There are at least three compelling
scientific arguments against the use of embryonic stem cells as a treatment for disease
and injury. First and foremost, there are profound immunological issues associated with putting cells derived from one human being into the body of another. The term "stem cell" is a general one for any cell that has the ability to divide, generating two progeny (or "daughter cells"), one of which is destined to become something new and one of which replaces the original stem cell. These early
embryonic stem cells give rise to all the tissues in the body, and are therefore considered "totipotent" or capable of generating all things. While the existence of early embryonic stem cells has been appreciated for some time, the potential medical applications of these cells have only recently become apparent. Much of the debate surrounding embryonic stem cells has centered on the ethical and moral questions raised by the use of human embryos in medical research.Scientists have proposed large scale genetic engineering of embryonic stem cells to alter their immune characteristics and provide a better match for the patient. Such a manipulation would not be trivial; there is no current evidence that it can be accomplished at all, much less as a safe and routine procedure for every patient.Alternatively, the use of "therapeutic cloning" has been proposed. In this scenario, the genetic information of the original stem cell would be replaced with that of the patient, producing an embryonic copy or "clone" of the patient. This human clone would then be grown as a source of stem cells for transplant. The second
scientific argument against the use of embryonic stem cells is based on what we know about embryology.inal proposed resolution has been to generate a large bank of embryos for use in transplants. This would almost certainly involve the creation of human embryos with specific immune characteristics. Many of the factors required for the correct differentiation of embryonic cells are not chemicals that can be readily "thrown into the bubbling cauldron of our petri dishes." Instead, they are structural or mechanical elements uniquely associated with the complex environment of the embryo. The final argument against using human embryonic stem cells for research is based on sound scientific practice: we simply do not have sufficient evidence from animal studies to warrant a move to human experimentation.Despite the serious limitations to the potential usefulness of embryonic stem cells, the argument in favor of this research would be considerably stronger if there were no viable alternatives.The scientific, ethical, and political advantages of using adult stem cells instead of embryonic ones are significant. Deriving cells from an adult patient’s own tissues entirely circumvents the problem of immune rejection. Adult stem cells do not form teratomas. Therapeutic use of adult stem cells raises very few ethical issues and completely obviates the highly polarized and acrimonious political debate associated with the use of human embryos. The field of stem cell research holds out considerable promise for the treatment of disease and injury, but this promise is not unlimited. There are real, possibly insurmountable, scientific challenges to the use of embryonic stem cells as a medical treatment for disease and injury.