Stem Cells

Cell Differentiation and Stem Cells

Major Topics for Discussion:1) What are Stem Cells?2) What are the major types of Stem

Cells and where are they found?3) Advantages & Disadvantages to

ESCs and ASCs4) Why are Stem Cells so very

important? 5) The Controversy over Stem Cells? 6) What are the new advances in

stem cell research?

What is cell differentiation?

• When unspecialized cells develop into specialized cells

• All cells have the same DNA but different genes are turned on in different cells.

• Also a cell’s location determine what it will become

Plants vs animals

• Animal cells can migrate to different areas but plants cannot.

• Outer layer becomes skin and nervous system.

Middle layer becomes bones and muscles.

Inner layer forms internal organs.

• However, plants continue to develop all of their lives.

What are Stem Cells?Stem Cells are extraordinary because:• They can divide and make identical copies of themselves over and over again, self- renewal

• Remain Unspecialized with no ‘specific’ function or become . . . .

• Specialized (Differentiated) w/ the potential to produce over 200 different types of cells in the body.

The Major Types of Stem Cells

A.Embryonic Stem Cells

B. Adult Stem Cells

Embryonic Stem Cells - come from cells of the blastocyst

(5-day old embryo) from IVF (In Vitro Fertilization) procedures

http://www.hhmi.org/biointeractive/media/human_emb_dev-lg.mov

How Big Is a Blastocyst?

Adult stem cells have been found in many organs and tissues, including brain, bone marrow, blood

vessels, skeletal muscle, skin, teeth, heart, corneas, liver, ovaries, and testis.

Go GGo Go Stem Cells!to see how adult stem cells work

http://learn.genetics.utah.edu/content/tech/stemcells/sctypes/

Stem cells are classified

• According to their potential to develop into other types of cells.

• Embryonic stem cells can develop into almost any type of cells but adult stem cells only give rise to closely related cells.

Stem Cell Classification:

• Totipotent stem cell – can grow into any type of cell…only in fertilized egg or very early embryos (5- days)

• Pluripotent stem cell – can give rise to almost any cell…in early embryonic cells

• Multipotent stem cell – adult stem cell, only gives rise to closely related cells

http://commons.wikimedia.org/wiki/Image:Stem_cells_diagram.png

multipotent

Pluripotent Stem Cells –more potential to become any

type of cell

Multipotent stem cells• Multipotent

stem cells – limited in what the cells can become

Advantages and Disadvantages to Embryonic and Adult Stem Cells.

Embryonic S.C. Adult S.C.“Pluripotent”

(can become almost any cell)

“Multipotent”“(can become many

but not all)

Stable. Can undergo many cell divisions.

Less Stable. Capacity for self-renewal is limited.

Embryo is destroyed. Difficult to isolate in adult tissue but not a moral issue

Growing an organism’s own stem cells

• Somatic Cell

Nuclear

Transfer

or Therapeutic Cloning

1) Transfer nucleus from a mature cell into a donor egg whose nucleus has been removed.2) Stem cells isolated from blastocyst tobe induced to formneeded tissues

Ideal because could use recipient’s own nuclei to build tissues

Why is Stem Cell Research So Important to All of Us?

Stem cells can replace diseased or damaged cells

Stem cells allow us to study development and genetics

Stem cells can be used to test different substances (drugs and chemicals)

Stem Cell Therapy has the Potential to:

• Regenerate tissues/organs

• Cure diseases like diabetes, multiple sclerosis, etc.

What Human Diseases are Currently Being Treated with Stem Cells?

• Cancer• Auto-immune diseases• Cardiovascular• Ocular (cornea)• Neural diseases• Wounds/injuries• Anemias and blood diseases

Technical Challenges

• Source - Cell lines may have mutations.

• Delivery to target areas

• Prevention of rejection

• Suppressing tumors

Why the Controversy Over Stem cells?• Embryonic Stem cells are derived from extra

blastocysts that would otherwise be discarded following IVF.

• Extracting stem cells destroys the developing blastocyst (embryo).

-Questions for Consideration-Is an embryo a person?Is it morally acceptable to use embryos for

research?When do we become “human beings?”

Teachers' Domain: Stem Cells: Seeds of Hope?

Current research

• New Research points to a new direction in Stem Cell Research

Teachers' Domain: Stem Cells Breakthrough

newnew research – reprogramming cells

Be informed about the status of stem cell research.

http://www.washingtonpost.com/wp-dyn/content/video/2009/03/09/VI2009030901268.html?sid=ST2009030901296