Stem Cells - PowerPoint PPT Presentation


PPT – Stem Cells PowerPoint presentation | free to view - id: 259005-NWY3N


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Stem Cells


... at WiCell Research institute recently published work that eliminates the ... Mouse ESC have been induced to make dopamine-producing cells in rats with ... – PowerPoint PPT presentation

Number of Views:52
Avg rating:3.0/5.0
Slides: 24
Provided by: westfiel
Tags: cells | stem | study | time


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Stem Cells

Stem Cells
  • What are they and what can we do with them?

Stem Cell Characteristics
  • They are undifferentiated cells that can divide
    indefinitely in culture.
  • They can divide asymmetrically producing one
    daughter resembling its mother and one that can
    differentiate into cells of all three germ layers
  • They must originate from an embryonic or adult
    stem cell
  • (New England Journal of Medicine. 349267-274.

Types of Stem Cells
  • Embryonic
  • Umbilical
  • Adult

Embryonic Stem Cells
  • The first human stem cell lines were developed at
    the Univ. of Wisconsin in 1998. 14 blastocysts
    were donated by couples in an in vitro
    fertilization program. The lab established 5 cell
    lines. The cells were able to develop into
    various cell types including neural, gut,
    cartilage, muscle and bone.

Embryonic Stem Cells
  • are derived from fertilized embryos less than a
    week old, the blastocyst stage of development.
  • (Photo from

Developmental Stages(Photo from J. Clinical
Investigation. 1141364-1370. 2004)
Morula Stage
  • A 32-128 solid ball of cells
  • Each cell is totipotent it can give rise to all
    embryonic cell types including extraembryonic
    tissues necessary for implantation and formation
    of the placenta and umbilical cord.

Blastocyst Stage
  • The blastocyst (3-5 days in humans) has two
  • the inner cells mass contains the
    undifferentiated stem cells that will form the
  • The surrounding cells (trophoblast) help form the
    placenta and umbilical cord

Inner Cell Mass
  • These cells are called pluripotent and will first
    form three germ layers (ectoderm, endoderm and
    mesoderm) through a process called gastrulation
  • The cells in each germ layer are now called
    multipotent and they follow a path of
    specialization to become progenitor cells which
    form specific cell types e.g. nerve or muscle

Pluripotent Cells(Photo from J. Clinical
Investigation. 1141364-1370. 2004)
Cellular Specialization
  • Cells become specialized as they occupy certain
    positions in an embryo at a specific time in the
    life of embryo
  • Specialization occurs as a result of the
    transcription of a specific set of genes in a
    cell to cause the translation of proteins that
    are unique to that cell type e.g. Dystrophin
    in muscle cells.

Stem Cells in the Lab
  • Currently, stem cells are grown in association
    with mouse feeder cells (fibroblasts) and animal
    proteins which form a matrix on which the stem
    cells grow
  • Feeder cells keep the stem cells in the
    undifferentiated state
  • Existing stem cells lines are contaminated with
    an animal protein

Stem Cells in the Lab
  • Scientists at WiCell Research institute recently
    published work that eliminates the need for
    feeder cells, one of the main sources of
    contamination with pathogens.
  • The research shows a protein called fibroblast
    growth factor 2 does the same job of the feeder
    cells keeping the stem cells undifferentiated.
  • Stem cell cultures still use Matrigel (a matrix
    of cells from mouse tumors and bovine serum
    replacement to keep the cells healthy.
  • (Nature Methods. 2185-190. 2005)

Stem Cell Images (http//
Establishing Stem Cell Lines
  • Inner cell mass cells are transferred to culture
    dishes where they divide and spread over the dish
  • Subculturing transfers the cells to additional
    dishes after the first one is filled
  • After 6 months there are millions of cells
  • The cells are evaluated before being called a
    cell line

How Are ESC Identified(http//
  • Growth and subculturing for many months
  • The presence of specific surface protein markers
    for undifferentiated cells
  • The presence of the protein, Oct-4, a
    transcription factor unique to ESC
  • Microscopic chromosomal examination
  • Subculturing potency after freezing and thawing
    and replating
  • Test for pluripotency

Test For Pluripotency(http//
  • Allow cells to differentiate spontaneously in
    cell culture
  • Manipulate cells to differentiate
  • Inject cells into immunosupressed mouse to form a
    teratoma (benign tumor containing many cell types)

Stem Cell Research
  • Other countries are beginning to take the lead in
    stem cell research Korea
  • Private companies in the US can do research with
    private funds
  • Universities are setting up labs supported solely
    by private funds- e.g. Univ. Wisconsin, Harvard
  • In 2004, Harvard produced 17 new human ESC lines
    using private funds

ESC Use in Basic Research(New England Journal of
Medicine. 349267-274. 2003)
  • Study unique aspects of early human development
  • Study origin and mechanisms of chromosomal
  • Preclinical testing of candidate therapeutic
    drugs in many human tissue types

ESC and Treating Diseases
  • Animal experiments have shown the potential
    therapeutic value of stem cells
  • Mouse ESC have been induced to make
    dopamine-producing cells in rats with Parkinsons
    disease. The symptoms stopped and the rats lived
    up to 3 months. (Nature. 417online. June 2002)

ESC and Treating Diseases
  • Mouse ESC have been induced to differentiate into
    spinal cord motor neurons.
  • The neurons were injected into the spinal cord of
    a chick embryo and migrated to the proper
    location in the cord.
  • Some sent out axons to developing limb muscles
    and formed synapses
  • (J. Clinical Investigation. 1141364-1370. 2004)

Spinal Cord Experiment(photo from J. Clinical
Investigation. 1141364-1370. 2004)
Human Trials Considerations
  • How do we control the stem cells e.g. start and
    stop differentiation, direct cells to specific
  • Risk of immune rejection
  • Prevent formation of tumors