Experiment cracks door to possible human organ source, but some worry what other doors might be opened.
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Work by an international team of scientists has raised hopes for a new source of human organs for transplantation, potentially easing a chronic shortage. But the scientific process the scientists engaged in is fraught with ethical concerns, according to Catholic bioethicists.
The team, consisting of scientists from the United States, China, and Spain, reported last week that they had injected embryos of long-tailed macaque monkeys with human pluripotent stem cells.
STAT, a website reporting on health, medicine, the life sciences and pharmaceuticals, explained that the scientists “injected 25 of a specific kind of human pluripotent stem cell (called ‘pinnacle stem cells’ because they can turn into any kind of cell, including extraembryonic cells such as placenta) into each of 132 6-day-old macaque monkey embryos.” They took advantage of a new technique that allowed them to grow monkey embryos outside the womb for up to 20 days, “a stage where the embryos were still largely undeveloped, but had formed layers and cavities.”
By the 19th day, only three of the chimeric embryos remained alive, the magazine explained. “After 20 days, monkey embryos grown outside the womb, even those that are not chimeric, simply collapse,” it said.
But what the scientists found by that point gave them encouragement: a high number of human cells in the chimeric embryos survived. “On average, 3% to 4% of the cells in the embryos were human, and in one embryo, up to 7% were,” said STAT.
For John F. Brehany, executive vice president of the National Catholic Bioethics Center, one concern is that the moral status of the chimera is vague.
“Do you actually have a human being here or not, based on the nature of the chimera that was created?” he questioned. “Do you have a human being, or do you have an animal with some human qualities or powers?”
Also not clear is the intent or goal of the experiment. “If they said, ‘We want to produce some kind of being that is right on the line between human beings and monkeys — perhaps human enough to be a source of organs for other human beings — so we can routinely harvest organs like hearts and other non-paired organs, that would be wrong, just as a goal,” Brehany said.
“Is it good for us human beings to create some sort of intermediate species, whose sort of nature and moral status is somewhere between us and animals?” he asked. “Is that good for us in our ability to clearly distinguish between human beings and animals and properly respect human beings as distinguished from animals? I think that in itself would be potentially a very confusing situation and one that is susceptible to abuse of that intermediate species.”
Giving birth to what?
The study’s lead author, Juan Carlos Izpisu Belmonte of the Salk Institute for Biological Studies in California, explained in the journal Cell the primary motive for the experimentation: “As we are unable to conduct certain types of experiments in humans, it is essential that we have better models to more accurately study and understand human biology and disease.”
But reading the study, Dominican Fr. Nicanor Pier Giorgio Austriaco, professor of biology and theology at Providence College in Rhode Island, found “no concern about human dignity, no concern about possibly breaking that human-non-human divide.”
Fr. Austriaco also expressed concern about what doors this experiment might eventually open.
“What happens if you’ve got human cells that enter the testicles of the monkey and what you now have are human sperm made by a monkey testicle,” he said. “So now you’ve got issues dealing with two monkeys that are chimeric mating, and just by random chance you’ve got a human egg made by one monkey and a human sperm made by the other monkey and they meet up, and you get a human.”
The Anscombe Bioethics Center in Great Britain called the experiments “deeply unethical,” saying they cross a “moral boundary because they mix human and nonhuman elements at a very early stage of development in a way that raises serious questions about moral status.”
“It is not apparent what such human-nonhuman chimeras would be like if they were born. It is not clear how far they share the orientation to develop essential human characteristics,” Anscombe’s director, David Albert Jones, said in a statement. “It is always wrong deliberately to create a being of uncertain and perplexing moral status.”
Jones added that even though the chimeras were not allowed to live after 19 days, “they raised questions about how we should regard them. Did these embryos have a share in human dignity?”
He called for an “immediate moratorium on the creation of embryos that mix human cells with those of nonhuman primates.”
“Science,” Jones said, “requires clear ethical boundaries if it is to maintain public trust and an essential moral boundary is that between the human and the nonhuman.”