But there has always been concern that these induced cells were not quite as good as cells derived from embryos. Recent research has suggested that some of the changes—and damage—the adult cell endured during its lifetime would remain when it was turned back into a stem cell, potentially triggering cancer.
Egli, a senior research fellow with the New York Stem Cell Foundation, says his new cells can be compared to induced cells, allowing scientists to spot potential problems in the cells. The research was paid for with private funds from the foundation.
Part of the challenge in carrying out nuclear transfer in humans has been the short supply of eggs. In a companion letter also published online today in Cell Stem Cell, Egli, along with Kevin Eggan and Douglas Melton, two stem cell scientists at Harvard, wrote about the difficulty of getting women to donate their eggs. (The process has the potential for serious side effects and can be painful.)
Instead, in a move that would have been illegal in California and Massachusetts, Egli’s team paid women $8,000 to donate their eggs—the same fee they would receive for donating their eggs to someone battling infertility. The women had already agreed to donate their eggs before they were offered the possibility of contributing to research instead of fertility. Several agreed. Once the scientists learned to leave the egg’s chromosomes intact, the remaining two donations led to one stem cell line each, Egli said.
In 2004, Korean scientist Woo Suk Hwang claimed to produce a stem cell line derived from cloning a human embryo. The work was later discredited. Egli says he was able to succeed where others failed by realizing that there was some key reproductive information in the egg’s genome that was missing in the adult skin cells he used.