The problemsBiology & HealthXenotransplant

Updated · July 2026

How close are we to transplanting animal organs into people?Can animal organs save people on the transplant list?

Can animal organs save people on the transplant list?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.

Current stageEngineeringEngineering a system that works outside the labBuilding a system that works outside the lab

Read the evidence Where we stand

The path so far

Recorded milestones

1963
Primate kidney supports a patient
Jul 2026
Formal trials replace anecdotes

Open tests · conceptual branches

TODAY

OPEN TEST03 ↗
Last a full yearSustain one dialysis-free yearThe best completed case reached 271 days; an ongoing case cannot count until the date passes.At least one living recipient retains a functional pig-kidney graft without dialysis for 365 days.
OPEN TEST04 ↗
Prove it across a groupProduce a survival distributionA few heroic cases cannot reveal the odds of success or rare infection harms.A controlled multicenter cohort reports recipient and graft survival, measured GFR, serious infections and quality of life.

TODAY

OPEN TEST03 ↗

Last a full yearSustain one dialysis-free yearThe best completed case reached 271 days; an ongoing case cannot count until the date passes.At least one living recipient retains a functional pig-kidney graft without dialysis for 365 days.

OPEN TEST04 ↗

Prove it across a groupProduce a survival distributionA few heroic cases cannot reveal the odds of success or rare infection harms.A controlled multicenter cohort reports recipient and graft survival, measured GFR, serious infections and quality of life.

Milestones are in recorded order. Open tests are separate questions, not a forecast.Milestones are in date order. Open tests are separate tests, not a promise.

XenotransplantWhere we stand

The path shows Formal trials replace anecdotes. Open thresholds are separate tests in a conceptual map, not a forecast. No single percentage represents progress.

01 · Where we standWhere we stand

Where we standWhere we stand

The current stage, the evidence recorded, and the single threshold that gates the next stage.The stage reached, the evidence recorded, and the one test still blocking the next step.

What the evidence has shownWhat the evidence has shown

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.

2 of 4 tests recorded2 of 4 thresholds achieved open

✓Survive the first attackAvoid immediate immune destructionAchieved

✓Go home without dialysisReplace dialysis in a living personAchieved

Last a full yearSustain one dialysis-free yearOpen test

Prove it across a groupProduce a survival distributionOpen test

The next testBlocking threshold

Last a full yearSustain one dialysis-free year

Publish a verified 365-day graft-function result, including GFR, rejection episodes and immunosuppression.Publish a verified 365-day graft-function result, including GFR, rejection episodes and immunosuppression.

02 · Thresholds & evidenceThresholds & evidence

What would count as proof?What would count as proof?

A clear test, the evidence behind it, and the limits of the claim.A clear test, the evidence behind it, and what it still leaves open.

Choose a threshold

✓Achieved · Sep 2021

Survive the first attackAvoid immediate immune destruction

The organ must not be destroyed as soon as human blood reaches it.A gene-edited pig kidney reperfuses, filters blood and makes urine in a human body without hyperacute rejection.

Recorded result A single-edit kidney functioned through NYU's 54-hour brain-dead-body study.

Next test Confirm the same across every recipient in the first six-person EXPAND cohort.

SOURCE RECORD

Timeline · Gene-edited kidney enters human body ↗

Still to demonstrateWhat this does not establishA separate system can still have different conditions and results.The named measurement has no wider implication until the supporting system test is also shown.

View every evidence record

Achieved

Survive the first attackAvoid immediate immune destruction

The organ must not be destroyed as soon as human blood reaches it.A gene-edited pig kidney reperfuses, filters blood and makes urine in a human body without hyperacute rejection.

Recorded result: Sep 2021 · A single-edit kidney functioned through NYU's 54-hour brain-dead-body study.

Next test: Confirm the same across every recipient in the first six-person EXPAND cohort.

Timeline · Gene-edited kidney enters human body ↗

Achieved

Go home without dialysisReplace dialysis in a living person

A real patient must live outside hospital without the dialysis machine.A living recipient leaves hospital with a functioning pig kidney and no dialysis requirement.

Recorded result: Apr 2024 · Richard Slayman was discharged 18 days after transplant and lived 52 days with the graft.

Next test: Repeat hospital discharge and stable measured GFR prospectively in all initial trial recipients.

Timeline · Living recipient leaves dialysis ↗

Open test

Last a full yearSustain one dialysis-free year

The best completed case reached 271 days; an ongoing case cannot count until the date passes.At least one living recipient retains a functional pig-kidney graft without dialysis for 365 days.

Next test: Publish a verified 365-day graft-function result, including GFR, rejection episodes and immunosuppression.

Open test

Prove it across a groupProduce a survival distribution

A few heroic cases cannot reveal the odds of success or rare infection harms.A controlled multicenter cohort reports recipient and graft survival, measured GFR, serious infections and quality of life.

Next test: The six-person EXPAND cohort reaches at least 12 weeks and undergoes independent safety review, followed by 24-week endpoint reporting.

03 · The recordThe record

The record behind the verdictThe record behind the verdict

Major milestones and smaller context events share one source-linked record. Scheduled targets are marked separately from recorded events.Milestones, smaller events and setbacks share one sourced record. Scheduled targets are marked separately from recorded events.

Event key

TheoryExperimentFundingSetbackPolicyDeployment Future / scheduled

Eras · click to jump

Every event links to its source. Setbacks are in red — part of the story.Every event has a source URL. Scheduled targets stay distinct from results.

Jump to era

1906-19621 event1 shown

Borrowed Organs, Blind Immunity

Recorded event: “First vascular organ attempts”.

1906

First vascular organ attemptsExperiment

Mathieu Jaboulay attached pig and goat kidneys to two women; both grafts failed within days.

Mathieu Jaboulay, Lyon

1963-19962 events0 shown

Primate Grafts and Rejection

This record spans “Chimp kidneys reach nine months” to “Baby Fae survives 21 days”.

1963

Chimp kidneys reach nine months

Reemtsma transplanted chimpanzee kidneys into 13 patients; one recipient returned to work and survived nearly 9 months.

Keith Reemtsma and Tulane University

1984

Baby Fae survives 21 days

A baboon heart supported the infant for 21 days before rejection and heart failure, intensifying scientific and ethical criticism.

Leonard Bailey and Loma Linda University Medical Center

1997-20143 events1 shown

Virus Risk Meets Gene Editing

This record spans “Pig retrovirus infects human cells” to “WHO sets trial principles”.

1997

Pig retrovirus infects human cells

Researchers showed porcine endogenous retrovirus could infect human cells in vitro, elevating population-level infection concerns.

Robin Weiss and collaborators

2002

Alpha-Gal knockout pigs bornExperiment

Pigs lacking both GGTA1 alleles removed the major alpha-Gal xenoantigen that drives hyperacute pig-organ rejection.

PPL Therapeutics and Immerge BioTherapeutics teams

2008

WHO sets trial principles

The first WHO global consultation set cross-border expectations for trial oversight, infection surveillance and public-health safeguards.

World Health Organization and International Xenotransplantation Association

2015-20203 events0 shown

Preclinical Barriers Begin Falling

This record spans “CRISPR disables 62 PERV copies” to “Life-supporting hearts pass six months”.

2015

CRISPR disables 62 PERV copies

Multiplex CRISPR disrupted 62 PERV pol copies in pig cells and cut transmission to human cells by more than 1,000-fold.

George Church, Luhan Yang and collaborators

2016

Pig heart lasts 945 days

A gene-edited pig heart survived up to 945 days in a baboon, but it was heterotopic and did not replace the baboon's own heart.

NIH and University of Maryland collaborators

2018

Life-supporting hearts pass six months

Orthotopic pig hearts sustained baboons for up to 195 days after perfusion preservation and control of graft overgrowth.

Bruno Reichart, Matthias Längin and collaborators

2021-207520 events4 shown

Humans Enter Controlled Trials

This record spans “Gene-edited kidney enters human body” to “EXPAND primary completion target” and includes scheduled targets.

2021

Gene-edited kidney enters human bodyExperiment

An alpha-Gal-knockout pig kidney made urine without hyperacute rejection during a 54-hour brain-dead-body study.

Robert Montgomery and NYU Langone

2022

First pig-heart recipient dies

David Bennett lived 60 days; the graft later contained porcine cytomegalovirus DNA, one of several possible contributors to failure.

Bartley Griffith, Muhammad Mohiuddin and University of Maryland Medicine

2023

Decedent kidney runs 61 days

A single-edit pig kidney functioned for 61 days; dense sampling later mapped about 5,100 human and pig genes during rejection.

Robert Montgomery and NYU Langone

2023

Second pig heart rejected

Lawrence Faucette died 40 days after transplant; the heart performed well for one month before showing rejection.

University of Maryland Medicine

2023

External pig liver supports a decedent

A gene-edited pig liver supported a brain-dead donor's circulation for 72 hours outside the body; the donor's native liver remained in place.

Penn Medicine, eGenesis, OrganOx and Gift of Life

2024

Pig liver is implanted in a human body

A six-edit auxiliary liver produced bile and porcine albumin during a planned ten-day brain-dead-recipient study; the native human liver remained.

Xijing Hospital xenotransplant team

2024

Living recipient leaves dialysisExperiment

Richard Slayman received a 69-edit pig kidney, left hospital dialysis-free and lived 52 days with the transplant.

Massachusetts General Hospital and eGenesis

2024

Combined transplant ends at 47 days

Lisa Pisano's single-edit pig kidney was removed after 47 days following hypotension-related damage; she died six weeks later.

NYU Langone

2024

First pig lung is transplanted

A six-edit left lung maintained gas exchange for 216 hours in a brain-dead recipient, but developed severe edema and antibody-mediated injury.

First Affiliated Hospital of Guangzhou Medical University

2024

Living recipient receives pig liver

A ten-edit auxiliary liver supported metabolic and synthetic functions but was removed on day 38 for thrombotic microangiopathy; the recipient died on day 171.

Anhui Medical University and Yunnan Agricultural University

2024

Pig liver and kidneys work together

A whole liver and both kidneys from one six-edit pig supported a brain-dead recipient for nearly five days; this was physiology testing, not recipient survival.

Guangxi Medical University collaborators

2024

Looney reaches 130 days

Towana Looney lived dialysis-free for 130 days; acute rejection followed reduced immunosuppression for an unrelated infection.

NYU Langone and United Therapeutics

2025

Andrews sets 271-day record

Tim Andrews remained dialysis-free for 271 days before declining function led surgeons to remove his 69-edit kidney on October 23.

Massachusetts General Hospital and eGenesis

2025

Asian pig-kidney case reaches 261 days

A six-edit kidney transplanted into a living recipient functioned for 261 days before deterioration and complications led to removal and resumed dialysis.

Xijing Hospital

2025

FDA clears pig-liver support trial

The first IND for temporary extracorporeal pig-liver support authorized a trial in living patients with acute-on-chronic liver failure, not routine treatment.

eGenesis, OrganOx and US Food and Drug Administration

2025

Stewart remains dialysis-free

Bill Stewart received a 69-edit kidney June 14; eGenesis later reported at least 250 days with the graft, an ongoing censored result.

Massachusetts General Hospital and eGenesis

2025

First controlled kidney trial startsDeployment

EXPAND transplanted its first participant and opened a six-person first cohort, with 24-week safety and efficacy endpoints.

NYU Langone and United Therapeutics

2026

Pig kidney bridges to human transplant

After his 271-day pig graft and return to dialysis, Tim Andrews received a human donor kidney, demonstrating practical bridge feasibility.

Massachusetts General Hospital and eGenesis

2026

Controlled trials, sparse outcomesDeploymentWe are here

EXPAND targets 50 participants, but no cohort-level 24-week survival distribution has yet been posted; 271 days remains the completed record.

United Therapeutics, NYU Langone and eGenesis

TODAY · scheduled targets are not results

2028

EXPAND primary completion targetDeploymentTarget

The 50-participant EXPAND registry record estimates primary completion in October 2028; this is scheduled, not achieved.

United Therapeutics

2075-20751 event0 shown

Additional records

Scheduled target: “Lifetime surveillance horizon”.

2075

Lifetime surveillance horizonDeploymentTarget

EXPAND lists study completion in 2075 because recipients require lifelong graft and zoonotic-infection follow-up.

United Therapeutics

— end of record · 30 events shown —

04 · The dataThe data

The data behind the verdictThe data behind the verdict

Read each measure with its units, conditions, uncertainty and source; targets remain distinct from observations.Read each chart with its conditions, limits and source. Future targets remain distinct from recorded results.

Open figure in archive: Observation windows expanded from 54 hours to 61 days, enabling richer physiology and rejection sampling, but these models are not clinical survival evidence.Open figure in archive: The 945-day heterotopic result did not support life; the more stringent orthotopic, life-supporting model reached 195 days, so this is a model comparison, not a declining trend.Open figure in archive: Engineering breadth increased, but edit count is not a performance score: competing clinical programs still test 10-edit and 69-edit kidneys.Open figure in archive: The U.S. kidney waiting list is more than three times annual kidney transplant volume.Open figure in archive: The completed living-recipient record has covered about three quarters of the first one-year durability target.Open figure in archive: Two kidney programs are testing radically different genome-engineering strategies; more edits are not proven better.Open figure in archive: A non-life-supporting heart model lasted far longer than the stricter replacement-heart model.

Choose a figureDialysis-free functional pig-kidney graft survival in living recipientsDialysis-free functional pig-kidney graft survival in living recipients

Dialysis-free functional pig-kidney graft survival in living recipientsDialysis-free functional pig-kidney graft survival in living recipients

010020030021354

1Lisa Pisano; graft explanted after hypotension-related damage · 47 days · 2024
2Richard Slayman; 52 days with the transplant before recipient death · 52 days · 2024
3Towana Looney; graft explanted after acute rejection · 130 days · 2025
4Bill Stewart; at least 250 days and ongoing at the last public update (right-censored) · 250 days · 2026 · living human kidney recipient; graft remained in place at last public update
5Tim Andrews; graft explanted after declining function · 271 days · 2025

AInitial one-year durability · 365 daysInitial one-year durability · 365 days

Records are separate measurements; no line joins them. This carries forward the candidate node's recommended metric. Values are individual cases, not a survival curve: compassionate-use recipients differed sharply in illness, donor edits and immunosuppression. Stewart's 250-day point is a published minimum while ongoing, not a final outcome. The one-year line is an editorial near-term goal; the candidate node's ten-year mature benchmark is deliberately not plotted because it is aspirational, not a dated forecast. Brain-dead-body experiments are excluded because they cannot establish recipient survival or durable clinical independence from dialysis.

View data table

All independent metric records
Date	Value	Status	Condition / label	Verification	CI	Censoring	Source
2024	52 days	observed	Richard Slayman; 52 days with the transplant before recipient death	unspecified	—	none	Timeline · Living recipient leaves dialysis
2024	47 days	observed	Lisa Pisano; graft explanted after hypotension-related damage	unspecified	—	none	Timeline · Combined transplant ends at 47 days
2025	130 days	observed	Towana Looney; graft explanted after acute rejection	unspecified	—	none	Timeline · Looney reaches 130 days
2025	271 days	observed	Tim Andrews; graft explanted after declining function	unspecified	—	none	AP report on the 271-day completed record
2026	≥250 days	observed	Bill Stewart; at least 250 days and ongoing at the last public update (right-censored) living human kidney recipient; graft remained in place at last public update	unspecified	—	right	Timeline · Stewart remains dialysis-free

Metric context · these are authored references, not observed records
Context	Value	Label	Basis	Source
Goal	365 days	Initial one-year durability	—	Timeline · Living recipient leaves dialysis · Timeline · Combined transplant ends at 47 days · Timeline · Looney reaches 130 days · AP report on the 271-day completed record · Timeline · Stewart remains dialysis-free

Read this figureThis carries forward the candidate node's recommended metric. Values are individual cases, not a survival curve: compassionate-use recipients differed sharply in illness, donor edits and immunosuppression. Stewart's 250-day point is a published minimum while ongoing, not a final outcome. The one-year line is an editorial near-term goal; the candidate node's ten-year mature benchmark is deliberately not plotted because it is aspirational, not a dated forecast. Brain-dead-body experiments are excluded because they cannot establish recipient survival or durable clinical independence from dialysis.This carries forward the candidate node's recommended metric. Values are individual cases, not a survival curve: compassionate-use recipients differed sharply in illness, donor edits and immunosuppression. Stewart's 250-day point is a published minimum while ongoing, not a final outcome. The one-year line is an editorial near-term goal; the candidate node's ten-year mature benchmark is deliberately not plotted because it is aspirational, not a dated forecast. Brain-dead-body experiments are excluded because they cannot establish recipient survival or durable clinical independence from dialysis.

Stated conditionsBrain-dead models, baboon hearts and living human kidneys answer different questions; the records are independent and do not form one survival curve.Brain-dead models, baboon hearts and living human kidneys answer different questions; the records are independent and do not form one survival curve.

Source recordTimeline · Living recipient leaves dialysis ↗Timeline · Combined transplant ends at 47 days ↗Timeline · Looney reaches 130 days ↗AP report on the 271-day completed record ↗Timeline · Stewart remains dialysis-free ↗

AS OF July 2026

View every data figure

Dialysis-free functional pig-kidney graft survival in living recipientsDialysis-free functional pig-kidney graft survival in living recipients

010020030021354

1Lisa Pisano; graft explanted after hypotension-related damage · 47 days · 2024
2Richard Slayman; 52 days with the transplant before recipient death · 52 days · 2024
3Towana Looney; graft explanted after acute rejection · 130 days · 2025
4Bill Stewart; at least 250 days and ongoing at the last public update (right-censored) · 250 days · 2026 · living human kidney recipient; graft remained in place at last public update
5Tim Andrews; graft explanted after declining function · 271 days · 2025

AInitial one-year durability · 365 daysInitial one-year durability · 365 days

View data table

All independent metric records
Date	Value	Status	Condition / label	Verification	CI	Censoring	Source
2024	52 days	observed	Richard Slayman; 52 days with the transplant before recipient death	unspecified	—	none	Timeline · Living recipient leaves dialysis
2024	47 days	observed	Lisa Pisano; graft explanted after hypotension-related damage	unspecified	—	none	Timeline · Combined transplant ends at 47 days
2025	130 days	observed	Towana Looney; graft explanted after acute rejection	unspecified	—	none	Timeline · Looney reaches 130 days
2025	271 days	observed	Tim Andrews; graft explanted after declining function	unspecified	—	none	AP report on the 271-day completed record
2026	≥250 days	observed	Bill Stewart; at least 250 days and ongoing at the last public update (right-censored) living human kidney recipient; graft remained in place at last public update	unspecified	—	right	Timeline · Stewart remains dialysis-free

Metric context · these are authored references, not observed records
Context	Value	Label	Basis	Source
Goal	365 days	Initial one-year durability	—	Timeline · Living recipient leaves dialysis · Timeline · Combined transplant ends at 47 days · Timeline · Looney reaches 130 days · AP report on the 271-day completed record · Timeline · Stewart remains dialysis-free

AS OF July 2026

Observation windows expanded from 54 hours to 61 days, enabling richer physiology and rejection sampling, but these models are not clinical survival evidence.Observation windows expanded from 54 hours to 61 days, enabling richer physiology and rejection sampling, but these models are not clinical survival evidence.

Independent records

Brain-dead human kidney-study duration linear scale · days

linear scale · days

20212.25 days

Conditionbrain-dead human model; no recipient survival evidence

20223.21 days

Conditionbrain-dead human model; no recipient survival evidence

20237 days

Conditionbrain-dead human model; no recipient survival evidence

202361 days

Conditionbrain-dead human model; no recipient survival evidence

observed self-reported target / pathway right-censored lower bound

View data table

All plotted observations
Series	Date	Value	Status	Condition / label	Verification	CI	Censoring	Source
Brain-dead human kidney-study duration	2021	2.25 days	observed	Brain-dead human kidney-study duration brain-dead human model; no recipient survival evidence	unspecified	—	none	Timeline · Gene-edited kidney enters human body
Brain-dead human kidney-study duration	2022	3.21 days	observed	Brain-dead human kidney-study duration brain-dead human model; no recipient survival evidence	unspecified	—	none	Series · Brain-dead human kidney-study duration
Brain-dead human kidney-study duration	2023	7 days	observed	Brain-dead human kidney-study duration brain-dead human model; no recipient survival evidence	unspecified	—	none	Series · Brain-dead human kidney-study duration
Brain-dead human kidney-study duration	2023	61 days	observed	Brain-dead human kidney-study duration brain-dead human model; no recipient survival evidence	unspecified	—	none	NYU Langone 61-day immune-mapping study

AS OF July 2026

The 945-day heterotopic result did not support life; the more stringent orthotopic, life-supporting model reached 195 days, so this is a model comparison, not a declining trend.The 945-day heterotopic result did not support life; the more stringent orthotopic, life-supporting model reached 195 days, so this is a model comparison, not a declining trend.

Independent records

Selected pig-heart survival in baboons linear scale · days

linear scale · days

2016945 days

Conditionheterotopic, non-life-supporting baboon model

2018195 days

Conditionorthotopic, life-supporting baboon model

observed self-reported target / pathway right-censored lower bound

View data table

All plotted observations
Series	Date	Value	Status	Condition / label	Verification	CI	Censoring	Source
Selected pig-heart survival in baboons	2016	945 days	observed	Selected pig-heart survival in baboons heterotopic, non-life-supporting baboon model	unspecified	—	none	Timeline · Pig heart lasts 945 days
Selected pig-heart survival in baboons	2018	195 days	observed	Selected pig-heart survival in baboons orthotopic, life-supporting baboon model	unspecified	—	none	Timeline · Life-supporting hearts pass six months

AS OF July 2026

Engineering breadth increased, but edit count is not a performance score: competing clinical programs still test 10-edit and 69-edit kidneys.Engineering breadth increased, but edit count is not a performance score: competing clinical programs still test 10-edit and 69-edit kidneys.

Independent records

Maximum donor-pig genome modifications used in a human kidney study linear scale · genome modifications

linear scale · genome modifications

20211 genome modifications

Conditiondonor-pig genome-edit count in a human kidney study

202210 genome modifications

Conditiondonor-pig genome-edit count in a human kidney study

202469 genome modifications

Conditiondonor-pig genome-edit count in a human kidney study

observed self-reported target / pathway right-censored lower bound

View data table

All plotted observations
Series	Date	Value	Status	Condition / label	Verification	CI	Censoring	Source
Maximum donor-pig genome modifications used in a human kidney study	2021	1 genome modifications	observed	Maximum donor-pig genome modifications used in a human kidney study donor-pig genome-edit count in a human kidney study	unspecified	—	none	Timeline · Gene-edited kidney enters human body
Maximum donor-pig genome modifications used in a human kidney study	2022	10 genome modifications	observed	Maximum donor-pig genome modifications used in a human kidney study donor-pig genome-edit count in a human kidney study	unspecified	—	none	Series · Brain-dead human kidney-study duration
Maximum donor-pig genome modifications used in a human kidney study	2024	69 genome modifications	observed	Maximum donor-pig genome modifications used in a human kidney study donor-pig genome-edit count in a human kidney study	unspecified	—	none	Series · Maximum donor-pig genome modifications used in a human kidney study

AS OF July 2026

The U.S. kidney waiting list is more than three times annual kidney transplant volume.The U.S. kidney waiting list is more than three times annual kidney transplant volume.

The U.S. kidney waiting list is more than three times annual kidney transplant volume.

People waiting for a kidney90,400 people

Kidney transplants performed in 202427,759 transplants

Each value is scaled against zero in its own unit; bar length is not a cross-unit comparison.

View data table

All aligned comparisons
Claim	A	B	Source / provenance
The U.S. kidney waiting list is more than three times annual kidney transplant volume.	90400 people · People waiting for a kidney	27759 transplants · Kidney transplants performed in 2024	Timeline · Looney reaches 130 days

AS OF July 2026

The completed living-recipient record has covered about three quarters of the first one-year durability target.The completed living-recipient record has covered about three quarters of the first one-year durability target.

The completed living-recipient record has covered about three quarters of the first one-year durability target.

Completed record271 days

Initial durability goal365 days · target

ConditionThis is a durability goal, not a completed record.The 365-day value is an initial durability goal, not a completed recipient record.

Each value is scaled against zero in its own unit; bar length is not a cross-unit comparison.

View data table

All aligned comparisons
Claim	A	B	Source / provenance
The completed living-recipient record has covered about three quarters of the first one-year durability target.	271 days · Completed record	365 days · Initial durability goal · target This is a durability goal, not a completed record.The 365-day value is an initial durability goal, not a completed recipient record.	AP report on the 271-day completed record

AS OF July 2026

Two kidney programs are testing radically different genome-engineering strategies; more edits are not proven better.Two kidney programs are testing radically different genome-engineering strategies; more edits are not proven better.

Two kidney programs are testing radically different genome-engineering strategies; more edits are not proven better.

eGenesis EGEN-278469 genome modifications

United Therapeutics UKidney10 gene edits

Each value is scaled against zero in its own unit; bar length is not a cross-unit comparison.

View data table

All aligned comparisons
Claim	A	B	Source / provenance
Two kidney programs are testing radically different genome-engineering strategies; more edits are not proven better.	69 genome modifications · eGenesis EGEN-2784	10 gene edits · United Therapeutics UKidney	Comparison · Two kidney programs are testing radically different genome-engineering strategies; more edits are not proven better.

AS OF July 2026

A non-life-supporting heart model lasted far longer than the stricter replacement-heart model.A non-life-supporting heart model lasted far longer than the stricter replacement-heart model.

A non-life-supporting heart model lasted far longer than the stricter replacement-heart model.

Heterotopic baboon record945 days

Orthotopic life-supporting record195 days

Each value is scaled against zero in its own unit; bar length is not a cross-unit comparison.

View data table

All aligned comparisons
Claim	A	B	Source / provenance
A non-life-supporting heart model lasted far longer than the stricter replacement-heart model.	945 days · Heterotopic baboon record	195 days · Orthotopic life-supporting record	Comparison · A non-life-supporting heart model lasted far longer than the stricter replacement-heart model.

AS OF July 2026

Technical note 1 of 8

What the 69 edits comprise

Method and conditions

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.

Source notes

New England Journal of Medicine

Technical notes and sources

Each note keeps its authored method, conditions and citations available for review.

What the 69 edits comprise

New England Journal of Medicine

The 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.

Nature

The 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.

Nature

Microangiopathy 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.

Journal of Hepatology

The 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.

Nature Medicine

Short 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.

Nature Medicine

The 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.

Med

Edit 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.

Nature Medicine

05 · What it unlocksWhat it unlocks

If the remaining tests pass.If the remaining tests pass.

Downstream capabilities remain conditional on results that are not yet in.These are possible next capabilities, conditional on results that are not yet in.

TODAY

PASSED · Sep 202101 ↗
Survive the first attackAvoid immediate immune destructionThe organ must not be destroyed as soon as human blood reaches it.A gene-edited pig kidney reperfuses, filters blood and makes urine in a human body without hyperacute rejection.
PASSED · Apr 202402 ↗
Go home without dialysisReplace dialysis in a living personA real patient must live outside hospital without the dialysis machine.A living recipient leaves hospital with a functioning pig kidney and no dialysis requirement.
OPEN TEST03 ↗
Last a full yearSustain one dialysis-free yearThe best completed case reached 271 days; an ongoing case cannot count until the date passes.At least one living recipient retains a functional pig-kidney graft without dialysis for 365 days.
OPEN TEST04 ↗
Prove it across a groupProduce a survival distributionA few heroic cases cannot reveal the odds of success or rare infection harms.A controlled multicenter cohort reports recipient and graft survival, measured GFR, serious infections and quality of life.

PASSED · Sep 202101 ↗

Survive the first attackAvoid immediate immune destructionThe organ must not be destroyed as soon as human blood reaches it.A gene-edited pig kidney reperfuses, filters blood and makes urine in a human body without hyperacute rejection.

PASSED · Apr 202402 ↗

Go home without dialysisReplace dialysis in a living personA real patient must live outside hospital without the dialysis machine.A living recipient leaves hospital with a functioning pig kidney and no dialysis requirement.

TODAY

OPEN TEST03 ↗

OPEN TEST04 ↗

Possible, if the open tests pass.

An expandable organ supply
This is a possible benefit only if an expandable organ supply works safely, reliably and at useful scale.Potential benefit only if the stated use (An expandable organ supply) is demonstrated with evidence for safety, reliability, affordability and scale.
Earlier treatment of organ failure
This is a possible benefit only if earlier treatment of organ failure works safely, reliably and at useful scale.Potential benefit only if the stated use (Earlier treatment of organ failure) is demonstrated with evidence for safety, reliability, affordability and scale.
Bridges to human transplants
This is a possible benefit only if bridges to human transplants works safely, reliably and at useful scale.Potential benefit only if the stated use (Bridges to human transplants) is demonstrated with evidence for safety, reliability, affordability and scale.
A replaceable organ supply
This is a possible benefit only if a replaceable organ supply works safely, reliably and at useful scale.Potential benefit only if the stated use (A replaceable organ supply) is demonstrated with evidence for safety, reliability, affordability and scale.
Related problem ↗

These are possible outcomes, if the open tests pass. They are conditional, not promises.

06 · The players & the moneyThe players & the money

Meet the builders.Meet the builders.

The organisations, their approaches, and the evidence behind them.The teams doing the work, the money around them, and what the record can support.

Choose a builder

Official mark

USA · company

eGenesis

Engineers multi-edited porcine kidneys, livers and other organs

Funding contextSeries D · $191M · Sep 2024

Named investorsLux Capital · ARCH Ventures · Khosla Ventures · Fresenius Medical Care Ventures · Leaps by Bayer · DaVita

Capital is context, not a demonstration.

Company source ↗

View every builder record

eGenesis

USA · company · Engineers multi-edited porcine kidneys, livers and other organs

Funding: Series D · $191M · Sep 2024

Named investors: Lux Capital · ARCH Ventures · Khosla Ventures · Fresenius Medical Care Ventures · Leaps by Bayer · DaVita

Company source ↗