Stem Cell Research Overview
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Transcript of 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
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 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.
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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