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An Introduction to Stem Cells

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Adult stem cell lines Adult stem cell lines isolated from mature tissues are another excellent resource for research studies. ... spinal cord injuries, ... – PowerPoint PPT presentation

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Title: An Introduction to Stem Cells


1
An Introduction to Stem Cells
2
What Are Stem Cells?
  • - unspecialized
  • - self renewal
  • can be induced to form specific cell types

3
Some Definitions
Totipotent having unlimited capacity,
extraembryonic membranes and tissues. Pluripotent
capable of giving rise to some tissues of an
organism Multipotent specialized pluripotent
cells
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5
Where Do ES Cells Come From ?
- fertilized embryos (in vitro) - primordial
(early stage) germ cells - somatic cell nuclear
transfer (therapeutic cloning)
6
Embryonic stem cells from IVF embryos. Human
embryonic stem cell lines can be derived from
embryos created through in vitro fertilization
(IVF). Usually, fertilization occurs within a
woman's body, but IVF technology has made it
possible to carry out fertilization and grow
embryos in the laboratory. This technology has
made it possible for many otherwise infertile
couples to have children. In many cases, however,
not all of the embryos created will be used, and
the remaining embryos are frozen and stored.
These embryos are potential resources for
scientific research.
7
This method for creating stem cells is called
therapeutic cloning. In this procedure, a
nucleus from an adult donor cell is inserted into
a recipient egg cell from which the nucleus has
been removed. The nucleus provides all of the
necessary genetic information, in the form of
DNA, for a cell to function and divide. The
resulting cell is then stimulated to divide as a
zygote would, resulting in the growth of
embryonic stem cells that are genetically
identical to the adult donor cell.
8
Adult stem cell lines Adult stem cell lines
isolated from mature tissues are another
excellent resource for research studies. Most
research is performed using adult stem cell lines
from model organisms such as mice and rats, since
obtaining adult stem cells from humans can
involve invasive surgical procedures.
9
The Blastocyst
Blastocyst 5-6 days after fertilization, the egg
develops into the cell ball pictured in the
image, which is called blastocyst by
developmental biologists. At the depicted stage
the ball is hollow, consisting of an envelope of
cells, surrounding the inner cell mass (ICM) from
which the embryonic stem cells are gathered.
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13
Multipotent Stem Cells
14
Bone Marrow Stem Cell
15
Why Are Stem Cells Important?
- cell replacement therapy - drug discovery -
early human development
16
How can Embryonic Stem Cells Be Used To Treat
Disease?
  • many cell based diseases
  • use stem cells to replace lost or defective
    cells eg. diabetes, Parkinsons disease
  • treat failing organs
  • eg. heart, liver

Rat brain replacement of stroke-damaged cells
17
Human Diseases With Known Cell Loss
Cardiovascular Diseases Autoimmune
Diseases Diabetes Osteoporosis Can
cer Alzheimers Disease Parkinsons
Disease Others burns, spinal cord injuries,
birth defects, male pattern baldness
18
What About Adult Stem Cells
- less plastic (multipotent) - limited
potential - less abundant
However, current research is changing some of
these ideas.
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Human Embryonic Stem Cells
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23
What types of cells have been produced from ES
cells?
  • - heart muscle
  • - nerve cells
  • insulin-secreting cells
  • - skin cells

24
Stem Cell Potential
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Creating Stem Cells
Creating stem cells for research
28
How Are Stem Cells Induced to Form Specific
Tissues?
  • Induced pluripotent stem cells (iPS) cells are
    typically derived by transfection of certain stem
    cell-associated genes into non-pluripotent cells,
    such as adult fibroblasts, using retroviruses.
    Transfected genes include the master
    transcriptional regulators Oct-3/4 (Pouf51) and
    Sox2.

29
  • After 34 weeks, small numbers of transfected
    cells begin to become morphologically and
    biochemically similar to pluripotent stem cells..

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31
Reducing agents inducing neuron-like morphology
(neurogenesis?)
2.5 h in serum-free medium
2.5 h with 0.1 mM dithioerythritol in serum-free
media
32
Stem Cell Therapy
  • Define the problem.
  • Researchers want to replace dead dopamine
    neurons with healthy ones

33
  • Finding The Right Type of Stem Cell.
  • Blastocyst stem cells?
  • At the time, unable to differentiate into
    neurons
  • Fetal stem cells? Excellent candidates, ethical
    problems
  • Adult stem cells? Hard to get, too little known

34
  • Match The Stem Cell With The Recipient.
  • Needs a good immunonlogical match.
  • Researchers knew that immune responses are muted
    in the brain. They predicted that fetal tissue
    would not trigger an intense immune response in
    the recipient.

35
  • Put The Stem Cells In The Right Place.
  • Surgical procedure usually required.
  • Small holes drilled in the skull, cells injected
    with a needle.

36
  • Make The Transplanted Stem Cells Perform.
  • There was no guarantee that the transplanted
    cells would behave. If they did not respond to
    the proper signals from their environment, they
    might have malfunctioned, formed tumors or died.

37
The treatment was partly successful. The
implanted cells survived and produced dopamine,
some patients reported a lessening in the
severity of their symptoms. Others experienced
severe side effects such as involuntary muscle
twitching and jerking.
He's even willing to have surgeons open his head
and transplant stem cells that might just might
give him a better life. Stobbe's plight
begins to describe the desperation of people who
suffer from Parkinson's, cancer, diabetes, heart
disease and other debilitating illnesses that
stem cells might one day cure.
Rodney Stobbe
38
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39
Why Study ES Cells
- what leads to cell specialization? - immune
rejection - tumor formation
40
Stem Cells And Down Syndrome
- window to early brain development - identify
critical genes - development of new drugs or gene
therapy
41
Rat bone marrow stem cells
42
Feline bone marrow stem cells
43
5/19/05
44
Current Research
Spinal Cord
Diabetes
Nerve Cells
Development
Heart Disease
Down Syndrome
Adult Stem Cells
45
  • New Jaw Bone from Stem Cells
  • Tissue Stem Cell Turning Into Tumor Stem Cell
  • Surgeons Transplant New Trachea Into Child Using
    His Own Stem Cells to Rebuild Airway
  • Wide Variety of Genetic Splicing in Embryonic
    Stem Cells Identified
  • Hormone Sensitivity of Breast Stem Cells Presents
    Drug Target

46
Stem Cell Information
NIH Stem cell Information
Embryonic Stem Cells at Wisconsin
American Association For the Advancement of
Science
Genetic Science Learning Center
47
10/05 Update
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