Stem Cells and Animal Cloning

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

1. Produce specialized descendants
2. Retain ability to reproduce themselves

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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.

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

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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)

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pluripotent Blood Stem Cell gives rise to many
different cell types
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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

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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)

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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
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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
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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

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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

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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?

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Cardiomyocyte differentiated from human embryonic
stem cells.
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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?

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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

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Animal CloningSpecies that have been cloned

• Cattle
• Goats
• Pigs
• Cat (CC the Copy Cat)
• Sheep (Dolly)
• Deer (Dewey)

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Methods used to clone animals

• Nuclear transfer (SCNT)

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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?

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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
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• Source of Nucleus is important
• Embryonic stem cells unprogrammed cloning
  blindly
• Adult cells programmed
• know the characteristics
• shop before you buy

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

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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/

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Reproductive Cloning When cloning results in an
organism
Gizmo and Little Gizmo
Mango and Peaches
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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?

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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

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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.