Although concerns have been raised about the unethical source of some cells used in Shinya Yamanaka's efforts to reprogram cells into stem cells, moral theologians insist that the work could lead to ethical advances in the field.

"The initial insight unfortunately involved tainted material, but it gives way to an application of that knowledge which can be perfectly morally licit," Father Thomas Berg, Professor of Moral Theology at St. Joseph's Seminary in Yonkers, N.Y., told CNA on Oct. 16.

The American Catholic published a post on Oct. 15 questioning praise in Catholic circles of the results of Yamanaka's research, which was initially performed using cells derived from aborted human fetuses and human embryonic stem cells.

"That in itself no one is praising … I wouldn't have described myself as praising the work of Yamanaka in that sense," Fr. Berg said in reference to an Oct. 8 interview with CNA.

"But I am praising the potential for the good that can come from this technology."

Yamanaka published a paper in 2006 demonstrating that intact, mature cells can become immature stem cells. He inserted genes into mouse cells which reprogrammed those cells so that they became stem cells, and was later able to perform the technique with human cells.

These reprogrammed cells are pluripotent, meaning they can develop into a wide variety of specialized cell types. Yamanaka's breakthrough opened the door to studying disease and developing diagnosis and treatments.

Since this technique produces a stem cell from any cell, it provides an alternative to human embryonic stem cells, which are derived from destroyed human embryos.

Yamanaka and John B. Gurdon, researchers in cell biology, were awarded the 2012 Nobel Prize in Physiology or Medicine for their discoveries about how to generate induced pluripotent stem cells.

Although he does not agree with methods that use unethical means, Fr. Berg said he has "absolutely no doubt that induced pluripotent stem cells (iPSCs) can be made without recourse to any morally tainted cells."

"With a little bit of good will and effort, it's possible to do this research free of any tainted materials," Fr. Berg affirmed.

He also stands by his earlier statement that Yamanaka's research "put human embryonic stem-cell research largely out of business."

Yamanaka was "motivated by reflection on the fact that his own daughters were once human embryos" and "that is something to be thankful to God for," Fr. Berg reflected.

Dr. Christian Brugger, who holds the Stafford Chair of Moral Theology at St. John Vianney Theological Seminary in Denver, Colo., agrees with Fr. Berg's assessments.

Brugger noted in an Oct. 16 article for the National Catholic Register that though "most any science can be used wrongly," "iPSC research in itself seems to me to be morally unproblematic."

Brugger affirmed that "Yamanaka's prestigious award is indeed a triumph for ethical research," and said that less money is being spent on human embryonic stem cell research because induced pluripotent cells represent a previously undiscovered branch of stem cell research.

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According to Brugger, some of the most prominent cell biologists in the world have announced a preference for the new method over human embryonic stem cells since they were discovered by Yamanaka.