Summer 2007 Workshop

gooseliverBiotechnology

Oct 22, 2013 (4 years and 18 days ago)

95 views


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


Millions of cells can
come from one
blastocyst

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

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

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)

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
Transfer

1.
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.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/2001/08/20
010809
-
2.html


Stem cells in class; Badran, Shahira; Bunker Hill
Community College, 2007, Boston Museum of Science
Biotechnology Symposium


Harvard Stem Cell Institute