A General Review on Stem Cells

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A General Review on Stem Cells

• Yu-Li Liu, Ph.D.

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What is Embryonic Stem Cells?
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Human Development
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Embryonic Stem Cells

• Derived from the inner cell mass of an
  early-stage embryo
• Undifferentiated cells
• Unlike any specific adult cell
• Ability to form any adult cell
• Proliferate indefinitely in culture
• An unlimited source of specific, clinically
  important adult cells
• Bone, muscle, liver, neural, gut, or blood cells

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How long have embryonic stem cells been studied?
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A science and political issue

• 1981 . culture mouse ESCs.
• 1986 . mouse knockout technology.
• 1992 . discovery of embryonic germ (EG) cells.
• 1996 . ESCs made from pigs, cows, rabbits, and
  sheep, from rhesus monkeys and marmosets.
• JULY 1997 . cultured ESCs derived from primordial
  germ cells (taken from aborted
• fetuses) for seven months.
• NOVEMBER 1998 .cultures of ESCs from human
  blastocysts
• MARCH 1999 . FDA (UPDRS), the patient improves
  4050 percent in certain motor tasks, and his
  dopamine uptake increases 62 percent.
• DECEMBER 1999 .Adult stem cells (ASCs), Science
  names stem cell research the Breakthrough of the
  Year.
• JUNE 2000 .ASCs turns skeletal muscle stem cells
  into blood cells.
• AUGUST 2000 . Identify progenitor cells in hair
  follicle in mice.
• OCTOBER 2000 . Nature Neuroscience publishes
  findings that neural ASCs can be directed to
  differentiate into skeletal muscle cells.

• JANUARY 31, 2000 .Stem Cell Research Act of 2000.
• AUGUST 25, 2000 .NIH Guidelines for Research
  Using Human Pluripotent Stem Cells, which permit
  use but not derivation of stem cells from human
  embryos.
• JANUARY 2001 . President George W. Bush takes
  office.
• JANUARY 17, 2001 .Bush receives a letter from 123
  organizations asking him to allow HSC research to
  continue with federal support.
• MARCH 15, 2001 . Deadline for submitting
  applications to the NIH for human ESC research
  projects.
• APRIL 2001 .Stem Cell Research Act of 2001 allow
  federally funded researchers to derive ESCs
  independently.
• APRIL 25, 2001 .Postpone Human Pluripotent Stem
  Cell Review Group (HPSCRG) until NIH guidelines
  have been reviewed.
• JUNE 2001 . Expected announcement of
  reassessments of NIH guidelines regarding funding
  of human pluripotent stem cell research. 

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Embryonic Stem Cells and Embryonic Germ Cells
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Where do human embryonic stem cells come from?
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Human Embryonic Stem Cells

• From in vitro fertilized embryos less than a week
  old
• These embryos were produced for clinical purposes
• No longer wanted for implantation

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Why are they important?
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Importance

• Capability to develop into virtually any other
  cell
• Possibility to grow into medical important organs
• bone marrow, neural tissue or muscle.

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How might they be used to treat disease?
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Applications of Stem Cells

• Growing tissues for transplantation purposes
• Treating disease because of defects in one of
  just a few cells types
• Juvenile onset diabetes mellitus
• Parkinson's disease
• Replacing faulty cells with healthy ones
• Failing hearts and other organs

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Are there other potential uses for these cells?
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Other Potential Applications

• Drug discovery
• New medications could be initially tested using
  human stem cell lines.
• This would not replace testing in whole animals
  and testing in human beings, but it would
  streamline the process of drug development.
• Permit the rapid screening of hundreds of
  thousands of chemicals

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Offer insights into cell development
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Development

• Human development have been difficult or
  impossible to study
• Offer opportunities to study developmental events
  in humans in utero
• Preventing or treating birth defects, infertility
  and pregnancy loss
• Reduce the risk of drug-related birth defects.

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If these cells were transferred to a woman, could
a pregnancy result?
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No !!

• They are not intact embryo
• Fail to implant
• Fail to develop into a fetus

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Is stem cell research the same as cloning?
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Goals in Stem Cell Research

• Develop new life-saving treatments
• Cannot be used to develop a human being
• Embryonic stem cells cannot give rise to a
  placenta, so a human being could not develop,
  even if the stem cells were implanted into a
  woman's uterus

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Why not using stem cells from adults?
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Disadvantages in Adult Stem Cells

• Already specialized
• Regenerate damaged tissue is very limited
• Adults do not have stem cells in many vital organs

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Human tissues harbored adult stem cells

• Skin
• Neurons
• Adipose
• P.A. Zuk et al Multilineage cells from human
  adipose tissue implications for cell-based
  therapies. Tissue Engineering 7211-8 April 2001
• Placenta

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Problems encountered for cell-based therapy
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Technical Problems

• This research is still in its infancy
• How to control the differentiation of stem cells
  so they will be therapeutically effective ?
• Study the potential of immune rejection of the
  cells, and how to overcome that problem

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Stem Cell Therapy

• Therapeutic cloning
• involves growing replacement organs (heart,
  liver, pancreas, skin, etc) from a sample of a
  patients DNA.
• Cellular reprogramming
• Fuse patients DNA with embryonic germ cells

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Does adult stem cell serve less in cell-based
therapy?
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Adult Stem Cells
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Multilineage potential of adult human mesenchymal
stem cells

• M.F. Pittenger, A.M. Mackay, S.C. Beck, R.K.
  Jaiswal, R. Douglas, J.D. Mosca, M.A. Moorman,
  D.W. Simonetti, S. Craig, D.R. Marshak,
  "Multilineage potential of adult human
  mesenchymal stem cells," Science, 284143-7,
  April 2, 1999. (Cited in 145 papers)

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Orlic D. et al. Bone marrow cells regenerate
infarcted myocardium. Nature. 410(6829)701-5,
2001 Apr 5.
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Bone marrow stem cells may repair vital tissues
and organs

• A transplanted bone marrow stem cell can not only
  reconstitute bone marrow, but also may play a
  role in healing these other tissues and organs as
  well.
• D.S. Krause et al. Multi-organ, multi-lineage
  engraftment by a single bone marrow stem cell.
  Cell, 105 369-77 May 4, 2001

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Using mice pancreatic duct to generate
insulin-producing cells

• Ramiya VK. Maraist M. Arfors KE. Schatz DA. Peck
  AB. Cornelius JG. Reversal of insulin-dependent
  diabetes using islets generated in vitro from
  pancreatic stem cells.
• Nature Medicine. 6(3)278-82, 2000 Mar

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How to overcome the immune rejection ?
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Differentiation of Embryonic Stem Cell Lines
Generated from Adult Somatic Cells by Nuclear
Transfer

Teruhiko Wakayama, Viviane Tabar, Ivan Rodriguez,
Anthony C. F. Perry, Lorenz Studer, and Peter
MombaertsScience Apr 27 2001 740-743.
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Somatic Cell Nuclear Transfer
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NT of Embryonic stem cells differentiated into
all kinds of tissues
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Teruhiko Wakayama

• University of Hawaii researcher Teruhiko Wakayama
  holds cloned mice.He is leaving after helping
  develop the Honolulu Technique, which enabled
  the mice to be cloned.
• His studies have utilized microinjection
  techniques to analyze the biology of
  fertilization.

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How far should we go to reach cell-based therapy
?
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Cellular replacement therapies for neurological
disorders

• Human stem cell sources
• Source control
• Eliminate HIV-positive donor
• Records of cell preparation with donors and
  patients
• What record should be kept?
• Who could access to them?
• How long should records be maintained?
• IF tissue origin is not traceable
• Stem cell source qualification
• Should genetic markers be evaluated?
• Are genetic tests sufficient and reliable?
• Source of derivation
• Autologous donation, allogeneic donation,
  embryonic stem cells or embryonic germ cells

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Cellular replacement therapies for neurological
disorders

• Manufacturing of stem cells
• Do stem cells isolation and maintenance
  procedures determine desirable cell fates and
  preclude undesired cell fates?
• Critical manufacturing process controls
• Qualification of sources
• Standard procedures to expand or maintain stem
  cells
• Development of validated tests to monitor the
  stem cell identity and heterogeneity

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Cellular replacement therapies for neurological
disorders

• Characterization of stem cell preparation and
  selection of specifications
• Heterogeneous cell populations
• Essential to intended effect, some deleterious,
  and some inert
• Purity specification
• Markers to identify cell phenotype, determination
  or fate
• Markers necessary to ensure correct functional
  phenotype expression
• Markers to indicate adverse events
• Ectopic tissue differentiation, tumor genesis etc

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Cellular replacement therapies for neurological
disorders

• Potency assays for stem cell products
• Stem cell potency assays
• Assessing intended bioactivity of stem cell
  implants
• Inter-assay variability
• Dosage unit of potency be expected?

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The Fourth US-Taiwan Neuroscience Symposium

• Stem Cells, from cell level to functional
  genomicsSan Diego Convention Center, San Diego,
  CaliforniaNov. 10, 2001 (130 pm to 530 pm)
• A satellite symposium of the 31st annual meeting
  of the Society for Neuroscience of the United
  States

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TBA meeting

• This symposium of Taiwanese Bioscientists of
  America (TBA) highlights recent advances in stem
  cell research, focusing on the functional and
  phenotypic analysis of different stem cells and
  their plasticity for multiple potentialities. The
  symposium program includes four major themes
• (1) neural stem cells,
• (2) mesenchymal stem cells,
• (3) embryonic stem cells, and
• (4) functional genomic analysis.

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TBA meeting

• How stem cells make a brain, and how to find the
  genes they use to do it.  Derek van der Kooy,
  Ph.D. Professor, Cell Biology, University of
  Toronto, Toronto
• Neural stem cells in the adult brain a
  perspective on neuropoiesis.  Dennis A.
  Steindler, Ph.D. Professor, Neuroscience,
  University of Florida, Gainesville, FL
• Neural crest stem cells.  David J. Anderson,
  Ph.D. Professor, Biology, and Howard Hughes
  Investigator, California Institute of Technology,
  Pasadena, CA
• Plasticity of multipotent stem cells from human
  bone marrow.  Catherine M. Verfaillie, M.D.
  Professor, Stem Cell Institute, University of
  Minnesota, Minneapolis, MN
• Mesenchymal stem cells in homeostasis and
  pathogenesis of mature articular cartilage. 
  Martin K. Lotz, M.D. Professor and Head, Division
  of Arthritis Research, Scripps Research
  Institute, La Jolla, CA
• Gene and protein expression with microarray
  technologies.  Edison T. Liu, M.D. Director,
  Singapore Genome Project, Republic of Singapore
• Overview on the functional genomics project in
  Taiwan.  Yuan-Tsong Chen, M.D., Ph.D. Professor
  Chief, Medical Genetics, Duke University Medical
  Center, Durham, NC

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Have a Happy Weekend !!