zhao ethic sym 2009 for notes

7/30/2019 Zhao Ethic Sym 2009 for Notes

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Stem Cells: Myths, Facts, and Ethics

Xinyu Zhao PhD

Assistant Professor

UNM School of MedicineDepartment of Neuroscience


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The ethical hot spots of stem cell research

Human embryonic stem cells isolated from

blastocyst stage human embryos

Cloning by somatic nuclear transfer

Induced pluripotent stem cells derived fromhuman skin cells.


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Part I: The myths and facts of stem cell research

Part II: The ethics of stem cell research


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Definition of stem cells:

Self-renewal

Multi-potency


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Lineage restricted

Limited self-renewal

Totipotent

Totipotent

Totipotent


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Differences betweenembryonic stem cells and adult stem cells

They have different self-renewal capabilities Embryonic stem cells: near indefinite self-renewal

Adult stem cells: limited self-renewal

They have different differentiation potentials .Embryonic stem cells: differentiate into all cell types in an

organism

Adult stem cells: differentiate into restricted cells types.

They differ in how they respond to external stimuli Embryonic stem cells are readily to change upon stimulation

Adult cells emphasize on stability and need to be activated by

cues, e.g. injuries.


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PluripotentES cells

Source of ES cells


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Human ES cellsHuman blastocyst

Inner cell mass

Mouse fibroblasts feeder layer


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DifferentiationES cells


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Applications of Human pluripotent stem Cells

Basic Knowledge of Human Development

Models of Human Disease

Transplantation-Cell Replacement

Drug Development

Organogenesis


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Scientific Challenges of Using Human ES Cells:

Challenges to cell-replacement and organtransplantation therapies:

Lack of cell type specific differentiation

Possible tumor formation

Immune rejection by recipients

Challenges to ES cells as models for studying

human diseasesDo not know the genes responsible for the diseases

Can not create the mutations corresponding to human

diseases


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Somatic cell nuclear transfer (SCNT)

For establishing and studying models of

human diseases

For generating patient-specificcells/organs for transplantation and repair


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Therapeutic Cloning: Organogenesis


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Human ES Cells: Studying the Cellular and Molecular Mechanisms of DiseaseTherapeutic cloning: Studying Mechanisms of Diseases

Example: ALS


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D

B E

C F

A

Mark Denham & Richard Mollard


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Not This


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induced pluripotent cells (iPSC)A combination of several genes can re-program

skin fibroblasts into pluripotent cells

(Takahashi and Yamanaka Cell 2007, Yu Science 07, Cowan Science 07, Wernig Nature 07, Okita Nature 07)

Why iPSC can not replace ESC research:1) Studying ESCs is critical for understanding iPSCs

2) iPSCs are induced by cancer genes therefore hinder their

use for therapies

Reprogramming


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People in the US affected by diseases that may behelped by stem cell research

Condition Number of Persons AffectedCardiovascular diseases 58 MillionAutoimmune diseases 30 MillionDiabetes 16 Million

Osteoporosis 10 MillionCancer 8.2 MillionAlzheimer's disease 4 MillionParkinson's disease 1.5 MillionBurns (severe) 0.3 Million

Spinal cord injuries 0.25 MillionBirth defects 150,000 (per year)Total 128.4 Million--------------------------------------------------------------------------------------Data from the Patients' Coalition for Urgent Research, Washington,

DC (according to Perry, Ref. 267).


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The 1st ethical hot spot of stem cell research

Human embryonic stem cells isolated fromblastocyst stage human embryos

In the case of embryonic stem cellresearch, the end that scientists hope to

achieve is the relief of human suffering.

That this is a humanitarian and worthy end

is not in dispute. The controversy is aboutthe means, namely, the consumption of

donated embryos. -- ISSCR website on stem cell ethics


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International Guideline for Stem Cell Research (by

ISSCR Stem Cell Ethics Committee):

Reproductive cloning is prohibited!!!

The 2nd ethical hot spot of stem cell research


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The 3rd ethical hot spot of stem cell research

Induced pluripotent stem cells derived from

human skin cells.

Protection of human subjects

Informed consent

Protection of genetic identity.


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Other Related Ethical Issues

Ethical issues in human clinical trialsInformed consent of patients

Protection of human subjects.

Protection of human genetic and cellular materials

Creating human/animal hybrid stem cells

Ethical issues in animal research.

Honest and integrity in biomedical research


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How can scientists ensure ethical conductin stem cell research

Education for researchers Routine emphasis by principle investigators

Emphasis by funding agencies

Classes and seminars

Education for the public Understand the importance of research

Understand that scientists are under ethical guidance

Communication and open dialogue Understand each others opinion

Reach a rationale common ground.

Last step: Legal reinforcement


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Useful Resources

National Institute of Health resource for stemcells (http://stemcells.nih.gov)

International Society for Stem Cell Research:Guidelines for the Conduct of Human Embryonic Stem CellResearch (www.isscr.org)

National Academy of Science: Guidelines forhuman embryonic stem cell research(http://www.nap.edu/openbook.php?isbn=0309096537)


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On March 9, 2009, President Obama issued

Executive Order 13505, entitled

"Removing Barriers to Responsible

Research Involving Human Stem Cells."


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Thank you !

zhao ethic sym 2009 for notes

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