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Liver Xenotransplantation Comprehensive Development Program
A. Joseph Tector MD PhD
Indiana University
School of Medicine
Clarian Transplant Institute
Need for Alternative Source of Organs
• 98,000 Americans are waiting for a solid organ transplant
• 46,000 have died waiting for a transplant since 2000
Xenotransplantation
• Unlimited source of donor organs for all types of transplants
• Potential to genetically engineer donor animals to eliminate immunological barriers
Problems with Xenotransplantation
• Immunological barriers– Hyperacute rejection– Acute vascular rejection– Cellular rejection
• Physiological barriers– Animal proteins may or may not work with human
counterparts Coagulation proteins
Problems with Xenotransplantation
• Risks of zoonotic infection– Porcine Endogenous Retrovirus (PERV)
• Finding an indication with immediate chance to benefit patient
The Case Against Cardiac and Renal Xenografts
• Dialysis can be tolerated for years
• Assist devices can bridge a patient for
12-18 months
• Xenograft would need to function at least 6 months to be considered for a clinical trial
The Case for Liver Xenotransplantation
• Temporary liver support is lacking
• Liver xenograft could be used to bridge patients for a period of days and be a success
The Patient
The Solution
Three Weeks Following Pig Liver Perfusion
Followed by Human Liver Transplant
Recipients with Liver Failure are Less Capable of Rejecting a Liver
Xenograft
The Program
Jose Estrada DVM PhDSanjeev Wagmere PhD
We Lou PhDJing Mo
Pig Cloning/Genetic EngineeringBashir Mir DVM PhD
Richard Sidner PhDLuz Estrada PhD
Vijay BindingnavileKathryn Dalbec MD
XenoimmunologyChris Burlak PhD
William Switzer PhDTom Folks PhD
Jay Fishman MDTony Goldberg DVM PhD
Zoonotic IssuesNathan Wolfe DsC
Regulatory/Community RelationsDave Bromund JD
Matthew Johnson MDEric Meslin PhD
Rafat Abonour MDPaul Helft MD
BioethicsJenny Girod RN JD PhD
R. Shane Mangus MD MSRodrigo Vianna MDAshesh Shah MD
Carrie Sanders RN
Preclinical ProgramA. Joseph Tector MD PhD
Liver XenotransplantationA. Joseph Tector MD PhD
Genetic Engineering of
Donor Pigs
Advantages of Genetic Engineering
• Decrease response of the human immune system
• Minimize zoonotic infectious risk
• Eliminate physiologic incompatibilities
Nuclear Transfer Procedure
EnucleatedEnucleated OocyteOocyte
Nucleated OocyteNucleated Oocyte
Fused dubletFused dublet
CLONECLONE
ActivationActivation
DubletDublet
Nuclear DonorNuclear DonorSomatic CellSomatic Cell
Enucleation
1st polar body
Enucleation
1st polar body Metaphase plate
Dublet Preparation
Nuclear donor
Enucleated oocyte or Cytoplast
Product of Genetic Engineering
Better Way to Make Pigs
• Bank fetal fibroblasts
• Make genetic modifications on fibroblast from latest generation of donor pig
• Eliminate expensive and time consuming breeding programs
Better Way to Make Pigs
• Eliminate need for large herds and big farms
• New pig every 6 months instead of 2-3 years
Gal Knockout Construct
LH PURO RH
SalI BstXI AscI MluIMluI
Human CD39/CD59 Construct
Human CD46/CD47 Construct
Next Steps in Donor Engineering
• Introduce GTKO, CD/39/59, and CD46/47 constructs into fetal fibroblasts (1 month)
• SCNT to produce pigs (5 months)
• Transgenes to minimize risks of zoonotic infections
• Transgenes to decrease cellular immunity
Xenograft Immunology
• Christopher Burlak PhD started July 1, 2008
– PhD student working on non-gal xenoantigens
– Surgical Resident studying T- cell xenoimmunology
Zoonotic Considerations
• May 2008 - Hired viral forecaster Dr. Nathan Wolfe DsC, UCLA School of Epidemiology, as a consultant to setup guidelines for monitoring xenograft recipients, their personal contacts, and health care workers
• He is in the process of establishing an advisory board to provide guidance with regards to infectious risks
Operative Considerations in Pig to Human Liver
Xenografts
Pig Liver in Situ
Human Cadaver
Suprahepatic Cava Anastamosis
Portal Venous and Hepatic Arterial Anastamoses
Next Steps
• We will transplant pig livers into brain-dead individuals
– We should have GTKO pigs in early January
– We could begin transplanting in late February or early March
• If the GTKO pig livers function for 24 hours we could begin to use these organs as a bridge to transplant for clinical liver transplantation