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Lamm V, Ekser B, Vagefi PA, Cooper DK. Bridging to Allotransplantation-Is Pig Liver Xenotransplantation the Best Option? Transplantation 2022; 106:26-36. [PMID: 33653996 PMCID: PMC10124768 DOI: 10.1097/tp.0000000000003722] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the past 20 y, the number of patients in the United States who died while waiting for a human donor liver totaled >52 000. The median national wait time for patients with acute liver failure and the most urgent liver transplant listing was 7 d in 2018. The need for a clinical "bridge" to allotransplantation is clear. Current options for supporting patients with acute liver failure include artificial liver support devices, extracorporeal liver perfusion, and hepatocyte transplantation, all of which have shown mixed results with regard to survival benefit and are largely experimental. Progress in the transplantation of genetically engineered pig liver grafts in nonhuman primates has grown steadily, with survival of the pig graft extended to almost 1 mo in 2017. Further advances may justify consideration of a pig liver transplant as a clinical bridge to allotransplantation. We provide a brief history of pig liver xenotransplantation, summarize the most recent progress in pig-to-nonhuman primate liver transplantation models, and suggest criteria that may be considered for patient selection for a clinical trial of bridging by genetically engineered pig liver xenotransplantation to liver allotransplantation.
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Affiliation(s)
- Vladimir Lamm
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Burcin Ekser
- Division of Transplant Surgery, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN
| | - Parsia A. Vagefi
- Division of Surgical Transplantation, Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX
| | - David K.C. Cooper
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
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2
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Naeem EM, Sajad D, Talaei-Khozani T, Khajeh S, Azarpira N, Alaei S, Tanideh N, Reza TM, Razban V. Decellularized liver transplant could be recellularized in rat partial hepatectomy model. J Biomed Mater Res A 2019; 107:2576-2588. [PMID: 31361939 DOI: 10.1002/jbm.a.36763] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 07/12/2019] [Accepted: 07/22/2019] [Indexed: 12/28/2022]
Abstract
In situ recellularization of the liver decellularized scaffold is a potential therapeutic alternative for liver transplantation. We aimed to develop an in situ procedure for recellularization of the rat liver using sodium lauryl ether sulfate (SLES) compared with Triton X-100/SDS. Rat liver specimens were rinsed with PBS, decellularized with either Triton X-100/SDS or SLES, and finally rinsed by distilled water. The efficiency of decellularized liver scaffolds was evaluated by histological, confocal Raman microscopy, histochemical staining, and DNA quantification assessments. Finally, in vivo studies were done to assess the biocompatibility of the liver scaffold by serum biochemical parameters and the recellularization capacity by histological and immunohistochemistry staining. Findings confirmed the preservation of extracellular matrix (ECM) components such as reticular, collagen, glycosaminoglycans, and neutral carbohydrates in both Triton X-100/SDS- and SLES-treated livers. Hoechst, feulgen, Hematoxylin and eosin, and DNA quantification assessments confirmed complete genetic content removal. The serological parameters showed no adverse impact on the liver functions. Transplantation of SLES-treated cell-free decellularized liver showed extensive neovascularization along with migration of the fibrocytes and adipocytes and some immune cells. Also, immunohistochemical staining showed that the oval cells, stellate cells, cholangiocytes and hepatocytes invaded extensively into the graft. It is concluded that SLES can be considered as a promising alternative in the liver decellularization process, and the transplanted decellularized liver can appropriately be revascularized and regenerated.
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Affiliation(s)
- Erfani M Naeem
- Department of Basic Sciences, Histology Section, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Daneshi Sajad
- Department of Basic Sciences, Histology Section, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Tahereh Talaei-Khozani
- Tissue Engineering Lab, Department of Anatomical Sciences, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.,Laboratory for Stem Cell Research, Department of Anatomical Sciences, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Sahar Khajeh
- Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Negar Azarpira
- Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Sanaz Alaei
- Department of Reproductive Biology, School of Advanced Medical Sciences and Applied Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Nader Tanideh
- Stem Cells Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Pharmacology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Tabandeh M Reza
- Department of Biochemistry and Molecular Biology, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Vahid Razban
- Stem Cells Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Molecular Medicine, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
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3
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Navarro-Alvarez N, Machaidze Z, Schuetz C, Zhu A, Liu WH, Shah JA, Vagefi PA, Elias N, Buhler L, Sachs DH, Markmann JF, Yeh H. Xenogeneic Heterotopic Auxiliary Liver transplantation (XHALT) promotes native liver regeneration in a Post-Hepatectomy Liver failure model. PLoS One 2018; 13:e0207272. [PMID: 30462716 PMCID: PMC6248961 DOI: 10.1371/journal.pone.0207272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 10/29/2018] [Indexed: 01/10/2023] Open
Abstract
The liver’s regenerative capacity is unique, but too small a segment can overwhelm its ability to simultaneously regenerate and support the host, resulting in liver dysfunction and death. Here we tested a temporary Xenogeneic Heterotopic Auxiliary Liver Transplant (XHALT) from Gal-KO miniature swine in a baboon model of Post-Hepatectomy Liver Failure (PHLF) by 90%- hepatectomy. Immunosuppression consisted of CVF, ATG, FK 506 and steroids. 90%-hepatectomized animals died within 4–5 days with the clinical picture of PHLF, (high LFTs and bilirubin, ascites, encephalopathy and coagulopathy). The 10% remnants had macroscopic and histological evidence of severe steatosis and absence of hepatocyte replication. In contrast, the addition of XHALT prolonged survival up to 11 days, with the cause of death being sepsis, rather than liver failure. The remnant liver appeared grossly normal, and on histology, there was no evidence of fatty infiltration, but there was pronounced Ki-67 staining. In conclusion, temporary auxiliary xenografts have the potential to support a small for size liver graft while it grows to adequate size or provide an opportunity for organ recovery in acute liver failure.
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Affiliation(s)
- Nalu Navarro-Alvarez
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Zurab Machaidze
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Christian Schuetz
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Alexander Zhu
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Wei-hui Liu
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Jigesh A. Shah
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Parsia A. Vagefi
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Nahel Elias
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Leo Buhler
- University of Geneva School of Medicine, Geneva, Switzerland
| | - David H. Sachs
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - James F. Markmann
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
| | - Heidi Yeh
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States of America
- * E-mail:
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4
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Chan JL, Miller JG, Singh AK, Horvath KA, Corcoran PC, Mohiuddin MM. Consideration of appropriate clinical applications for cardiac xenotransplantation. Clin Transplant 2018; 32:e13330. [DOI: 10.1111/ctr.13330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Joshua L. Chan
- Cardiothoracic Surgery Research Program/National Heart; Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
| | - Justin G. Miller
- Cardiothoracic Surgery Research Program/National Heart; Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
| | - Avneesh K. Singh
- Cardiothoracic Surgery Research Program/National Heart; Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
| | - Keith A. Horvath
- Cardiothoracic Surgery Research Program/National Heart; Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
| | - Philip C. Corcoran
- Cardiothoracic Surgery Research Program/National Heart; Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
| | - Muhammad M. Mohiuddin
- Cardiothoracic Surgery Research Program/National Heart; Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
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5
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Ogoke O, Oluwole J, Parashurama N. Bioengineering considerations in liver regenerative medicine. J Biol Eng 2017; 11:46. [PMID: 29204185 PMCID: PMC5702480 DOI: 10.1186/s13036-017-0081-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 09/25/2017] [Indexed: 12/19/2022] Open
Abstract
Background Liver disease contributes significantly to global disease burden and is associated with rising incidence and escalating costs. It is likely that innovative approaches, arising from the emerging field of liver regenerative medicine, will counter these trends. Main body Liver regenerative medicine is a rapidly expanding field based on a rich history of basic investigations into the nature of liver structure, physiology, development, regeneration, and function. With a bioengineering perspective, we discuss all major subfields within liver regenerative medicine, focusing on the history, seminal publications, recent progress within these fields, and commercialization efforts. The areas reviewed include fundamental aspects of liver transplantation, liver regeneration, primary hepatocyte cell culture, bioartificial liver, hepatocyte transplantation and liver cell therapies, mouse liver repopulation, adult liver stem cell/progenitor cells, pluripotent stem cells, hepatic microdevices, and decellularized liver grafts. Conclusion These studies highlight the creative directions of liver regenerative medicine, the collective efforts of scientists, engineers, and doctors, and the bright outlook for a wide range of approaches and applications which will impact patients with liver disease.
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Affiliation(s)
- Ogechi Ogoke
- Department of Chemical and Biological Engineering, University at Buffalo (State University of New York), Furnas Hall, Buffalo, NY 14260 USA.,Clinical and Translation Research Center (CTRC), University at Buffalo (State University of New York), 875 Ellicott St., Buffalo, NY 14203 USA
| | - Janet Oluwole
- Clinical and Translation Research Center (CTRC), University at Buffalo (State University of New York), 875 Ellicott St., Buffalo, NY 14203 USA.,Department of Biomedical Engineering, University at Buffalo (State University of New York), Furnas Hall, 907 Furnas Hall, Buffalo, NY 14260 USA
| | - Natesh Parashurama
- Department of Chemical and Biological Engineering, University at Buffalo (State University of New York), Furnas Hall, Buffalo, NY 14260 USA.,Clinical and Translation Research Center (CTRC), University at Buffalo (State University of New York), 875 Ellicott St., Buffalo, NY 14203 USA.,Department of Biomedical Engineering, University at Buffalo (State University of New York), Furnas Hall, 907 Furnas Hall, Buffalo, NY 14260 USA
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6
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Shah JA, Patel MS, Elias N, Navarro-Alvarez N, Rosales I, Wilkinson RA, Louras NJ, Hertl M, Fishman JA, Colvin RB, Cosimi AB, Markmann JF, Sachs DH, Vagefi PA. Prolonged Survival Following Pig-to-Primate Liver Xenotransplantation Utilizing Exogenous Coagulation Factors and Costimulation Blockade. Am J Transplant 2017; 17:2178-2185. [PMID: 28489305 PMCID: PMC5519420 DOI: 10.1111/ajt.14341] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/14/2017] [Accepted: 04/29/2017] [Indexed: 01/25/2023]
Abstract
Since the first attempt of pig-to-primate liver xenotransplantation (LXT) in 1968, survival has been limited. We evaluated a model utilizing α-1,3-galactosyltransferase knockout donors, continuous posttransplant infusion of human prothrombin concentrate complex, and immunosuppression including anti-thymocyte globulin, FK-506, methylprednisone, and costimulation blockade (belatacept, n = 3 or anti-CD40 mAb, n = 1) to extend survival. Baboon 1 remained well until postoperative day (POD) 25, when euthanasia was required because of cholestasis and plantar ulcers. Baboon 2 was euthanized following a seizure on POD 5, despite normal liver function tests (LFTs) and no apparent pathology. Baboon 3 demonstrated initial stable liver function but was euthanized on POD 8 because of worsening LFTs. Pathology revealed C4d positivity, extensive hemorrhagic necrosis, and a focal cytomegalovirus inclusion. Baboon 4 was clinically well with stable LFTs until POD29, when euthanasia was again necessitated by plantar ulcerations and rising LFTs. Final pathology was C4d negative and without evidence of rejection, inflammation, or thrombotic microangiopathy. Thus, nearly 1-mo rejection-free survival has been achieved following LXT in two of four consecutive recipients, demonstrating that the porcine liver can support life in primates for several weeks and has encouraging potential for clinical application as a bridge to allotransplantation for patients with acute-on-chronic or fulminant hepatic failure.
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Affiliation(s)
- J A Shah
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - M S Patel
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - N Elias
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - N Navarro-Alvarez
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - I Rosales
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - R A Wilkinson
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - N J Louras
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - M Hertl
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - J A Fishman
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - R B Colvin
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - A B Cosimi
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - J F Markmann
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - D H Sachs
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
| | - P A Vagefi
- Center for Transplantation Sciences, Massachusetts General Hospital/Harvard Medical School, Boston, MA
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7
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Cooper DK, Wijkstrom M, Hariharan S, Chan JL, Singh A, Horvath K, Mohiuddin M, Cimeno A, Barth RN, LaMattina JC, Pierson RN. Selection of Patients for Initial Clinical Trials of Solid Organ Xenotransplantation. Transplantation 2017; 101:1551-1558. [PMID: 27906824 PMCID: PMC5453852 DOI: 10.1097/tp.0000000000001582] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Several groups have reported extended survival of genetically engineered pig organs in nonhuman primates, varying from almost 10 months for life-supporting kidney grafts and more than 2 years for non-life-supporting heart grafts to less than 1 month for life-supporting liver and lung grafts. We have attempted to define groups of patients who may not have an option to wait for an allograft. These include kidney, heart, and lung candidates who are highly-allosensitized. In addition, some kidney candidates (who have previously lost at least 2 allografts from rapid recurrence of native kidney disease) have a high risk of further recurrence and will not be offered a repeat allotransplant. Patients with complex congenital heart disease, who may have undergone previous palliative surgical procedures, may be unsuitable for ventricular assist device implantation. Patients dying of fulminant hepatic failure, for whom no alternative therapy is available, may be candidates for a pig liver, even if only as a bridge until an allograft becomes available. When the results of pig organ xenotransplantation in nonhuman primates suggest a realistic potential for success of a pilot clinical trial, highly selected patients should be offered participation.
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Affiliation(s)
- David K.C. Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA
| | - Martin Wijkstrom
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA
| | - Sundaram Hariharan
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA
| | - Joshua L. Chan
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Avneesh Singh
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Keith Horvath
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Muhammad Mohiuddin
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Arielle Cimeno
- Division of Transplantation Surgery, Department of Surgery, University of Maryland, Baltimore VAMC, Baltimore, MD
| | - Rolf N. Barth
- Division of Transplantation Surgery, Department of Surgery, University of Maryland, Baltimore VAMC, Baltimore, MD
| | - John C. LaMattina
- Division of Transplantation Surgery, Department of Surgery, University of Maryland, Baltimore VAMC, Baltimore, MD
| | - Richard N. Pierson
- Division of Cardiac Surgery, Department of Surgery, University of Maryland, Baltimore VAMC, Baltimore, MD, USA
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8
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Abstract
Experience with clinical liver xenotransplantation has largely involved the transplantation of livers from nonhuman primates. Experience with pig livers has been scarce. This brief review will be restricted to assessing the potential therapeutic impact of pig liver xenotransplantation in acute liver failure and the remaining barriers that currently do not justify clinical trials. A relatively new surgical technique of heterotopic pig liver xenotransplantation is described that might play a role in bridging a patient with acute liver failure until either the native liver recovers or a suitable liver allograft is obtained. Other topics discussed include the possible mechanisms for the development of the thrombocytopenis that rapidly occurs after pig liver xenotransplantation in a primate, the impact of pig complement on graft injury, the potential infectious risks, and potential physiologic incompatibilities between pig and human. There is cautious optimism that all of these problems can be overcome by judicious genetic manipulation of the pig. If liver graft survival could be achieved in the absence of thrombocytopenia or rejection for a period of even a few days, there may be a role for pig liver transplantation as a bridge to allotransplantation in carefully selected patients.
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9
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Cooper DKC. Early clinical xenotransplantation experiences-An interview with Thomas E. Starzl, MD, PhD. Xenotransplantation 2017; 24:10.1111/xen.12306. [PMID: 28421681 PMCID: PMC5431570 DOI: 10.1111/xen.12306] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 03/20/2017] [Accepted: 03/20/2017] [Indexed: 11/29/2022]
Abstract
Dr Thomas E. Starzl, who died on March 4, 2017, was one of the great pioneers of organ transplantation. He was also a pioneer in the field of xenotransplantation. In 1964, he carried out baboon kidney transplants in six patients with terminal renal disease for whom no living or deceased donor became available; graft survival was for 19-60 days, the grafts being lost largely through continuous complement activation. Between 1966 and 1974, he carried out one ex vivo liver perfusion and three orthotopic liver transplants using chimpanzees as sources of organs; graft survival was for <14 days. In 1992 and 1993, his team carried out baboon liver transplantation in two patients with cirrhosis from hepatitis B infection; graft survival was for 70 and 26 days, respectively. This early clinical experience is briefly discussed. Toward the end of his life, Dr Starzl was somewhat disillusioned by what he considered excessive regulation of medical research in the United States and believed that new advances were now likely to take place in countries such as China, where the regulatory framework is less developed.
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Affiliation(s)
- David K C Cooper
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham (UAB), Birmingham, AL, USA
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10
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Cooper DKC, Ezzelarab MB, Hara H, Iwase H, Lee W, Wijkstrom M, Bottino R. The pathobiology of pig-to-primate xenotransplantation: a historical review. Xenotransplantation 2016; 23:83-105. [PMID: 26813438 DOI: 10.1111/xen.12219] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 12/22/2015] [Indexed: 12/16/2022]
Abstract
The immunologic barriers to successful xenotransplantation are related to the presence of natural anti-pig antibodies in humans and non-human primates that bind to antigens expressed on the transplanted pig organ (the most important of which is galactose-α1,3-galactose [Gal]), and activate the complement cascade, which results in rapid destruction of the graft, a process known as hyperacute rejection. High levels of elicited anti-pig IgG may develop if the adaptive immune response is not prevented by adequate immunosuppressive therapy, resulting in activation and injury of the vascular endothelium. The transplantation of organs and cells from pigs that do not express the important Gal antigen (α1,3-galactosyltransferase gene-knockout [GTKO] pigs) and express one or more human complement-regulatory proteins (hCRP, e.g., CD46, CD55), when combined with an effective costimulation blockade-based immunosuppressive regimen, prevents early antibody-mediated and cellular rejection. However, low levels of anti-non-Gal antibody and innate immune cells and/or platelets may initiate the development of a thrombotic microangiopathy in the graft that may be associated with a consumptive coagulopathy in the recipient. This pathogenic process is accentuated by the dysregulation of the coagulation-anticoagulation systems between pigs and primates. The expression in GTKO/hCRP pigs of a human coagulation-regulatory protein, for example, thrombomodulin, is increasingly being associated with prolonged pig graft survival in non-human primates. Initial clinical trials of islet and corneal xenotransplantation are already underway, and trials of pig kidney or heart transplantation are anticipated within the next few years.
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Affiliation(s)
- David K C Cooper
- The Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mohamed B Ezzelarab
- The Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Hidetaka Hara
- The Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Hayato Iwase
- The Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Whayoung Lee
- The Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Martin Wijkstrom
- The Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rita Bottino
- Institute for Cellular Therapeutics, Allegheny-Singer Research Institute, Pittsburgh, PA, USA
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11
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Ekser B, Markmann JF, Tector AJ. Current status of pig liver xenotransplantation. Int J Surg 2015; 23:240-246. [PMID: 26190837 DOI: 10.1016/j.ijsu.2015.06.083] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 06/28/2015] [Indexed: 12/26/2022]
Abstract
The shortage of organs from deceased human donors is a major problem limiting the number of organs transplanted each year and results in the death of thousands of patients on the waiting list. Pigs are currently the preferred species for clinical organ xenotransplantation. Progress in genetically-engineered (GE) pig liver xenotransplantation increased graft and recipient survival from hours with unmodified pig livers to up to 9 days with normal to near-normal liver function. Deletion of genes such as GGTA1 (Gal-knockout pigs) or adding genes such as human complement regulatory proteins (hCD55, hCD46 expressing pigs) enabled hyperacute rejection to be overcome. Although survival up to 9 days was recorded, extended pig graft survival was not achieved due to lethal thrombocytopenia. The current status of GE pig liver xenotransplantation with world experience, potential factors causing thrombocytopenia, new targets on pig endothelial cells, and novel GE pigs with more genes deletion to avoid remaining antibody response, such as beta1,4-N-acetyl galactosaminyl transferase 2 (β4GalNT2), are discussed.
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Affiliation(s)
- Burcin Ekser
- Transplant Division, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - James F Markmann
- Division of Transplantation, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
| | - A Joseph Tector
- Transplant Division, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
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12
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Clinical Outcome of Autologous Hematopoietic Stem Cell Infusion via Hepatic Artery or Portal Vein in Patients with End-stage Liver Diseases. ACTA ACUST UNITED AC 2014; 29:15-22. [DOI: 10.1016/s1001-9294(14)60018-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Ekser B, Burlak C, Waldman JP, Lutz AJ, Paris LL, Veroux M, Robson SC, Rees MA, Ayares D, Gridelli B, Tector AJ, Cooper DKC. Immunobiology of liver xenotransplantation. Expert Rev Clin Immunol 2012; 8:621-34. [PMID: 23078060 PMCID: PMC3774271 DOI: 10.1586/eci.12.56] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pigs are currently the preferred species for future organ xenotransplantation. With advances in the development of genetically modified pigs, clinical xenotransplantation is becoming closer to reality. In preclinical studies (pig-to-nonhuman primate), the xenotransplantation of livers from pigs transgenic for human CD55 or from α1,3-galactosyltransferase gene-knockout pigs+/- transgenic for human CD46, is associated with survival of approximately 7-9 days. Although hepatic function, including coagulation, has proved to be satisfactory, the immediate development of thrombocytopenia is very limiting for pig liver xenotransplantation even as a 'bridge' to allotransplantation. Current studies are directed to understand the immunobiology of platelet activation, aggregation and phagocytosis, in particular the interaction between platelets and liver sinusoidal endothelial cells, hepatocytes and Kupffer cells, toward identifying interventions that may enable clinical application.
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Affiliation(s)
- Burcin Ekser
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
- Department of Surgery, Transplant Institute, Indiana University School of Medicine, Indiana University Health, Indianapolis, IN, USA
- Department of Surgery, Transplantation and Advanced Technologies, Vascular Surgery and Organ Transplant Unit, University Hospital of Catania, Catania, Italy
| | - Christopher Burlak
- Department of Surgery, Transplant Institute, Indiana University School of Medicine, Indiana University Health, Indianapolis, IN, USA
| | - Joshua P Waldman
- Department of Urology, University of Toledo Health Sciences Campus, Toledo, OH, USA
| | - Andrew J Lutz
- Department of Surgery, Transplant Institute, Indiana University School of Medicine, Indiana University Health, Indianapolis, IN, USA
| | - Leela L Paris
- Department of Surgery, Transplant Institute, Indiana University School of Medicine, Indiana University Health, Indianapolis, IN, USA
| | - Massimiliano Veroux
- Department of Surgery, Transplantation and Advanced Technologies, Vascular Surgery and Organ Transplant Unit, University Hospital of Catania, Catania, Italy
| | - Simon C Robson
- Liver Center, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Michael A Rees
- Department of Urology, University of Toledo Health Sciences Campus, Toledo, OH, USA
| | | | - Bruno Gridelli
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy
| | - A Joseph Tector
- Department of Surgery, Transplant Institute, Indiana University School of Medicine, Indiana University Health, Indianapolis, IN, USA
| | - David KC Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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Li J, Li WC, Song J, Zhang HM, Yu MH, He XJ, Wang MH, Wang HQ, Huang TZ. Effect of Sex on Biomechanical Properties of the Proper Hepatic Artery in Pigs and Humans for Liver Xenotransplant. EXP CLIN TRANSPLANT 2012; 10:356-62. [DOI: 10.6002/ect.2011.0136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ekser B, Klein E, He J, Stolz DB, Echeverri GJ, Long C, Lin CC, Ezzelarab M, Hara H, Veroux M, Ayares D, Cooper DKC, Gridelli B. Genetically-engineered pig-to-baboon liver xenotransplantation: histopathology of xenografts and native organs. PLoS One 2012; 7:e29720. [PMID: 22247784 PMCID: PMC3256162 DOI: 10.1371/journal.pone.0029720] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 12/02/2011] [Indexed: 11/18/2022] Open
Abstract
Orthotopic liver transplantation was carried out in baboons using wild-type (WT, n = 1) or genetically-engineered pigs (α1,3-galactosyltransferase gene-knockout, GTKO), n = 1; GTKO pigs transgenic for human CD46, n = 7) and a clinically-acceptable immunosuppressive regimen. Biopsies were obtained from the WT pig liver pre-Tx and at 30 min, 1, 2, 3, 4 and 5 h post-transplantation. Biopsies of genetically-engineered livers were obtained pre-Tx, 2 h after reperfusion and at necropsy (4–7 days after transplantation). Tissues were examined by light, confocal, and electron microscopy. All major native organs were also examined. The WT pig liver underwent hyperacute rejection. After genetically-engineered pig liver transplantation, hyperacute rejection did not occur. Survival was limited to 4–7 days due to repeated spontaneous bleeding in the liver and native organs (as a result of profound thrombocytopenia) which necessitated euthanasia. At 2 h, graft histology was largely normal. At necropsy, genetically-engineered pig livers showed hemorrhagic necrosis, platelet aggregation, platelet-fibrin thrombi, monocyte/macrophage margination mainly in liver sinusoids, and vascular endothelial cell hypertrophy, confirmed by confocal and electron microscopy. Immunohistochemistry showed minimal deposition of IgM, and almost absence of IgG, C3, C4d, C5b-9, and of a cellular infiltrate, suggesting that neither antibody- nor cell-mediated rejection played a major role.
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Affiliation(s)
- Burcin Ekser
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- Department of Surgery, Transplantation and Advanced Technologies, Vascular Surgery and Organ Transplant Unit, University Hospital of Catania, Catania, Italy
| | - Edwin Klein
- Division of Laboratory Animal Resources, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jing He
- Division of Immunogenetics, Department of Pediatrics, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Donna B. Stolz
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Gabriel J. Echeverri
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy
| | - Cassandra Long
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Chih Che Lin
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mohamed Ezzelarab
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Hidetaka Hara
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Massimiliano Veroux
- Department of Surgery, Transplantation and Advanced Technologies, Vascular Surgery and Organ Transplant Unit, University Hospital of Catania, Catania, Italy
| | - David Ayares
- Revivicor Inc., Blacksburg, Virginia, United States of America
| | - David K. C. Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| | - Bruno Gridelli
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy
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Ekser B, Gridelli B, Veroux M, Cooper DK. Clinical pig liver xenotransplantation: how far do we have to go? Xenotransplantation 2011; 18:158-67. [DOI: 10.1111/j.1399-3089.2011.00642.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Hara H, Campanile N, Tai HC, Long C, Ekser B, Yeh P, Welchons D, Ezzelarab M, Ayares D, Cooper DKC. An in vitro model of pig liver xenotransplantation--pig complement is associated with reduced lysis of wild-type and genetically modified pig cells. Xenotransplantation 2011; 17:370-8. [PMID: 20955293 DOI: 10.1111/j.1399-3089.2010.00602.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND After pig liver transplantation in humans, the graft will produce pig complement (C). We investigated in vitro the lysis of wild-type (WT), α1,3-galactosyltransferase gene-knockout (GTKO), and CD46 transgenic (CD46) pig peripheral blood mononuclear cells (PBMC) caused by human anti-pig antibodies (Abs) + pig C. METHODS Human serum IgM/IgG binding to WT and GTKO PBMC was determined by flow cytometry, and lysis of pig PBMC by a C-dependent cytotoxicity assay using (i) human serum (human Abs + C), (ii) GTKO pig serum (anti-Gal Abs + pig C), (iii) heat-inactivated human serum (human Abs) + rabbit C, or (iv) human Abs + pig C (serum). RESULTS Binding of human IgM and IgG to GTKO PBMC was less than to WT PBMC (P < 0.05). In the presence of human Abs, lysis of WT and GTKO PBMC by rabbit C was 87 and 13%, respectively (WT vs. GTKO, P < 0.01), but was only 37 and 0.4% in the presence of pig C (WT vs. GTKO, P < 0.05). Human/rabbit C-induced lysis was greater than pig C-induced lysis for both WT and GTKO PBMC. CD46 pig PBMC reduced rabbit/human C- and pig C-mediated lysis (P < 0.05). CONCLUSIONS Pig livers, particularly from GTKO and CD46 pigs, are likely to have an immunologic advantage over other organs after transplantation into humans. In the absence of pig antibodies directed to human tissues, pig complement is unlikely to cause problems after liver xenotransplantation, especially if GTKO/CD46 pigs are used as the source of the livers.
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Affiliation(s)
- Hidetaka Hara
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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Ekser B, Cooper DKC. Overcoming the barriers to xenotransplantation: prospects for the future. Expert Rev Clin Immunol 2010; 6:219-30. [PMID: 20402385 PMCID: PMC2857338 DOI: 10.1586/eci.09.81] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cross-species transplantation (xenotransplantation) has immense potential to solve the critical need for organs, tissues and cells for clinical transplantation. The increasing availability of genetically engineered pigs is enabling progress to be made in pig-to-nonhuman primate experimental models. Potent pharmacologic immunosuppressive regimens have largely prevented T-cell rejection and a T-cell-dependent elicited antibody response. However, coagulation dysfunction between the pig and primate is proving to be a major problem, and this can result in life-threatening consumptive coagulopathy. This complication is unlikely to be overcome until pigs expressing a human 'antithrombotic' or 'anticoagulant' gene, such as thrombomodulin, tissue factor pathway inhibitor or CD39, become available. Progress in islet xenotransplantation has been more encouraging, and diabetes has been controlled in nonhuman primates for periods in excess of 6 months, although this has usually been achieved using immunosuppressive protocols that might not be clinically applicable. Further advances are required to overcome the remaining barriers.
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Affiliation(s)
- Burcin Ekser
- Thomas E Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA, and Department of Surgery and Organ Transplantation, University of Padua, Padua, Italy
| | - David KC Cooper
- Thomas E Starzl Transplantation Institute, University of Pittsburgh Medical Center, Starzl Biomedical Science Tower, W1543, 200 Lothrop Street, Pittsburgh, PA 15261, USA, Tel.: +1 412 383 6961, Fax: +1 412 624 1172,
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Ekser B, Long C, Echeverri GJ, Hara H, Ezzelarab M, Lin CC, de Vera ME, Wagner R, Klein E, Wolf RF, Ayares D, Cooper DKC, Gridelli B. Impact of thrombocytopenia on survival of baboons with genetically modified pig liver transplants: clinical relevance. Am J Transplant 2010; 10:273-85. [PMID: 20041862 DOI: 10.1111/j.1600-6143.2009.02945.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A lack of deceased human donor livers leads to a significant mortality in patients with acute-on-chronic or acute (fulminant) liver failure or with primary nonfunction of an allograft. Genetically engineered pigs could provide livers that might bridge the patient to allotransplantation. Orthotopic liver transplantation in baboons using livers from alpha1,3-galactosyltransferase gene-knockout (GTKO) pigs (n = 2) or from GTKO pigs transgenic for CD46 (n = 8) were carried out with a clinically acceptable immunosuppressive regimen. Six of 10 baboons survived for 4-7 days. In all cases, liver function was adequate, as evidenced by tests of detoxification, protein synthesis, complement activity and coagulation parameters. The major problem that prevented more prolonged survival beyond 7 days was a profound thrombocytopenia that developed within 1 h after reperfusion, ultimately resulting in spontaneous hemorrhage at various sites. We postulate that this is associated with the expression of tissue factor on platelets after contact with pig endothelium, resulting in platelet and platelet-peripheral blood mononuclear cell(s) aggregation and deposition of aggregates in the liver graft, though we were unable to confirm this conclusively. If this problem can be resolved, we would anticipate that a pig liver could provide a period during which a patient in liver failure could be successfully bridged to allotransplantation.
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Affiliation(s)
- B Ekser
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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Ekser B, Gridelli B, Tector AJ, Cooper DKC. Pig liver xenotransplantation as a bridge to allotransplantation: which patients might benefit? Transplantation 2009; 88:1041-9. [PMID: 19898198 PMCID: PMC2778799 DOI: 10.1097/tp.0b013e3181ba0555] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Acute liver failure is a potentially devastating clinical syndrome that, without liver transplantation (Tx), is associated with high mortality. Rapid deterioration in clinical status and a shortage of deceased human organs prohibits liver Tx in many patients. Bridging to liver Tx has been attempted by various approaches, for example, bioartificial liver support, extracorporeal pig liver perfusion, and hepatocyte Tx, but none of these approaches has convincingly improved patient survival. The orthotopic Tx of a genetically engineered pig liver could theoretically provide successful bridging. Immediate availability, perfect metabolic condition, adequate size-match and hepatocyte mass, and freedom from potentially pathogenic microorganisms could be assured. The advantages and disadvantages of bridging by pig liver Tx compared with other approaches are discussed. The selection of patients for an initial clinical trial of pig liver Tx would be similar to that of various prior trials in patients experiencing rapid and severe deterioration in liver function. The ability to give truly informed consent for a pig bridging procedure at the time of listing for liver Tx renders the patient with acute-on-chronic liver failure or primary allograft failure is a preferable candidate for this procedure than a patient who is admitted urgently with acute (fulminant) liver failure in whom consent may not be possible. Although several barriers to successful pig organ xenoTx remain, for example, coagulation dysfunction between pig and primate, if these can be resolved by further genetic engineering of the organ-source pigs, a pig liver may prove life saving to patients dying rapidly of liver failure.
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Affiliation(s)
- Burcin Ekser
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA
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MATAL J, TUNKOVÁ A, ŠILLER M, ANZENBACHEROVÁ E, ANZENBACHER P. Isolation of two cytochrome P450 forms, CYP2A19 and CYP1A, from pig liver microsomes. J Vet Pharmacol Ther 2009; 32:470-6. [DOI: 10.1111/j.1365-2885.2009.01076.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Current world literature. Curr Opin Organ Transplant 2009; 14:211-7. [PMID: 19307967 DOI: 10.1097/mot.0b013e32832ad721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Baertschiger RM, Buhler LH. Xenotransplantation literature update March-April, 2008. Xenotransplantation 2008; 15:277-80. [PMID: 18957050 DOI: 10.1111/j.1399-3089.2008.00485.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ekser B, Rigotti P, Gridelli B, Cooper DKC. Xenotransplantation of solid organs in the pig-to-primate model. Transpl Immunol 2008; 21:87-92. [PMID: 18955143 DOI: 10.1016/j.trim.2008.10.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2008] [Accepted: 10/09/2008] [Indexed: 12/12/2022]
Abstract
Xenotransplantation using pig organs could solve the significant increasing shortage of donor organs for allotransplantation. In the last two decades, major progress has been made in understanding the xenoimmunobiology of pig-to-nonhuman primate transplantation, and today we are close to clinical trials. The ability to genetically engineer pigs, such as human decay-accelerating factor (hDAF), CD46 (membrane cofactor protein), or alpha1,3-galactosyltransferase gene-knockout (GT-KO), has been a significant step toward the clinical application of xenotransplantation. Using GT-KO pigs and novel immunosuppressant agents, 2 to 6 months' survival of heterotopic heart xenotransplants has been achieved. In life-supporting kidney xenotransplantation, promising survival of close to 3 months has been achieved. However, liver and lung xenotransplantations do not have such encouraging survival as kidney and heart xenotransplantation. Although the introduction of hDAF and GT-KO pigs largely overcame hyperacute rejection, acute humoral xenograft rejection (AHXR) remains a challenge to be overcome if survival is to be increased. In several studies, when classical AHXR was prevented, thrombotic microangiopathy and coagulation dysregulation became more obvious, which make them another hurdle to be overcome. The initiating cause of failure of pig cardiac and renal xenografts may be antibody-mediated injury to the endothelium, leading to the development of microvascular thrombosis. Potential contributing factors toward the development of the thrombotic microangiopathy include: 1) the presence of preformed anti-non-Gal antibodies, 2) the development of very low levels of elicited antibodies to non-Gal antigens, 3) natural killer cell or macrophage activity, and 4) inherent coagulation dysregulation between pigs and primates. The breeding of pigs transgenic for an 'anticoagulant' or 'anti-thrombotic' gene, such as human tissue factor pathway inhibitor, hirudin, or CD39, or lacking the gene for the prothrombinase, fibrinogen-like protein-2, is anticipated to inhibit the change in the endothelium to a procoagulant state that takes place in the pig organ after transplantation. A further limitation for organ xenotransplantation is the potential for cross-species infection. As far as exogenous viruses are concerned, porcine cytomegalovirus has been detected in the tissues of recipient non-human primates, although no invasive disease was reported. Until today, no formal evidence has been presented from in vivo studies in non-human primates or from humans exposed to pig organs, tissues, or cells that porcine endogenous retroviruses infect primate cells. Xenotransplantation is a potential answer to the current organ shortage. Its future depends on; 1) further genetic modification of pigs, 2) the introduction of novel immunosuppressive agents that target the innate immune system and plasma cells, and 3) the development of clinically-applicable methods to induce donor-specific tolerance.
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Affiliation(s)
- Burcin Ekser
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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Cooper DK. Frankenswine, or bringing home the bacon: How close are we to clinical trials in xenotransplantation? Organogenesis 2008; 4:1-10. [PMID: 19279708 DOI: 10.4161/org.5383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 01/31/2008] [Indexed: 11/19/2022] Open
Abstract
Xenotransplantation-specifically from pig into human-could resolve the critical shortage of organs, tissues and cells for clinical transplantation. Genetic engineering techniques in pigs are relatively well-developed and to date have largely been aimed at producing pigs that either (1) express high levels of one or more human complement-regulatory protein(s), such as decay-accelerating factor or membrane cofactor protein, or (2) have deletion of the gene responsible for the expression of the oligosaccharide, Galalpha1,3Gal (Gal), the major target for human anti-pig antibodies, or (3) have both manipulations. Currently the transplantation of pig organs in adequately-immunosuppressed baboons results in graft function for periods of 2-6 months (auxiliary hearts) and 2-3 months (life-supporting kidneys). Pig islets have maintained normoglycemia in diabetic monkeys for >6 months. The remaining immunologic barriers to successful xenotransplantation are discussed, and brief reviews made of (1) the potential risk of the transmission of an infectious microorganism from pig to patient and possibly to the public at large, (2) the potential physiologic incompatibilities between a pig organ and its human counterpart, (3) the major ethical considerations of clinical xenotransplantation, and (4) the possible alternatives that compete with xenotransplantation in the field of organ or cell replacement, such as mechanical devices, tissue engineering, stem cell biology and organogenesis. Finally, the proximity of clinical trials is discussed. Islet xenotransplantation is already at the stage where clinical trials are actively being considered, but the transplantation of pig organs will probably require further genetic modifications to be made to the organ-source pigs to protect their tissues from the coagulation/anticoagulation dysfunction that plays a significant role in pig graft failure after transplantation in primates.
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Affiliation(s)
- David Kc Cooper
- Thomas E. Starzl Transplantation Institute; Department of Surgery; University of Pittsburgh; Pittsburgh, Pennsylvania USA
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