FDA Guidance On Source Animal, Product, Preclinical and Clinical Issues Concerning the Use of Xenotranspantation Products in Humans – Implications for 3D BioPrinting of Regenerative Tissue
Curator: Stephen J. Williams, Ph.D.
UPDATE: 07/09/2026
This update concern use of porcine xenotransplated tissue in human patients and examines the biochemical and genetic changes occurring both in host and transplanted material. With advances in pig genetic engineering (see post at bottom on the SCID Pig), this has allowed the feasability of improving the outcomes of several porcine to human xenotransplations, including pig to human heart, kidney, lung and even bain xenotransplantation. Studies had demonstrated that gene-edited porcine
livers can function in human recipients with intact native livers under intensive immunosuppression. Guo et al. had perfomed longitudinal multiomics studies (1) after genetically-modified porcine liver to human xenotransplation suggest future strategies and important biomarkers which can improve the biocompatibility of porcine-human xenotransplatation from short to long term outcomes.
The genetic modification to livers of Yucatan minipigs EGEN-5784, were supplied by the company eGenesis (Cambridge, MA). EGEN-5784 livers were from ESUS-1784 Yucatan minipigs have the following gene edits: (1) knock out of three porcine genes (GGTA1, CMAH and B4GALNT2) to eliminate three glycan antigensresponsible for hyperacute rejection in humans and old world mon-keys; (2) insertion of seven human transgenes (CD46, CD55, THBD, PROCR, CD47, TNFAIP3 and HMOX1) to improve compatibility with
inflammatory, coagulation and complement pathways in humans; (3) inactivation of the porcine endogenous retroviruses in the genome.
(1) Guo, Q., Wang, C., Mauduit, V. et al. Longitudinal multiomics profiling of extracorporeal cross-circulation with pig liver xenografts in human decedents. Nat Med (2026). https://doi.org/10.1038/s41591-026-04511-6
(2) Anand, R. P. et al. Design and testing of a humanized porcine
donor for xenotransplantation. Nature 622, 393–401 (2023) https://doi.org/10.1038/s41586-023-06594-4
Human-Pig Interactions in Liver Xenotransplant Recipients: A Multi-Omics Study
Source: https://www.insideprecisionmedicine.com/topics/translational-research/human-pig-interactions-in-liver-xenotransplant-recipients-a-multi-omics-study/?_hsenc=p2ANqtz-9h_Iwa3u-JgsZr3-j7hT69VLt4Cv1Vksaa70tJpCjUNFjcDfT10eR0qgcM_D9aeTiR6fQnOi0ptB0coHEi_vsB5JlOqQ&_hsmi=427683749
A comprehensive multi-omics analysis published in Nature Medicine provides new mechanistic insights into extracorporeal liver cross-circulation (ELC) using gene-edited porcine liver xenografts, advancing understanding of the molecular and cellular interactions that will shape the clinical translation of xenogeneic liver support.The study builds on a previously reported first-in-human decedent model in which blood from four brain-dead human recipients was circulated through ten-gene-edited porcine livers for up to 84 hours. While the initial work demonstrated that ELC could provide meaningful metabolic support, significant thrombocytopenia and evidence of host immune activation remained major barriers. The new study applies longitudinal, species-resolved multi-omics to dissect these biological responses at unprecedented resolution.
Researchers from NYU Langone Health, NYU Grossman School of Medicine, and the Perelman School of Medicine at the University of Pennsylvania profiled 64 serial blood samples using proteomics, metabolomics, and lipidomics alongside spatial transcriptomic analysis of 25 porcine liver biopsies and three native human liver samples. This integrated approach enabled simultaneous tracking of human and porcine molecular signatures throughout the xenoperfusion procedures. Spatial transcriptomics revealed progressive infiltration of human innate immune cells into the porcine xenografts, dominated by inflammatory macrophages and neutrophils. These infiltrating cells expressed pro-inflammatory cytokines including IL1B, TNF, and IL6, while resident porcine Kupffer-like macrophages and T cells declined over time. Adaptive immune cell infiltration remained comparatively limited, suggesting that the extensive genetic engineering of the donor pigs may mitigate early adaptive rejection during short-term support. One of the study’s most important findings was the distinct behavior of the human and porcine complement systems. While human complement proteins declined during ELC, the pig liver continued producing high levels of complement components C3 and C5 alongside acute-phase proteins and coagulation factors. The findings suggest that the xenograft actively drives innate immune and inflammatory responses rather than simply replacing liver function. Because currently available complement inhibitors are designed to target human proteins, they may not adequately suppress pig-derived complement activity, highlighting a potential need for species-specific therapeutics and additional genetic engineering to improve xenograft compatibility.
Original Article
The FDA has submitted Final Guidance on use xeno-transplanted animal tissue, products, and cells into human and their use in medical procedures. Although the draft guidance was to expand on previous guidelines to prevent the introduction, transmission, and spread of communicable diseases, this updated draft may have implications for use of such tissue in the emerging medical 3D printing field. This document is to provide guidance on the production, testing and evaluation of products intended for use in xenotransplantation. The guidance includes scientific questions that should be addressed by sponsors during protocol development and during the preparation of submissions to the Food and Drug Administration (FDA), e.g., Investigational New Drug Application (IND) and Biologics License Application (BLA). This guidance document finalizes the draft guidance of the same title dated February 2001.
For the purpose of this document, xenotransplantation refers to any procedure that involves the transplantation, implantation, or infusion into a human recipient of either (a) live cells, tissues, or organs from a nonhuman animal source, or (b) human body fluids, cells, tissues or organs that have had ex vivo contact with live nonhuman animal cells, tissues or organs. For the purpose of this document, xenotransplantation products include live cells, tissues or organs used in xenotransplantation. (See Definitions in section I.C.)This document presents issues that should be considered in addressing the safety of viable materials obtained from animal sources and intended for clinical use in humans. The potential threat to both human and animal welfare from zoonotic or other infectious agents warrants careful characterization of animal sources of cells, tissues, and organs. This document addresses issues such as the characterization of source animals, source animal husbandry practices, characterization of xenotransplantation products, considerations for the xenotransplantation product manufacturing facility, appropriate preclinical models for xenotransplantation protocols, and monitoring of recipients of xenotransplantation products. This document recommends specific practices intended to prevent the introduction and spread of infectious agents of animal origin into the human population. FDA expects that new methods proposed by sponsors to address specific issues will be scientifically rigorous and that sufficient data will be presented to justify their use.
Examples of procedures involving xenotransplantation products include:
- transplantation of xenogeneic hearts, kidneys, or pancreatic tissue to treat organ failure,
- implantation of neural cells to ameliorate neurological degenerative diseases,
- administration of human cells previously cultured ex vivo with live nonhuman animal antigen-presenting or feeder cells, and
- extracorporeal perfusion of a patient’s blood or blood component perfused through an intact animal organ or isolated cells contained in a device to treat liver failure.
The guidance addresses issues such as:
- Clinical Protocol Review
- Xenotransplantation Site
- Criteria for Patient Selection
- Risk/Benefit Assessment
- Screening for Infectious Agents
- Patient Follow-up
- Archiving of Patient Plasma and Tissue Specimens
- Health Records and Data Management
- Informed Consent
- Responsibility of the Sponsor in Informing the Patient of New Scientific Information
A full copy of the PDF can be found below for reference:
fdaguidanceanimalsourcesxenotransplatntation
An example of the need for this guidance in conjunction with 3D printing technology can be understood from the below article (source http://www.geneticliteracyproject.org/2015/09/03/pig-us-xenotransplantation-new-age-chimeric-organs/)
David Warmflash | September 3, 2015 | Genetic Literacy Project
Imagine stripping out the failing components of an old car — the engine, transmission, exhaust system and all of those parts — leaving just the old body and other structural elements. Replace those old mechanical parts with a brand new electric, hydrogen powered, biofuel, nuclear or whatever kind of engine you want and now you have a brand new car. It has an old frame, but that’s okay. The frame wasn’t causing the problem, and it can live on for years, undamaged.
When challenged to design internal organs, tissue engineers are taking a similar approach, particularly with the most complex organs, like the heart, liver and kidneys. These organs have three dimensional structures that are elaborate, not just at the gross anatomic level, but in microscopic anatomy too. Some day, their complex connective tissue scaffolding, the stroma, might be synthesized from the needed collagen proteins with advanced 3-D printing. But biomedical engineering is not there yet, so right now the best candidate for organ scaffolding comes from one of humanity’s favorite farm animals: the pig.
Chimera alarmists connecting with anti-biotechnology movements might cringe at the thought of building new human organs starting with pig tissue, but if you’re using only the organ scaffolding and building a working organ from there, pig organs may actually be more desirable than those donated by humans.
How big is the anti-chimerite movement?
Unlike anti-GMO and anti-vaccination activists, there really aren’t too many anti-chemerites around. Nevertheless, there is a presence on the web of people who express concern about mixing of humans and non-human animals. Presently, much of their concern is focussed on the growing of human organs inside non-human animals, pigs included. One anti-chemerite has written that it could be a problem for the following reason:
Once a human organ is grown inside a pig, that pig is no longer fully a pig. And without a doubt, that organ will no longer be a fully human organ after it is grown inside the pig. Those receiving those organs will be allowing human-animal hybrid organs to be implanted into them. Most people would be absolutely shocked to learn some of the things that are currently being done in the name of science.
The blog goes on to express alarm about the use of human genes in rice and from there morphs into an off the shelf garden variety anti-GMO tirade, though with an an anti-chemeric current running through it. The concern about making pigs a little bit human and humans a little bit pig becomes a concern about making rice a little bit human. But the concern about fusing tissues and genes of humans and other species does not fit with the trend in modern medicine.
Utilization of pig tissue enters a new age
A porcine human ear for xenotransplantation. source: The Scientist
For decades, pig, bovine and other non-human tissues have been used in medicine. People are walking around with pig and cow heart valves. Diabetics used to get a lot of insulin from pigs and cows, although today, thanks to genetic engineering, they’re getting human insulin produced by microorganisms modified genetically to make human insulin, which is safer and more effective.
When it comes to building new organs from old ones, however, pig organs could actually be superior for a couple of reasons. For one thing, there’s no availability problem with pigs. Their hearts and other organs also have all of the crucial components of the extracellular matrix that makes up an organ’s scaffolding. But unlike human organs, the pig organs don’t tend to carry or transfer human diseases. That is a major advantage that makes them ideal starting material. Plus there is another advantage: typically, the hearts of human cadavers are damaged, either because heart disease is what killed the human owner or because resuscitation efforts aimed at restarting the heart of a dying person using electrical jolts and powerful drugs.
Rebuilding an old organ into a new one
How then does the process work? Whether starting with a donated human or pig organ, there are several possible methods. But what they all have in common is that only the scaffolding of the original organ is retained. Just like the engine and transmission of the old car, the working tissue is removed, usually using detergents. One promising technique that has been applied to engineer new hearts is being tested by researchers at the University of Pittsburgh. Detergents pumped into the aorta attached to a donated heart (donated by a human cadaver, or pig or cow). The pressure keeps the aortic valve closed, so the detergents to into the coronary arteries and through the myocardial (heart muscle) and endocardial (lining over the muscle inside the heart chambers) tissue, which thus gets dissolved over the course of days. What’s left is just the stroma tissue, forming a scaffold. But that scaffold has signaling factors that enable embryonic stem cells, or specially programed adult pleuripotent cells to become all of the needed cells for a new heart.
Eventually, 3-D printing technology may reach the point when no donated scaffolding is needed, but that’s not the case quite yet, plus with a pig scaffolding all of the needed signaling factors are there and they work just as well as those in a human heart scaffold. All of this can lead to a scenario, possibly very soon, in which organs are made using off-the-self scaffolding from pig organs, ready to produce a custom-made heart using stem or other cells donated by new organ’s recipient.
David Warmflash is an astrobiologist, physician, and science writer. Follow @CosmicEvolution to read what he is saying on Twitter.
And a Great Article in The Scientist by Dr. Ed Yong Entitled
To cope with a growing shortage of hearts, livers, and lungs suitable for transplant, some scientists are genetically engineering pigs, while others are growing organs in the lab.
By Ed Yong | August 1, 2012
Source: http://www.the-scientist.com/?articles.view/articleNo/32409/title/Replacement-Parts/
.. where Joseph Vacanti and David Cooper figured that using
“engineered pigs without the a-1,3-galactosyltransferase gene that produces the a-gal residues. In addition, the pigs carry human cell-membrane proteins such as CD55 and CD46 that prevent the host’s complement system from assembling and attacking the foreign cells”
… thereby limiting rejection of the xenotransplated tissue.
In addition to issues related to animal virus transmission the issue of optimal scaffolds for organs as well as the advantages which 3D Printing would have in mass production of organs is discussed:
To Vacanti, artificial scaffolds are the future of organ engineering, and the only way in which organs for transplantation could be mass-produced. “You should be able to make them on demand, with low-cost materials and manufacturing technologies,” he says. That is relatively simple for organs like tracheas or bladders, which are just hollow tubes or sacs. Even though it is far more difficult for the lung or liver, which have complicated structures, Vacanti thinks it will be possible to simulate their architecture with computer models, and fabricate them with modern printing technology. (See “3-D Printing,” The Scientist, July 2012.) “They obey very ordered rules, so you can reduce it down to a series of algorithms, which can help you design them,” he says. But Taylor says that even if the architecture is correct, the scaffold would still need to contain the right surface molecules to guide the growth of any added cells. “It seems a bit of an overkill when nature has already done the work for us,” she says.
Other articles of FDA Guidance and 3D Bio Printing on this Open Access Journal Include:
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