Cardiac allograft tolerance can be achieved in nonhuman primates by donor bone marrow and kidney cotransplantation.

Long-term, immunosuppression-free allograft survival has been induced in human and nonhuman primate (NHP) kidney recipients after nonmyeloablative conditioning and donor bone marrow transplantation (DBMT), resulting in transient mixed hematopoietic chimerism. However, the same strategy has consistently failed in NHP heart transplant recipients. Here, we investigated whether long-term heart allograft survival could be achieved by cotransplanting kidneys from the same donor.

A novel technique for heart-thymus en bloc transplantation in nonhuman primates.

The thymus is a rich source of regulatory T cells and plays a role in self-tolerance. Therefore, transplantation of a vascularized donor thymus may facilitate the induction of tolerance in recipients of a cotransplanted heart allograft. To investigate this hypothesis, we developed a new technique to procure the heart and thymus en bloc from juvenile donors and transplant the composite allograft into thymectomized recipients.

Selective Bcl-2 inhibition promotes hematopoietic chimerism and allograft tolerance without myelosuppression in nonhuman primates.

Hematopoietic stem cell transplantation (HSCT) has many potential applications beyond current standard indications, including treatment of autoimmune disease, gene therapy, and transplant tolerance induction. However, severe myelosuppression and other toxicities after myeloablative conditioning regimens have hampered wider clinical use. To achieve donor hematopoietic stem cell (HSC) engraftment, it appears essential to establish niches for the donor HSCs by depleting the host HSCs.

A Mixed-chimerism Protocol Utilizing Thymoglobulin and Belatacept Did Not Induce Lung Allograft Tolerance, Despite Previous Success in Renal Allotransplantation.

Background: In kidney transplantation, long-term allograft acceptance in cynomolgus macaques was achieved using a mixed-chimerism protocol based on the clinically available reagents, rabbit anti-thymocyte globulin (ATG), and belatacept. Here, we have tested the same protocol in cynomolgus macaques transplanted with fully allogeneic lung grafts.

Methods: Five cynomolgus macaques underwent left orthotopic lung transplantation.

Development of a Transplantable GFP+ B-Cell Lymphoma Tumor Cell Line From MHC-Defined Miniature Swine: Potential for a Large Animal Tumor Model.

The lack of a reliable and reproducible large animal tumor model for the study of hemolymphatic malignancies limits the ability to explore the underlying pathophysiology and testing of novel therapies. The goal of this study was to develop an aggressive, trackable swine tumor cell line in mice for adoptive transfer into MHC matched swine. Two tumor cell lines, post-transplant lymphoproliferative disease (PTLD) 13271 and chronic myelogenous leukemia (CML) 14736, were previously established from the Massachusetts General Hospital (MGH) miniature swine herd.

Role of Bone Marrow Maturity, Insulin-Like Growth Factor 1 Receptor, and Forkhead Box Protein N1 in Thymic Involution and Rejuvenation.

Thymic involution is associated with age-related changes of the immune system. Utilizing our innovative technique of transplantation of a thymus as an isolated vascularized graft in MHC-inbred miniature swine, we have previously demonstrated that aged thymi are rejuvenated after transplantation into juvenile swine. Here we have studied the role of insulin-like growth factor (IGF) and forkhead-box protein-N1 (FOXN1) as well as bone marrow (BM) in thymic rejuvenation and involution.

A novel approach to measuring cell-mediated lympholysis using quantitative flow and imaging cytometry.

In this study, we established a novel isotope-free approach for the detection of cell-mediated lympholysis (CML) in MHC defined peripheral blood mononuclear cells (PBMCs) using multiparameter flow and imaging cytometry. CML is an established in vitro assay to detect the presence of cytotoxic effector T-lymphocytes precursors (CTLp). Current methods employed in the identification of CTLp in the context of transplantation are based upon the quantification of chromium ((51)Cr) released from target cells.

Effect of Irradiation on Incidence of Post-Transplant Lymphoproliferative Disorder after Hematopoietic Cell Transplantation in Miniature Swine.

Post-transplant lymphoproliferative disease (PTLD) is a major complication of clinical organ and cell transplantation. Conditioning and immunosuppressive regimens that significantly impair T cell immunity, including depleting antibodies and calcineurin inhibitors, increase the risk of PTLD after transplantation. Swine PTLD has been shown to closely resemble human PTLD in morphology, histology, and viral-driven reactivation of B cells.

Porcine cytomegalovirus infection is associated with early rejection of kidney grafts in a pig to baboon xenotransplantation model.

Background: Recent survivals of our pig-to-baboon kidney xenotransplants have been markedly shorter than the graft survivals we previously reported. The discovery of high levels of porcine cytomegalovirus (pCMV) in one of the rejected xenografts led us to evaluate whether this reduction in graft survival might be because of the inadvertent introduction of pCMV into our α1,3-galactosyltransferase gene knockout swine herd.

Methods: Archived frozen sections of xeno-kidney grafts over the past 10 years were analyzed for the presence of pCMV, using real-time polymerase chain reaction.

Rituximab treatment prevents the early development of proteinuria following pig-to-baboon xeno-kidney transplantation.

We previously reported life-supporting α1,3-galactosyltransferase knockout (GalTKO) thymokidney xenograft survival of >2 months in baboons. However, despite otherwise normal renal function, recipients developed proteinuria with morphologic changes (podocyte effacement), a condition that presents a major obstacle to long-term studies in this model. A recent clinical study showed that rituximab therapy after allogeneic transplant prevented proteinuria possibly associated with loss of sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b).

Lack of antidonor alloantibody does not indicate lack of immune sensitization: studies of graft loss in a haploidentical hematopoietic cell transplantation swine model.

Loss of chimerism is an undesirable outcome of allogeneic hematopoietic cell transplantation (HCT) after reduced-intensity conditioning. Understanding the nature of cellular and humoral immune responses to HCT after graft loss could lead to improved retransplantation strategies. We investigated the immunologic responses after graft loss in miniature swine recipients of haploidentical HCT that received reduced-intensity conditioning.

Development of a diphtheria toxin based antiporcine CD3 recombinant immunotoxin.

Anti-CD3 immunotoxins, which induce profound but transient T-cell depletion in vivo by inhibiting eukaryotic protein synthesis in CD3+ cells, are effective reagents in large animal models of transplantation tolerance and autoimmune disease therapy. A diphtheria toxin based antiporcine CD3 recombinant immunotoxin was constructed by fusing the truncated diphtheria toxin DT390 with two identical tandem single chain variable fragments (scFv) derived from the antiporcine CD3 monoclonal antibody 898H2-6-15. The recombinant immunotoxin was expressed in a diphtheria-toxin resistant yeast Pichia pastoris strain under the control of the alcohol oxidase promoter.