Genetically‐modified pig mesenchymal stromal cells: xenoantigenicity and effect on human T‐cell xenoresponses

Ezzelarab, Mohamed; Ezzelarab, Corin; Wilhite, Tyler; Kumar, Gopal; Hara, Hidetaka; Ayares, David; Cooper, David K.C.

doi:10.1111/j.1399-3089.2011.00635.x

Cited by 29 publications

(31 citation statements)

References 39 publications

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“…Studies by Wilhite et al have demonstrated a significant reduction in the primate mixed lymphocyte reaction to pig ECs when Gal is absent or an hCRP is expressed (54,55) (Figure 3). Although there is a definite reduction in the human T cell proliferative response to GTKO/hCRP pig cells in vitro, it is difficult to quantify this effect in vivo in pig-to-NHP transplantation models as so many other factors, e.g., coagulation dysregulation, affect the outcome.…”

Section: Suppression Of the Immune Responsesmentioning

confidence: 96%

“…Although encouraging in vitro data have been reported, the immunomodulatory efficacy of regulatory T cells (Tregs) (10,91,92) or MSCs (55,93,94) has yet to be demonstrated in large animal models of xenotransplantation. Tregs have been demonstrated to suppress the xenoreactive effector T cell response in vitro , as have MSCs.…”

Section: Cell Therapy Approachesmentioning

confidence: 99%

“…The immunomodulatory, anti-inflammatory, and/or regenerative potential of pig MSCs is being explored (55,93) as the ready availability of adipose-derived MSCs from large pigs would minimize the logistics of providing unlimited numbers of these cells. Initial in vitro studies indicate that MSCs from genetically-engineered pigs are no more immunogenic than human MSCs, and yet have a comparable immunomodulatory effect on the human T cell response (55,93). …”

Section: Cell Therapy Approachesmentioning

confidence: 99%

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New Concepts of Immune Modulation in Xenotransplantation

et al. 2013

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The shortage of human organs for transplantation has focused research on the possibility of transplanting pig organs into humans. Many factors contribute to the failure of a pig organ graft in a primate. A rapid innate immune response (natural anti-pig antibody, complement activation, and an innate cellular response, e.g., neutrophils, monocytes, macrophages, NK cells) is followed by an adaptive immune response, although T cell infiltration of the graft has rarely been reported. Other factors (e.g., coagulation dysregulation, inflammation) appear to play a significantly greater role than in allotransplantation. The immune responses to a pig xenograft cannot therefore be controlled simply by suppression of T cell activity. Before xenotransplantation can be introduced successfully into the clinic, the problems of the innate, coagulopathic, and inflammatory responses will have to be overcome, most likely by the transplantation of organs from genetically-engineered pigs. Many of the genetic manipulations aimed at protecting against these responses also reduce the adaptive response. The T cell and elicited antibody responses can be prevented by the biologic and/or pharmacologic agents currently available, in particular, by costimulation blockade-based regimens. The exogenous immunosuppressive regimen may be significantly reduced by the presence of a graft from a pig transgenic for a mutant (human) class II transactivator gene, resulting in downregulation of SLA class II expression, or from a pig with ‘local’ vascular endothelial cell expression of an immunosuppressive gene, e.g., CTLA4-Ig. The immunomodulatory efficacy of regulatory T cells or mesenchymal stromal cells has been demonstrated in vitro, but not yet in vivo.

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Section: Suppression Of the Immune Responsesmentioning

confidence: 96%

Section: Cell Therapy Approachesmentioning

confidence: 99%

Section: Cell Therapy Approachesmentioning

confidence: 99%

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New Concepts of Immune Modulation in Xenotransplantation

et al. 2013

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“…High CD55 expression levels have already been shown to inhibit NK cell activation (Miyagawa et al, 2004). CD46 expression has significant effects on inhibition of procoagulant and antifibrinolytic pathways (Bongoni et al, 2015) and a combination of GGTA1 knockout and CD46 expression was shown to down-regulate the human T-cell response to porcine cells (Ezzelarab et al, 2011;Wilhite et al, 2012). A20 expression also inhibits T-cell activation (Coornaert et al, 2008).…”

Section: Multi-transgenic Animalsmentioning

confidence: 99%

Multi‐transgenic pigs for xenotransplantation

Fischer

Kraner-Scheiber

Flisikowski

et al. 2013

Xenotransplantation

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Genetically modified pigs offer a solution to the severe shortage of organs available for human transplantation. Inactivation of the α1,3‐galactosyltransferase gene, responsible for α1,3‐Gal epitope synthesis (1–2) was a major breakthrough and essentially solved the problem of hyperacute rejection. However, further modifications of donor pigs are required to enable long term xenograft survival. These include expression of complement regulatory, antithrombotic, endothelium protective and immuno‐regulatory transgenes. Current evidence indicates that complement regulator transgenes, such as CD46 and CD55, must be expressed at least fivefold more than their human endogenous equivalent to effectively protect grafted tissue (3). To explore means of achieving high expression, we produced a series of BAC‐ and PAC‐vector constructs containing different sized genomic complement regulatory genes, from 70 to 190 kb, under the control of endogenous or CAGGs (CMV enhancer chicken β actin) promoter sequences. Using these vectors we obtained high levels of CD46 and CD55 expression in vitro. To prepare multi‐transgene “packages” for introduction into animals, the most effective constructs were combined with one or two further xenoprotective transgenes, including A20 (4), HO‐1 (5), thrombomodulin (6) and CTLA4‐Ig (LEA 29Y). In cotransfection experiments single cell clones expressing up to five different xenogenes could be detected. Achieving desired levels of transgene expression in an animal is not only a function of the transgene construct, but also of the location at which it integrates. Position effect variation in expression of random transgenes is well‐documented. Transgene placement by gene targeting at a permissive locus offers a useful means of achieving reliable transgene expression. In mice the ROSA26 locus is widely used to support ubiquitous expression of inserted transgenes (7–8). Murine ROSA26 encodes no functional genes and extensive gene targeting of this locus has not led to deleterious effects on development or physiology (9). To enable a similar approach in pigs, we recently identified a strong candidate for the porcine ROSA26 locus. Gene targeted placement of a neomycin reporter gene construct under the control of the ROSA26 promoter showed expression in all examined porcine tissues of all three germ layers. This strongly suggests that porcine ROSA 26 may resemble the murine locus as a suitably permissive site for transgene expression. We are currently proceeding with gene targeting to place various xenoprotective transgene constructs at this locus. References: 1. Dai Y, Vaught TD, Boone J et al. Targeted disruption of the alpha1,3‐ galactosyltransferase gene in cloned pigs. Nat Biotechnol 2002; 20: 251–255. 2. Lai L, Kolber‐Simonds D, Park K et al. Production of alpha‐1,3‐galactosyltransferase knockout pigs by nuclear transfer cloning. Science 2002; 295: 1089–1092. 3. Miyagawa S, Fukuta D, Kitano E et al. Effect of tandem forms of DAF(CD55) on complement‐mediated xenogeneic cell lysis. Xenotransplantation 20...

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“…33 Accompanying in vitro studies indicated that the overexpression of human TFPI by pig bone marrow-derived mesenchymal stromal cells inhibited clotting, which is an observation that may be of potential therapeutic importance and warrants further investigation. 34,35 …”

Section: Introductionmentioning

confidence: 99%

Pig Liver Xenotransplantation

et al. 2016

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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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Genetically‐modified pig mesenchymal stromal cells: xenoantigenicity and effect on human T‐cell xenoresponses

Abstract: Genetically modified pMSC is significantly less immunogenic than WT pMSC. GTKO/CD46 pMSC downregulates the human T-cell responses to pig antigens as efficiently as human MSC, which can be advantageous for therapeutic cell xenotransplantation.

Cited by 29 publications

References 39 publications

New Concepts of Immune Modulation in Xenotransplantation

New Concepts of Immune Modulation in Xenotransplantation

Multi‐transgenic pigs for xenotransplantation

Pig Liver Xenotransplantation

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