The world of stem-cell science was rocked Wednesday by news that researchers at Oregon Health & Science University, led by Dr. Shoukhrat Mitalipov, had cloned embryos from rhesus monkeys and derived embryonic stem cells from the clones. Their work was published online in the journal Nature. For those opposed to embryo-destructive research, some might be thinking of yesterday as a kind of “black Wednesday.” I am inclined to disagree. In fact, history may well show us that November 14, 2007, marked a turning point in the battle against embryo-destructive research.
Mitalipov and his team are the first to successfully clone primate embryos. Only several months ago, such a milestone seemed to be facing nearly insurmountable and poorly understood technical obstacles. Mitalipov and his team, by making some simple modifications to the cloning technique, were able to overcome those obstacles, and an independent team of scientists has already experimentally validated Mitalipov’s work.
So, we find ourselves today at a milestone in stem-cell research. You don’t have to be a stem-cell scientist to understand that successful monkey-embryo cloning could pave the way to successful human-embryo cloning. That, of course, is the moral danger here. So called “therapeutic cloning” has long been holy grail of human-embryonic-stem-cell research: clone the sick patient, derive stem cells from the clone that are genetically matched to the patient, coax the stem cells into useful tissues to treat and cure the patient. Embryonic stem cells from a cloned human embryo, because they would be genetically identical to a patient, could be used in potential treatments without prompting an immune rejection response. However, the scientific community generally agrees that prospective treatments from embryonic stem cells are likely many years away.
Moreover, Mitalipov’s work shows that the cloning process is still somewhat inefficient requiring more than 160 eggs to produce just one stem-cell line. Obtaining human eggs for research on human cells opens the door to exploitation of women for their eggs, and exposes women to dangerous health complications from the egg extraction process. Mitalipov’s breakthrough doesn’t overcome the egg hurdle — a moral landmine that most embryonic-stem-cell researchers would prefer to avoid.
Mitalipov has been quoted as saying he would hope that his work at OHSU will profit the work being done with human cells at other labs. But I also have heard him state his moral opposition to human reproductive cloning, as well as his hope that human therapeutic or research cloning could be side-stepped all together. It is apparent to me, however, from many interactions with Dr. Mitalipov in the past months that his own scientific interests lie elsewhere — not in human therapeutic cloning. As he explained to reporters Wednesday, Mitalipov and his team now want to use the technique to create cloned monkeys that carry genes for human diseases, by adding human-disease genes to the skin cells of adult rhesus monkeys before doing the cloning. The result would be cloned monkeys carrying the human disease gene in every one of their cells. They will then be able to study those monkeys to understand and treat the disease — a wonderful and promising upshot from this story that should not be lost on us.
But there is more to the silver lining here. OHSU molecular biologist and Westchester Institute Senior Fellow Dr. Markus Grompe expressed his excitement about Mitalipov’s success for a different reason. His work, stated Grompe, “provides a platform for the scientific investigation of direct cell reprogramming in primates, while avoiding the use of human eggs or human embryos.” Reprogramming is one of the most promising alternative sources of human “pluripotent” stem cells.
In reprogramming (also called de-differentiation) adult-cell nuclei are sent back to a pluripotent state. In other words, the reprogrammed cells would be capable of producing any tissue type in the human body — essentially equivalent in versatility to human embryonic stem cells. Furthermore, reprogramming achieves the same goal as therapeutic cloning: patient-matched tissues. Stem cells resulting from reprogramming would be genetically matched to the person who donated the body cells, and as such would not be rejected by the donor’s immune system. The key difference, of course, is that reprogramming could accomplish this without creating, cloning, damaging or destroying human embryos.
Grompe noted that prior to Mitalipov’s success, it was unclear whether nuclear reprogramming would work at all in a primate species. Grompe cogently noted that if reprogramming had proven impossible, human embryos would have remained the sole source of pluripotent stem-cell lines. Mitalipov’s work now raises the hope that the factors required for direct (no eggs, no embryos involved) reprogramming of primate cells will be discovered very soon, thus obviating the all moral conundrums inherent in human embryonic stem cell research and therapeutic cloning.
Last March, Dr. Grompe, a board member of the International Society for Stem Cell Research, speculated that perhaps as many as 50 labs around the world, and upwards of 200 stem cell researchers are currently pursuing cell reprogramming. He now speculates that the majority of labs doing embryonic-stem-cell research are getting poised to do reprogramming.
Reprogramming will certainly now receive an enormous boost from Miltalipov’s work. Therapeutic cloning is essentially a process of cell reprogramming: the cytoplasm of the egg reprograms the genetic material in the nucleus of the body cell that is fused to the egg during the cloning procedure. If scientists can learn how monkey egg cells reprogram body cells to an embryonic-like state, this could give us the key to reprogramming human body cells without having to damage or destroy, let alone clone, human embryos.
Professor Robert George, McCormick Professor of Jurisprudence at Princeton University and member of the President’s Council on Bioethics said that, on the one hand, he applauds Dr. Mitlipov’s achievement which “if properly used…can advance the cause of science while respecting the ethical norms by which science maintains its integrity and goodness.” On the other hand, George, like so many of us, is concerned that, while Mitalipov’s work is good in itself, it might lead to cloning of human beings who would be destroyed “in a misguided attempt to benefit others.” “And that,” he affirms, “would be a moral and human tragedy.”
– Father Thomas. Berg. L.C. is executive director of the Westchester Institute for Ethics and the Human Person, and member of the ethics committee of New York’s Empire State Stem Cell Board.