Download Genetically-engineered pigs

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 General
Hospital, 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)
Islets
Corneas
Neuronal cells
Hepatocytes
Skin
Red 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
ABH
NeuGc
NeuAc
ß4GalNT2
XENOTRANSPLANTATION:
EXPERIMENTAL PROGRESS
Solution 1
Gene-knockout of known
antigenic targets for human
anti-pig antibodies, e.g.,
αGal, NeuGc, ß4GalNT2
D
/C
O
an
O
6
um
cK
46
IgM
H
eu
G
D
8
46
/N
/C
0
O
*
TK
*
T
20
Relative MFI
30
W
um
an
O
10
H
cK
eu
G
46
40
G
46
/N
D
/C
*
TK
D
/C
O
O
50
G
TK
G
TK
G
T
W
Relative MFI
Human antibody binding to the AECs
IgG
*
*
4
*
2
0
*p<0.05 (n=6)
Solution 2
Pigs transgenic for a human
protein, e.g., complementregulatory, coagulationregulatory, anti-inflammatory,
immunosuppressive agent
Surface expression on genetically-engineered (GE) pig
and human aortic endothelial cells (AECs)
Isotype
GE pig AECs
CD46
CD55 (DAF)
CD141 (TBM)
CD46
CD55 (DAF)
CD141 (TBM)
Human AECs
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 lifesupporting 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 pig
2. No serious ethical objections to
the genetic procedure
- brain (pig or human)
- reproduction of one species by
the other
The Netherlands
“There are many ways of losing
money.
Women are the most fun.
Gambling is the fastest.
Research is the most certain.”
Lord Hives
Chairman of Rolls Royce
GENETICALLY-ENGINEERED PIGS
Recent new technologies, e.g.,
Zinc finger nucleases
TALENS
CRISPR/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 cells
2. Regenerative medicine
3. 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, 1710
Royal Academy of Science
Paris
One day “making a
pig of yourself” could
have a whole new
meaning
THANK YOU