Stem Cell Research

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Stem Cell Research
Jacques Mistrot M.D.
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Can we vs. Should we?

• Dramatic advances of modern molecular biology and
  genetics will continue at an accelerating pace
• We must ask the morality questions before
  attempting the can we questions?
• We must not commit moral evil to produce moral
  good

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• Humanitys moral capacity has not kept pace
  with its technological skill . . . contemporary
  society is truly ill.
• Joseph Cardinal Ratzinger,
• October 24, 2004.

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Stem Cell/Cloning Topics

• What are stem cells?
• Possible uses of the technology
• Current status/knowledge
• Questions and known problems
• Ethics, morality and Church teaching

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Stem Cell Definition

• Self renewable a cell that has the ability to
  continuously divide
• Pluripotent ability to develop into several
  different kinds of cells/tissues
• Repair ability to return function to damaged
  cells in the living organism

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Kinds of Stem Cells
Totipotent
Pluripotent
Multipotent
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Stages of Embryogenesis
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Derivation and Use of Embryonic Stem Cell Lines
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ESCs Differentiate Into Different Tissue Types
(Tumors)
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Possible Uses of Stem Cell Technology

• Repair of defective cell types (Type 1 diabetes,
  Parkinsons disease, heart disease, nerve damage)
• Replace tissues/organs?
• Study of embryology and diseases
• Development of new drugs

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Embryonic Stem Cells (ESCs) vs. Adult Stem
Cells (ASCs)
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Sources of ESCs

• Excess embryos from In Vitro Fertilization
• Therapeutic Cloning
• Induced pluripotent stem cells - iPS

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In Vitro Fertilization

• Combination of sperm and eggs in the laboratory
  to produce a zygote (embryo)
• Multiple embryos are produced
• Embryos are grown in the laboratory until they
  reach the 6-10 cell stage (day 2-3)
• Embryos are implanted (usually 3-4) in the
  mothers uterus
• Excess embryos are frozen for possible later use

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Conceptualization of Therapeutic Cloning
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Cloned Embryonic Stem Cells Advantages/Problems

• Advantages
• Minimal rejection (patients own DNA)
• Problems
• Only 25 of clones became embryos
• Only 5 of embryos survived to become a cell line
• 1 success rate (animals)
• Embryo destroyed

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Therapeutic vs. Reproductive Cloning

• SCNT Somatic Cell Nuclear Transfer
• The technique of nuclear transfer to a
  de-nucleated egg cell is the same for either type
  of cloning
• The difference is the destination of the newly
  formed human life (embryo)
• Implantation (reproductive) vs. Destruction
  (therapeutic)

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Therapeutic vs. Reproductive Cloning

• Once therapeutic cloning is legalized who
  will stop implantation ?
• Genetic enhancement could be around the corner
  once reproductive cloning is legalized
  athletes, geniuses

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Claims for ESCs UnsubstantiatedCurrent and
potential problems for ESCs

• No current clinical treatments in humans
• -Geron Corporation
• Few therapy successes in animal models
• Difficulties in obtaining pure cultures in vitro
• Questions regarding what tissues they will
  develop into
• Problems of immune rejection (foreign DNA)
• Potential for tumor formation and destruction of
  normal tissue into which they are implanted
• Ethically contentious when source is destroyed
  IVF or cloned embryos

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Early Successes Adult Stem Cells

• Human bone marrow stem cells (when exposed to
  various growth factors) turned on genes found in
  bone, cartilage, fat, muscle, blood, endothelial,
  nerve and liver cells.
• Amnionic fluid stem cells recently shown to have
  similar traits to ESCs with less chance of
  rejection.
• Umbilical cord blood promises to replace bone
  marrow as a source of stem cells with less chance
  of rejection.

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Adult Stem Cells

• Adult stem cells have been isolated from
• amniotic fluid heart
• peripheral blood cartilage
• umbilical cord blood thymus
• placenta dental pulp
• brain tissue adipose tissue
• muscle cornea
• salivary gland pancreas
• tendon liver
• skin nasal mucosa

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Ample Evidence that Adult Stem Cells show
Pluripotent Capacity

• Adult stem cells from bone marrow can form new
  neurons in the human brain. Proceedings of the
  National Academy of Sciences USA 100, 1364-1369,
  4 Feb 2003.
• Transplantation of adult bone marrow stem cells
  can repair patients hearts. The Lancet 361,
  45-46, 4 Jan 2003.
• Adult stem cells from bone marrow can form all
  body tissues. Nature 418, 41-49, 4 July 2002.
• Patients receiving adult bone marrow stem cell
  transplant stem cells also formed liver, skin,
  digestive tract. NEJM 346, 738-746, 7 March
  2002.
• A single adult mouse bone marrow stem cell can
  form functional marrow, blood cells, liver, lung,
  gastrointestinal tract, skin, heart and skeletal
  muscle. Cell 105, 369-377, 4 May 2001.
• Adult stem cells from brain can grow into a wide
  variety of organs heart, lung, intestine,
  kidney, liver, nervous system, muscle, and other
  tissues. Science 288, 1660-1663, 2 June 2000.

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Current Clinical Uses of Adult Stem Cells

• Cancers Lymphoma, leukemias, breast, renal,
  ovarian, etc.
• Autoimmune diseases multiple sclerosis,
  systemic lupus, rheumatoid arthritis, etc.
• Anemias (incl. sickle cell anemia)
• Immunodeficiencies including human gene therapy
• Bone/cartilage deformities children with
  osteogenic imperfecta
• Corneal scarring generation of new corneas to
  restore sight
• Repairing cardiac tissue after heart attack
  bone marrow or muscle stem cells from patient
• Parkinsons retinal, nasal or neural stem cells
• Growth of new blood vessels to prevent gangrene
• Gastrointestinal lining regenerate ulcerous
  tissue
• Skin grafts grown from hair follicle stem cells
  burns, etc.
• Wound healing bone marrow stem cells stimulate
  skin healing
• Spinal cord injury clinical trials currently in
  Portugal, Italy, S. Korea

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Current Uses of Stem Cells

• Adult Stem Cells ESC
• Retinoblastoma None
• Ovarian Cancer
• Merkel Cell Cancer
• Testicular Cancer
• Lymphoma
• Acute Lymphobolastic Leukemia
• Acute Myelogenous Leukemia
• Chronic Myelogenous Leukemia
• Juvenile Myelomonocytic Leukemia
• Angioimmunoblastic Lymphadenopathy
• with Dysproteinemia
• Multiple Myeloma
• Myelodysplasia
• Breast Cancer
• Neuroblastoma
• Non-Hodgkin's Lymphoma
• Hodgkin's Lymphoma

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Current Uses of Stem Cells

• Adult Stem Cells ESC
• Soft Tissue Sarcoma None
• Scleromyxedema
• Multiple Sclerosis
• Crohn's Disease
• Rheumatoid Arthritis
• Juvenile Arthritis
• Systemic Lupus
• Polychondritis
• Systemic Vasculitis
• Sjogren's Syndrome
• Behcet's Disease
• Myasthenia
• Red Cell Aplasia
• Autoimmune Cytopenia
• X-Linked Lymphoproliferative Syndrome
• X-Linked Hyperimmunoglobuline-M Syndrome
• Severe Combined Immunodeficiency Syndrome-X1

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Current Uses of Stem Cells

• Adult Stem Cells ESC
• Waldenstrom's Macroglobulinemia None
• Aplastic Anemia
• Amegakaryocytic Thrombocytopenia
• Chronic Epstein-Barr Infection
• Fanconi's Anemia
• Diamond Blackfan Anemia
• Thalassemia
• Stroke
• Osteogenesis Imperfecta
• Sandhoff Disease
• Corneal Regeneration
• Hemophagocytic Lymphohistiocytosis
• Primary Amyloidosis
• Limb Gangrene
• Surface Wound Healing
• Heart Damage
• Parkinson's Disease

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Adult Stem Cells Problems

• Found in small numbers in most tissues except
  bone marrow, placenta, amnionic fluid and cord
  blood
• Grow slowly in tissue culture
• OCT4, NANOG genes (2005)
• NASA micro-gravity growth technique (2005)
• Growth factor cocktail 10x increase (2006)
• Amnionic fluid cells grow rapidly

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Adult Stem Cells Advantages

• Promising source of treatment
• Able to generate virtually all adult tissues
• Can multiply almost indefinitely, providing
  numbers sufficient for clinical treatments
• Proven success in laboratory culture
• Proven success in animal models of disease
• Proven success in current clinical treatments
• Ability to home in on damage
• Avoid problems with tumor formation
• Avoid problems with transplant rejection (same
  person donor or good tissue-match)
• Avoid ethical dilemma

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Moral and Ethical Considerations of Stem Cell and
Cloning Research

• Adult stem cells
• None
• Cloned embryonic stem cells
• Embryo destroyed
• Reproductive cloning is a possible result
• Embryonic stem cells from IVF
• Embryo must be destroyed
• Defense of embryo destruction is based on embryos
  not being persons utilitarian philosophy

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Right to Life

• The Declaration of Independence of the United
  States guarantees certain unalienable Rights,
  that among those are Life, Liberty and the
  pursuit of Happiness

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When Does Human Life Begin? Medical Embryology
Textbooks

• The Developing Human Clinically Oriented
  Embryology
• Zygote this cell results from the union of an
  oocyte and a sperm. A zygote is the beginning of
  a new human being (i.e., an embryo). Human
  development begins at fertilization This highly
  specialized, totipotent cell marks the beginning
  of each of us as a unique individual.

Moore and Persaud The Developing Human.
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Personhood
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Common Definitions of Personhood

• Functional -
• Self-consciousness
• Capacity to reason
• Capacity to communicate
• Potentiality-
• Arguments For Using Embryos
• Utility -
• Size -

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Embryo Is Not a Person

• Personality definition problems
• What traits define personhood?
• Who makes the definition?
• Society has excluded certain humans from
  personhood before (e.g., African slaves, Jews,
  etc.) Should we make a new list of human
  non-persons?

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PersonhoodFunctional Embryo Is Not a Person.
. .

• Persons . . . are members of a social community
  that shapes and values them, and personhood must
  be defined in terms of interactions and
  relationships with others.
• Susan Sherwin. 1999. Ethical Issues Perspectives
  for Canadians. Ed. Soifer, Eldon. Peterborough,
  Ontario Broadview Press, p. 267

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PersonhoodFunctional

• The lack of certain functional personality traits
  would remove from personhood
• Those who are in a coma
• Elderly with degenerative disorders (Alzheimer's,
  etc.)
• Most children under 3 years old
• Mentally deficient
• Is is okay to consider these human beings as
  non-persons?

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PersonhoodPotentiality

• Claim
• Embryos are only potential life because most do
  not result in births in nature
• Science estimates
• Only 1/3 of natural embryos implant
• Once implanted only 2/3 embryos survive to birth
  80 lost

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Potential Life

• Nature takes life in many ways
• a Tsunami may take thousands of lives
• Because life is lost through natural means is not
  the same thing as taking those lives by intent!
• To destroy an embryo because it is only potential
  life in nature is also not justified

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UtilityFrozen embryos are going to be
discarded anyway and should be used for research
to help mankind

• Utility dictates the sacrifice of some for the
  benefit of others
• Always arbitrary usually strong vs weak
• Nazi experimentation was utilitarian
• Prisoners on death row are also going to die, so
  why not do research on them?

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SizeJust a small ball of cells

• Does size defines humanness?
• Is a teenager more human than an infant because
  of size?
• Is a basketball player more human than a dwarf?

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The Human Embryo

• Biologically a human being
• An integral being a self-sustaining
• organism
• Retains the same genetic identity
• through all subsequent stages of
• development
• -from embryo to death!
• Once, we all looked just like this!

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Catholic Church Teachings
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Is the Catholic Church opposed to all stem cell
research?

• The Church is not opposed to research involving
  adult stem cells, normally obtained from adult
  tissue, umbilical cord blood, placenta and other
  sources that pose no moral problem.

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Why is the Church opposed to stem cell research
using the embryo?

• Because harvesting these stem cells kills the
  living human embryo.
• The Church opposes the direct destruction of
  innocent human life for any purpose, including
  research.

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Is the human embryo a person?

• By person the Church means an individual human
  being endowed with a rational and immortal human
  soul.
• Does the embryo have an immortal soul from the
  moment of conception?

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Donum Vitae, I.1

• The conclusions of science regarding the human
  embryo provide a valuable indication for
  discerning a personal presence at the moment of
  this first appearance of human life how could a
  human individual not be a human person?
• CONGREGATION FOR THE DOCTRINE OF THE FAITH   

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• Reason tells us that by virtue of the fact that
  the embryo is a human being, it should be
  accorded all the respect of a human person.
• The Church teaches us that we should treat the
  embryo, from the moment of conception as if it
  were a human person.

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Is the Church telling us to choose the lives of
embryos over the lives of suffering patients?

• No. We are called to respect both, without
  discrimination . . .
• We must help those who are suffering, but we may
  not use an evil means to justify a good end.

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Non Embryo-Destructive Methods To Produce
Embryonic-Like Stem Cells
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Could ES cells be generated without the
destruction of embryos?
YES

• Controlled nuclear reprogramming of adult cells

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Nuclear Reprogramming

• Biological rationale
• The DNA sequence of most somatic cells (the
  cells that make up the adult organism) is
  completely identical to that of the embryo.
• During development, no new DNA is added to our
  cells
• Cell identity is determined by which of the
  30,000 genes are on or off.

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Cloning reprogramming

• Factors in the cytoplasm of the oocyte reprogram
  the transplanted somatic nucleus to become like
  the nucleus of an embryo.
• Adult genes are shut off and embryonic genes are
  switched on.
• The nucleus of the adult cell is being
  reprogrammed.

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Could an adult somatic cell be reprogrammed to
become a pluripotent cell, rather than an embryo?

• Yes!
• If ES cells are fused to somatic cells, adult
  genes are shut off and pluripotent genes are
  turned on in the somatic cell.

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• Embryonic stem cell
• Green genes on
• Red genes off

Hybrid cell with 2 nuclei
Nuclei fuse
Problem Hybrid cell has genes from both cells
-gt Immune mismatch

• Stable hybrid
• Green genes on
• Red genes off

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• Reprogramming genes -
• OCT 4
• SOX2
• NANOG
• LIN28

Pluripotent stem cell
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Practical Scenario

• Patient has diabetes.
• A skin biopsy is used to establish a culture of
  growing skin fibroblasts from the patient (no
  immune rejection possible).
• The skin cells are manipulated with a cocktail of
  factors that result in nuclear reprogramming and
  establishment of a pluripotent stem cell.
• The cells are expanded to a large quantity and
  then differentiated into insulin secreting
  pancreatic beta-cells.
• The beta-cells are harvested and transplanted
  into the liver of the patient where they produce
  insulin, thereby curing the diabetes.

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Nuclear Reprogramming

• Has been done successfully in the mouse and human
• Chance for eventual therapeutic success in humans
  is good.
• Technology is much easier/cheaper.
• Egg donors not needed.
• Ethical considerations appear sound.

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Thank You
jmistrot_at_nc.rr.com www.catholic-bioethics-nc.org