Is it ever moral to insert any human cells into an animal for research

CNS News uncovered the linked story that
I just learned of another action by government: “a government project conducted by government researchers funded by government money” which I find disturbing on many fronts. “Back on April 25, 2013, …the Ragon Institute of Massachusetts General Hospital, MIT and Harvard put out a press release announcing this $12.4 million federal grant.”

The NIH is forbidden by law to experiment on humans. “In March 1988, the Department of Health and Human Services issued a moratorium on federal funding of research that involved transplanting human fetal tissue into human subjects.”

“The moratorium did not extend to research that involves transplanting human fetal tissue into animals.”

It seems that since 2013 the NIH has been taking “tissues cut from human livers and thymuses taken from babies at 17 to 22 weeks gestational age” and implanting them into mice — “called the TKO-BLT mouse—with TKO standing for triple knockout (representing changes in the mouse’s system) and BLT standing for bone marrow, liver and thymus.”

“Each mouse would get a piece of thymus and a piece of liver taken from the same 17-to-22-week gestational age human baby. The part of the liver not cut into small pieces and transplanted under the kidney capsules of mice was cut into small pieces and processed to make stem cells that were injected into the mice after they underwent their transplantation surgeries.”

They thus make what NIH terms: “humanized mice”.

NIH reports that they “use ‘humanized’ mice, mice that contain human immune systems, as a model to study immune responses to HIV infection and to help us determine the basic mechanisms of vaccine protection against acute and chronic retroviral infections. The goal of these studies is to develop new ideas for HIV vaccines and therapies”.

“The researchers noted that they followed NIH rules in the treatment of animals.”

“The same government researchers had collaborated on another journal article about the “humanized” mouse with an NIH-funded researcher at Massachusetts General Hospital–which has an ongoing federal grant that also involves humanizing mice using human fetal livers and thymuses.”

CNS News has uncovered this. They have asked the NIH thirty questions.

This was the NIH’s only answer:
"Neither the NIH nor the co-authors responded to the specific questions. Instead, the NIH responded with this statement:

‘NIH is a biomedical research agency and conducts and funds research to enhance health, lengthen life, and reduce illness and disability. NIH does not regulate and is not involved with medical services for abortions. Additionally, NIH is not a direct source of human fetal tissue for researchers. In connection with some research projects, NIH-funded researchers obtain human fetal tissue that is donated to organizations for biomedical research under conditions governed by law, specifically sections 498A and 498B of the PHS Act, 42 U.S.C. 298g-1 [sic 289g-1] and 298g-2 [sic 289g-2], through an intermediary such as university tissue banks, clinics associated with universities and companies.’ "

It is also restricted in what it may do:
“Section 289g-2 of the law cited by NIH focuses on “Prohibitions regarding human fetal tissue.” It says in part: “It shall be unlawful for any person to knowingly acquire, or otherwise transfer any human fetal tissue for valuable consideration if the transfer affects interstate commerce.””

The debate on fetal “stem cell” research has been publicized to a fair extent. That said, as much as I have read on the topic — mainstream publications, mostly — until yesterday I had been totally unaware that any human cells were ever inserted into non-human animals. I, personally, was shocked.

From my reading — little done very recently — no medical benefits have accrued from fetal stem cell research. There have been many and valuable medical break-throughs using adult stem-cells.

There are a multitude of questions raised by the NIH humanized-mice:

  1. Is it legal? My understanding (as quoted) was it might not be.

  2. Should the NIH have the responsibility of doing their own “due diligence” to assure legal compliance by their “parts” providers?

  3. Do the abortionists explain to the woman having the abortion that her “baby’s” (the NIH term) liver and thymus will be used to breed “humanized mice”?

  4. Are the members of Congress aware that the NIH is inserting a “baby’s” liver and thymus into a mouse to breed “humanized mice”?

  5. In each person’s opinion, is it right to use the insertion of fetal cells to justify abortions?

  6. Is it moral to insert ANY human cells into any other animal?

  7. If not moral, do any potential — but unprecedented — medical benefits that might be found justify such immoral research?

Do adult stem cells get inserted into animals for research?

In essence, who believes that the “end” justifies the “means”?

What do others think about this?

What is the Church teaching?

Out of pure common sense - it may be if the person is in the age of consent and gives consent.

I usually teach Christology, and the historical Jesus is my area of specialization, however I have taught Ethics classes, and my answer would be “no.”

This is what is being done with the aborted babies…they are trying to make humanized mice! It is NOT ETHICAL.

Thanks so much for the responses.

I am hoping someone can point me to the formal teaching of the Catholic Church on this. I understand that the Church considers artificial insemination to be a mortal sin, but I suspect this is because of the destructive treatment of zygotes which are not implanted. Is that right?

Does anyone know if there has been a formal Church directive on this?

This ‘common sense’ approach seems to assume that every person has total authority over his/her body.

Under the laws of various republics that assumption might be true.

Under Catholic Church teaching is not every human body a ‘temple of the Holy Spirit’ ?

As such are we not bound by Church teaching before evaluating the morality of any “consent” by a person old enough to normally do that? The old “rightly formed conscience” rule.

Thanks for your opinion.

I, too, find this practice to be repugnant.

It is my understanding that the Catholic Church does not give a blanket-condemnation to research using adult stem-cells and that — unlike embryonic stem cell research — there have been scores of medical breakthroughs using adult stem-cells.

Are any of those adult stem-cells transplanted into ‘humanized mice’?

My gut agrees with you!

Given your specialization, I would love to get your thoughts on numerous “Jesus Project” questions but that would hijack this thread. Can you point me to other threads thereon in which you participated?


I would disagree

The Vatican has already looked at Xenotransplation, where human genetics are used to make animal body parts more suitable for human transplantation.

With certain caveats, it was deemed to be acceptable

The associated caveats

  1. Concern for the well-being of genetically modified animals should be guaranteed so that the effect of the transgene’s expression, possible modification of the anatomical, physiological and/or behavioural aspects of the animal may be assessed, all the while limiting the levels of stress and pain, suffering and anxiety experienced by the animal;
  1. The effects on the offspring and possible repercussions for the environment should be considered;
  1. Such animals should be kept under tight control and should not be released into the general environment;
  1. The number of animals used in experiments should be kept to a bare minimum;
  1. The removal of organs and/or tissues must take place during a single surgical operation;
  1. Every experimental protocol on animals must be evaluated by a competent ethics committee.

So if human genes can be ethically transplanted into animals, why not something as simple as cell injection.

The link is a very valuable contribution, but I think it is important to read the whole article. As I read it the specific focus is on transplanting animal organs (e.g. kidneys) from pigs (not primates) into humans. I could find no specific reference to implanting human cells into animals. There is a brief discussion of the bioethics of gene implanting into animals, but as I read it the genes so discussed were from other animals. If you read this differently I would be pleased to learn how.

It does specifically state:

genetic modifications that could significantly alter the biodiversity and the balance of the species in the animal world must be avoided.(57)

Reference 57 is to: “Reflections on human responsibility for animal life may be found in Schockenhoff E.”

I could find no date on that link. Can you? I suspect it might be 10-14 years old. I found no citation published after 2001.

Thanks for the contribution!

To my mind this does not specifically address implanting human cells into animals.

I googled “implant human cells in animals” and found these:

These links include headlines such as:
"Mice have been created whose brains are made up of half human cells. These
animals are much smarter than their siblings
. The idea is not to create a science "

CNET: "Dec 2, 2014 … Mice implanted with human brain cells become smarter … “This does not provide the animals with additional capabilities that could in any way …”

DailyMail: "Embryos involving the genes of animals mixed with humans have …Jul 22, 2011 … … ‘cybrids’, in which a human nucleus is implanted into an animal cell; and ’
chimeras’, in which human cells are mixed with animal embryos. "

"Human Cells Make Mice Smarter - Scientific American

Jun 6, 2013 … A subset of the implanted human stem cells matured into rotund, humanlike astrocytes in the animals’ brains, taking over operations from the … "

"Human Stem Cells Successfully Implanted In Pigs | IFLScience

Jun 5, 2014 … Human Stem Cells Successfully Implanted In Pigs. June 5 … co-author of the study and Curators Professor of Animal Science and Biochemistry. "

“risk when implanting human cells in rodents at Animal Biosafety Level 2 (ABSL-2
). … a hazard ID card on cages that contain animals implanted with human cells.”

"1997 May 15;31(3):168-74. Orthotopic implantation of human prostate
cancer cell lines: a clinically relevant animal model for metastatic prostate "

“One way to improve the translation of drugs from animal models to the … it much
more efficient to implant human immune cells in the animals”

Not only have I read it in it’s entirety, I did a paper on it for one of my Moral Theology classes in the seminary

Reference section 15

  1. The use of organs from engineered animals for xenotransplantation raises the need for certain reflections on transgenesis and its ethical implications.

The term “transgenic animal” is used to indicate an animal whose genetic make-up has been modified by the introduction of a new gene (or genes). In contrast, the term “knock out” is used to designate those animals in which a given endogenous gene (or genes) is no longer expressed. In either case, such animals will express particular characteristics which will be transmitted to the offspring.

As we have already observed, the possibility of working out such genetic modifications, using genes of human origin as well, is morally acceptable when done in respect for the animal and for biodiversity, and with a view to bringing significant benefits to man himself. Therefore, while recognizing that transgenesis does not compromise the overall genetic identity of the mutated animal or its species, and reaffirming man’s responsibility towards the created order and towards the pursuit of improving health by means of certain types of genetic manipulation, we will now enumerate some fundamental ethical conditions which must be respected:

I searched the Vatican website on the same phrase and got these:

"’ NUCLEAR CLONING, EMBRYONIC STEM CELLS’ …technology for tissue therapy in humans " 2007


"Scientific and Therapeutic Use of Human Embryonic Stem … " 8/24/2000

Cloning articles – all older

I hope I did not offend you.

I see your quotations — they are in that paper.

Please lay them out clearly for me. I am slow.

How can they coexist with the following?

I did find this reference on the Vatican website from 2009:


from “Conference of Cardinal William Levada, Prefect of the Congregation for the Doctrine of the Faith”

Recently, hybrid cloning has been proposed, in which the oocytes of animals are reprogrammed in order to produce human somatic stem cells from the resulting embryos without having to use human embryos. The Instruction states: “From the ethical standpoint, such procedures represent an offense against the dignity of human beings on account of the admixture of human and animal genetic elements capable of disrupting the specific identity of man” (n.33).

Is this the key phrase from that 2001 paper?

recognizing that transgenesis does not compromise the overall genetic identity of the mutated animal

Does the “genetic identity” phrase mean that so long as the gene implant does not make the recipient seem human-like?

And the corollary from the Cardinal’s symposium I suspect is this:

The Instruction states: “From the ethical standpoint, such procedures represent an offense against the dignity of human beings on account of the admixture of human and animal genetic elements capable of disrupting the specific identity of man

Those are diffenet things entirely. Xenotransplantation with transgenesis is the genetic altering of an animal so that it’s organs may be transplanted into another species ( generally human). Certain genes are introduced into the animal, say a pig, that makes it’s organs more compatible for transplantation, but the organ ( and the animal ) remains ‘pig’

Hybrid cloning is the removal of the primary genetic material and the replacement with other genetic material. In the case that +Levada refers to, the ovum of a cow, for example, is replaced with sufficient genetic material so that it becomes, in effect, a human stem cell.

You can see that in this quote

in which the oocytes of animals are reprogrammed in order to produce human somatic stem cells

In the case of xenotransplantion with transgeneiss, the intent is not to create a human heart, but a pig heart that can be used in humans.

Do you see the difference?

That flows nicely into the second quote you provided

The Instruction states: “From the ethical standpoint, such procedures represent an offense against the dignity of human beings on account of the admixture of human and animal genetic elements capable of disrupting the specific identity of man

The key phrase being the one that you underlined, the disruption of the specific identity of man (human)

The question becomes, does the genetic altering change the identity of the body sufficiently that it is no longer recognizable as being the intended form of the soul.

That would be a mutilation, which is morally prohibited.

But in the case of the article that I listed, and the OP’s question about a simple injection, such alteration is clearly not happening.

I suggest contacting The National Catholic Bioethics Center:


I can’t recall any “Jesus Project” threads, but if you start one, I’ll participate.

Thank you for your interest, and God bless.

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