News from China this week: Qi Zhou of the Institute of Zoology in Beijing and Fanyi Zeng of Shanghai Jiao Tong University used iPS (induced pluripotent stem) cells to grow entire healthy mice, proving definitively that cells from adult tissues can be "reprogrammed" to develop into any tissue in the body. (A news report can be found at: http://www.nature.com/news/2009/090723/full/460560a.html.)Thus stem cells without destruction of embryos is possible. Or is it? An interesting philosophical puzzle arises when we try to figure out how to ascribe personhood (mousehood? Muritas?), which is a yes-or-no question, to the complex developmental processes of embryonic life. In current Catholic teaching, personhood is imputed to human embryos from conception, which is straightforward enough. Here an an iPS cell was inserted into a crippled embryo, whereupon it took over the cellular machinery, and then was brought to term. (Of course before studies like this could pass Catholic muster for humans, this would need to be done without the damaged embryo, maybe in eggs. That may well be a simple technological hurdle.) Perhaps, in time, scientists can figure out how to go partway back--so a cell "thinks" it is fetal liver, for example, and would produce only that tissue, not a whole person. But by definition, an iPS cell is capable of producing ANY tissue (except extra-fetal stuff like placenta,) therefore it is capable of producing EVERY tissue, as the Chinese study proves. So...a few questions concerning possible human application of this technology: 1. Should iPS cells be protected in Catholic teaching as persons (therefore subjects of rights, including the right to life,) because they are pluripotent, or are they fair game for research and therapy, like other tissues? Human iPS cells have been around since 2007.2. Or do they "become" persons when placed in an environment in which they can manifest their complete potential? If so, why wouldn't the same be true for ordinary embryos--that they're persons only when in a conducive environment like someone's uterus? But then what about personhood at conception?3. If regular embryos are different because they are totipotent (they can grow everything themselves, including placenta,) then does our personhood inhere principally in our ability to grow our own placentas? But no adult can do that anymore--only embryos grow their own. Surely we don't lose our personhood with our placentas!These are indeed interesting times.