How close are we to transplanting animal organs into people?Can animal organs save people on the transplant list?
or, simply: Can animal organs save people on the transplant list?or, precisely: How close are we to transplanting animal organs into people?
Gene-edited pig organs have kept people alive for months; the open question is whether they can replace human donors for years, not weeks.Thousands die waiting for organs. Gene-edited pig kidneys and hearts could close the gap - if they last.
Controlled trials, sparse outcomes - EXPAND targets 50 participants, but no cohort-level 24-week survival distribution has yet been posted; 271 days remains the completed record. Next up - EXPAND primary completion target (expected Oct 2028).
State of playWhere xenotransplant stands right now
The current stage, the honest metric, and the single threshold that gates the next stage. Each threshold is a falsifiable claim with a named next test.How far up the ladder we've climbed, the honest verdict, and the one thing blocking the next step.
Thousands die waiting for organs. Gene-edited pig kidneys and hearts could close the gap - if they last.Gene-edited pig organs have kept people alive for months; the open question is whether they can replace human donors for years, not weeks.
Last a full yearSustain one dialysis-free year Next test: Publish a verified 365-day graft-function result, including GFR, rejection episodes and immunosuppression.
The thresholds that gate the next stageWhat has to happen next
Each threshold is a falsifiable claim with a named next test; the gap chart shows how far today's metric sits from the goal.Each row is one thing that has to be proven — and how far today's number is from the target.
The record behind the verdict
Major events set large; context events set small but never hidden. Everything below the TODAY rule is a schedule, not a result.
Borrowed Organs, Blind Immunity
Borrowed Organs, Blind Immunity begins with first vascular organ attempts. The result established the next question for the field.
Primate Grafts and Rejection
Primate Grafts and Rejection moved the field from chimp kidneys reach nine months to baby fae survives 21 days. The results narrowed the next question without closing it.
Virus Risk Meets Gene Editing
Virus Risk Meets Gene Editing moved the field from pig retrovirus infects human cells to who sets trial principles. The results narrowed the next question without closing it.
Preclinical Barriers Begin Falling
Preclinical Barriers Begin Falling moved the field from crispr disables 62 perv copies to life-supporting hearts pass six months. The results narrowed the next question without closing it.
Humans Enter Controlled Trials
Humans Enter Controlled Trials moved the field from gene-edited kidney enters human body to expand primary completion target. The results narrowed the next question without closing it.
Events outside the declared eras
Events outside the declared eras begins with lifetime surveillance horizon. The result established the next question for the field.
Why the meters read the way they do
The learning curves and comparisons that justify each threshold's percentage. Every series is measured, with the source event linked in the timeline above.
Read the evidence more closely
Definitions, system boundaries and experimental caveats behind the headline record.
01What the 69 edits comprise
The “69 edits” in EGEN-2784 are not 69 compatibility genes: they comprise three glycan-antigen knockouts, seven human transgenes and inactivation of 59 porcine endogenous-retrovirus sequences. Slayman experienced biopsy-confirmed T-cell-mediated rejection on day 8, reversed with intensified immunosuppression; autopsy found no evident graft rejection when he died on day 52.
02The 61-day study showed delayed rejection
The 61-day NYU decedent study detected antibody-mediated rejection at postoperative day 33 and combined antibody- and T-cell-mediated rejection by day 49, despite avoiding hyperacute rejection. That is mechanistic evidence of delayed immune escape, not 61 days of rejection-free function.
03The auxiliary liver did not work alone
The ten-day auxiliary liver produced only 66.5 ml cumulative bile by day 10 and detectable porcine albumin. Because the native human liver remained, the experiment did not show that the pig graft could independently sustain life.
04Microangiopathy ended the living liver trial
In the living liver recipient, early biopsies showed no hyperacute or acute rejection, but xTMA emerged around day 31 with complement activation, hemolysis, thrombocytopenia and organ dysfunction. Eculizumab and plasma exchange were insufficient until the graft was removed on day 38.
05The lung sustained severe early injury
The lung graft avoided hyperacute rejection and infection for 216 hours, but severe edema resembling primary graft dysfunction appeared at 24 hours; antibody-mediated rejection contributed to injury on days 3 and 6, with only partial recovery by day 9. The recipient’s right human lung remained.
06Short liver support coexisted with injury
Four extracorporeal liver experiments ran 72-84 hours with native livers present; one hepatectomized decedent received 48 hours of support from the pig liver alone. Preserved architecture and bile production coexisted with IgM deposition, immune infiltration and severe thrombocytopenia.
07The multi-organ study tested physiology
The 2026 multi-organ experiment found no hyperacute rejection during the first 24 hours, but early immune injury appeared after roughly 36 hours. Its approximately 106-hour observation window tests physiology and liver-kidney immune interactions, not recipient survival.
08Edit count is not an efficacy score
Competing kidney platforms remain genuinely different hypotheses: United Therapeutics uses ten edits, whereas eGenesis uses 69 genomic modifications. Edit count should not be treated as an efficacy score; only comparative cohort outcomes can establish which design performs better.
If the remaining tests pass
Downstream capabilities, drawn dashed because they depend on results not yet in.
Who is building it-and what the money saysCapital, institutions and the global race
The teams doing the work, where they are based, and whether the money points to real delivery or only a plan.Company finance, public programmes, institutional leadership and market evidence-kept separate from valuations, forecasts and announced capacity.
Two US organ-engineering programs have moved gene-edited pig kidneys into regulated clinical studies, while Chinese teams have broadened the organ types tested. The unmet need is enormous, but the human evidence is still a handful of recipients and small planned trials. Authorization, survival for months and capital raised are not the same as durable safety, efficacy or approval.
Who is building itCompanies, laboratories and programmes
eGenesis
USAEngineers multi-edited porcine kidneys, livers and other organs
United Therapeutics / Revivicor
USASupplies the 10-gene-edited UKidney used in the EXPAND clinical trial
NYU Langone Transplant Institute
USAClinical center for EXPAND and earlier decedent and living-recipient xenokidney studies
| Player | Country | What they are doing | Funding | Named investors | Source |
|---|---|---|---|---|---|
| eGenesiscompany | USA | Engineers multi-edited porcine kidneys, livers and other organs | Series D · $191M · Sep 2024 | Lux Capital · ARCH Ventures · Khosla Ventures · Fresenius Medical Care Ventures · Leaps by Bayer · DaVita | Source · egenesisbio.com |
| United Therapeutics / Revivicorcompany | USA | Supplies the 10-gene-edited UKidney used in the EXPAND clinical trial A registered trial is not product approval. | Not disclosed | Not disclosed | Source · clinicaltrials.gov |
| NYU Langone Transplant Institutelab | USA | Clinical center for EXPAND and earlier decedent and living-recipient xenokidney studies | Not disclosed | Not disclosed | Source · nyulangone.org |
| Massachusetts General Hospitallab | USA | Clinical center for eGenesis expanded-access kidney recipients and planned clinical study | Not disclosed | Not disclosed | Source · egenesisbio.com |
| eGenesis / OrganOxcompany | USA / UK | Developing temporary external pig-liver perfusion support for acute-on-chronic liver failure The cleared study is external perfusion, not an implanted replacement liver. | Not disclosed | Not disclosed | Source · egenesisbio.com |
| Xijing Hospital / ClonOrganlab | China | Reported a six-gene-edited pig-liver study in a brain-dead recipient Ten-day mechanistic experiment with the recipient's original liver retained. | Not disclosed | Not disclosed | Source · nature.com |
Where every number comes from
10 sources — every figure on this page traces to one.
- International Xenotransplantation Association 2025 position paperpmc.ncbi.nlm.nih.gov
- FDA xenotransplantation guidancefda.gov
- ClinicalTrials.gov EXPAND record NCT06878560clinicaltrials.gov
- NYU Langone EXPAND trial launchnyulangone.org
- AP report on the 271-day completed recordapnews.com
- eGenesis EGEN-2784 IND clearance and patient updateegenesisbio.com
- NYU Langone 61-day immune-mapping studynyulangone.org
- University of Maryland lessons from the first pig-heart recipientmedschool.umaryland.edu
- Science paper on multiplex PERV inactivationpubmed.ncbi.nlm.nih.gov
- Historical review of cross-species organ transplantationpmc.ncbi.nlm.nih.gov