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Singh AK, Goerlich CE, Shah AM, Zhang T, Tatarov I, Ayares D, Horvath KA, Mohiuddin MM. Cardiac Xenotransplantation: Progress in Preclinical Models and Prospects for Clinical Translation. Transpl Int 2022; 35:10171. [PMID: 35401039 PMCID: PMC8985160 DOI: 10.3389/ti.2022.10171] [Citation(s) in RCA: 1] [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: 11/01/2021] [Accepted: 01/11/2022] [Indexed: 12/02/2022]
Abstract
Survival of pig cardiac xenografts in a non-human primate (NHP) model has improved significantly over the last 4 years with the introduction of costimulation blockade based immunosuppression (IS) and genetically engineered (GE) pig donors. The longest survival of a cardiac xenograft in the heterotopic (HHTx) position was almost 3 years and only rejected when IS was stopped. Recent reports of cardiac xenograft survival in a life-sustaining orthotopic (OHTx) position for 6 months is a significant step forward. Despite these achievements, there are still several barriers to the clinical success of xenotransplantation (XTx). This includes the possible transmission of porcine pathogens with pig donors and continued xenograft growth after XTx. Both these concerns, and issues with additional incompatibilities, have been addressed recently with the genetic modification of pigs. This review discusses the spectrum of issues related to cardiac xenotransplantation, recent progress in preclinical models, and its feasibility for clinical translation.
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Affiliation(s)
- Avneesh K. Singh
- Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Corbin E. Goerlich
- Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Aakash M. Shah
- Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Tianshu Zhang
- Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Ivan Tatarov
- Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, United States
| | | | - Keith A. Horvath
- National Heart, Lung, and Blood Institute, National Institute of Health, Bethesda, MD, United States
| | - Muhammad M. Mohiuddin
- Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, United States
- *Correspondence: Muhammad M. Mohiuddin,
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Bikhet M, Iwase H, Yamamoto T, Jagdale A, Foote JB, Ezzelarab M, Anderson DJ, Locke JE, Eckhoff DE, Hara H, Cooper DKC. What Therapeutic Regimen Will Be Optimal for Initial Clinical Trials of Pig Organ Transplantation? Transplantation 2021; 105:1143-1155. [PMID: 33534529 DOI: 10.1097/tp.0000000000003622] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We discuss what therapeutic regimen might be acceptable/successful in the first clinical trial of genetically engineered pig kidney or heart transplantation. As regimens based on a calcineurin inhibitor or CTLA4-Ig have proved unsuccessful, the regimen we administer to baboons is based on induction therapy with antithymocyte globulin, an anti-CD20 mAb (Rituximab), and cobra venom factor, with maintenance therapy based on blockade of the CD40/CD154 costimulation pathway (with an anti-CD40 mAb), with rapamycin, and a corticosteroid. An anti-inflammatory agent (etanercept) is administered for the first 2 wk, and adjuvant therapy includes prophylaxis against thrombotic complications, anemia, cytomegalovirus, and pneumocystis. Using this regimen, although antibody-mediated rejection certainly can occur, we have documented no definite evidence of an adaptive immune response to the pig xenograft. This regimen could also form the basis for the first clinical trial, except that cobra venom factor will be replaced by a clinically approved agent, for example, a C1-esterase inhibitor. However, none of the agents that block the CD40/CD154 pathway are yet approved for clinical use, and so this hurdle remains to be overcome. The role of anti-inflammatory agents remains unproven. The major difference between this suggested regimen and those used in allotransplantation is the replacement of a calcineurin inhibitor with a costimulation blockade agent, but this does not appear to increase the complications of the regimen.
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Affiliation(s)
- Mohamed Bikhet
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Hayato Iwase
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Takayuki Yamamoto
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Abhijit Jagdale
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Jeremy B Foote
- Department of Microbiology and Animal Resources Program, University of Alabama at Birmingham, Birmingham, AL
| | - Mohamed Ezzelarab
- Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Douglas J Anderson
- Division of Transplantation, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Jayme E Locke
- Division of Transplantation, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Devin E Eckhoff
- Division of Transplantation, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Hidetaka Hara
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - David K C Cooper
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
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DiChiacchio L, Singh AK, Chan JL, Shockcor NM, Zhang T, Lewis BG, Ayares D, Corcoran P, Horvath KA, Mohiuddin MM. Intra-Abdominal Heterotopic Cardiac Xenotransplantation: Pearls and Pitfalls. Front Cardiovasc Med 2019; 6:95. [PMID: 31404245 PMCID: PMC6669937 DOI: 10.3389/fcvm.2019.00095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 06/25/2019] [Indexed: 11/22/2022] Open
Abstract
Heterotopic cardiac xenotransplantation in the intra-abdominal position has been studied extensively in a pig-to-baboon model to define the optimal donor genetics and immunosuppressive regimen to prevent xenograft rejection. Extensive investigation using this model is a necessary stepping stone toward the development of a life-supporting animal model, with the ultimate goal of demonstrating suitability for clinical cardiac xenotransplantation trials. Aspects of surgical technique, pre- and post-operative care, graft monitoring, and minimization of infectious risk have all required refinement and optimization of heterotopic cardiac xenotransplantation over time. This review details non-immunologic obstacles relevant to this model described by our group and in the literature, as well as strategies that have been developed to address these specific challenges.
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Affiliation(s)
- Laura DiChiacchio
- Department of Surgery, University of Maryland Medical Center, Baltimore, MD, United States
| | - Avneesh K. Singh
- Department of Surgery, University of Maryland Medical Center, Baltimore, MD, United States
| | - Joshua L. Chan
- National Heart, Lung, Blood Institute, National Institute of Health, Bethesda, MD, United States
| | - Nicole M. Shockcor
- Department of Surgery, University of Maryland Medical Center, Baltimore, MD, United States
| | - Tianshu Zhang
- Department of Surgery, University of Maryland Medical Center, Baltimore, MD, United States
| | - Billeta G. Lewis
- Department of Surgery, University of Maryland Medical Center, Baltimore, MD, United States
| | | | - Philip Corcoran
- National Heart, Lung, Blood Institute, National Institute of Health, Bethesda, MD, United States
| | - Keith A. Horvath
- National Heart, Lung, Blood Institute, National Institute of Health, Bethesda, MD, United States
| | - Muhammad M. Mohiuddin
- Department of Surgery, University of Maryland Medical Center, Baltimore, MD, United States
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Yamamoto T, Li Q, Hara H, Wang L, Zhou H, Li J, Eckhoff DE, Joseph Tector A, Klein EC, Lovingood R, Ezzelarab M, Ayares D, Wang Y, Cooper DKC, Iwase H. B cell phenotypes in baboons with pig artery patch grafts receiving conventional immunosuppressive therapy. Transpl Immunol 2018; 51:12-20. [PMID: 30092338 PMCID: PMC6249078 DOI: 10.1016/j.trim.2018.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/03/2018] [Accepted: 08/03/2018] [Indexed: 12/29/2022]
Abstract
BACKGROUND In the pig-to-baboon artery patch model with no immunosuppressive therapy, a graft from an α1,3-galactosyltransferase gene-knockout (GTKO) pig elicits a significant anti-nonGal IgG response, indicating sensitization to the graft. A costimulation blockade-based regimen, e.g., anti-CD154mAb or anti-CD40mAb, prevents sensitization. However, neither of these agents is currently FDA-approved. The aim of the present study was to determine the efficacy of FDA-approved agents on the T and B cell responses. METHODS Artery patch xenotransplantation in baboons was carried out using GTKO/CD46 pigs with (n = 2) or without (n = 1) the mutant transgene for CIITA-knockdown. Immunosuppressive therapy consisted of induction with ATG and anti-CD20mAb, and maintenance with different combinations of CTLA4-Ig, tacrolimus, and rapamycin. In addition, all 3 baboons received daily corticosteroids, the IL-6R blocker, tocilizumab, at regular intervals, and the TNF-α blocker, etanercept, for the first 2 weeks. Recipient blood was monitored for anti-nonGal antibody levels by flow cytometry (using GTKO/CD46 pig aortic endothelial cells), and mixed lymphocyte reaction (MLR). CD22+B cell profiles (naïve [IgD+/CD27-], non-switched memory [IgD+/CD27+], and switched memory [IgD-/CD27+] B cell subsets) were measured by flow cytometry. At 6 months, the baboons were euthanized and the grafts were examined histologically. RESULTS No elicited anti-pig antibodies developed in any baboon. The frequency of naïve memory B cells increased significantly (from 34% to 90%, p = 0.0015), but there was a significant decrease in switched memory B cells (from 17% to 0.5%, p = 0.015). MLR showed no increase in the proliferative T cell response in those baboons that had received CTLA4-Ig (n = 2). Histological examination showed few or no features of rejection in any graft. CONCLUSIONS The data suggest that immunosuppressive therapy with only FDA-approved agents may be adequate to prevent an adaptive immune response to a genetically-engineered pig graft, particularly if CTLA4-Ig is included in the regimen, in part because the development of donor-specific memory B cells is inhibited.
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Affiliation(s)
- Takayuki Yamamoto
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Qi Li
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA; Second Affiliated Hospital, University of South China, Hengyang City, Hunan, China
| | - Hidetaka Hara
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Liaoran Wang
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA; Second Affiliated Hospital, University of South China, Hengyang City, Hunan, China
| | - Hongmin Zhou
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Cardiothoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Juan Li
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA; Second Affiliated Hospital, University of South China, Hengyang City, Hunan, China
| | - Devin E Eckhoff
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - A Joseph Tector
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Edwin C Klein
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ray Lovingood
- Kirklin Clinic Pharmacy, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Mohamed Ezzelarab
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Yi Wang
- Second Affiliated Hospital, University of South China, Hengyang City, Hunan, China
| | - David K C Cooper
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hayato Iwase
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA.
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Porcine to Human Heart Transplantation: Is Clinical Application Now Appropriate? J Immunol Res 2017; 2017:2534653. [PMID: 29238731 PMCID: PMC5697125 DOI: 10.1155/2017/2534653] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 10/08/2017] [Indexed: 11/24/2022] Open
Abstract
Cardiac xenotransplantation (CXTx) is a promising solution to the chronic shortage of donor hearts. Recent advancements in immune suppression have greatly improved the survival of heterotopic CXTx, now extended beyond 2 years, and life-supporting kidney XTx. Advances in donor genetic modification (B4GALNT2 and CMAH mutations) with proven Gal-deficient donors expressing human complement regulatory protein(s) have also accelerated, reducing donor pig organ antigenicity. These advances can now be combined and tested in life-supporting orthotopic preclinical studies in nonhuman primates and immunologically appropriate models confirming their efficacy and safety for a clinical CXTx program. Preclinical studies should also allow for organ rejection to develop xenospecific assays and therapies to reverse rejection. The complexity of future clinical CXTx presents a substantial and unique set of regulatory challenges which must be addressed to avoid delay; however, dependent on these prospective life-supporting preclinical studies in NHPs, it appears that the scientific path forward is well defined and the era of clinical CXTx is approaching.
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Denner J. Xenotransplantation and porcine cytomegalovirus. Xenotransplantation 2016; 22:329-35. [PMID: 26381491 DOI: 10.1111/xen.12180] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/19/2015] [Indexed: 11/29/2022]
Abstract
Porcine microorganisms may be transmitted to the human recipient when xenotransplantation with pig cells, tissues, and organs will be performed. Most of such microorganisms can be eliminated from the donor pig by specified or designated pathogen-free production of the animals. As human cytomegalovirus causes severe transplant rejection in allotransplantation, considerable concern is warranted on the potential pathogenicity of porcine cytomegalovirus (PCMV) in the setting of xenotransplantation. On the other hand, despite having a similar name, PCMV is different from HCMV. The impact of PCMV infection on pigs is known; however, the influence of PCMV on the human transplant recipient is unclear. However, first transplantations of pig organs infected with PCMV into non-human primates were associated with a significant reduction of the survival time of the transplants. Sensitive detection methods and strategies for elimination of PCMV from donor herds are required.
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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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Cooper DK, Ekser B, Ramsoondar J, Phelps C, Ayares D. The role of genetically engineered pigs in xenotransplantation research. J Pathol 2016; 238:288-99. [PMID: 26365762 PMCID: PMC4689670 DOI: 10.1002/path.4635] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 07/22/2015] [Accepted: 09/06/2015] [Indexed: 12/12/2022]
Abstract
There is a critical shortage in the number of deceased human organs that become available for the purposes of clinical transplantation. This problem might be resolved by the transplantation of organs from pigs genetically engineered to protect them from the human immune response. The pathobiological barriers to successful pig organ transplantation in primates include activation of the innate and adaptive immune systems, coagulation dysregulation and inflammation. Genetic engineering of the pig as an organ source has increased the survival of the transplanted pig heart, kidney, islet and corneal graft in non-human primates (NHPs) from minutes to months or occasionally years. Genetic engineering may also contribute to any physiological barriers that might be identified, as well as to reducing the risks of transfer of a potentially infectious micro-organism with the organ. There are now an estimated 40 or more genetic alterations that have been carried out in pigs, with some pigs expressing five or six manipulations. With the new technology now available, it will become increasingly common for a pig to express even more genetic manipulations, and these could be tested in the pig-to-NHP models to assess their efficacy and benefit. It is therefore likely that clinical trials of pig kidney, heart and islet transplantation will become feasible in the near future.
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Affiliation(s)
- David K.C. Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA
| | - Burcin Ekser
- Transplant Division, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN
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Denner J, Mueller NJ. Preventing transfer of infectious agents. Int J Surg 2015; 23:306-311. [PMID: 26316157 PMCID: PMC7185644 DOI: 10.1016/j.ijsu.2015.08.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/27/2015] [Accepted: 08/04/2015] [Indexed: 12/13/2022]
Abstract
Xenotransplantation using pig cells, tissues and organs may be associated with the transfer of porcine infectious agents, which may infect the human recipient and in the worst case induce a disease (zoonosis). To prevent this, a broad screening program of the donor animals for putative zoonotic microorganisms, including bacteria, viruses, fungi and others, using sensitive and specific detection methods has to be performed. As long as it is still unknown, which microorganism represents a real risk for the recipient, experience from allotransplantation should be brought in. Due to the fact that pigs can be screened long before the date of transplantation, xenotransplantation will become eventually safer compared with allotransplantation. Screening and selection of animals free of potential zoonotic microorganisms, Caesarean section, vaccination and/or treatment with chemotherapeutics are the strategies of choice to obtain donor animals not transmitting microorganisms. In the case of porcine endogenous retroviruses (PERVs) which are integrated in the genome of all pigs and which cannot be eliminated this way, selection of animals with low virus expression and generation of genetically modified pigs suppressing PERV expressions may be performed.
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Affiliation(s)
| | - Nicolas J Mueller
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Switzerland
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Cooper DKC, Satyananda V, Ekser B, van der Windt DJ, Hara H, Ezzelarab MB, Schuurman HJ. Progress in pig-to-non-human primate transplantation models (1998-2013): a comprehensive review of the literature. Xenotransplantation 2014; 21:397-419. [PMID: 25176336 DOI: 10.1111/xen.12127] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/03/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND The pig-to-non-human primate model is the standard choice for in vivo studies of organ and cell xenotransplantation. In 1998, Lambrigts and his colleagues surveyed the entire world literature and reported all experimental studies in this model. With the increasing number of genetically engineered pigs that have become available during the past few years, this model is being utilized ever more frequently. METHODS We have now reviewed the literature again and have compiled the data we have been able to find for the period January 1, 1998 to December 31, 2013, a period of 16 yr. RESULTS The data are presented for transplants of the heart (heterotopic and orthotopic), kidney, liver, lung, islets, neuronal cells, hepatocytes, corneas, artery patches, and skin. Heart, kidney, and, particularly, islet xenograft survival have increased significantly since 1998. DISCUSSION The reasons for this are briefly discussed. A comment on the limitations of the model has been made, particularly with regard to those that will affect progression of xenotransplantation toward the clinic.
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Affiliation(s)
- David K C Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
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Corcoran PC, Horvath KA, Singh AK, Hoyt RF, Thomas ML, Eckhaus MA, Mohiuddin MM. Surgical and nonsurgical complications of a pig to baboon heterotopic heart transplantation model. Transplant Proc 2011; 42:2149-51. [PMID: 20692430 DOI: 10.1016/j.transproceed.2010.05.116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A modified immunosuppressive regimen, developed at the National Institutes of Health, has been employed in a large animal model of heterotopic cardiac xenotransplantation. Graft survival has been prolonged, but despite this, our recipients have succumbed to various surgical or nonsurgical complications. Herein, we have described different complications and management strategies. The most common complication was hypercoagulability (HC) after transplantation, causing thrombosis of both small and large vasculature, ultimately leading to graft loss. While managing this complication we discovered that there was a delicate balance between HC and consumptive coagulopathy (CC). CC encountered in some recipient baboons was not able to be reversed by stopping anticoagulation and administering multiple blood transfusions. Some complications had iatrogenic components. To monitor the animals, a solid state left ventricular telemetry probe was placed directly into the transplanted heart via the apex. Induction of hypocoagulable states by continuous heparin infusion led to uncontrollable intra-abdominal bleeding in 1 baboon from this apical site. This occurrence necessitated securing the probe more tightly with multiple purse strings and 4-quadrant pledgeted stay sutures. One instance of cardiac rupture originated from a lateral wall infarction site. Earlier studies have shown infections to be uniformly fatal in this transplant model. However, owing to the telemetry placement, infections were identified early by temperature spikes that were treated promptly with antibiotics. We had several cases of wound dehiscence due to recipients disrupting the suture line. These complications were promptly resolved by either re-approximating the wound or finding distractions for the baboon. A few of the most common problems we faced in our earlier experiments were related to the jacket, tether, and infusion pumps. It was difficult to keep the jackets on some baboons and the tether had to be modified several times before we assured long-term success. Infusion catheter replacement resulted in transplant heart venous obstruction and thrombosis from a right common femoral venous line. Homeostatic perturbations such as HC and CC and baboon-induced wound complications comprised most complications. Major bleeding and death due to telemetry implantation and infarct rupture occurred in 2 baboons. Despite the variety of complications, we achieved significant graft prolongation in this model.
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Affiliation(s)
- P C Corcoran
- Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, USA
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Cooper DK, Teuteberg JJ. Pig heart xenotransplantation as a bridge to allotransplantation. J Heart Lung Transplant 2010; 29:838-40. [DOI: 10.1016/j.healun.2010.03.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 03/26/2010] [Accepted: 03/30/2010] [Indexed: 11/27/2022] Open
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Pierson RN, Dorling A, Ayares D, Rees MA, Seebach JD, Fishman JA, Hering BJ, Cooper DKC. Current status of xenotransplantation and prospects for clinical application. Xenotransplantation 2009; 16:263-80. [PMID: 19796067 PMCID: PMC2866107 DOI: 10.1111/j.1399-3089.2009.00534.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Xenotransplantation is one promising approach to bridge the gap between available human cells, tissues, and organs and the needs of patients with diabetes or end-stage organ failure. Based on recent progress using genetically modified source pigs, improving results with conventional and experimental immunosuppression, and expanded understanding of residual physiologic hurdles, xenotransplantation appears likely to be evaluated in clinical trials in the near future for some select applications. This review offers a comprehensive overview of known mechanisms of xenograft injury, a contemporary assessment of preclinical progress and residual barriers, and our opinions regarding where breakthroughs are likely to occur.
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Affiliation(s)
- Richard N Pierson
- Division of Cardiac Surgery, Department of Surgery, University of Maryland, Baltimore VAMC, Baltimore, MD 21201, USA.
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Ricci D, Tazelaar HD, Miyagi N, Rao VP, Pedersen RA, Kremers WK, Byrne GW, McGregor CGA. The utility of right ventricular endomyocardial biopsy for the diagnosis of xenograft rejection after CD46 pig-to-baboon cardiac transplantation. J Heart Lung Transplant 2007; 26:1025-32. [PMID: 17919623 DOI: 10.1016/j.healun.2007.07.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 07/05/2007] [Accepted: 07/15/2007] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION Endomyocardial biopsy is the standard means of establishing cardiac allograft rejection diagnosis. The efficacy of this procedure in xenotransplantation has not been determined. In this study we compare the histology of right ventricular endomyocardial biopsy specimens with the corresponding full cross sections of explanted right ventricle (RV). We also compare RV with the related left ventricle (LV) cross sections. METHODS Heterotopic CD46 pig-to-baboon cardiac xenotransplants (n = 64) were studied. RV endomyocardial biopsy specimens were taken at cardiac explant by using a standard bioptome (n = 24) or by sharp dissection (n = 40). Hematoxylin and eosin stained sections of RV and LV cross-section and RV endomyocardial biopsy specimens were compared in a blinded fashion. Characteristics of delayed xenograft rejection and a global assessment of ischemia were scored from 0 to 4 according to the percentage of myocardium involved (0, 0%; 1, 1%-25%; 2, 26%-50%; 3, 51%-75%; and 4, 76%-100%). RESULTS Median graft survival was 30 days (range, 3-137 days). Linear regression analysis of histology scores demonstrated that specimens from both bioptome and sharp dissection equally represented the histology of the RV cross section. Global ischemic injury was strongly correlated between RV and RV endomyocardial biopsy (R(2) = 0.84) and between RV and LV cross sections (R(2) = 0.84). Individual characteristics of delayed xenograft rejection showed no significant variation between RV and RV endomyocardial biopsy or between RV and LV (p < 0.05). CONCLUSIONS These results indicate that delayed xenograft rejection is a widespread process involving both right and left ventricles similarly. This study shows that histologic assessment of RV endomyocardial biopsy specimens is an effective method for the monitoring of delayed xenograft rejection after cardiac xenotransplantation.
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Affiliation(s)
- Davide Ricci
- Mayo Clinic William J von Liebig Transplant Center, Mayo Clinic, Rochester, Minnesota 55905, USA
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Cooper DKC, Dorling A, Pierson RN, Rees M, Seebach J, Yazer M, Ohdan H, Awwad M, Ayares D. Alpha1,3-galactosyltransferase gene-knockout pigs for xenotransplantation: where do we go from here? Transplantation 2007; 84:1-7. [PMID: 17627227 DOI: 10.1097/01.tp.0000260427.75804.f2] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The ability to genetically engineer pigs that no longer express the Galalpha1,3Gal (Gal) oligosaccharide has been a significant step toward the clinical applicability of xenotransplantation. Using a chronic immunosuppressive regimen based on costimulatory blockade, hearts from these pigs have survived from 2 to 6 months in baboons. Graft failure was predominantly from the development of a thrombotic microangiopathy. Potential contributing factors include the presence of preformed anti-nonGal antibodies or the development of low levels of elicited antibodies to nonGal antigens, natural killer (NK) cell or macrophage activity, and inherent coagulation dysregulation between pigs and primates. The breeding of pigs transgenic for an "anticoagulant" 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. The identification of the targets for anti-nonGal antibodies and/or human macrophages might allow further genetic modification of the pig, and xenogeneic NK cell recognition and activation may be inhibited by the transgenic expression of human leukocyte antigen molecules and/or by blocking the function of activating NK receptors. The ultimate goal of induction of T-cell tolerance may be possible only if these hurdles in the coagulation system and innate immunity can be overcome.
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Affiliation(s)
- David K C Cooper
- The Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
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Yang YG, Sykes M. Xenotransplantation: current status and a perspective on the future. Nat Rev Immunol 2007; 7:519-31. [PMID: 17571072 DOI: 10.1038/nri2099] [Citation(s) in RCA: 231] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Xenotransplantation using pigs as the transplant source has the potential to resolve the severe shortage of human organ donors. Although the development of relatively non-toxic immunosuppressive or tolerance-inducing regimens will be required to justify clinical trials using pig organs, recent advances in our understanding of the biology of xenograft rejection and zoonotic infections, and the generation of alpha1,3-galactosyltransferase-deficient pigs have moved this approach closer to clinical application. This Review highlights the major obstacles impeding the translation of xenotransplantation into clinical therapies and the potential solutions, providing a perspective on the future of clinical xenotransplantation.
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Affiliation(s)
- Yong-Guang Yang
- Bone Marrow Transplantation Section, Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA
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Ezzelarab M, Yeh P, Wagner R, Cooper DKC. Babesia as a complication of immunosuppression following pig-to-baboon heart transplantation. Xenotransplantation 2007; 14:162-5. [PMID: 17381691 DOI: 10.1111/j.1399-3089.2007.00375.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a baboon that developed anemia, leukocytosis, fever, and anorexia while immunosuppressed following a pig heart transplant. Blood smears indicated babesia infection of the erythrocytes, and this was confirmed by polymerase chain reaction. A 1-week course of treatment with doxycycline successfully eradicated the organism. Babesia, a widespread blood parasite that can infect humans, has been reported to be present in the erythrocytes of approximately a third of baboons housed in facilities in the USA, without overt signs of infection. Immunosuppression can reduce the host's immune system, and result in proliferation of the parasite, leading to hemolysis and other features of infection, sometimes with fatal outcome.
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Affiliation(s)
- Mohamed Ezzelarab
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA. [corrected]
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Xenotransplantation of thoracic organs. Curr Opin Organ Transplant 2007. [DOI: 10.1097/mot.0b013e32809876fc] [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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Byrne GW, Davies WR, Oi K, Rao VP, Teotia SS, Ricci D, Tazelaar HD, Walker RC, Logan JS, McGregor CGA. Increased immunosuppression, not anticoagulation, extends cardiac xenograft survival. Transplantation 2007; 82:1787-91. [PMID: 17198277 DOI: 10.1097/01.tp.0000251387.40499.0f] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cardiac xenograft function is lost due to delayed xenograft rejection (DXR) characterized by microvascular thrombosis and myocardial necrosis. The cause of DXR is unknown but may result from thrombosis induced by antibody-mediated activation of endothelial cells and/or by incompatibilities in thromboregulatory interactions. METHODS To examine these issues, a series (Groups 1-6) of previous transgenic CD46 pig-to-baboon heterotopic cardiac transplants were reanalyzed for baseline immunosuppressive levels, graft survival and infectious complications with and without systemic anticoagulation. Groups 1-4 received low dose tacrolimus and sirolimus maintenance therapy, with splenectomy, anti-CD20 and daily alpha-Gal polymer. Group 1 recipients received no anticoagulation. Groups 2-4 were anticoagulated with aspirin and Plavix, Lovenox, or Coumadin, respectively. Group 5 was treated with Lovenox and high dose tacrolimus and sirolimus maintenance therapy. Group 6 recipients received no postoperative anticoagulation but the same immunosuppression as group 5. RESULTS Median survival (15-22 days) within groups 1-4 was not significantly different. At rejection all tissues exhibited microvascular thrombosis, coagulative necrosis and similar levels of platelet and fibrin deposition. Groups 5 and 6 median survival (76 days) was significantly increased compared to groups 1-4. There was no significant difference in median survival between Lovenox treated recipients (68 days) and anticoagulant free recipients (96 days). Rejected tissues showed vascular antibody deposition, microvascular thrombosis, and myocyte necrosis. CONCLUSION Significant prolongation in xenograft survival is achieved by improved immunosuppression. These results suggest that ongoing immune responses remain the major stimulus for DXR.
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Affiliation(s)
- Guerard W Byrne
- William J. von Liebig Transplant Center, Mayo Clinic-Rochester, Rochester, MN 55905, USA.
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Pierson RN. Primate T-cell responses to porcine antigens: implications for clinical xenotransplantation. Xenotransplantation 2006; 13:14-8. [PMID: 16497208 DOI: 10.1111/j.1399-3089.2005.00268.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Richard N Pierson
- Department of Surgery, University of Maryland Medical System Staff Surgeon, Baltimore VAMC, Baltimore, MD, USA.
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Xenotransplantation: the road ahead. Curr Opin Organ Transplant 2006. [DOI: 10.1097/01.mot.0000218928.96901.b1] [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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McGregor CGA, Davies WR, Oi K, Teotia SS, Schirmer JM, Risdahl JM, Tazelaar HD, Kremers WK, Walker RC, Byrne GW, Logan JS. Cardiac xenotransplantation: recent preclinical progress with 3-month median survival. J Thorac Cardiovasc Surg 2005; 130:844-51. [PMID: 16153938 DOI: 10.1016/j.jtcvs.2005.04.017] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 04/07/2005] [Accepted: 04/07/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Transplantation is limited by a lack of human organ donors. Organs derived from animals, most likely the pig, represent a potential solution to this problem. For the heart, 90-day median graft survival of life-supporting pig hearts transplanted to nonhuman primates has been considered a reasonable standard for entry into the clinical arena. Overcoming the immune barrier to successful cardiac xenotransplantation is most appropriately first explored with the non-life-supporting heterotopic model. METHODS We performed a series of 7 heterotopic heart transplantations from CD46 transgenic pigs to baboons using a combination of therapeutic agents largely targeted at controlling the synthesis of anti-pig antibodies. Rituximab (anti-CD20) and Thymoglobulin (rabbit antithymocyte globulin [ATG]; SangStat Medical Corp, Fremont, Calif) were used as induction therapy. Baseline immunosuppression consisted of splenectomy, tacrolimus, sirolimus, steroids, and TPC (an anti-Gal antibody therapeutic). Rejection events were not treated. RESULTS By using Kaplan-Meier analysis, median graft survival was 96 days (range, 15-137 days; 95% confidence interval, 38-99 days). Only 2 grafts were lost as a result of rejection, as defined by cessation of graft palpation. There was no evidence of a consumptive coagulopathy, infectious complications were treatable, and no posttransplantation lymphoproliferative disorders occurred. No cellular infiltration was observed. CONCLUSIONS This study reports the longest median survival to date (96 days) of pig hearts transplanted heterotopically into baboons. Duplication of these results in the orthotopic life-supporting position could bring cardiac xenotransplantation to the threshold of clinical application.
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Affiliation(s)
- Christopher G A McGregor
- Division of Cardiovascular Surgery, Department of Surgery, Mayo Clinic, Rochester, Minn 55905, USA.
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Baertschiger RM, Buhler LH. Xenotransplantation literature update March-April, 2005. Xenotransplantation 2005; 12:333-7. [PMID: 15943784 DOI: 10.1111/j.1399-3089.2005.00238.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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