What are the New Discoveries?

Human embryonic stem cells (hES cells) are cells that are self-renewing--virtually immortal--and have the capacity to develop into any or all tissue types in the human body. If medical scientists could gain the ability to turn on selected genes to grow selected tissues and organs for transplantation, hES cell-based therapies would revolutionize treatment of degenerative age-related diseases such as Parkinson's disease, diabetes, and congestive heart failure.

Two recent claims of laboratory triumph are relevant. First is the isolation of human embryonic stem cells (hES cells) by James Thomson, an associate veterinarian in the University of Wisconsin's Regional Primate Research Center. Thomson began with fertilized ova--spare embryos from in vitro fertilization (IVF) not placed in a uterus--and cultured them to the blastocyst stage, about four to six days. At this point he removed the outer shell of the blastocyst, separated out the individual cells, and placed them on a feeder tray. The cells divided. They reproduced themselves. Because these cells are as yet undifferentiated--that is, they are pluripotent and able to make any part of a human body--they are the cells from which other cells stem. Because they replicate themselves indefinitely, Thomson in effect created an immortal line of embryonic stem cells.

Second, John Gearhart, a professor of gynecology and obstetrics at Johns Hopkins University School of Medicine, drew human embryonic germ cells (hEG cells) from fetal gonadal tissue. These cells, when taken from an aborted fetus, resemble in nearly all respects the pluripotent stem cells described above.I will provide more detail on the Gearhart discovery in the description that follows.

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