Induced pluripotent stem cells as treatment for Angelman syndrome

¶ … Induced Pluripotent Stem Cells to Treat the Severe Neurological Disorder Angelman Syndrome

With Additional Theoretical Application to Treating Other Neurological Disorders

Concepts, Issues, and Definitions

Statement of General Topic Area: Neurological Disorders and Stem Cell Treatment

Angelman Syndrome

Induced Pluripotent Stem Cell Research

Possibilities for therapeutic cross-over benefit to other Neurological Disorders

Animal Model for Testing

Potential Therapeutic and Other Areas of Concern

Concepts, Issues, and Definitions

Statement of Purpose

The possibility of stem cell treatment as a therapeutic and/or as a cure for many disorders has been widely studied. Barriers to success have been political, social, ethical, and scientific (Fischback & Fischback, 2004). However, the field has continued to develop, with many new breakthroughs occurring within the last year, 2009. Significant progress has been made which tackles ethical and political issues, such as using induced pluripotent cells derived from somatic cells rather than embryonic cells. Induced pluripotent cells are cells that have been altered in the lab to become pluripotent, meaning they have the potential to develop into almost any type of body cell (Condic & Rao, 2008). In 2006, the first iPS cells were created using a retrovirus to modify the DNA of somatic cells. The concerns of using iPS cells revolved around the dangers associated with retroviruses. However, recent developments remove that danger by using adenoviruses instead of retroviruses to create iPS cells. (Stadtfeld, Nagaya, Utikal, Weir, & Hochedlinger, 2008). The exponential leaps in knowledge that are occurring on the scientific and medical fronts may be indicative of a soon-to-be-realized safe, effective, and widely available treatment for many diseases and disorders (Mimeault, Hauke, & Batra, 2007). The purpose of the project will be to assess whether using iPS cells to create a deliverable brain cell vehicle which expresses the gene produce known as UBE3A-E6AP, will alleviate and/or cure Angelman Syndrome.

1.2 Objectives of Research

The objectives of the research focus on the following areas:

1) To identify and assess an accurate animal model to use for iPS stem cell research in Angelman Syndrome.

2) To ascertain the proper data design to capture the relevant material.

3) To administer iPS stem cell treatment to the animal model.

4) To assess the success/failure of the research.

5) To identify areas of future study.

1.3 State of General Topic Area: Neurological Disorders and Stem Cell Treatment

Neurological disorders have been a hardship for society and individuals, with costs extending beyond healthcare costs (MacDonald, Cockerell, & Sander, 2000). Indeed, the cost of human suffering is immeasurable. It is the goal of many research scientists around the world to find answers the underlying causes of neurological disorders, and offer a scientific basis for developing therapeutics and offering cures. Stem cell treatment is one area of great promise, and has been studied as a potential treatment in many neurological conditions, such as Alzheimer's, Parkinson's Disease, Stroke patients, Cerebral Palsy, Autism, and the more rare genetic disorders, such as Angelman Syndrome (Rossi & Cattaneo, 401-409). It is with much critical thought to offer this point of question: there exists more than some slight potential of these disorders sharing common biological markers within the brain, and therefore offer the thought that what might be a viable therapeutic in one area, may indeed hold potential in neurological conditions overall (Abuhatzira, Shemer, & Razin, 2009).

1.4 The Research Problem

As Angelman Syndrome is a neurological disorder with a genetic basis, as well as being a disorder of brain-specific imprinting, the challenge of this proposal is to present sufficient evidence that using iPS-derived stem cells to grow mature, genetically normal brain cells, is viable. Moreover, administering this particular type of stem cell to an animal model of Angelman Syndrome, in order to assess the potential benefits, is a goal of this project.

2. Literature Review

2.2 Induced Pluripotent Stem Cell Research

Induced pluripotent stem cells have been manipulated in the laboratory to become pluripotent. Pluripotent stem cells have the potential to develop into virtually any other kind of body cell. The only naturally occurring pluripotent stem cells are embryonic stem cells (ES cells).

It is the hope of scientific research in this field that induced pluripotent stem cells (iPS cells) will provide a source of artificial pluripotent cells. The mechanism involved in producing these cells is through genetically coaxing an ordinary body cell, called a somatic cell, into becoming a stem cell. Somatic cells lack the ethical problems that embryonic cells have, though hypothetically they should have the same potential to treat diseases, ailments and injuries in many fields of medicine (Dobkin, 2007).

Induced pluripotent cells could theoretically be used for the identical purposes as embryonic stem cells. IPS cells have several advantages over embryonic stem cells. They can be autologous (derived from the host's own cells) and therefore would not cause an immune response. They can be isolated from patients with genetic diseases, such as Angelman Syndrome, to further research into those diseases. Chiefly, iPS cells are free of the ethical constraints that cast a pall over the use of ES cells (Condic & Rao, 2008). Moreover, they are obtained without the destruction of embryos.

2.3 Possibilities for therapeutic cross-over benefit to other Neurological Disorders

Research has indicated that there may be links underlying the cognitive deficits of various neurological disorders, such as Rett Syndrome, Angelman Syndrome, Autism, and others (Abuhatzira, Shemer, & Razin, 2009). Moreover, as the research accumulates on Alzheimer's Disease and Parkinson's Disease, we may even see common neuronal pathways involved in the etiologies of various neurological disorders and neurological diseases. A treatment in one field of study, may indeed hold great promise for treating another disorder using the same methods. Such is the reach of science and technology as scientists continue to diligently gather information on the causes of various neurological disorders.

3. Research Methodology

3.1 Animal Model for Testing

This research will utilize a scientifically-vetted mouse model of Angelman Syndrome, with unique properties. This mouse model will be null-model UBE3A mouse, which for all intents and purposes, is a deletion mouse model. This animal model does not have the maternally active copy of the UBE3A gene. Additionally, the early generation UBE3A-null models led to a demand for a model that held all the functions of the null-model, while including the ability to "report" on the status of UBE3A via a fluorescent signature marker in the brain, where UBE3A was active (Heck, Zhao, Snigdha, & LeDoux, 2008). This newer generation of the UBE3A-null model is called the UBE3A Reporter Mouse. The advantage is that, in vivo, the research scientist is able to stain the slices and view any neural genetic activity of an attempted rescue of the phenotype, in order to ascertain any success and/or to what degree success occurred (Landers, Calciano, Colosi, Wagstaff, Glatt-Deeley, & Lalande, 2005). This project is proposing to use this UBE3A Reporter Mouse Model to assess if iPS treatment rescues the motor and cognitive deficits associated with Angelman Syndrome.

3.2 Hypotheses:

H1: Transplanting iPS stem cells (from wildtype mice) into the UBE3A Reporter Mouse will result in widespread differentiation of the iPS cells into UBE3A-maternally active neurons,

H2: Following iPS treatment, maternal UBE3A will be expressing normally in the brain, thereby alleviating/curing the motor and cognitive deficits associated with Angelman Syndrome.

3.3 Data Collection

Is maternal UBE3A active following iPS treatment: Data will be gathered on the iPS-treated mice via positron emission tomography, and in vivo brain slice preparation, and Western Blot Analysis. H1 will essentially be ascertained following these tests.

Does iPS treatment rescue the motor and cognitive deficits associated with Angelman Syndrome: Data will be gathered from testing the treated mice in scientifically recognized tests of cognitive ability in a mouse model. This project proposes using the water maze test, the electric shock test, and the submerged platform test. H2 will effectively be answered using the data gleaned from these tests.

4. Conclusion

4.1. Potential Therapeutic and Other Considerations

The potential of using iPS treatment to rescue/alleviate the severe motor and cognitive deficits witnessed in Angelman Syndrome is theoretically viable. Reliable mouse models of AS exist with which to run the tests. The technology needed to tease iPS stem cells into fully functioning brain cells that express the UBE3A gene product is available and viable to conduct in a controlled setting. Therefore, the proposal as set forth is a logical one which addresses an urgent need in an uncharted territory -- treating imprinted neurological disorders using iPS treatment. If successful, the potential to treat not only other imprinted neurological disorders (Rett Syndrome, Prader Willi Syndrome) but to also treat other neurological disorders that share similar dysfunctional brain pathway etiologies, is immense. If the hypotheses in the proposal are proven, the door to researching viable and cutting-edge treatments for neurological disorders harkens to the researchers. Devastating disorders that cost immeasurable amounts of human suffering and untold millions of dollars in health care and long-term care, could be cured. A novel therapeutic that bypasses the ethical, political, and social backlash associated with stem cell research, could potentially change the course of mankind.