stem cell research overview

Stem Cell Research Overview

Straight Path

Outline

What are Stem Cells? Potential Uses for Stem Cells Cloning Stem Cells and Cancer Worldwide Status What do you think? Summary

What are Stem Cells?

Stem cells are different from all other cells in the body.

Stem cells have 2 distinct properties:– They are unspecialized cells that are

capable of renewing (regenerating) for long periods of time.

– They can give rise to different cell types (differentiation).

Stem Cell Differentiation

http://stemcells.nih.gov/info/basics/basics4.asp

2 types of Stem Cells

Embryonic– Obtained from in

vitro fertilization, or aborted embryos

– 3 or 4 day old embryo; blastocyst stage

Adult– Found among some

differentiated cells in a specific tissue or organ; placental cord; baby teeth

Unique Properties of Stem Cells Regeneration

– Stem cells can replicate themselves over longer periods of time than other body cells

Differentiation– Stem cells are

unspecialized cells that can produce specialized body cells by first producing an intermediary cell

http://www.kumc.edu/stemcell/images.html

Differentiation Animation

Differentiation (http://learn.genetics.utah.edu/units/biotech/microarray/)

Embryonic Stem Cells -Blastocyst Stage

3 parts:– Trophoblast– Blastocoel

(“blastoseel”) or blastocyst cavity

– Inner cell mass

Millions of cells can come from one blastocyst


Blastocyst Vocabulary

Trophoblast - outer shell of blastocyst. Blastocoel - fluid-filled space within

blastocyst. Inner cell mass - group of 30+ cells on

one end of the blastocoel, this is what produces the specialized cells needed for adult life.

Stem Cell Potential Cell Type Description Examples

Totipotent Each cell can develop into a new individual

Cells from 1-4 day old embryos

Pluripotent Cells can form any cell type

Some cells of blastocyst (5-14 days old)

Multipotent Cells differentiated, but can form a number of other tissues

Fetal tissue, cord blood, and adult stem cells

Pluripotent Differentiation


Adult Stem Cells (ASC)

ASCs are undifferentiated cells found among differentiated cells in a tissue or organ

They are able to regenerate and differentiate into the major cell type of the tissue or organ in which they are found. (Multipotent)

Recent experiments have raised the possibility that stem cells from one tissue/organ can create other cell types– This is known as PLASTICITY

http://www.stemcellresearch.org/testimony/20040929prentice.htm Reprinted with permission of Do No Harm.

Adult Stem Cell Facts

Adult stem cells were found in many more tissues than expected

Some may be able to differentiate into a number of different cell types, given the right conditions

General consensus among scientist:– Adult stem cells DO NOT have as much potential

as embryonic stem cells CLARIFICATION: not all new adult cells arise

from stem cells– Most arise by MITOSIS of differentiated cells

Potential Uses for Stem Cell Research Basic research – clarification of

complex events that occur during human development & understanding molecular basis of cancer

Biotechnology(drug discovery & development) – stem cells can provide specific cell types to test new drugs

Potential Uses Continued. . . .

Cell based therapies:– Regenerative therapy to treat Parkinson’s,

Alzheimer’s, ALS, spinal cord injury, stroke, severe burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis

– Stem cells in gene therapy• Stem cells as vehicles after they have been

genetically manipulated

– Stem cells in therapeutic cloning– Stem cells in cancer

Adult Stem Cells Embryonic Stem Cells

Aka Mature, somatic Aka Early, blastocytic

Come from developed body tissues, umbilical cord, placenta (after birth)

Come from the inner cell mass of a blastocyst

Multipotent - produces limited cell types

Pluripotent - produces all cell types

First isolated in 1960s First Isolated in 1998

Funding (1999-2004) $2.24 billion

Funding (2002-2004) $55 million

Results - over 50 therapeutic uses for humans

Results - no human trials, some success with animal trials to date

How Do You Make Stem Cells?

1. Fertilized Egg

2. Isolate blastocyst

3. Remove inner cell mass

4. Place into petri dish coated with feeder cells to promote division

5. Differentiation!

Cloning

Reproductive Cloning– Producing new organisms genetically identical to

donor Therapeutic Cloning

– Make a therapeutic product (vaccine, human protein etc)

– Deliver organs that will not be rejected– Act as animal models for human disease

Breeding animals or plants with genetically favorable traits (genetic engineering)

SCNT - Somatic Cell Nuclear Transfer1. Remove nucleus from

egg cell and implant nucleus from patient’s cell to create fertilized egg.

2. Remove inner cell mass from blastocyst and place in petri dish for stem cell development & differentiation

3. Cells will be almost identical to patient so rejection will not occur when transplantated. http://www.kumc.edu/stemcell/early.html Reprinted with permission from the

University of Kansas Medical Center.

1.

2.

3.

http://www.stemcellresearch.org/testimony/20040929prentice.htm Reprinted with permission of Do No Harm.

Problems with Therapeutic Cloning (1) Some immune rejection may occur -

WHY?– About 1% of DNA in the clone will not be

identical to patient – It will be identical to egg cell used in SCNT

due to the mitochondrial DNA in the cytoplasm of the egg cell

Problems with Therapeutic Cloning Large number of eggs needed for SCNT

which can only be obtained with:– Excessive hormone treatment of females– Surgery to remove eggs

Both processes are potentially harmful to females!

Current Efforts with SC and Cancer Determine difference

between cancer & normal stem cells

Identify potential points in pathways critical for the survival of cancer SCs

Develop therapies that specifically target cancer SC

Duke University Explanation

Tumor stem cell

Tumor cell

Drawn by Christine Rodriguez

Status of SC research in other countries

Great Britain– Very liberal policies on research– Therapeutic cloning allowed, use of excess embryos &

creation of embryos allowed– Stem cell research allowed

France– Less liberal politics– Use of excess embryos from IVF allowed– Reproductive AND therapeutic cloning banned

Germany– Very strict policies– Use of excess embryos and creation of embryos banned– Scientists can IMPORT embryos

Click here to see a map of the stem cell policy around the world!

Debate in US Federal funding available for research using

the Bush lines only:– ES cell lines that were already in existence by

8/9/01 Disadvantage of Bush stem cell lines:

– May have lost regenerative ability– May have accumulated mutations or infections

Private companies continue to pursue stem cell research– Use of human embryos for IVF (in vitro

fertilization) & therapeutic cloning is legal in most states

• No federal funding

– Some states are considering banning both

Global Status

Ongoing debate regarding use of embryos

United Nations: proposal for a global policy to ban reproductive cloning only

What do you think?

Click on the link to take a poll on YOUR opinion regarding using cloning for stem cell research.

Cloning for Stem Cell Research Poll

Summary

Stem Cell Review Film Clip

References Stem cells & Cloning Stem cells & Cloning; David A.

Prentice, Benjamin Cummings, 2003 http://www.pbs.org/wgbh/nova/sciencenow/

3302/06.html http://www.stemcellresearch.org http://www.stemcells.nig.gov/info/nasics/nasics7.asp http://www.stemcells.nig.gov/info/scireport/

2006report.htm http://www.whitehouse.gov/news/releases/

2001/08/20010809-2.html Stem cells in class; Badran, Shahira; Bunker Hill

Community College, 2007, Boston Museum of Science Biotechnology Symposium

Harvard Stem Cell Institute

stem cell research overview

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