Dr. Abdullah Aldahmash

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Introduction to Pluripotent Stem Cells

• Dr. Abdullah Aldahmash

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Stem Cell Definition

• A cell which has the ability to continuously
  divide and differentiate into various other kinds
  of cells/tissues

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Classifications of stem cells I
Description Potency
1-3 days, differentiate into embryonic and extraembryonic cell types Totipotent
Descendants of totipotent cells and differentiate into cells of 3 germ layers Pluripotent
Produce cells of a closely related family of cell (e.g. hematopoietic stem cells Multipotent
Differentiate into ONLY a few cells, such as lymphoid or myeloid stem cells Oligopotent
Produce ONLY one cell type (e.g. muscle stem cells) Unipotent
The terminal cell Nullpotent
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Adult stem cells (Tissue Specific Stem Cell)
Found in specific mature body tissues as well as
the umbilical cord and placenta after birth. They
also can be isolated of developing embryos
different tissues
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Embryonic Stem Cell

• Embryonic human stem cells were first isolated in
  1995 by Dr. James Thomson.
• Source of ESC is Blastocysts (IVF, SCNT)

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SCNT

• The aim of this procedure is to obtain stem cells
  that are genetically matched to the donor
  organism.
• Not all of the donor cell's genetic information
  is transferred, as the donor cell's mitochondria
  that contain their own mitochondrial DNA are left
  behind
• The basis of this technique is cloning animals
  (such as the famous Dolly, the sheep).
• The importance of SCNT-based stem cell research
  has been decreased by the development and
  improvement of alternative methods of generating
  stem cells.

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SCNT
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iPS

• It occurs by the introduction of a defined and
  limited set of transcription factors and
  culturing these cells under ES cells conditions.
• A retroviral-mediate introduced to four
  transcription factor (OCT3/4, SOX2, c-MYC, KLF4)
  could induce pluripotency.
• This protocols has been applied to mouse cells
  and human somatic cells.

Nishikawa, S et.al., 2008
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iPS

• Skin cells were taken from the tail tip of a
  sickle-cell model mouse.
• The cells were differentiated into hematopoietic
  cells.
• The produced cells were transfused back into the
  sick mouse

Hanna J. et.al., 2007
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Where are pluripotent Stem Cells derived from?
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Generation of Embryonic Stem Cells (pluripotent
stem cells)
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Criteria for growing stem cells

• Embryonic stem cells can be turned into any other
  type of cell in the body and have potential uses
  in treatments where sick cells need to be
  replaced
• ONE problem, however, is that it is difficult to
  culture and develop human embryonic stem cells
  without simultaneously contaminating them.
• How where they cultured in the beginning of their
  derivation

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Criteria for growing stem cells

• Purpose for growing hESCs
• Maintaining the undifferentiated state.
• Expand and differentiate the cells to larger
  number to be used in clinical application

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Characterization of Human ESCs
SSEA-4
Sox-2
Oct-4
Endoderm
Mesoderm
Ectoderm
Sox9
Beta-III tubulin
Sox17
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Derivation and Use of Embryonic Stem Cell Lines
Inner cells (forms fetus)
Day 5-6 Blastocyst
Special sauce(largely unknown)
Beta-cells
Heart muscle
Neurons
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The Promise of Stem Cell Technology

• Replacement of tissues/organs
• Repair of defective cell types.
• Study cell differentiation
• Toxicity testing.
• Understanding prevention and treatment of birth
  defects.
• Study of development and gene control.
• Study of drugs therapeutic potential.

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current advances in Stem Cells therapy
Tissue engineering
Cell based therapy
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Obstacles of Stem Cell Research

• How to find the right type of stem cells?
• How to put the stem cells into the right place?
• Will the stem cells perform the desired function
  in the body?
• Differentiation protocols for many cell types
  have not been developed.