New technologies like transplantation force society to continually reexamine the value and boundaries of life and death. The procurement of organs from deceased individuals (with their prior permission) to be used for transplantation would appear to be straightforward and ethically uncontroversial. But how do we define "deceased"? Is death an event or a process? Is it when your heart stops? Is it brain death? If so, how do you define "brain death"?

Certain organs need not always come from the deceased. In fact, for reasons of histocompatibility, organs from living donors are often preferred. Usually, these organs are donated by a relative, e.g., a mother donating a kidney to her child, a brother donating bone marrow to his twin, a cousin donating a lobe of her lung to her baby niece. However, living related transplants themselves have come under close scrutiny from the medical and bioethical fields.

Even greater controversy arises when considering the sources that do not or cannot give informed consent to donate their organs. For example, when President Clinton lifted the moratorium on fetal tissue research and transplantation in 1993, he opened the door to huge advances in the treatment of Parkinson's, Alzheimer's, and other neurodegenerative diseases. However, the lifting of the ban came under immediate and intense criticism, bringing the debate over fetal rights and abortion to an unprecedented level.

Today, efforts to develop artificial organs have been largely unsuccessful. While development and use of these devices would no doubt alleviate much of the moral ambiguity of organ procurement, it does not seem likely that this technology will be available (or even affordable) for many years. However, an even more fantastic and terrifying scientific reality has emerged that may forever change the way we think about organ procurement. Advances in the cloning of animals from fetal and adult cells make it likely that someday this technology could be used to make animal donors that are more compatible with human biology. Perhaps, too, cloning could be used to make human tissues or even human organs.

Clearly, the shortage of transplantable organs drives the search for new sources of organs. Yet, will the demand for organs become so overwhelming that society will shift its values? What will be the ultimate social cost of meeting the need of those facing death unless a transplantable organ or tissue can be found for them? As research advances pave the way for new sources of organs, we must carefully weigh the potential alleviation of shortage against the ethical permissibility of using these new sources. One thing is for sure: the demand for transplantable organs must be balanced against a framework of acceptable values. What that framework should be will continue to be the subject of much discussion, debate, and legislative attention...