Retired surgeon Robert Bernhoft’s letter (“Put money where it will do most good,” Oct. 15) offers little medical reality. He claims that adult stem cells can be changed into practically any tissue. In reality, the adult stem cell taken from mature tissue can renew itself but has limited ability to transform into specialized cell types.

Production of large numbers of adult cells is much more difficult than the case for embryonic cells. Based upon present knowledge, it appears unlikely human adult stem cells alone will provide all the necessary cell types required for the most important areas of research.

Adult stem cells are multipotent; the number of tissues that they can regenerate compares poorly with the pluripotency of embryonic stem cells and embryonic germ cells. Adult stem cells are capable of differentiating into bone, cartilage, muscle, fat, and a few other tissue types. Adult-derived stem cell therapies will complement, but cannot replace, therapies that may be eventually obtained from embryonic cells.

The use of embryonic stem cells for therapeutic cloning (SCNT) holds great promise for treating and curing patients by creating tailor-made, genetically identical cells that their bodies won’t reject, eliminating the need for lifelong immunosuppressing drugs. Proof of principle for SCNT has been established in published research (March 2002 issue of “Cell”).

Consider that one in three children born today will develop diabetes and that embryonic stem cell research may find a cure for diabetes. Then contemplate the hopeful 134 million U.S. patients who are currently awaiting stem cell based therapies. Moreover, think of how much money would be saved each year if stem cell research finds cures for diseases like diabetes, Parkinson’s, cardiovascular disease and many others. We must invest in the future of stem cell therapies so that many will have a future.

Pat Kessler

Mukilteo