported by the Federal Government. At that time the
21 embryonic stem cell lines that were approved by former president George W.
Bush’s administration were made available for researchers. The importance of
this stem cell bank was two-fold: firstly to provide a consistent and
reproducible source of cells for experimentation that scientists across the
nation could use and compare results; and secondly to reduce costs of accessing
the stem cells. Usually they would cost tens of thousands of dollars, however
thanks to WiCell they were made available for approximately $500 for academic
use.
Since creation of the bank, the nature of embryonic stem
cell research has markedly changed. In particular, the July 2009 order issued
by President Barack Obama to allow federal funding for stem cells other than the
original 21 cell lines has stimulated expansion into the cells available for
research. Last week the contract that formed WiCell’s National Stem Cell Bank
expired and a new bank called Wisconsin International Stem Cell (WISC) Bank was
formed. This bank offers not only the original 21 cell lines but also several
newer types of embryonic stem cells, as well as induced pluripotent stem cells (iPS).
This new type of stem cell has attracted much publicity
because it is derived from non-embryonic sources but seems to have identical
characteristics to embryonic stem cells. Particularly, iPS cells can become all
tissues of the body, in the same way that embryonic stem cells can, and
additionally, these cells are capable of forming tumors when injected in mice.
Tumor formation in animals is a defining characteristic of embryonic stem
cells.
Janet Kelly a representative from WiCell said under WISC
Bank, lines now cost $1,000.
"Without a national bank or provision for the NIH to fund
any type of stem cell bank, it will be challenging for researchers to obtain
stem cells that are thoroughly tested and meet high standards for quality
assurance in a reliable and efficient manner," Kelly said in an e-mail to the
Badger Herald. "Researchers already are confused about how to obtain the newly
approved cell lines and many of the originators of these lines do not want to
operate a distribution service."
Despite the fact that the WISC bank is not federally
funded, Erik Forsberg, executive director of WiCell believes that business will
flourish. "In some ways you could view it as a setback, but the reputation is
so well-established I think in the long run it won’t have a big effect,"
Forsberg said. "It certainly helps to have the connections with the U.S.
government or the national stem cell bank, but because we have stem cell lines
all over the world, I think the reputation will remain."
For more information on iPS cells, you can watch the video
at
http://www.youtube.com/watch?v=_RLlUdJLy74
The Senescence-Related Mitochondrial/Oxidative Stress Pathway is Repressed in Human Induced Pluripotent Stem Cells
Embryonic stem cells possess the ability to propagate in
tissue culture indefinitely. This is different than differentiated cells, for
example, skin cells which can only multiple in tissue culture approximately 50
times before undergoing senescence. The ability of embryonic stem cells to
escape senescence is related to expression of the protein telomerase. Usually
when cells multiply the ends of the chromosomes, called telomeres, progressively
reduce in size. When the telomeres become critically short, the gene p53 is
activated, which is involved in instructing the cells to stop multiplying and
exist in a semi-alive state called senescence. Tumor cells and embryonic stem
cells escape senescence by expressing the enzyme telomerase. This enzyme
essentially allows cells to repair their telomeres by progressively adding new
nucleic acids. Although much is known about senescence or lack thereof in adult
cells and embryonic stem cells, little research has been performed in whether
inducible pluripotent stem cells (iPS) can also escape proliferative
senescence. In a recent publication this question was examined.
In a similar manner to embryonic stem cells, iPS cells were
shown to express high levels of the enzyme telomerase, and propagation in tissue
culture was achieved up to 200 passages without senescence occurring.
Furthermore the investigators studied the mitochondrial stress pathway. It was
found that somatic mitochondria within human iPSCs revert to an immature
ESC-like state with respect to organelle morphology and distribution, expression
of nuclear factors involved in mitochondrial biogenesis, content of
mitochondrial DNA, intracellular ATP level, oxidative damage, and lactate
generation. When iPS cells were differentiated into adult cells, mitochondria
within iPSCs demonstrated maturation and anaerobic-to-aerobic metabolic
modifications. This same finding was observed in embryonic stem cells.
These data suggest that iPS cells possess several important
properties similar to embryonic stem cells, which further supports the
possibility of interchangeably using ES and iPS cells for experimental purposes.
The next question is whether iPS cells may be generated in large quantities so
that their mitochondria may be transferred to aged cells.
Another interesting finding in the current study is that
the metabolic pathway used by both iPS and embryonic stem cells is analogous to
that found in cancer cells. Therefore it will be interesting to follow studies
using iPS as a model of cancer.
Fat May Serve a Purpose in Stem Cell Research
Scientist Dr. Joseph Wu at the Stanford University School
of Medicine has recently published a new and improved method to generate stem
cells "artificially". For almost a decade there has been substantial
controversy regarding the use of embryonic stem cells, with the debate becoming
socially and politically focused as opposed to based on science: one camp
believing that embryonic stem cell research must be supported at all costs, the
other camp believing that adult stem cells can do anything that embryonic stem
cells can do, so there should be no research performed in this area. This
debate became somewhat irrelevant when the Japanese group of Yamanaka discovered
a method of "dedifferentiating" adult cells into cells that appear at a
molecular and functional level similar to embryonic stem cells. These
"artificial" stem cells, called inducible pluripotent stem cells (iPS) have
several unique properties: They don’t need to be extracted from embryos; they
can be made from the same patient that they will be used on; and the methods of
manufacturing can be relatively standardized.
To date these cells have been demonstrated to be capable of
generating not only every tissue in the body tested, but they also can improve
disease conditions in animal models ranging from heart attacks, to liver
failure, to bone marrow reconstitution. Unfortunately the biggest problem with
iPS cells is that they are difficult to generate. In order to understand this,
it is important to first mention how the cells are made. Adult cells have the
same DNA blueprint as embryonic stem cells. However in adult cells certain
portions of the DNA are not used to make proteins. So in liver cells the DNA
that encodes for proteins found in the skin is "silenced" or "blocked" from
making proteins by various chemical modifications that occur as a cell is
maturing. Embryonic stem cells are considered "blank slate" cells because the
DNA is capable of expressing every protein found in the body. In order to make
an adult stem cell "younger" so as to resemble an embryonic stem cell, it is
necessary to somehow reprogram the DNA in order to allow it to express every
gene. So how would one go about doing this? There is one biological condition
in which adult cells take the phenotype of younger cells. This is in cancer.
This is the reason why some types of cancer start expressing proteins that other
cells normally produce. For example certain liver cancers can produce insulin,
even though liver cells do not produce insulin. The concept that certain cancer
genes can evoke a "rejuvenation" of adult cells was used by Yamanaka as a
starting point. His group found that if you insert the oncogene c-myc, together
with the stem cell genes Nanog, Oct-4, and SOX-2 skin cells will start to look
like embryonic stem cells. If these cells are placed on top of feeder cells
then they can be expanded and used as a substitute for embryonic stem cells.
The current problem with wide-scale use of this approach is
that insertion of the various genes into the cells requires the use of viruses
that literally infect the cells with the foreign genes. Not only can the
viruses cause cancer, but also the genes administered can cause cancer because
they are oncogenes. The other hurdle is that generation of iPS cells is a very
inefficient process. It takes approximately 2-3 months to generate stable
cells, and these cells are usually generated from approximately 1 out of
100-300,000 starting cells. We previously discussed advances that allowed for
uses of non-hazardous means of inserting genes into cells to make iPS
https://www.celllmedicine.com/thomson-safer-ips.asp , in this current article
another approach was described to increase efficacy.
Scientists used as starting population not skin cells,
which are considered substantially differentiated, but instead used fat derived
stem cells. This type of stem cell is very much a mesenchymal stem cell
http://www.youtube.com/watch?v=qJN2RyBj78I and possesses ability to
transform into different tissues already. Thus by starting with a cell that is
already more "immature", scientists have been able to increase the rate of iPS
generation, as well as, alleviate the need for the oncogene c-myc.
Other approaches being investigated on increasing
generation of iPS cells include use of chemicals that affect the DNA structure
such as valproic acid. This is interesting because simple administration of
valproic acid on bone marrow stem cells has been demonstrated to increase their
"stemness"
http://www.youtube.com/watch?v=3Hc4LCUOSiA .
Although we are still far from the day when
individual-specific stem cells will be available for widespread use, we are
getting closer to this dream at a very fast pace.
