Transcript Stem Cell Research Overview

Summer 2007 Workshop
 in Biology and Multimedia
 for High School Teachers

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

http://www.kumc.edu/stemcell/images.html
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
Cells from 1-4
develop into a new day old
individual
embryos
Pluripotent
Cells can form any Some cells of
cell type
blastocyst (514 days old)
Multipotent Cells
differentiated, but
can form a
number of other
Fetal tissue,
cord blood,
and adult stem
cells
Pluripotent Differentiation
http://www.kumc.edu/stemcell/images.html
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)
Multipotent - produces
limited cell types
First isolated in 1960s
Come from the inner cell
mass of a blastocyst
Funding (1999-2004)
$2.24 billion
Results - over 50
therapeutic uses for
humans
Funding (2002-2004)
$55 million
Results - no human
trials, some success with
animal trials to date
Pluripotent - produces all
cell types
First Isolated in 1998
How Do You Make Stem Cells?
1.
2.
3.
4.
5.
Fertilized Egg
Isolate blastocyst
Remove inner cell
mass
Place into petri
dish coated with
feeder cells to
promote division
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
Transfer
1.
1.
2.
3.
Remove nucleus from
egg cell and implant
nucleus from patient’s
cell to create fertilized
egg.
Remove inner cell
mass from blastocyst
and place in petri dish
for stem cell
development &
differentiation
Cells will be almost
identical to patient so
rejection will not occur
when transplantated.
2.
3.
http://www.kumc.edu/stemcell/early.html Reprinted with permission from the
University of Kansas Medical Center.
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



Tumor stem cell
Tumor cell
Drawn by Christine Rodriguez

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
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.ht
ml
 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/2001/08/200
10809-2.html
 Stem cells in class; Badran, Shahira; Bunker Hill
Community College, 2007, Boston Museum of Science
Biotechnology Symposium
 Harvard Stem Cell Institute