Stem Cells (SCs) are relatively unspecialized cells that can reproduce themselves and also produce the more specialized cells and tissues of the body

Embryonic Stem Cells (ESCs) are obtained from embryos at the very beginning of human life.

• ESCs are generalized (pluripotent,) and grow into all the tissue and organs of the body.
• ESCs are presumed, by many, to offer the most promise for developing therapies to cure diseases.
• ESCs are obtained by a protocol which destroys the human embryo which is a human life.
• ESCs have to overcome rejection because their genetic structure differs from that of the patient.
• ESCs used in therapies have no demonstrated track record of success. (ESCs have treated NO human patients.)

Adult Stem Cells (ASCs) are present in the fully formed human body.

• ASCs are generally more specific and grow into narrower ranges of tissue and organs in the body.
• ASCs are presumed, by many, to offer less promise for developing therapies to cure diseases.
• ASCs are obtained by protocols that do not destroy human life.
  ASCs taken from the patient are genetically identical to the patient and do not encounter rejection.
• ASCs have been shown in recent studies to be far more versatile and useful than previously imagined.
• ASCs used in therapies have established a strong track record of success.

Readily available umbilical Cord Blood Stem Cells (CBSCs), have been employed in the treatment of  67 diseases. With CBSCs rejection is less of an issue even without a genetic match. Furthermore, CBSCs are pluripotent (can turn into any cell type in the body). Other readily available ASCs have been employed in the treatment of over 58 diseases.

Nevertheless, scientists are looking for ethical ways to obtain ESCs without destroying human life.
Four recent proposals are:

1. Derive SCs from technically dead embryos.
2. Extract SCs from embryos using a non-lethal biopsy protocol.
   Derive SCs from specially engineered tissue, that grows only tissue, and is not an actual embryo.
3. Derive generalized (pluripotent,) cells by regressing ASCs to earlier more generalized cells.

All four of these proposals are theoretical in humans. No ethical problem is presented by testing these protocols with animals.

The ethical status of any of these proposals will depend on the details of the actual protocol proposed. Any procedure that destroys or desecrates human life will be unethical. 

Cloning is a protocol that removes the nucleus of a human egg, replaces it with the nucleus of an adult somatic cell, and stimulates the new cell to begin embryonic development, thereby creating a clone of the original adult.

Andrew D. Cannon is a consultant at The Culture of Life Foundation. He holds an MA in Moral Theology and is working on a PhD at Catholic University of America.