Z Song

Effects of immunosuppressive treatment on host responses against intracerebral porcine neural tissue xenografts in rats

Background. Embryonic xenogeneic neural tissue is an alternative for transplantation in Parkinson’s disease, but immune responses limit the application. The aims of this study were to enhance the in vitro viability rates by donor tissue pretreatment; to compare the efficacy of cyclosporine A (CsA) and tacrolimus (FK) in inhibiting xenograft rejection in rats; to evaluate additional inductive therapy with prednisolone (PRE) or mycophenolate mofetil (MMF). Methods. Tirilazad (a lipid peroxidase inhibitor) or FK and acYVAD-cmk (a caspase inhibitor), were added to embryonic porcine ventral mesencephalic tissue and viability was assessed in vitro. Tirilazad-treated tissue was grafted to the striatum of rats that were either left untreated or immunosuppressed with FK (1 mg/kg) or CsA (15 mg/kg) alone or in combination with a 2-week PRE (20 mg/kg) or MMF (40 mg/kg) induction course. Xenograft survival and host responses were determined using immunohistochemistry. Results. Pretreatment with tirilazad enhanced tissue survival in vitro. After transplantation into untreated controls, there was no graft survival at twelve weeks. Neural cell counts were significantly improved in immunosuppressed recipients, but there were no differences between the treatment groups. Additional inductive treatment reduced the infiltration with CD4+ and CD8+ cells, and macrophage infiltration was reduced compared with animals given CsA or FK alone. Conclusion. Pretreatment of the donor tissue with free-radical scavengers reduces cell loss caused by tissue trauma. Porcine neural tissue xenografts survive significantly better in animals immunosuppressed with either FK or CsA. Additional inductive treatment with PRE or MMF reduced the infiltration of host cells into the xenografts.

Procurement of human pancreases for islet isolation-the initiation of a Scandinavian collaborative network.

Procurement of human pancreases for islet isolation - the initiation of a Scandinavian collaborative network

Soluble complement receptor 1 (TP10) preserves adult porcine islet morphology after intraportal transplantation into cynomolgus monkeys.

Soluble complement receptor 1 (TP10) preserves adult porcine islet morphology after intraportal transplantation into cynomolgus monkeys

Importance of the Gal alpha1-3 Gal antigen in discordant islet xenotransplantation: immunosuppression, which inhibits porcine islet xenograft rejection in ordinary mice, is equally effective in Gal-knockout mice.

Background. Islet xenotransplantation will most likely be performed in diabetic patients treated with immunosuppressive drugs. The importance of the galactosyl alpha(1–3) galactose (Gal&agr;1–3Gal) antigen in immunosuppressed islet xenograft recipients has not been studied. Methods. Fetal porcine islet-like cell clusters (ICCs) were transplanted into the renal subcapsular space of both Gal-knockout mice and ordinary mice. Transplantations were performed in untreated mice and mice immunosuppressed with cyclosporine A (CsA) plus 15-deoxyspergualin (DSG). Studies were also performed in immunosuppressed Gal-knockout mice that had been actively immunized against Gal&agr;1–3Gal. Evaluation was performed 12 days after transplantation using morphologic techniques. The levels of serum immunoglobulin (Ig)G and IgM to the Gal&agr;1–3Gal antigen or to the ICCs were determined. Results. No difference in the morphologic appearance could be seen between ordinary mice and Gal-knockout mice. No deposits of IgG, IgM, or C3 could be detected. Almost no difference could be seen between immunosuppressed Gal-knockout mice and immunosuppressed ordinary mice. In immunosuppressed, immunized Gal-knockout mice, the results were similar. In ordinary mice treated with CsA+DSG, the levels of anti-Gal IgM were lower than they were in untreated mice, whereas the levels of anti-Gal IgG were similar. In Gal-knockout mice (including immunized animals) treated with CsA+DSG, the levels of anti-Gal IgG and IgM were lower than they were in untreated Gal-knockout mice. Conclusions. After renal subcapsular transplantation, antibodies against Gal&agr;1–3Gal have no major influence on islet xenograft rejection in the pig-to-mouse model. Immunosuppression, which inhibits rejection in the pig-to-mouse model, is equally effective when transplantation is performed across the Gal&agr;1–3Gal barrier.

FTY720 in combination with CsA inhibits islet xenograft rejection: a study in the pig-to-rat model

FTY720 in combination with CsA inhibits islet xenograft rejection: a studyin the pig-to-rat model.

Tacrolimus inhibits discordant islet xenograft rejection: a study in the pig-to-rat model.

Abstract: The aim of the present study was to evaluate the immunosuppressive effect of tacrolimus (TAC) in discordant islet xenotransplantation. Fetal porcine islet‐like cell clusters (ICCs) were transplanted under the kidney capsule in normoglycemic rats treated with TAC monotherapy, TAC plus other immunosuppressive drugs or cyclosporin A (CsA) monotherapy. Twelve or 24 days after transplantation, the extent of a cellular infiltration in the xenografts was evaluated using immunohistochemistry. In some animals, the grafts were examined for antibody and complement deposition and the levels of xenoreactive antibodies in serum were determined. In untreated rats, the xenografts were completely rejected after 12 days and no intact ICCs remained. TAC monotherapy (at 0.5 and 1.0 mg/kg b.w.) almost completely inhibited rejection for up to 12 days. In animals treated with TAC monotherapy (at 0.5 mg/kg b.w.), rejection was markedly inhibited for up to 24 days. However, the effect after 24 days was not consistent and in some grafts there were signs of rejection. The protective effect of TAC observed in this study is in contrast to the findings in rats given CsA monotherapy in which no or only a marginal effect on islet xenograft rejection was observed. Only when CsA was given at 20 mg/kg b.w., an inhibitory effect could be observed. Immunosuppression with TAC at a suboptimal dose (0.3 mg/kg b.w.) plus 15‐deoxyspergualin or brequinar also had an inhibitory effect on the rejection. In animals given TAC plus mycophenolate mofetil, a protective effect was observed as well; however, this effect was not consistent.

Porcine Islets of Langerhans Isolated From Normal and hDAF Transgenic Pigs Elicit the Same Acute Inflammatory Reaction During Exposure to Human Blood; Inhibition of the Response With Soluble Complement Receptor 1 and Heparin

WE HAVE previously reported that porcine islets exposed to fresh human blood in vitro elicit an immediate inflammatory reaction, resulting in disruption of islet integrity. Complement inhibition prevents hyperacute rejection of vascularized discordant xenografts. We investigated whether inhibition of the complement and coagulation systems in human blood affected the outcome of porcine islet damage. We also tested whether islets from a single founder line (A74) of hDAF transgenic (TG) pigs are protected from this reaction.

Efficacy of malononitriloamide 279 and 715 in islet xenotransplantation: a study in the pig-to-rat model.

Efficacy of malononitriloamide 279 and 715 in islet xenotransplantation: astudy in the pig-to-rat model.

Brequinar in combination with cyclosporine a inhibits islet xenograft rejection for up to 24 days: a study in the pig-to-rat model.

Brequinar in combination with cyclosporine a inhibits islet xenograftrejection for up to 24 days: a study in the pig-to-rat model.

Diabetic rats transplanted with adult porcine islets and immunosuppressed with cyclosporine, mycophenolate mofetil, and leflunomide remain normoglycemic for up to 100 days

BACKGROUND Transplantation of adult porcine islets (APIs) offers a possible means of treating diabetes. However, isolating APIs has been notoriously difficult. Furthermore, islet xenograft rejection must be prevented. MATERIALS AND METHODS APIs were isolated by a modified automated method. API quality was assessed by static glucose stimulation (SGS), by transplantation to diabetic nude mice and by intraperitoneal glucose tolerance tests (IPGTTs). The morphologic characteristics of API xenograft rejection in rats were studied immunohistochemically. Furthermore, APIs were transplanted to diabetic rats that were either left untreated or immunosuppressed with cyclosporine A (CsA), mycophenolate mofetil (MMF) and leflunomide (LEF). B-glucose and porcine C-peptide levels were monitored and grafts were studied morphologically. RESULTS Large numbers of APIs were isolated. At SGS, insulin release increased significantly. All nude mice transplanted with APIs were normoglycemic within 24 hr and remained so for up to 1 year. During IPGTTs, B-glucose levels were rapidly regulated to porcine levels. In untreated rats, API xenografts were destroyed within 6 days by a cellular infiltrate consisting mainly of macrophages. In untreated diabetic rats normoglycemia was sustained for 5.5+/-0.3 days. Rats immunosuppressed with CsA+MMF+LEF remained normoglycemic for 59.6+/-11.3 days. In 3 of 11 rats, normoglycemia was sustained for up to 101 days. Porcine C-peptide was detected in serum. At recurrence of hyperglycemia, many mononuclear cells were found close to the xenografts. However, only occasional cells infiltrated the grafts and many APIs were intact. CONCLUSIONS Well-functioning APIs can be isolated in large numbers. API xenografts can be protected from rejection and can maintain an adequate function for up to 100 days, in rats immunosuppressed with CsA+MMF+LEF.