kidney xenotransplantation - the next great breakthrough in nephrology? david k.c. cooper md, phd,...

KIDNEY XENOTRANSPLANTATION- THE NEXT GREAT BREAKTHROUGH IN

NEPHROLOGY?

David K.C. Cooper MD, PhD, FRCS Thomas E. Starzl Transplantation Institute

University of Pittsburgh

COMPETING INTERESTS

I am Chairman of the Scientific Advisory Board of Revivicor, Inc., Blacksburg, VA, but I have no financial interest in the company and do not receive any remuneration whatsoever.

REVIVICOR

Small biotechnology company (25 staff) that concentrates its effort on the genetic engineering of pigs for medical purposes:

1. Xenotransplantation 2. Human immunoglobulin

(also for biodefense)

ACKNOWLEDGEMENTS

Many colleagues at STI, Allegheny GeneralHospital, and Revivicor

HISTORY OF XENOTRANSPLANTATION

XENOTRANSPLANTATION:

THE PIG AS THE ORGAN-SOURCE

XENOTRANSPLANTATION

Advantages 1:

1. Unlimited supply of donor organs.

2. Organs available electively.

3. Avoids effects of brain death.

4. Infection-free donors.

XENOTRANSPLANTATION

Advantages 2:

1. Borderline candidates

2. “Cultural” barriers to deceased donation (e.g. Japan)

3. Diabetes mellitus/cell transplants

CLINICAL PIG-TO-HUMAN XENOTRANSPLANTATION

Organs (kidney, heart, liver, lung)IsletsCorneas Neuronal cellsHepatocytesSkinRed blood cells

XENOTRANSPLANTATION:

BARRIERS

BARRIERS TO XENOTRANSPLANTATION

IMMUNOLOGIC Physiologic Safety (risk of infection) Ethical Regulatory / Legal

BARRIERS TO XENOTRANSPLANTATION

“Immunologic” includes: 1. Innate immune response (e.g.,

antibody, complement, macrophages)

2. Adaptive immune response (e.g., T and B cells)

3. Coagulation dysfunction (e.g., thrombin, platelets)

4. Inflammation

PIG ORGAN XENOTRANSPLANTATION

IN NONHUMAN PRIMATES

PIG-TO-BABOON KIDNEY TX (DAY 0)

PIG-TO-BABOON KIDNEY TX (HAR)

PORCINE HUMAN

αGal

NeuGc

ß4GalNT2

ABH

NeuAc

XENOTRANSPLANTATION:

EXPERIMENTAL PROGRESS

Solution 1

Gene-knockout of known antigenic targets for human anti-pig antibodies, e.g., αGal, NeuGc, ß4GalNT2

WT

GTKO/CD46

GTKO/CD46

/Neu

GcKO

Human

0

2

4

6

8

Rel

ativ

e M

FI

Human antibody binding to the AECs

*p<0.05 (n=6)

WT

GTKO/CD46

GTKO/CD46

/Neu

GcKO

Human

0

10

20

30

40

50

Rel

ativ

e M

FI

* *

*

*

**

IgM IgG

Solution 2

Pigs transgenic for a human protein, e.g., complement-

regulatory, coagulation-regulatory, anti-inflammatory, immunosuppressive agent

IsotypeGE pig AECs

Human AECs

Surface expression on genetically-engineered (GE) pig and human aortic endothelial cells (AECs)

CD55 (DAF) CD141 (TBM)CD46

CD55 (DAF) CD141 (TBM)CD46

GENETICALLY-ENGINEERED PIGS CURRENTLY AVAILABLE

Revivicor has produced pigs with 20 different genetic manipulations

Some pigs have 7 modifications

Worldwide, 40 different manipulations

ELICITED ANTI-PIG ANTIBODIES

Unless prevented by

immunosuppressive therapy, after

exposure to a pig organ or cells,

anti-pig antibodies can increase

>10-fold

PROGRESS IN PIG-TO-NHP KIDNEY TX

Progress in immunosuppressive therapy:Conventional (e.g., tacrolimus, steroids)Costimulation blockade(Genetically-engineered pigs)

PROGRESS IN PIG-TO-NHP KIDNEY TX

The Emory group had one monkey surviving >10 months with a life-supporting pig kidney graft

(The NIH group had two baboons surviving >1 year after a heterotopic heart graft)

PIG-TO-NHP RENAL XENOTX

GTKO/hDAF Rhesus macaque:

T cell depletion,

anti-CD154, MMF/steroids

BARRIERS TO XENOTRANSPLANTATION

Immunologic PHYSIOLOGIC Safety (risk of infection) Ethical Regulatory / Legal

B9313 - INCREASE IN SIZE OF KIDNEY

BARRIERS TO XENOTRANSPLANTATION

Immunologic Physiologic SAFETY (RISK OF

INFECTION) Ethical Regulatory / Legal

SAFETY OF XENOTRANSPLANTATION

Concern regarding potential transfer of infectious microorganisms to (1) recipient, (2) public

SAFETY OF XENOTRANSPLANTATION

‘Remaining’ potential risk:

Porcine endogenous retroviruses (PERVs)

BARRIERS TO XENOTRANSPLANTATION

Immunologic Physiologic Safety (risk of infection) ETHICAL REGULATORY / LEGAL

GENETICALLY-ENGINEERED PIGS

1. No unacceptable implications for the health and welfare of the pig2. No serious ethical objections to the genetic procedure

- brain (pig or human)- reproduction of one species by

the otherThe Netherlands

“There are many ways of losing money.

Women are the most fun. Gambling is the fastest. Research is the most certain.”

Lord HivesChairman of Rolls Royce

GENETICALLY-ENGINEERED PIGS

Recent new technologies, e.g., Zinc finger nucleasesTALENSCRISPR/Cas9

will facilitate the production of pigs with multiple genetic modifications

History tells us that procedures that were inconceivable yesterday, and are barely achievable today, often become routine tomorrow.

Thomas E. Starzl, 1982

POTENTIAL ALTERNATIVES TO XENOTRANSPLANTATION

1. Human stem cells2. Regenerative medicine3. Cell-based mechanical devices

FIRST CLINICAL TRIAL

? Patients highly-sensitized to alloantigens (high PRA)

? Patients with problems of vascular access for dialysis

“It is often sufficient to know, in the large, that

a thing may be possible”

Littre, 1710Royal Academy of

ScienceParis

One day “making a pig of yourself” could have a whole new meaning

THANK YOU