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Stem Cells

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Stem Cells * * * * * * * * * * * * * * * * The Stem Cell Concept A stem cell is an undifferentiated, dividing cell that gives rise to a daughter cell like itself and ... – PowerPoint PPT presentation

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Title: Stem Cells


1
Stem Cells
2
The Stem Cell Concept
A stem cell is an undifferentiated, dividing cell
that gives rise to a daughter cell like itself
and a daughter cell that becomes a specialized
cell type.
3
What Is a Stem Cell?
  • Unspecialized cells
  • Give rise to more than 225 specialized cells in
    the body
  • Serve as the bodys repair system
  • Renew itself
  • Replenish other cells

4
In Summary Two Major Types of SC
Mature Stem Cells Early Stem Cells
a.k.a. Adult (includes umbilical cord placenta) a.k.a. Embryonic blastocystic
Cells obtained from specific mature body tissues, umbilical cord, placenta Cells obtained from inner cell mass of a blastocyst
Multipotent Give rise to multiple but limited cell types Pluripotent Flexible, give rise to any cell type in the body
5
What Are the Sources of Mature Stem Cells?
Mature Body Tissues
6
Stem Cells are Found in the Adult, but the Most
Promising Types of Stem Cells for Therapy are
Embryonic Stem Cells
7
Where Are Early Stem Cells Found?
  • Who did it first?
  • In 1998, U. Wisconsin research team isolates
    stem cells from IVF-blastocysts

5 days of development
8
The Inner Cell Mass is the Source of Embryonic
Stem Cells
The embryo is destroyed by separating it into
individual cells for the collection of ICM cells.
9
How Big Is a Blastocyst?
10
What Are the Characteristics?
  • Early stem cells are pluripotent
  • Retain the special ability to develop into nearly
    any cell type
  • teratoma

11
Teratoma
12
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13
Additional Potential Dilemmas Therapeutic
Cloning to Obtain Matched Embryonic Stem Cells
Cells from any source other than you or an
identical twin present the problem of rejection.
If so, how can matched embryonic stem cells be
obtained?
A cloned embryo of a person can be made, and
embryonic stem cells harvested from these clones.
14
Some Thorny Ethical Questions
Are these masses of cells a human?
Is it ethical to harvest embryonic stem cells
from the extra embryos created during in vitro
fertilization?
15
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16
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17
Somatic Cell Nuclear Transfer (SCNT)
  • Sometimes referred to as
  • therapeutic cloning

18
SCNT Asexual Reproduction
  • No sperm involved
  • Transfers nucleus from a mature cell into a
    donor egg
  • Requires electric or chemical stimulus to begin
    dividing
  • Functionally different from regular fertilized
    egg

19
What Should You Know About SCNT?
  • Purpose
  • Find cures and therapies for diseases
  • Awaken the natural capacity for self-repair that
    resides in our genes
  • Potential Results
  • Patients will receive own stem cells to treat
    disease
  • No need for donor match
  • Like transplantation, but without rejection

20
How Would SCNT Treat Disease?
21
What Should You Know About SCNT?
  • No reputable scientist wants to clone human
    beings
  • SCNT stem cells are alive in a Petri dish
  • Unless implanted in uterus, you can not generate
    a fetus
  • Evidence suggests that SCNT stem cells may never
    develop into a human even when implanted

22
The Biotechnology of Reproductive Cloning
Even under the best of circumstances, the current
technology of cloning is very inefficient.
Cloning provides the most direct demonstration
that all cells of an individual share a common
genetic blueprint.
23
Therapeutic Cloning
Is there any ethical difference between
therapeutic and reproductive cloning?
24
The Next Step?
Highly unlikely.
Attempts at human cloning are viewed very
unfavorably in the scientific community.
25
  • http//learn.genetics.utah.edu/units/cloning/click
    andclone/

26
Both Kinds of SCR are Needed
Mature Stem Cells Early Stem Cells
First isolated in 1960s First isolated in 1998
50 years of research 9 years of research
Federal Funding gt2.7 Billion (FY02-06) Federal Funding 132 Million (FY02-06)
Results 50 human therapies Results Only in animal trials No human trials
27
What Are the Current State Restrictions?
28
Which States Currently Support ESCR?
29
  • http//www.pbs.org/wgbh/nova/sciencenow/3209/04.ht
    ml
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