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What Does the Church Teach About Stem Cell Research?

The Short Answer

The Catholic Church is not against stem cell research. She supports research using adult stem cells, umbilical cord blood and reprogrammed cells, none of which harms anyone. What she opposes is obtaining stem cells by destroying human embryos, because a human embryo is a living human being, and “human life must be respected and protected absolutely from the moment of conception” (CCC 2270). The good that research might do cannot justify taking an innocent life to do it.

Critics see this as religion blocking medical progress, and as putting microscopic embryos ahead of suffering patients with Parkinson’s, diabetes or spinal injuries. That is a serious objection, because the suffering is real.

What the Church Does and Does Not Claim

The Church does not claim:

The Church does claim that “from the first moment of his existence, a human being must be recognized as having the rights of a person,” among them “the inviolable right of every innocent being to life” (CCC 2270), and that “since it must be treated from conception as a person, the embryo must be defended in its integrity” (CCC 2274).

Why Catholics Believe It

The source is what matters

Stem cells can develop into many kinds of specialised cells, which is why researchers hope to use them to repair damaged tissue. They come from several sources:

The Church has no objection to the first three. Her objection is to the fourth.

The embryo is a human being

This is not a religious claim but a biological one. From fertilisation, the embryo is a living, distinct, whole human organism, with its own genetic identity, which will develop, if nothing interrupts it, through every stage of human life. Every one of us was once an embryo. Its size, location and dependence on others do not change what it is.

Scripture speaks of human life before birth as known and loved by God: “Before I formed you in the womb I knew you” (Jeremiah 1:5); “you knitted me together in my mother’s womb” (Psalm 139:13). The commandment “You shall not kill” (Exodus 20:13) protects every innocent human life.

A good end does not justify an evil means

The principle at stake is one that everyone accepts in other cases. We do not harvest organs from one person, without consent, to save five others, however many lives it might save. We do not experiment on prisoners or the dying because the results could help others. St Paul rejected the idea that we may “do evil that good may come” (Romans 3:8). The same principle applies to the smallest and youngest human beings.

Common Objections

”The embryos will be discarded anyway. Why not use them for good?”

The Church shares the sorrow over the very large numbers of embryos frozen in clinics with no prospect of being born. But a human being does not lose the right not to be killed because others have decided he or she is unwanted. That these embryos exist at all is itself a result of practices the Church warns against. Destroying them for research adds a second wrong to the first. (See Why Does the Church Oppose IVF?)

”An embryo is just a cluster of cells.”

So, at one level of description, is every one of us. What matters is what kind of thing the cluster is. An embryo is not a part of another organism, like a skin cell; it is a whole human organism at an early stage, directing its own development. That is why biology textbooks describe the start of a human life at fertilisation.

”The Church is putting embryos ahead of real, suffering patients.”

The Church cares deeply for the sick, and is one of the largest providers of health care in the world. She is not choosing embryos over patients; she is refusing to accept that one human life may be destroyed to benefit another. Ethical research, which she supports, aims to help patients without that cost.

”What about vaccines developed using cell lines from abortions?”

Some vaccines were developed or tested using cell lines derived decades ago from aborted foetuses. The Church distinguishes between doing evil and benefiting remotely from an evil done long ago by others. In 2020 the Congregation for the Doctrine of the Faith said that, when no ethically sound alternative is available, “it is morally acceptable to receive Covid-19 vaccines that have used cell lines from aborted fetuses,” and that doing so “does not constitute formal cooperation with the abortion,” while urging that ethical alternatives be developed (Note on the Morality of Using Some Anti-Covid-19 Vaccines; Dignitas Personae 34–35).

In Summary

The Church supports stem cell research that does not destroy human life: adult stem cells, cord blood and reprogrammed cells. She opposes destroying human embryos to obtain stem cells, because the embryo is a living human being, and no good result can justify killing an innocent person to obtain it. Her position does not depend on which kind of research proves most useful; it rests on the dignity of every human life, from its first moment.

See also Why Is the Church Against Abortion and Euthanasia? and Why Does the Church Oppose IVF?

This article follows the method St Robert Bellarmine used in his Controversies*: state the question fairly, clear away misunderstandings, make the case, then answer each objection. See How We Answer Objections.*

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