Topic
Transplantation
About: Transplantation is a research topic. Over the lifetime, 276584 publications have been published within this topic receiving 7961661 citations.
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TL;DR: It is shown that hematopoietic stem cells become liver cells when cocultured with injured liver separated by a barrier and that HSCs contribute to the regeneration of injured liver by converting into functional hepatocytes without fusion.
Abstract: Both plasticity and cell fusion have been suggested to have a role in germ-layer switching1,2,3,4,5,6,7. To understand the mechanisms underlying cell fate changes, we have examined a highly enriched population of hematopoietic stem cells (HSCs)8,9,10 in vitro or in vivo in response to injury for liver-specific phenotypic and functional changes. Here we show that HSCs become liver cells when cocultured with injured liver separated by a barrier. Chromosomal analyses and tissue-specific gene and/or protein expression show that microenvironmental cues rather than fusion are responsible for conversion in vitro. We transplanted HSCs into liver-injured mice and observed that HSCs convert into viable hepatocytes with increasing injury. Notably, liver function was restored 2–7 d after transplantation. We conclude that HSCs contribute to the regeneration of injured liver by converting into functional hepatocytes without fusion.
564 citations
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TL;DR: It is learned from adoptive immunotherapy of viral diseases and HLA-haploidentical stem cell transplantation that T-cell memory may be essential for the effective treatment of leukemia and other malignancies.
564 citations
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TL;DR: This protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.
Abstract: Background Hyperacute rejection (HAR) and acute humoral rejection (AHR) remain recalcitrant conditions without effective treatments, and usually result in graft loss. Plasmapheresis (PP) has been shown to remove HLA- specific antibody (Ab) in many different clinical settings. Intravenous gamma globulin (IVIG) has been used to suppress alloantibody and modulate immune responses. Our hypothesis was that a combination of PP and IVIG could effectively and durably remove donor-specific, anti-HLA antibody (Ab), rescuing patients with established AHR and preemptively desensitizing recipients who had positive crossmatches with a potential live donor. Methods The study patients consisted of seven live donor kidney transplant recipients who experienced AHR and had donor-specific Ab (DSA) for one or more mismatched donor HLA antigens. The patients segregated into two groups: three patients were treated for established AHR (rescue group) and four cross-match-positive patients received therapy before transplantation (preemptive group). Results Using PP/IVIG we have successfully reversed established AHR in three patients. Four patients who were cross-match-positive (3 by flow cytometry and 1 by cytotoxic assay) and had DSA before treatment underwent successful renal transplantation utilizing their live donor. The overall mean creatinine for both treatment groups is 1.4+/-0.8 with a mean follow up of 58+/-40 weeks (range 17-116 weeks). Conclusions In this study, we present seven patients for whom the combined therapies of PP/IVIG were successful in reversing AHR mediated by Ab specific for donor HLA antigens. Furthermore, this protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity (AHG-CDC) cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.
563 citations
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TL;DR: It is shown that a heterologous immune response--specifically, virally induced alloreactive memory--is a potent barrier to tolerance induction, and a critical threshold of memory T cells is needed to promote rejection, and CD8(+) "central" memory T Cells are primarily responsible.
Abstract: Many strategies have been proposed to induce tolerance to transplanted tissue in rodents; however, few if any have shown equal efficacy when tested in nonhuman primate transplant models. We hypothesized that a critical distinction between specific pathogen-free mice and nonhuman primates or human patients is their acquired immune history. Here, we show that a heterologous immune response--specifically, virally induced alloreactive memory--is a potent barrier to tolerance induction. A critical threshold of memory T cells is needed to promote rejection, and CD8(+) "central" memory T cells are primarily responsible. Finally, treatment with deoxyspergualin, an inhibitor of NF-kappa B translocation, together with costimulation blockade, synergistically impairs memory T cell activation and promotes antigen-specific tolerance of memory. These data offer a potential explanation for the difficulty encountered when inducing tolerance in nonhuman primates and human patients and provide insight into the signaling pathways essential for memory T cell activation and function.
563 citations
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TL;DR: Lower initial doses of cyclosporine, followed by more rapid tapering may reduce the incidence of nephrotoxicity without compromising improved graft outcome.
Abstract: Cyclosporine, a cyclic endecapeptide of fungal origin, has recently been released for use in clinical transplantation. Trials in kidney, heart, liver and bone marrow recipients were encouraging: 1-year graft survival rates were 70% to 80% for kidney and heart recipients, and 60% to 65% for liver allograft recipients. Cyclosporine is also effective in treating bone marrow recipients with acute graft-versus-host disease. The drug selectively inhibits T-helper cell production of growth factors essential for B cell and cytotoxic T-cell differentiation and proliferation, while allowing expansion of suppressor T-cell populations. Drug absorption varies greatly, necessitating monitoring of drug level and individualization of therapy. Nephrotoxicity is the most frequent side effect of cyclosporine. An increased incidence of B-cell lymphomas seen when cyclosporine was used in conjunction with cytotoxic agents or anti-lymphocyte globulin has very rarely been observed when concomitant immunosuppression has been limited to low-dose corticosteroids. Lower initial doses of cyclosporine, followed by more rapid tapering may reduce the incidence of nephrotoxicity without compromising improved graft outcome.
562 citations