STEM CELL RESEARCH - Basics

M. Arshad Chaudhry, Ph.D.Michael Smith LaboratoriesUBC, Vancouverma_chaudhry@hotmail.com

Outline of This Presentation

• Stem cell research

• The nature and promise of stem cell research

• The ethical debate

What Are Stem Cells?

Stem cells are the raw material from which all of the body’s mature, differentiated cells are made. Stem cells give rise to brain cells, nerve cells, heart cells, pancreatic cells, etc.

What’s So Special About Stem Cells?

They have the potential to replace cell tissue that has been damaged or destroyed by severe illnesses.

They can replicate themselves over and over for a very long time.

Understanding how stem cells develop into healthy and diseased cells will assist the search for cures.

Two Kinds of Stem Cells

Embryonic (also called “pluripotent”) stem cells are capable of developing into all the cell types of the body.

Adult stem cells are less versatile and more difficult to identify, isolate, and purify.

Stages of Early Embryonic Development

Stages of Early Embryonic Development

Embryonic Stem Cells:Researchers extract stem cells from a 5-7 days oldResearchers extract stem cells from a 5-7 days old blastocystblastocyst..

Stem cells can divide in culture to form more of their own kind, Stem cells can divide in culture to form more of their own kind, thereby creating a stem cell line.thereby creating a stem cell line.

The research aims to induce these cells to generate healthy tissue needed by patients.

Two Sources of Embryonic Stem Cells

1. Excess fertilized eggs from IVF (in-vitro fertilization) clinics

2. Therapeutic cloning (somatic cell nuclear transfer)

Tens of thousands of frozen embryos are routinely destroyed when couples finish their treatment.

These surplus embryos can be used to produce stem cells.

Regenerative medical research aims to develop these cells into new, healthy tissue to heal severe illnesses.

Somatic Cell Nuclear Transfer

The nucleus of a donated egg is removed and replaced with the nucleus of a mature, "somatic cell" (a skin cell, for example).

No sperm is involved in this process, and no embryo is created to be implanted in a woman’s womb.

The resulting stem cells can potentially develop into specialized cells that are useful for treating severe illnesses.

Adult Stem Cells

• Fundamental feature of adult stem cells– They maintain the ability to divide throughout

life and give rise to specific cell type• Blood vessel stem cells can not give rise to brain or heart

muscle cells

– The fact that developmental potential of adult stem cells is restricted has recently been challenged

• Why some tissues maintain stem cells and others don’t is not understood

The Ethical DebateIn favor of ESCR:

Embryonic stem cell research (ESCR) fulfills the ethical obligation to alleviate human suffering.

• Since excess IVF embryos will be discarded anyway, isn’t it better that they be used in valuable research?

• SCNT (Therapeutic Cloning) produces cells in a petri dish, not a pregnancy.

Against ESCR:

In ESCR, stem cells are taken from a human blastocyst, which is then destroyed. This amounts to “murder.”

• There is a risk of commercial exploitation of the human participants in ESCR.

• Slippery slope argument: ESCR will lead to reproductive cloning.

Key Ethical Issues

• The blastocyst used in stem cell research is microscopically small and has no nervous system. Does it count as a “person” who has a right to life?

• What do various religions say about when personhood begins? Does science have a view on this?

• In a society where citizens hold diverse religious views, how can we democratically make humane public policy?

Stem Cell Research Worldwide