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Xenotransplantation and its Associated Safety and Ethical Issues

Mary E. White-Scharf. Vice President of Research, Biotransplant, Inc.

Glossary: endogenous

Xenotransplantation, Safety and Ethical Issues

  • Xenotransplantation: Transplantation of tissue from one species to another
  • Allotransplantation: Transplantation of tissue from one individual to another within a given species

Types of Xenotransplantation

  • Cell Transplants
    Fetal neural
  • Ex vivo Organ Assist
  • Solid Organ Transplants

Non-human Primates as Donors

Breeding Issues

  • Long gestation period
  • Single births
  • Lack of controlled environment

Ethical Issues

  • Non-human primates are genetically more closely related to humans

Potential Health Risks

Regulatory Update

  • FDA Issued Guidelines for Comments in April 1999: Guidance for Industry – Public Health Issues Posed by the Use of Non-human Primate Xenografts in Humans”

    Non-human primate donors for xenotransplantation cannot be proposed for clinical use until scientific research and evaluation can identify risks associated with such transplant protocols.

Pigs as Organ Donors

Breeding Issues

  • Short gestation period
  • Born in litters
  • Barrier facilities established

Ethical Issues

  • Over 93 million pigs per year in the US are slaughtered for food

Potential Health Risks

  • Exogenous viruses: eliminated by raising in barrier facilities
  • Endogenous retroviruses: no pathogens identified

Advantage of Inbred Miniature Swine

  • MHC Inbred and Recombinant Lines are Available
  • Twenty-five Years of Breeding and Medical History
  • Physiology Similar to that of Humans
  • Transplantation Technology Available Including Species Specific Cytokines and Antibody Reagents
  • Model Consistent with Clinical Findings

Scientific Issues Associated with Xenotransplantation

Two Major Hurdles

  • Humans have naturally occurring antibodies which react with carbohydrates on the surface of pig cells
  • The human immune response to xenogeneic tissue is very strong and difficult to manage

Major Scientific Approaches to Achieving Xenotransplantation

  • Develop Specific Immune Tolerance
  • Genetically Engineer Pigs

Ethical Issues Associated with Xenotransplantation

Potential Health Risks

  • Risks to the Patient
  • Risks to Society

Risks to the Patient

  • Allotransplants
    HIV, Hepatitis, CMV
  • Xenotransplants
    PERVs, unknown viruses

Risks to Society

  • Potential for Recombination Among Pig and Human Retroviruses to Form Pathogenic, Infectious Strains
  • Potential for Emergence of Unknown Zoonosis

What Can Be Done to Manage Risks?

  • Identify and Characterize PERVs
  • Develop Assays to Monitor Infection
  • Acquire and Test Samples
    From individuals with long-term exposure to pigs or pig products, such as pig farmers
    From burn patients who had pig skin transplants
  • Perform Carefully Controlled and Well Monitored Clinical Studies in a Limited Number of Individuals

Email link | Feedback | Contributed by: Boston University. Video adapted from the Issues for the Millennium Workshop

Xenotransplantation and its Associated Safety and Ethical Issues

Introduction: Jensine Andresen and Robert Neville
John Westling - Introduction: Do we have dominion over ourselves?
Overcoming Preconception Relating to Assisted Reproductive Technologies
Implications of Animal Cloning Experiments for the Potential Cloning of Human Beings
Production of Embryonic Stem Cells from Differentiated Somatic Cells
Application of Cloning to the Production of Biopharmaceuticals to Treat Human and Animal Disease
Excluding Life from Patenting: Arguments against the Patenting of Genes
Science Panel Discussion
Ethical Challenges in a Post Genome Era
Human Rights and the New Genetics
Human Rights and Cloning
Democratizing Decision Making Relating to Biotechnology
Genetics, the Market, and Policy
Much Ado About Mutton: An Ethical Review of the Cloning Controversy
Why Worry about Human Cloning?
Modified Natural-Law Approach to Genetic Technologies
Ethics Panel Discussion
The World is Our Parish...So...?
Re-engineering Creation: Theological Reservations Concerning Genetic Technology
Possible Presbyterian Responses to Cloning
Biostewardish Updates
No, Not Yet, Maybe, and Why Not: Protestant Ambivalence Or Moral Discretion?
Beginning Reflections of One Unitarian Universalist on Cloning and Genetic Technologies
A Catholic Perspective on Cloning and Stem Cell Research
Created in Whose Image and Likeness? An Orthodox Christian Approach to Human Cloning
Thomas Shannon - "Playing God"
But Who Speaks for Me? The Need for the Religous Voice in Bioethics
In God's Garden: Creation and Cloning in Jewish Thought
A Jewish Perspective on Cloning and Other Techniques to Overcome Infertility
Islamic Perspectives on Cloning and Genetic Enginerring
A Hindu View based on Dharma, Karma and Yoga of Human Cloning and Genetic Technologies
The Bioethics of Interdependence: Shin Buddhist Attitudes on Human Cloning
Moral Imagination
Interreligious Panel Discussion
Science and the Courts
Beyond Biology: Regulating Ownership in a Knowledge-based Economy
Biotechnology and International Trade
Disharmonization in Agricultural Biotechnology
Historical Notes Relating to the Patenting of Biological Inventions
Should Morality be Within the Purview of Patent Law?
The International Treatment of Biotechnological Intellectual Property (BIP)
Legal Issues Panel Discussion
Science, Politics and Ethics of Cloning and Genetic Engineering: Who will Decide the Future of Humankind?
Cloning and Beyond: Making Laws for Making Babies
Issues For the Millennium: Cloning and Genetic Technologies - Index


Boston University

See also:

Pain and Suffering
Books on Biology, Genetics and Theology
Dolly the Cloned Sheep
Egg Manipulation
DNA Double-Helix