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Stem Cells and Animal Cloning

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Stem Cell Therapy Most stem cell therapies are in the ... different cells express different subsets of genes Somatic cells Germ line cells Totipotency Capability of ... – PowerPoint PPT presentation

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Title: Stem Cells and Animal Cloning


1
Stem Cells and Animal Cloning
2
5. Stem Cell Research
1. Human Genome Project
2. Genetic Testing
6. Animal Cloning
3. Genetic Engineering
4. ARTs
3
Stem cells are essentially undifferentiated
cells They can become many different kinds of
cells
4
A stem cell must be able to do the following
  1. Produce specialized descendants
  2. Retain ability to reproduce themselves

5
Two Classes of Stem Cells
  • Totipotent stem cells
  • Give rise to all cell types
  • Embryonic Stem Cells derived from the inner cell
    mass of the blastocyst.
  • Cannot give rise to an individual organism
  • pluripotent stem cells
  • Give rise to several specialized cell types
  • Adult Stem cells
  • Adult Stem cells are used by the body to repair
    and regenerate damaged organs and tissues
    throughout life.

6
From where stem cells are isolated
7
  • All adult cells including adult stem cells come
  • from one of 3
  • cell lineages
  • Endoderm
  • Ectoderm
  • Mesoderm

8
Adult Stem Cells
  1. Blood Stem Cells Hematopoietic cells are found
    in the bone marrow and give rise to all red and
    white blood cells
  2. Mesenchymal Cells give rise to new bone,
    cartilage, and connective tissue
  3. Neuronal Stem Cells nervous system tissue
    (mostly produced during embryonic development)

9
pluripotent Blood Stem Cell gives rise to many
different cell types
10
Adult Tissues and Organs Known To Have Stem Cells
  • Brain can become 3 kinds of nerve cells and even
    some blood cells
  • Skin replace all types of skin cells
  • Bone Marrow Blood, bone and cartilage
  • Endothelium Blood vessels and cardiomyocytes
  • Skeletal Muscle muscle growth
  • Digestive System Epithelial lining of the gut
  • Pancreas pancreatic ß cells
  • Liver stem cells from bone marrow may repair the
    liver

11
The Promise of Adult Stem Cells
  • Advantages
  • Can be used to cure some diseases
  • Directed differentiation possible
  • If isolated from the same patient, no tissue
    rejection issues
  • No ethical issues
  • Disadvantages
  • Limited use
  • Currently difficult to isolate (except for bone
    marrow)

12
Growing Body Parts From Cell Cultures
  • Biojewellry Wedding rings grown from each others
    bones!
  • http//www.biojewelry.co.uk

Bone cell culture from a cow, inlaid with silver
13
In contrast, embryonic stem (ES) cells are not
limited in their potential to become every cell
type. It is the versatility of these cells that
gives them the potential to have more therapeutic
applications than adult stem cells
14
Stem Cells
  • Embryonic stem cells are the precursors to all
    more specialized stem cells
  • They are found in the inner cell mass of the
    blastocyst
  • 1998 the first culture of embryonic stem cells
    maintained in the laboratory

15
Biology of Embryonic Stem Cells
  • Blastocyst is made of the trophoblast and the
    inner cell mass
  • There is no way to remove the ICM without killing
    the embryo
  • Once the ICM is separated from the trophoblast,
    the embryo can no longer develop into a fetus
  • Directed Differentiation
  • Requires the trophoblast
  • Otherwise, the ICM is like a child who has lost
    its way home, with no map to guide them
  • Requires growth factos and hormones to coax cell
    in to becoming specialized tissues

16
Source of Embryonic Stem Cells
  • Obtained from IVF (In Vitro Fertilization)
    clinics
  • Ethical issues
  • Is it ever OK to use human embryos?
  • When is it OK to use human embryos?
  • What is done with all the frozen embryos not used
    for implantation?

17
Cardiomyocyte differentiated from human embryonic
stem cells.
18
Stem Cell Therapy
  • Most stem cell therapies are in the research
    stage with mice and rats
  • Treatments for humans would include
  • Leukemia (using patients bone marrow)
  • Diabetes a cure vs treatment (using patients
    adult stem cells to create a population of cells
    that produce insulin)
  • Cardiovascular disease injecting stem cells into
    the patient
  • Neurological disorders
  • Alzheimers
  • Tay-Sachs
  • Huntingtons Chorea
  • Spinal Chord injuries
  • Parkinsons
  • Organ Factories?

19
Reality Check
  • The problem of immune rejection depends on the
    source of the stem cells
  • Adult Stem Cell therapy
  • Not easy to isolate
  • Unknowns in regard to repair of neural tissue
  • Memory retention
  • Psychology
  • Umbilical Chord Stem Cells (UCS)
  • Can replace bone marrow transplants
  • Successfully used to treat leukemia in humans
  • Growth Factors might also cause cancers
  • Wandering Stem Cells Will stem cells always go
    where they are intended?
  • Stem Cell Cancer Induction

20
Animal CloningSpecies that have been cloned
  • Cattle
  • Goats
  • Pigs
  • Cat (CC the Copy Cat)
  • Sheep (Dolly)
  • Deer (Dewey)

21
Methods used to clone animals
  • Nuclear transfer (SCNT)

22
Somatic Cell Nuclear Transfer (SCNT)
  • First done in 1951 with frogs
  • The mystery of development and differentiation
    from a single endowment of DNA
  • The principle of Nuclear equivalence
  • Nuclei of all cells are genetically identical
  • But, different cells express different subsets of
    genes
  • Somatic cells
  • Germ line cells
  • Totipotency
  • Capability of cells to direct development of
    entire organism
  • Can pre-programmed chromosomes be used for
    cloning whole organisms?

23
Somatic Cell Nuclear Transfer SCNT
  • uses unfertilized eggs
  • nucleus is removed from the egg
  • nucleus from a donor cell is injected

Empty Egg Seeks Nucleus for LTR
24
  • Source of Nucleus is important
  • Embryonic stem cells unprogrammed cloning
    blindly
  • Adult cells programmed
  • know the characteristics
  • shop before you buy

25
How Dolly was made
What happened to Dolly?
26
  • The main problems associated with cloning animals
    from adult cells
  • cloned lambs with immature lungs
  • deformed kidneys
  • hearts with thickened walls and
  • skeletal abnormalities

27
Cloning Pets
  • Reproductive Cloning Cloning to produce an
    individual
  • Genetic Savings and Clone
  • gene banking and cloning of exceptional pets
  • http//www.savingsandclone.com/
  • PerPETuate Inc.
  • http//www.perpetuate.net/

28
Reproductive Cloning When cloning results in an
organism
Gizmo and Little Gizmo
Mango and Peaches
29
Therapeutic Cloning Creating tissues and organs
for individuals
  • Requires a nucleus from YOU and an enucleated egg
    cell (SCNT)
  • Grow embryonic stem cells that are genetically
    identical to the individual. The cells are grown
    into tissue for repair of damaged organs
  • It would create perfect-match tissue. No more
    tissue rejection issues.
  • Is generating a few cloned embryonic cells for
    tissue repair from an adult the same as using a
    zygote from invitro fertilization?

30
Therapeutic Cloning vs. Reproductive Cloning
  • Adult stem cell research (no problem)
  • Embryonic stem cell research
  • IVF embryos
  • Therapeutic cloning
  • Reproductive Cloning is relegated to the cloning
    of non-human animals

31
Those opposed to stem cell research
  • Opposed to the use of Embryonic stem cells
  • Research underway to reprogram adult cells for
    tissue repair so that they can be as versatile as
    ES.
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