Friday, April 4, 2008

Stem Cells, Regenerative Medicine, and Animal Models of Disease

Dennis A. Steindler

Abstract

The field of stem cell biology and regenerative medicine is rapidly moving toward translation to clinical practice, and in doing so has become even more dependent on animal donors and hosts for generating cellular reagents and assaying their potential therapeutic efficacy in models of human disease. Advances in cell culture technologies have revealed a remarkable plasticity of stem cells from embryonic and adult tissues, and transplantation models are now needed to test the ability of these cells to protect at-risk cells and replace cells lost to injury or disease. With such a mandate, issues related to acceptable sources and controversial (e.g., chimeric) models have challenged the field to provide justification of their potential efficacy before the passage of new restrictions that may curb anticipated breakthroughs. Progress from the use of both in vitro and in vivo regenerative medicine models already offers hope both for the facilitation of stem cell phenotyping in recursive gene expression profile models and for the use of stem cells as powerful new therapeutic reagents for cancer, stroke, Parkinson's, and other challenging human diseases that result in movement disorders. This article describes research in support of the following three objectives: (1) To discover the best stem or progenitor cell in vitro protocols for isolating, expanding, and priming these cells to facilitate their massive propagation into just the right type of neuronal precursor cell for protection or replacement protocols for brain injury or disease, including those that affect movement such as Parkinson's disease and stroke; (2) To discover biogenic factors—compounds that affect stem/progenitor cells (e.g., from high-throughput screening and other bioassay approaches)—that will encourage reactive cell genesis, survival, selected differentiation, and restoration of connectivity in central nervous system movement and other disorders; and (3) To establish the best animal models of human disease and injury, using both small and large animals, for testing new regenerative medicine therapeutics.

Key Words: drug discovery; human therapeutics; recursive gene profiling; regenerative medicine; stem cell; transplantation

Introduction

Stem cells have the propensity to produce tissue, an attribute that not only contributes to normal human development but also can lead to oncogenic transformation and hyperplasia (Gibbs et al. 2005; Ignatova et al. 2002; Steindler 2006). Two characteristics of stem (and progenitor) cells reveal their dual nature: (1) "poiesis" (generation) and (2) the overgeneration of cells and tissue (the so-called oncogenic transformation that leads to neoplasia). Because of these particular attributes, there is widespread interest in stem cells and regenerative medicine and their potential to treat and cure human diseases. But controversy and debates surround the question of which cells might be both the best and the most ethically acceptable therapeutic reagents, likewise determining which animal models are indeed the most effective. Animal models of disease are certainly necessary for the regenerative medicine field. Clinical trials of adult (e.g., bone marrow or cord blood transplantation) as well as fetal stem or progenitor cells have already demonstrated the efficacy of such regenerative medicine cell therapies for protecting, repairing, and replacing at-risk cells and tissues (Bjorklund 2005; Reier 2004; Press Release, Yahoo! Finance, November 15, 2006). Yet there is also a daunting side to the emerging field of regenerative medicine. Great expectations and desperate hope for immediate clinical application have driven intense debates at the state level, and international hearings to establish guidelines also try to respond to demands from different citizen groups with disparate agendas. The situation has also prompted patients all over the world to seek alternative and usually unproven stem cell "therapies" that can put them at risk. These challenges justify support for more science that must include both in vitro and in vivo studies of stem/progenitor cells from a variety of tissues and organs.

This article describes advances to date in the use of cells and animal models in regenerative medicine, expectations for future discoveries of the best stem and progenitor cell populations from different tissues and organs, and how in vitro high-throughput screening (HTS¹) bioassays might best utilize the potency of embryonic, fetal, and adult stem cells. The article also describes uses of modeling, in vitro studies, and dynamic stem cell and biogenic stem cell factor screening that could lead to more rapid developments in translational regenerative medicine. The reasoning below suggests that research in regenerative biology and regenerative medicine, although human-centric because of the eventual need for cells from a variety of human tissues and organs at different stages of development and aging, nonetheless requires animals, both as sources of immature cells and as recipients for cell and engineered tissue grafts to establish therapeutic proof-of-principle for any new cell or drug therapy. In vitro bioassay screening and use of simpler organisms could reduce the need for experimentation with mammalian models once researchers better understand the nature of different stem/progenitor cell populations and also further refine HTS. Thus, it is worthwhile to further develop cell culture assays, explore virtual gene and protein screens, and establish standardized and efficient rodent and other animal models of human disease to generate universal bioassays that can be used to establish the required safety and efficacy of any potential new regenerative medicine therapy before going on to human clinical trials. In particular, immunocompromised animals with diseased and injured tissues should continue to host human cell transplants, and investigators should continue to test new drugs gleaned from studies of the bioactive compounds associated with the growth and differentiation of stem cells in the same animal models.

There is no question that animal models of stem cell research in support of regenerative medicine will facilitate rapid translation to the bedside. The regenerative medicine field will continue to foster respect for the animal kingdom amid a pressing need to find new cures for human suffering. With the remarkable paradigm shift that has occurred in scientists' understanding of human self-regenerative potential, there is a high level of confidence that stem cell biology and regenerative medicine will lead to exceptionally effective new therapeutics for movement disorders and all other neurological challenges in the not too distant future.

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The full article is available via below link.

Stem cells, regenerative medicine, and animal models of disease.

Stem cells, regenerative medicine, and animal models of disease. Steindler DA. Program in Stem Cell Biology and Regenerative Medicine, University of Florida ...
www.ncbi.nlm.nih.gov/pubmed/17712220

Tuesday, April 1, 2008

The world of stem cells

The world of stem cells
A newly fertilized egg has cells that have no particular function.
Stem cells from embryos can become any kind of cell in the human body.
We are aware that different types of cells make up our body (e.g., blood cells, skin cells, cervical cells) but usually forget to appreciate that all of these different cell types arose from a single cell, the fertilised egg. Developmental biologists study the awesome events that occur between the fertilised egg and the formation of a new individual.
 The first steps simply involve cell division: one cell becomes two cells; two cells become four cells, etc.
 Each of these individual cells of early development is not specialized (undifferentiated), that is it does not have a specific body function, and has the capability to contribute to all of the organs in an individual and thus are called totipotent.
 These cells are embryonic stem (ES) cells and have both the capacity to self-renew, thus maintaining a continuous supply of stem cells and the ability to give rise to specialized (differentiated) cell types, such as liver cells or brain cells.
 It is believed that once differentiated, cells remain so and usually lose their ability to divide.
Stem cells from adults can also be used in cell therapy, with limitations.
Stem cells also exist in adults and allow specific tissues to regenerate throughout life. They also have the ability for self-renewal and multi-lineage differentiation. In fact, the list for identifying adult stem cells and lineage specific progenitor cells (with limited self-renewal ability) is growing.
Sources of stem cells
The main clinical application of stem cells is as a source of donor cells to be used to replace cells in transplantation therapy. Stem cells can be obtained from several sources:
 Spare embryos: stem cells can come from leftover embryos stored at fertility clinics that were not used by couples to have children.
 Special purpose embryos: embryos are created in vitro fertilization (artificially in the lab) for the sole purpose of extracting their stem cells.
Embryos and living or dead adult tissue provide stem cells.
 Cloned embryos: embryos are cloned in labs using somatic nuclear transfer method in order to harvest their stem cells.
 Aborted fetuses: stem cells are taken from fetuses in early development that have been aborted.
 Umbilical cords: this after-childbirth tissue holds potential for research.
 Adult tissue or organs: stem cells are obtained from the tissue or organs of living adults during surgery.
 Cadavers: isolation and survival of neural progenitor cells from human post-mortem tissues (up to 20 hours after death) has been reported and provides an additional source of human stem cells.1
Embryonic stem cells must be obtained when an embryo is in early development, that is, when the fertilised egg has divided to form about 1000 cells. These cells are separated and maintained in a cell culture dish, thereby halting embryonic development towards creating an individual. This is why embryonic stem cell research is the subject of ethical debates. Utilization of adult stem cells pose less of an ethical dilemma: however, adult stem cells may not have the same potential as those derived from embryos for medical therapeutics.
Comparing embryonic and adult stem cells
Embryonic stem cells have advantages and disadvantages for therapy.
Advantages: They are
Embryos can contribute an endless supply of stem cells.
 Flexible: They have the potential to make any body cell.
 Immortal: One cell line can potentially supply endless amounts of cells with carefully defined characteristics.
 Easily available: human embryos can be obtained from fertility clinics.
Disadvantages: They could be
 Difficult to control: The method for inducing the cell type needed to treat a particular disease must be defined and optimized .
 At odds with a patient’s immune system: It is possible that transplanted cells would differ in their immune profile from that of the recipient and so would be rejected.
 Ethically controversial: Those who believe life begins at conception say that doing research on human embryos is unethical even if donors give their consent.
Adult stem cells also have good and difficult characteristics for therapy.
Advantages: They are
 Already somewhat specialized: Inducement may be simpler.
 Immune hardy: Recipients who receive the products of their own stem cells will not experience immune rejection.
 Flexible: Adult stem cells may be used to form other tissue types.
 Mixed degree of availability: Some adult stem cells are easy to harvest and others, such as neural (brain) stem cells, can be dangerous to the donor.
Adult stem cells are sometimes hard to obtain and don’t last long.
Disadvantages: They could be
 Minimal quantity: They are difficult to obtain in large quantities.
 Finite: They don’t live as long in a culture as embryonic stem cells.
 Genetically unsuitable: The harvested stem cells may carry genetic mutations for disease or become defective during experimentation.
Stem cells can develop into liver, heart, blood, or any other cell.
The surprising property of adult stem cells: transdifferentiation
Adult stem cells were thought to be restricted to produce differentiated cells, which were specific to the organ from which they were isolated. Recently, several examples have been reported which demonstrate that these stem cells, under certain conditions, can be induced to form other cell types (transdifferentiation). For example:
 neural stem cells (NSC) can give rise to blood and skeletal muscle
 bone marrow cells can give rise to muscle, liver cells, and astrocytes
Stem cells can be transplanted directly into the patient.
When NSCs were used to form muscle, no inducers were needed other than co-culturing them with muscle progenitor cells (myoblasts) or injecting them into muscle.2 This holds promise for cell transplantation therapies in that the experiment suggests that host tissue can instruct transplanted cells to a desired result. Scientists, then, can consider whether it is best for stem cells to be differentiated in vitro (artificially) prior to transplantation or by transplanting them directly into the defective tissue. Some experiments have shown that naturally transplanted stem cells were able to migrate to regions where cells had died due to stroke (called ischaemia).
Stem cell therapies
Stem cells can renew blood and bones after chemotherapy.
Stem cells offer the opportunity of transplanting a live source for self-regeneration. Bone marrow transplants (BMT) are a well known clinical application of stem cell transplantation. BMT can repopulate the marrow and restore all the different cell types of the blood after high doses of chemotherapy and/or radiotherapy, our main defence used to eliminate endogenous cancer cells. The isolation of additional stem and progenitors cells is now being developed for many other clinical applications. Several are described below.
Stem cells from hair can grow into skin.
Skin replacement The knowledge of stem cells has made it possible for scientists to grow skin from a patient’s plucked hair. Skin (keratinocyte) stem cells reside in the hair follicle and can be removed when a hair is plucked.3 These cells can be cultured to form an epidermal equivalent of the patients own skin and provides tissue for an autologous graft, bypassing the problem of rejection. It is presently being studied in clinical trials as an alternative to surgical grafts used for venous ulcers and burn victims.
Brain cell transplantation Neural stem cells were only until recently thought to be strictly embryonic. Many findings have proved this incorrect. The identification and localisation of neural stem cells, both embryonic and adult, has been a major focus of current research. Potential targets of neural stem cell transplants include stroke, spinal cord injury, and neurodegenerative diseases such as Parkinson’s Disease.
Stem cells can provide dopamine - a chemical lacking in victims of Parkinson’s Disease.
Parkinson’s Disease involves the loss of cells which produce the neurotransmitter dopamine. The first double-blind study of fetal cell transplants for Parkinson’s Disease reported survival and release of dopamine from the transplanted cells and a functional improvement of clinical symptoms.4 However, some patients developed side effects, which suggested that there was an oversensitization to or too much dopamine. Although the unwanted side effects were not anticipated, the success of the experiment at the cellular level is significant. Again, further studies are needed and ongoing. Over 250 patients have already been transplanted with human fetal tissue.
Several biotechnology companies are developing different strategies of stem cell therapies.
 Diacrin has been developing xenotransplants using fetal pig cells. Clinical trials for chronic stroke patients have begun. Presently, stroke patients require treatment within 24 hours after stroke for effective therapeutic results. Many patients do not receive treatment in time because the symptoms are not initially obvious. Diacrin’s therapy could be applied weeks to months after the initial trauma.
 NeuroNova’s strategy is to culture adult human cells from donors, differentiate them in culture to produce the cell type (dopaminergic neurons) which is lost in Parkinson Disease, and to transplant them into the brain of patients.
 Neurotech is using genetically altered brain endothelial cells (engineered to produce human Interleukin-2) as immunotherapy for gliomas. Results from experiments in rats showed that these cells "mopped up" the tumour cells and as a result a clinical study has commenced.
Mouse stem cells were made to produce their own insulin.
Treatment for diabetes Diabetes affects 16 million people in the U.S. and is caused by the abnormal metabolism of insulin. Normally, insulin is produced and secreted by the cellular structures called the islets of Langerhans in the pancreas. Recently, insulin expressing cells from mouse stem cells have been generated.5 In addition, the cells self assemble to form structures, which closely resemble normal pancreatic islets and produce insulin. Future research will need to investigate how to optimise conditions for insulin production with the aim of providing a stem cell-based therapy to treat diabetes to replace the constant need for insulin injections.
Future directions
Mouse brain stem cells could self-repair.
The generation of new neurons in the adult brain is limited. However, self-repair of neuronal cell death has been recently demonstrated in the mouse and suggests that stem cells which normally reside in the brain may someday be able to be stimulated by inducers in a manner similar to how we induce our immune system by vaccination.6 This would bypass the need for cell transplantation. Intensive research needs to be pursued into the cell mechanisms involved.
The potential of embryonic stem cells to provide other differentiated cell types needs to be investigated. The production of cardiac muscle cells, which have thus far been evasive, would hold tremendous promise for the number one killer: heart disease.
Scientists and stem cell research
Poll: The majority of Americans favor stem cell research.
Scientists believe that stem-cell research could lead to cures for a myriad of diseases afflicting humans. Anti-abortion groups, some religious groups, and conservative citizens say that using cells from embryos is immoral because it destroys life. However, a recent ABCNews/Beliefnet poll has shown that Americans support stem cell research by a 2-1 margin and say that it should be funded by the federal government, despite controversy over the use of human embryos.7
Conclusion: Stem cell research should be pursued but under legislative guidance.
Most scientists Do Not support applications for human reproductive cloning (that is, they do not want any embryos altered during stem cell research to develop past a defined stage). They agree with governments and concerned citizens that it should be banned worldwide. However, they Do want the opportunity to continue stem cell research for clinical applications under appropriate regulation and legislation with the hope of alleviating human suffering.

Wednesday, March 26, 2008

Keeping faith in stem cell research

The Guardian

Tuesday March 25 2008

Cardinal Cormac Murphy-O'Connor (We are made for more, March 24) writes movingly about love and truth, what it is to be human, and the purpose of existence; but he is wrong to exclude atheists from the beauty of his vision. We too can see deep responsibility for others as part of our freedom, just as we can see existence as having a great and wonderful purpose.

However, we do not believe in things because of tradition and dogma. The archbishop writes about meeting a nun who cares for HIV/Aids patients in Zimbabwe, but the Catholic church could drastically cut the incidence of HIV across the world if only it would encourage the use of condoms.

Catholics believe a soul enters the fertilised cell at the moment of conception, thereby making a full human being of it - they believe this despite there being no evidence for it and many philosophical arguments against this view. From this absurd superstition they proscribe much that is beneficial. His Scottish colleague calls the use of hybrid embryos Frankenstein science; a better analogy is with the Frankenstein film where Boris Karloff's monster kills something beautiful and innocent, the little girl, because he does not understand it and fears it. The church is the monster; the beautiful innocent is a science that hurts no one but will save innumerable lives.
Joe Morison
London

What Cardinal Cormac Murphy-O'Connor means by a "free vote" on the human embryology bill - one that is not subject to the Labour whip - is not a free vote at all. At least in so far as Catholic MPs are concerned, it is simply a vote subject to a different whip, namely a Vatican one.

The sight of MPs who are members of a religious sect being urged on by their leader to blackmail the government (by threatening to resign) is one that should raise all sorts of alarm bells with voters. They will be asking who runs Britain - Westminster or Rome? Is Ruth Kelly the MP for Bolton West or Vatican East?
Alistair McBay
National Secular Society

You are right to draw attention to the plight of patients with incurable diseases (Therapeutic cloning offers hope of treatment for Parkinson's; Johnson tries to defuse embryos bill crisis, March 24). However, it is mistaken to believe that embryo stem cell research is the way forward to find cures for these diseases. In spite of the huge sums of money the government has spent so far in supporting this line of research, to date it has yielded nothing of significant therapeutic value.

On the other hand, adult stem cell research is yielding promising results along several lines of research into serious diseases. A clear example is that of bone marrow transplants, and bone marrow harvesting in cancer, a successful application of stem cells in treatment.

Several religious faiths in this country have very grave concerns about the proposed direction of research in the current human fertilisation and embryology bill, and have expressed horror at the idea of mixing animal and human gametes in order to find cures.

If the government professes that we have a democratic multicultural and multi-faith society in this country, it needs to justify its vast expenditure and its continued promotion of a scientific route that is fraught with moral and ethical concerns.
Dr Matthew Thalanany
Colchester, Essex

The Cardinal Archbishop of Glasgow asserts that the fertilisation of animal eggs by human DNA involves the making of babies which are then raided for their constituent parts, demonstrating a lack of respect for human life.

If blastulae are babies then nature itself (or God) demonstrates just such lack of respect since the majority of naturally fertilised human eggs fail to implant and are flushed, unnoticed, into the drains in their thousands every day.
David McBrien
Maidenhead, Berkshire

Surely the logical moral corollary of the premise that there is no animal-human divide is for all who support it to become vegetarian?
Rose Frain
Edinburgh

Thursday, March 20, 2008

Story Map of Stem Cells

1. Story map

what does research say about embryonic stem cells, five years after their discovery?whyfiles.org/189stem_cell/

2. Researchers first to map gene that regulates adult stem cell growth

Researchers first to map gene that regulates adult stem cell growth. A new discovery in stem cell research may mean big things for cancer patients in the ...
www.physorg.com/news88013088.html

3. Stem cell plans include creation of embryo bank | The San Diego ...

Oct 5, 2006 ... California's stem cell institute yesterday unveiled its plans for ... insiders met regularly to develop the road map that will guide the ...
www.signonsandiego.com/uniontrib/20061005/news_1n5stem.html -

4. The Stem Cell Story - JDRF Kids Online

The Stem Cell Story. Stem cell research is a topic on which the Juvenile Diabetes Research Foundation International (JDRF) has taken the lead, because it's ...
kids.jdrf.org/index.cfm?fuseaction=home.viewpage&page_id=938B773C-5004-D739-A5CFDCC492B34

Saturday, March 15, 2008

Talk about Stem Cells (Video Show)

The Politics of Stem Cell Research
Cell Research...A fertility clinic asks President Bush for advice on Stem Cell Research....jerry zucker stem cell research president bush veto national banana
http://www.youtube.com/watch?v=_QiO6cl8WOk

Autistic Patient After Adult Stem Cell Treatment
Cell Treatment...A young girl with autism shows her amazing improvement following treatment with adult
http://crackle.com/c/Family_Friendly/Autistic_Patient_After_Adult_Ste...

Sam Harris - Stem Cells and Morality
using the case of stem cells. Check out The Science Network at http://thesciencenetwork.org/...Sam Harris Stem Cells science morality atheism
http://www.youtube.com/watch?v=kUwnMX8ht3U

The Charlie Rose Science Series: The Latest on Stem Cell Research
Harvard Stem Cell Institute, George Daley of Children's Hospital Boston and the Harvard Stem Cell Institute, Larry Goldstein, director of the UC San Diego Stem Cell program
http://video.google.com/videoplay?docid=1361375465524090858

Stem Cell Breakthrough
breakthrough in stem cell science, with new technology that lets doctors recover and bank cells from the placenta, too. “By collecting and banking stem cells from
http://www.gofish.com/player.gfp?gfid=30-1154699

Adult Stem Cells (part 6)
6)...An introduction to Adult Stem Cells: The benefits Stem Cell technology can bring to everyday life.
http://www.metacafe.com/watch/734303/adult_stem_cells_part_6/

Stem Cell Primer
Learn all about stem cells in 2-1/2 minutes or less. This is the ending of a weekly show....stem cells embryonic berashis
http://www.youtube.com/watch?v=XoggT8quHYs

Stem Cell Breakthrough
in stem cell science, with new technology that lets doctors recover and bank cells from the placenta, too. â�œby collecting and banking stem cells from
http://sharkle.com/video/138811/

Adult Stem Cells (part 6)
6)...An introduction to Adult Stem Cells: The benefits Stem Cell technology can bring to
http://tw.video.yahoo.com/video/play?vid=809645