December 29, 2010 by

Mechanisms of a New Stem Cell Mobilizer

Jarcome-Galarza et al. J Bone Miner Res.

It is known that the bone marrow contains three main types of stem cells: a) hematopoietic stem cells, which make blood; b) endothelial progenitor cells, which maintain healthy blood vessels; and c) mesenchymal stem cells, which repair a variety of tissues and are capable of producing high amounts of growth factors. After major tissue injury or trauma all three of the bone marrow derived stem cells leave the bone marrow and enter systemic circulation in an attempt to heal the tissue damage. The original compound that was discovered to “mobilize” bone marrow stem cells was granulocyte colony stimulating factor (G-CSF). Studies in mice with lung injury in the late 1970s demonstrated that a lung-derived protein was capable of stimulating bone marrow to multiply and produce higher numbers of granulocytes. It was not until the late 1980s that scientists started injecting purified G-CSF into animals as a method of increasing the number of circulating stem cells. Why would people want to increase circulating stem cells? Commercially one of the main reasons is associated with the process of bone marrow transplantation. In bone marrow transplantation donors were historically required to undergo the painful procedure of bone marrow extraction, which requires an excess of 20 holes to be drilled into their hip bones. Compounds such as G-CSF could be administered to donors in order to make their stem cells enter circulation, and then the stem cells could be isolated from the blood instead of the bone marrow. This makes the procedure a lot less painful and arguably a lot safer. Additionally, the possibility of mobilizing stem cells by administration of a drug has the possibility of artificially increasing stem cell numbers in patients with degenerative diseases in order to attempt to naturally heal the condition.

The clinical use of G-CSF for mobilization and also for increasing granulocytes in the blood has resulted in multibillion dollars per year in sales for companies such as Amgen. Naturally, this has stimulated much interest in the process of how to make stem cells leave the bone marrow. G-CSF stimulates bone marrow stem cell release through several mechanisms. The main mechanism appears to be associated with stimulation of osteoclasts, which cause modulation of the bone marrow structure and physically release the stem cells from their environment. Other mechanisms exist such as breakdown of stromal derived growth factor (SDF-1). This protein is made by the bone marrow and literally keeps the hematopoietic stem cells stuck to the bone. When the bone marrow levels of SDF-1 decrease, the hematopoietic stem cells are no longer “stuck” to the marrow and as a result enter circulation. Yet another mechanism is that G-CSF activates neutrophils to produce various enzymes that cleave proteins on the bone marrow. These cleaved proteins are then recognized by pre-formed antibodies, which activate complement, which causes small holes in the bone marrow and thus releases stem cells.

The second “stem cell mobilizer” to be approved by the FDA is a drug called Mozibil which blocks the interaction between SDF-1 and its receptor CXCR4. This drug was sold by Anormed to Genzyme in a deal worth more than half a billion dollars. Mozibil is a superior stem cell mobilizer to G-CSF in many patients and as a result has rapidly been implemented clinically. Interestingly, it appears that Mozibil causes redistribution of different ratios of hematopoietic, mesenchymal and endothelial progenitor cells than G-CSF.

One of the most recent mobilizers under development is Parathyroid Hormone. This naturally –occurring substance has been demonstrated in clinical trials to mobilize stem cells, but apparently through a mechanism different than G-CSF and Mozibil. Specifically, both of these drugs appear to cause a temporary depletion of the stem cells in the bone marrow, whereas Parathyroid Hormone seems to preserve the stem cells inside of the bone marrow.

A recent paper (Jacome-Galarza et al. Parathyroid hormone regulates the distribution and osteoclastogenic potential of hematopoietic progenitors in the bone marrow. J Bone Miner Res. 2010 Dec 29) explored the activities of Parathyroid Hormone on osteoclasts in the bone marrow of mice. The authors found that treatment of mice with Parathyroid Hormone for 7 or 14 days increased the number of osteoclastic progenitors in the bone marrow as well as the absolute number of hematopoietic progenitors. These data suggest that the hormone acts not only as a means of stimulating redistribution of hematopoietic stem cells, but also may be involved in directly stimulating their multiplication, possibly through modulating activity of osteoclasts.

Filed Under: News, Stem Cell Research Tagged With: , , , , ,
December 29, 2010 by

Enhancing Efficacy of Bone Marrow Transplant

Huang et al. Blood. [Epub ahead of print]

Bone marrow transplantation has cured many patients of hematological diseases such as leukemias and lymphomas. Additionally, bone marrow transplantation is becoming used more and more in treatment of autoimmune diseases such as type 1 diabetes and multiple sclerosis. Unfortunately, there are still numerous limitations to this procedure. One of the biggest ones is that occurrence of graft versus host disease, in which the transplanted stem cells produce immune cells that attack the recipient. The other major problem is graft failure, in which the transplanted stem cells do not “take”.

The group of Dr. Ildstad from the University of Louisville has been working on enhancing bone marrow transplantation by co-administration of other cells called “facilitator cells.” In a recent publication (Huang et al. CD8{alpha}+ plasmacytoid precursor DC induce antigen-specific regulatory T cells that enhance HSC engraftment in vivo. Blood. 2010 Dec 29) it was shown that a type of dendritic cell, called the plasmacytoid dendritic cell, is capable of promoting bone marrow transplant efficacy through stimulation of T regulatory cells.

The scientists demonstrated that after bone marrow transplant from mismatched donors, there are immune suppressive cells, called T regulatory cells, that develop under specific conditions that stop the new (donor derived) immune system cells from attacking the recipient. When a mismatched bone marrow transplant is performed together with plasmacytoid dendritic cells, these cells “instruct” the donor immune system to generate T regulatory cells, which prevent graft versus host disease.

Implications of this research may be profound in areas outside of bone marrow transplantation for leukemias. In solid organ transplants, patients are required to take life-long immune suppressants to prevent the transplanted organ from being rejected. If donor bone marrow transplantation is performed with the donor organ, then the body does not reject the organ. Unfortunately this is not possible because bone marrow transplantation has a high risk of graft versus host disease. If the discovery of Dr. Ilstad’s group can be translated to humans, it may be possible to induce “immunological tolerance”, which is a state of immune un-responsiveness to the transplanted organ, while maintaining a functioning immune system towards pathogens and bacteria.

Filed Under: Adult Stem Cells, Bone Marrow, News, Stem Cell Research Tagged With: , , , ,
December 29, 2010 by

Resveratrol Suppresses Cancer Stem Cells

Pandey et al. Breast Cancer Res Treat.

Resveratrol is a compound found in grapes, red wine, purple grape juice, peanuts, and berries that has been associated with many health benefits, particularly reduction in heart disease. Some studies have demonstrated that resveratrol increases life span when administered at high concentrations. One area of controversy has been the potential of resveratrol in the treatment of cancer.

One way of testing the anti-cancer efficacy of compounds is to administer the compound of interest to cancer cells that are growing “in a test tube”, or “in vitro.” Recently it was shown that cancer cells taken from a patient and propagated in vitro are usually not representative of the original tumor from which the cancer cells were excised. Specifically, it has been shown that in patients, cancer cells can broadly be classified into the rapidly multiplying cells, and the “sleeping cells” otherwise known as tumor stem cells. It appears that in vitro the rapidly multiplying cells continue multiplying, but the cancer stem cells do not multiply. This is important because the cancer stem cells seem to be the cells responsible for causing the tumor to spread, whereas in the rapidly multiplying cells actually seem to be weaker and more sensitive to chemotherapy.

To date the majority of studies investigating effects of resveratrol on cancer have focused on testing with the rapidly multiplying cells. The paper published today investigated the effects of resveratrol on tumor stem cells. Breast cancer tumor stem cells where isolated based on expression of the proteins CD44 and ESA, and lacking CD24. Tumor stem cells were harvested from patients that were both estrogen receptor positive and negative. It was found that addition of resveratrol caused death of the tumor stem cells, as well as blocked their ability to form three dimensional tumors in tissue culture called “mammospheres.”

Interestingly it seemed like the effects of the resveratrol were mediated by manipulating the way in which the cancer stem cells make fat. Specifically, resveratrol caused a significant reduction in fat synthesis which is associated with down-regulation of the enzyme fatty acid synthase (FAS). The suppression of the enzyme FAS was correlated with upregulation of the genes DAPK2 and BNIP3, which are known to stimulate a process called “apoptosis”, or cellular suicide.

This recent paper belongs to a growing example of scientific reports in which various “treatments” advocated by naturopathic doctors seem to have effects on cancer stem cells. For example, a previous publication (Kakarala et al. Targeting breast stem cells with the cancer preventive compounds curcumin and piperine. Breast Cancer Res Treat. 2010 Aug;122(3):777-85.) reported that the chemical curcumin, which is a component of the Indian spice turmeric, selectively inhibits cancer stem cells.

It appears that many of the chemotherapeutic drugs that are conventionally used in the treatment of cancer do not affect the cancer stem cell because chemotherapy requires tumor cells to be actively proliferating. In contrast, many of the “natural remedies” seem to suppress cancer stem cells because their activities seem to be mediated by other means than the ones in which chemotherapy works. It will be interesting to see if more papers such as the present one appear, which seem to provide scientific rationale for a more “compassionate approach” to cancer therapy

Filed Under: Cancer, News, Stem Cell Research Tagged With: , , , , ,
December 29, 2010 by

Increasing Efficacy of Stem Cell Therapy for Spinal Cord Injury

Jin et al. Spine (Phila Pa 1976).

Clinical trials of stem cells for treatment of spinal cord injury are currently being conducted in the United States and abroad. For example, the Covington Louisiana company TCA Cellular Therapy LLC is recruiting 10 patients with spinal cord injury to receive intrathecal infusion (lumbar puncture) of autologous, ex vivo expanded bone marrow-derived mesenchymal stem cells. Completed clinical trials have demonstrated some rationale that stem cells may be useful. For example, Kumar et al. (Autologous bone marrow derived mononuclear cell therapy for spinal cord injury: A phase I/II clinical safety and primary efficacy data. Exp Clin Transplant. 2009 Dec;7(4):241-8) reported on 297 spinal cord injury patients that were treated with their own bone marrow cells injected intrathecal. 33% of the patients reported an objective improvement.

As with other clinical trials of stem cell therapy, it appears that in the area of spinal cord injury there still remains room for improvement. We at Cellmedicine have reported a stunning improvement in a spinal cord injury patient by using a combination of CD34 and mesenchymal stem cells, which was recently published http://www.intarchmed.com/content/pdf/1755-7682-3-30.pdf. Unfortunately this was only one patient and more studies are required.

In an attempt to improve efficacy of stem cell therapy for spinal cord injury, a group from the Department of Neurosurgery, Spine and Spinal Cord Institute, at the Yonsei University College of Medicine, Seoul, Republic of Korea, has created an artificial method of increasing growth factor production from stem cells of the nervous system called neural progenitor cells. Previous studies have shown that neural progenitor cells are capable of treating several models of spinal cord injury, however their effects appear to be transient. Vascular endothelial growth factor (VEGF) is a protein that increases blood vessel production in tissues and has been previously demonstrated to stimulate integration of nervous system cells after spinal cord injury. Since increasing VEGF production could hypothetically increase efficacy of neural stem cells, a series of experiments were performed in order to generate modified neural stem cells which have enhanced VEGF production.

It is known that insertion of a gene into a cell can cause the cell to produce the protein made by the gene. So theoretically all the researchers had to do is to transfect (insert) the VEGF gene into the neural stem cells and the neural stem cells would be more effective. The problem with this is that too much VEGF can have negative effects. A more attractive approach would be to program the progenitor cells in such a manner so that they produce VEGF only when it is necessary. During spinal cord injury, the area of damage is associated with reduced oxygen, a condition called hypoxia. Ideally one would want to engineer the stem cells in a manner so that they produce VEGF only during times of hypoxia. One way of doing this is to control the expression the gene by using an inducible promoter.

Promoters are pieces of DNA that control expression of genes that are in front of them. Some promoters always turn on gene expression (these are called constitutive promoters), others turn on expression only under specific conditions (these are called inducible promoters. The promoter that turns on erythropoietin is an inducible promoter. Erythropoietin is made by the kidney and stimulates production of red blood cells. Its expression is turned on under conditions of lack of oxygen. This is why people who live in high altitudes have higher expression of erythropoietin. The scientists in the current publication developed a genetically engineered neural stem cell that contains the VEGF gene under control of the erythropoietin promoter. What this means is that the cells will be producing VEGF only under conditions of hypoxia. In order to selectively detect the areas of hypoxia, the scientists also developed stem cells that have the luciferase gene in front of the erythropoietin promoter. Luciferase is a protein that generates light and allows for easy detection in vitro and in vivo of the hypoxic cells.

The scientists found that the stem cells administered during hypoxia generated significantly higher concentrations of VEGF, which was associated with the promoter being turned on, as assessed by luciferase expression. Furthermore, rats receiving the VEGF expressing stem cells possessed a significantly lower amount of nerve damage and higher ability to recuperate after spinal cord injury.

These data suggest that it is feasible to combine inducible promoters with stem cells in order to augment various activities of the stem cells. This concept could be applied to numerous settings. For example, mesenchymal stem cells are known to selectively migrate to areas of inflammation. In the setting of cancer, mesenchymal stem cells could be transfected with genes that are encoding toxic substances. This way chemotherapy could be targeted only to cancer cells and therefore have a better safety profile.

Gene therapy has failed to a large extent because of lack of ability to control where the genes are administered. It may be possible that advancements in stem cell technologies will allow for a rebirth of gene therapy in that the stem cells may be used to deliver genes only to the tissues where they are needed.

Filed Under: Adult Stem Cells, News, Spinal Cord Injury, Stem Cell Research Tagged With: , , , , , ,
December 27, 2010 by

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.

Filed Under: News, Stem Cell Research Tagged With: , , , , , ,
August 27, 2010 by

A Fall for Stem Cells Injunction Halting Stem Cell Research Funds May Have Far-Reaching Consequences

(STEPHEN BROZAK and LARRY JINDRA, M.D. ABC News) There is some anticipation that this fall will be an important season for the debate on embryonic stem cell research. On Aug 30, 2010 a Washington, DC district judge (Lamberth), issued a temporary injunction halting all federal funding for basic research into embryonic stem cell technology. The injunction states there is a legitimate basis for arguing the matter in court. A full hearing will soon decide the final outcome. If the decision is upheld, federal funding for embryonic stem cell research will cease, in a similar manner to the previous funding moratorium on this research during the Bush administration.

According to this article, Judge Lamberth’s decision “reflects the lack of awareness in the U.S. around research and development of embryonic stem cells”. This statement was made because subsequent to the ruling, the price of numerous stem cell company stocks fell, including of companies working in the area of adult stem cells. These companies in no way should be affected by the controversy surrounding embryonic stem cells.

The article highlights the important difference between these two stem cell types. Embryonic stem cells are generated from a fertilized egg in vitro. These stem cells are highly undifferentiated and form tumors when administered into immune deficient mice called teratomas. The other type of stem cells, adult stem cells, are derived from sources such as bone marrow, menstrual blood, cord blood, placenta, and fat. These cells do not generated tumors and have been used therapeutically in the treatment of many diseases. To date, the only use of embryonic stem cells in humans has been by the company Geron that is generating oligodendrocytes from embryonic stem cells for use in the treatment of patients with spinal cord injury.

Geron has spend years trying to attain FDA approval for its approach. A temporary approval was granted under the Obama administration which was rapidly rescinded. Subsequently the trial was allowed to continue, however no data has been reported at the time of writing.

Adult stem cell companies include Osiris, who are working on bone marrow derived mesenchymal stem cells for treatment of heart failure, graft versus host disease, and Crohn’s Disease, Pluristem, who are working on placental mesenchymal stem cells for treatment of critical limb ischemia, and Medistem Inc, who are using menstrual blood derived Endometrial Regenerative Cells (ERC) for treatment of the same condition.

The authors of the article are Stephen Brozak, president of WBB Securities, an independent broker-dealer and investment bank specializing in biotechnology, medical devices and pharmaceutical research and Dr. Lawrence Jindra who is director of research for WBB Securities.

Filed Under: Embryonic Stem Cells, News, Stem Cell Research Tagged With: , , , ,
May 16, 2010 by

Hope for Brain Injury Victims

Traumatic brain injury (TBI) is a major health problem
caused by a sudden trauma to one or more areas of the brain. Today the
conventional method of treating patients with TBI is based on administration of
supplements to rebalance the brain’s chemistry. In the early phases of TBI
reduction of the ongoing inflammation using various antioxidants and
anti-inflammatory compounds has demonstrated some promise. Unfortunately, after
the injury has occurred there is little that can be done with the exception of
physiotherapy programs to allow the patient to cope with loss of function.

Although the traditional belief has been that once the
brain is damaged, regeneration is non-existent, recent findings suggest that
this may not be entirely true. Specific parts of the brain (subventricular
zone) have been demonstrated to contain stem cells that begin to multiply and
make new brain cells (neurons) after injury. Although this healing process is
often not potent enough to cause a robust effect that can be seen clinically,
the fact that it exists pushes scientists to find ways of amplifying it.

It was discovered more than twenty years ago that pregnant
pigs have areas of the brain in which cells multiply. The more recent finding
of brain stem cells has prompted researchers to ask whether administration of
pregnancy-related hormones can actually accelerate healing of injury brains.
Scientists at the Canadian company Stem Cell Therapeutics have shown that
administration of the hormone human chorionic gonadotrophin (the same hormone
detected by the pregnancy test) to animals with TBI can accelerate recovery. We
have previously discussed here that this company is now in clinical trials with
this approach for stroke, another type of brain injury
www.cellmedicine.com/stem-cell-therapeutics-placement.asp.

Another approach to treating TBI involves administration of
stem cells from outside of the body. This approach has previously been used for
conditions like heart failure

http://www.youtube.com/watch?v=flv0RmzPyLU , liver failure

http://www.youtube.com/watch?v=DdH6Mm4w98I , or multiple sclerosis

http://www.youtube.com/watch?v=wIcUaKZWOSE.

Recent studies have demonstrated that animals in which TBI
was induced, the administration of bone marrow stem cells results in
regeneration of damaged areas. It is currently unclear whether the stem cells
themselves are becoming new neurons, or whether the stem cells are producing an
environment in which the existing brain stem cells may exert their activity.
The University of Texas has recently completed a 10 patient clinical trial of
children with TBI treated with their own stem cells

http://www.clinicaltrials.gov/ct2/results?term=NCT00254722, however the
results have not been published yet.

One example of the potential of adult stem cells in
treatment of brain damage is illustrated in a scientific report from Russia in
which comatose patients where treated with stem cells and consciousness was
regained (Seledstove et al. Cell therapy of comatose states. Bull Exp Biol
Med. 2006 Jul;142(1):129-32).

The potential of stem cell therapy for TBI is anticipated
to be promising. Dr. Paul Breen, a specialist in TBI stated ""This new research
in stem cell research is a huge breakthrough and highly anticipated. We hope
that this could help pave the way for future research in stem cell usage for
brain trauma treatment in the coming years. If it works, it could give thousands
of people who have suffered brain injury hope of, if not a complete recovery,
then certainly a much better quality of life and a restoration of many of their
physical and mental functions. It’s a strong case in favour of continued stem
cell research."

Filed Under: Adult Stem Cells, Brain Injury, News Tagged With: , , , ,
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