ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Grafts from so-called “marginal donors” are increasingly used for organ transplantation. The combination of reduced organ quality and additional inflammatory damages may be particularly detrimental in these grafts. In a previous study, we showed the beneficial effects on long-term graft outcome of “suboptimal” grafts by the induction of heme oxygenase-1. Here we tested the impact of short-term donor treatment with established immunosuppressants.Methods.Twelve-month-old Fischer 344 donor rats either were treated with prednisolone, mycophenolate mofetil, RAD, or FK506 24 hr and 1 hr before organ harvesting or remained untreated. Renal allografts were perfused with University of Wisconsin solution and kept at 4°C for an ischemic period of 2 hr. Morphologic, immunohistologic, and real time reverse transcriptase-polymerase chain reaction analyses for relevant markers were performed at serial intervals and at the end of the observation period (6 months).Results.All animals survived the observation period, although the ischemic time resulted in accelerated chronic graft dysfunction. Grafts from donors treated with prednisolone or FK506 demonstrated significantly improved graft function and structure by 6 months. Mononuclear infiltrates were significantly reduced by the end of the observation period, whereas intragraft mRNA levels of tumor necrosis factor-&agr; and interleukin-10 were significantly altered during the early period after transplantation. Minor improvements in graft function and histologic alterations of suboptimal grafts were observed after pretreatment with mycophenolate mofetil and RAD.Conclusion.Donor treatment with approved immunosuppressants, in particular prednisolone or FK506, represents a novel therapeutic strategy of clinical relevance, most importantly when using grafts from marginal donors.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.University of Wisconsin (UW) solution (Viaspan) is currently used to preserve organs from nonheartbeating donors. Histidine-tryptophan-ketoglutarate (HTK) solution (Custodiol) is of proven efficacy in experimental pancreas preservation, but its efficacy in combined warm ischemia (WI) and cold ischemia (CI) is unknown. The viability of HTK-preserved porcine pancreatic grafts was assessed after various periods of WI and compared with grafts flushed and preserved with UW solution.Methods.A total of 14 pigs were used: G1 (n=4, UW) and G2 (n=4, HTK) with 15-min WI and 16-hr cold storage; G3 (n=3, UW) and G4 (n=3, HTK) with 30-min WI and 16-hr cold storage.Results.All animals in G1 and G2 were normoglycemic, whereas only 66% of pancreases were functioning in G3 and G4. HTK perfusion was associated with increased wet weight. Transient hyperinsulinemia was noted in all the groups on postoperative day 1 (mean range: 8.9–12.4 &mgr;U/L). Postoperative serum amylase and lipase were more pronounced in G3 and G4. However, HTK-stored grafts exhibited less evidence of biochemical pancreatitis as compared with UW-stored grafts on the first postoperative day in the group with 15-min WI. Mean K values of intravenous glucose tolerance tests on postoperative day 14 were similar in both groups. Vascular congestion was uniformly observed and was considered a typical feature of WI.Conclusions.Porcine pancreatic grafts are viable after 16-hr CI following 15-min WI in this experimental nonheartbeating donor model. HTK solution seems to provide reliable graft function in this setting and to be equivalent to UW.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Spleen transplantation (Tx) between some strains of rodents can lead to donor-specific tolerance either spontaneously or after a short course of immunosuppression. This study developed a surgical technique for spleen Tx in miniature swine to investigate its immunologic impact in a large animal model.Methods.The preferred surgical technique of spleen Tx (n=8) involved excision of the donor spleen with its vascular pedicle to the aorta and portal vein. Carrel patches of donor aorta and portal vein were anastomosed to the abdominal aorta and inferior vena cava, respectively, of the (splenectomized) recipient. The results in four major histocompatibility complex-matched pairs that were mismatched for the porcine allelic antigen are reported. Two recipients were untreated, one received a 12-day course of cyclosporine A (CsA) alone, and one received thymic irradiation (700 cGy) and CsA. Hematopoietic cell chimerism was followed by fluorescence-activated cell sorter, and graft survival was assessed by histology.Results.Spleen Tx was technically successful. In two untreated pigs, chimerism was detected in the blood (maximum 5% for 17 and 25 days) and lymph nodes (maximum 6% for 28 and 56 days), but both grafts showed histologic rejection by day 28. In two treated pigs, chimerism was present in the blood for 47 and 57 days, and rejection was prevented, with follow-up for 57 and 217 days, respectively.Conclusion.Spleen Tx in major histocompatibility complex-matched pairs treated with CsA±thymic irradiation results in prolonged chimerism and is associated with the development of in vivo unresponsiveness to the transplanted spleen.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.We developed an extracorporeal liver perfusion (ECLP) system as a liver-assist device. In this study, we evaluated the safety of the ECLP using human decay accelerating factor (hDAF) transgenic porcine livers in healthy baboons.Methods.Livers were isolated from five hDAF transgenic pigs and five nontransgenic pigs for the ECLP. Ten cross-circulations between the ECLP and healthy baboons were performed without immunosuppressive agents. Cross-circulation was discontinued in any of the following circumstances: elevated hepatic arterial (>200 mm Hg) or portal (>60 mm Hg) perfusion pressure, massive exudate from the graft liver, mild macroscopic hemolysis, thrombocytopenia, or 24-hr well-conditioned cross-circulation.Results.The cross-circulations with nontransgenic porcine livers were discontinued at 4.4±1.2 hr (mean±standard deviation) because of high perfusion pressure (n=2) or hemolysis (n=3). Three cross-circulations with hDAF transgenic porcine livers were performed for 24 hr; the other two cross-circulations were discontinued at 13 and 17 hr because of massive exudate and thrombocytopenia, respectively. The duration was 20.4±5.1 hr. Deposition of membrane attack complex in the hDAF transgenic porcine liver was less than that in the nontransgenic liver, although immunoglobulin-M deposition was comparable. The porcine livers showed no apparent interlobular bleeding or lobular necrosis. All porcine livers maintained bile production during the cross-circulation. No baboons showed any serious complications after the cross-circulation.Conclusion.The hDAF transgenic porcine liver reduced complement activation in xenoperfusion with healthy nonhuman primate blood and led to extended duration of cross-circulation.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Nonobese diabetic (NOD) mice develop autoimmune diabetes with features similar to those observed in the human disease. The concurrence of allorecognition and recurrence of autoimmunity might explain why most of the treatments successful in preventing islet allograft destruction in other nonautoimmune combinations often fail in NOD recipients. To assess the value of the NOD mouse model for the evaluation of treatments relevant to clinical islet transplantation, the authors have tested the effect of a protocol closely resembling the one successfully used in the Edmonton clinical trial on the survival of islet allografts in NOD mice.Methods.C57BL/6 islets were transplanted under the kidney capsule of spontaneously diabetic NOD mice. Treatment consisted of a combination of rapamycin, tacrolimus, and anti–interleukin (IL)-2 monoclonal antibody. Control groups received each treatment alone, a combination of two agents, or no treatment.Results.Untreated animals invariably lost their graft within 13 days. Administration of rapamycin and tacrolimus significantly prolonged graft survival, with two of seven animals bearing a functional graft longer than 100 days. Addition of anti–IL-2 antibody therapy further improved graft survival, with six of eight grafts functioning longer than 100 days and two of eight grafts functioning longer than 200 days.Conclusions.In view of the limited success obtained with other treatments in this model, the dramatic prolongation of graft survival observed in the authors’ study, by using a therapy that mimics one successfully used in clinical trials, seems to validate the NOD mouse as a meaningful model for the study of therapeutic interventions for the prevention of islet graft loss.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Murine umbilical cord blood cells (UCBCs) were studied for their ability to reconstitute the hematopoietic system.Methods.On average, 150 &mgr;L of cord blood per fetus containing 1.2 to 2×104nucleated cells were collected from day 18.5 fetal umbilical cord, and 3 to 6×103cells per fetus were obtained after separation by gradient centrifugation.Results.Although lineage marker−, c-Kit+, and Sca-1+cells were detectable among UCBCs, cells designated to be in the side population (SP) by Hoechst 33342 staining were hardly detectable within this population; the frequency of cells of this phenotype was less than 1 of 105. Instead, the lineage marker−, c-Kit+, and Sca-1−population contained a considerable number of SP cells. Nevertheless, UCBCs obtained from fetuses of green fluorescent protein-transgenic mice successfully reconstituted the blood cells of lethally irradiated recipients. Fluorescent cells could be readily detected in every blood cell lineage and among immature cell populations. Furthermore, fluorescent SP cells sorted from the recipient bone marrow cells could also reconstitute the blood cells in the secondary recipients, indicating that UCBCs also replenished bone marrow stem cells.Conclusion.Murine UCBC could fully reconstitute the hematopoietic system of lethally irradiated recipients including hematopoietic stem cells in bone marrow.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Development of an auxiliary liver is of interest for treating several conditions. To examine whether an isolated intestinal segment will support development of a heterotopic auxiliary liver, we studied the fate of liver microfragments in rats.Methods.Small intestinal segments with intact circulation were created, and the small intestinal mucosa was removed. The intestinal segments were filled with autologous liver microfragments, and animals were studied for various periods.Results.Initially, liver microfragments were engulfed by a serosanguineous exudate enriched in polymorphonuclear leukocytes, suggesting an early granulation-type response. Transplanted liver fragments were subsequently reorganized and showed morphologic integrity with typical hepatic lobular organization. Transplanted tissue contained healthy hepatocytes with abundant glycogen content. Transplanted liver remained intact in the small intestine for up to 40 days, although at later times portal fibrosis and bile ductular proliferation were apparent, despite the absence of cholestasis or hepatocellular abnormalities. In contrast, instillation of liver microfragments in the peritoneal cavity led to rapid loss of tissue integrity and phagocytotic clearance of transplanted tissue.Conclusions.Small intestinal segments denuded of the mucosal layer can support heterotopically transplanted liver. Further development of this auxiliary liver system will provide insights into mechanisms concerning neo-organogenesis and into potential therapeutic applications of heterotopic liver in specific diseases.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.CD4 T-cell reconstitution and xenogeneic tolerance is achieved in T cell-depleted, thymectomized C57BL/6 (B6) mice and nude mice by grafting of fetal pig thymus (FP THY). Sixty percent of grafted nude mice and 10% of grafted thymectomized B6 mice develop a clinical illness resembling chronic graft-versus-host disease.Methods.Negative selection of mouse T cells in FP THY grafts was studied in “AND” TCR transgenic mice with a negative selecting MHC. Pathologic and immunohistochemical examinations and adoptive transfer assays were performed to determine the role of mouse CD4+cells in the occurrence of autoimmune disease in this model.Results.Marked clonal deletion of mouse thymocytes bearing a transgenic TCR (“AND”), which recognizes H2sexpressed by host hematopoietic cells, was observed in FP THY grafts. Pathologic and immunohistochemical examinations of the liver, skin, lungs, and kidneys of mice with wasting syndrome showed marked mouse CD4+T-cell infiltration without detectable pig cells. After adoptive transfer of splenocytes, but not of CD4+cell–depleted splenocytes, from sick mice along with B6 bone marrow cells to lethally irradiated syngeneic B6 mice, the secondary recipients developed a similar autoimmune syndrome as the donors. Cotransfer of naïve syngeneic splenocytes prevented the occurrence of autoimmune disease in secondary recipients of splenocytes from healthy FP THY-grafted BALB/c nude mice.Conclusion.These results demonstrate a key role for mouse CD4+T cells in causing autoimmune disease in this model and suggest the importance of regulatory mechanisms in addition to intrathymic clonal deletion for the maintenance of tolerance to recipient antigens.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID