But technical problems remain. Much has been learned in the past decade, but the pathway to medical treatments still faces many challenging problems. One worry in particular is that implanted stem cells might develop into cancer. Others challenges including getting the cells to multiply, integrate with other cells, function as they should, and avoid being rejected as an infection.
A new solution may be on the horizon, one that addresses many of these problems—moral and technical—all at once. At least that’s the claim made by a team led by Wolfram Zimmerman and colleagues at Georg-August-Universität Göttingen in Germany. Working with laboratory mice, Zimmerman’s team used mouse eggs to create what are known as parthenotes. Without being fertilized, the mouse eggs were manipulated so that they began to develop as if they were fertilized, up to a point.
PHOTO: Mouse embryonic stem cells. This image is a work of a National Science Foundation employee, taken or made as part of that person's official duties. As a work of the U.S. federal government, the image is in the public domain. This image was copied from wikipedia:en.
Parthenogenesis exists in nature. It has been observed in some plants, fish, and reptiles. Over the past decade, researchers have learned how to induce parthenogenesis in mice, monkeys, and humans. In every case, however, the resulting parthenotes fail to develop normally, which means they could never be implanted to produce a child. But they do develop for a few days, long enough for the precursors of pluripotent stem cells to develop.
What is new in the research reported on February 22, 2013 is unexpected success in the use of these stem cells derived from mouse parthenotes. These cells—parthenogenetic stem cells or PSCs—were developed and eventually implanted into damaged mouse hearts. Quite simply, they worked in ways that seem to overcome most if not all of the technical hurdles.
The research appears in the Journal of Clinical Investigation, which carried a companion article claiming that the new research “may overcome all…formidable barriers” that currently stand in the way of stem cell medicine. The original article makes this claim: “One of our key observations involved the capacity of PSCs to exhibit essentially normal cardiogenesis in vitro and in vivo.” In other words, both in the dish and in the mouse, implanted cells fully integrate into the beating heart.
Both the research article and the companion piece make another claim: PSCs are ethically acceptable. That’s because parthenotes are not embryos. Taking cells from parthenotes avoids all the moral concerns that surround the use of cells derived from embryos. Here is the claim: Research using human PSCs, derived from human parthenotes, involves “no destruction of viable embryos,” according to the research article. The companion piece simply notes that compared to embryonic stem cells, PSCs “do not have the same ethical implications.”
If only it were that simple. But plain the fact is that some who object to the use of human embryos in research are already on record as objecting to the use of human parthenotes.
Their logic is fairly straightforward. If human embryos are off limits and if parthenotes cannot be clearly and definitely distinguished from embryos, then human parthenotes are equally off limits to research.
They are not claiming that parthenotes are little people, nor are they being silly or obstructionist. They are only claiming that we do not have enough scientific clarity and certitude to proceed with moral confidence in the work of creating and destroying parthenotes, regardless of the benefit.
Just to be clear, I personally disagree with this objection. But researchers and regulators should be aware that some, at least, will balk at this new line of research, technically attractive as it may be.
For example, in a statement given to the UK Parliament, the Church of Scotland made this comment:
“We reject the suggestion made by various researchers that hybrid embryos, parthenotes and embryos that have been modified to make then non-viable would be an ethical solution to deriving stem cells from embryos. Whatever the status of such creations, it is would be at least as unethical to use methods that would create an ‘embryo’ so deformed that it could not be viable and which therefore inherently denies its potential to develop.”Politically more important is the response that will come from Catholics. Some Catholic scholars have defended the moral legitimacy of research using human parthenotes. There is simply no way, they argue, to equate the parthenote with the embryo. The parthenote is not a product of conception. In more popular rhetoric: If “life begins at conception,” then the parthenote is not “life.” Nor can it develop normally. It meets none standard definitions of an embryo.
Others are not so certain. They translate scientific and theological uncertainty into a moral prohibition. Creating and destroying a parthenotes requires that we know for sure that they are not embryos. Such certainty is lacking, at least for now. In the face of uncertainty, they argue, we must not proceed.
On the Catholic website www.ewtn.com, E. Christian Brugger addresses the question: Is the parthenotes enough like and embryo to be considered an embryo? His answer:
“The question presently is unsettled.” He adds this: “Although the empirical question of the status of a human parthenote is unsettled, the underlying moral principle is straightforward. Unless we have moral certainty that a dividing parthenogenetically activated human oocyte is not an embryo, we have an obligation to avoid research with human parthenotes.”And at the end he concludes:
“Having said this, the present evidence on whether parthenotes are ever embryos seems to me inconclusive. Given the evidence to date, at least with which I am familiar, I do not think it can be established with moral certitude that parthenotes are never human embryos.”Personally, I want to see this research go forward, and so I have some suggestions for researchers and reporterss in this field.
First, help religious scholars build the case scientifically, showing in clear terms to the wider public why parthenotes are not functionally like embryos and why a morally robust boundary separates the two. Science itself cannot create that boundary, but it can provide evidence supporting moral and philosophical arguments in favour of such a boundary.
Second, stop using provocative phrases like “virgin birth.” Regrettably, the companion piece in the Journal of Clinical Investigation is published with this title: “Virgin birth: engineered heart muscles from parthenogenetic stem cells.”
Sure, “parthenos” is Greek for virgin, so the etymology supports the use of the term “virgin birth.” But for billions of Christians around this world, this term has a very special religious meaning, one that many associate with the most tender core of their faith.
For scientists to claim they are simulating the “virgin birth” is offensive to anyone who takes the religious meaning of the phrase seriously. It is needlessly provocative, almost the worst thing that could be said if religious support for research is desired.
What’s more, associating parthenogenesis with the “virgin birth” has the bizarre effect of equating the parthenote with the embryo. Christians who hold to the “virgin birth” will claim that in one profoundly non-trivial example (Jesus), what scientists now claim they are creating turned out to be a fully viable embryo. And then they say, “But don’t worry; it’s not a human being”?
The original article, entitled "Parthenogenetic stem cells for tissue engineered heart repair," is published in the February 22, 2013 issue of the Journal of Clinical Investigation, together with the companion piece.
