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Summer 2007 Workshop in Biology and Multimedia for High School Teachers - PowerPoint PPT Presentation

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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?.

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Presentation Transcript
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  • What are Stem Cells?

  • Potential Uses for Stem Cells

  • Cloning

  • Stem Cells and Cancer

  • Worldwide Status

  • What do you think?

  • Summary

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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).

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Stem Cell Differentiation

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Obtained from in vitro fertilization, or aborted embryos

3 or 4 day old embryo; blastocyst stage


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

2 types of Stem Cells

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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

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Differentiation Animation

  • Differentiation


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Embryonic Stem Cells -Blastocyst Stage

  • 3 parts:

    • Trophoblast

    • Blastocoel (“blastoseel”) or blastocyst cavity

    • Inner cell mass

  • Millions of cells can come from one blastocyst

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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.

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Pluripotent Differentiation

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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

Slide14 l.jpg Reprinted with permission of Do No Harm.

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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

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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

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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

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How Do You Make Stem Cells?

  • Fertilized Egg

  • Isolate blastocyst

  • Remove inner cell mass

  • Place into petri dish coated with feeder cells to promote division

  • Differentiation!

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  • 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)

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SCNT - Somatic Cell Nuclear Transfer


  • 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.


3. with permission from the University of Kansas Medical Center.

Slide22 l.jpg Reprinted with permission of Do No Harm.

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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

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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!

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Tumor stem cell

Tumor cell

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

Drawn by Christine Rodriguez

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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!

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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

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Global Status

  • Ongoing debate regarding use of embryos

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

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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

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  • Stem Cell Review Film Clip

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  • Stem cells & Cloning Stem cells & Cloning; David A. Prentice, Benjamin Cummings, 2003






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

  • Harvard Stem Cell Institute