摘要:

Syngeneic transplantation of rat islets into subcutaneous tissue failed to cure streptozocin diabetes. The reason is unknown, but poor vascularization may play a role. We hypothesize that if a well-vascularized subcutaneous site could be created, islet grafts would do well. Four hundred freshly isolated mouse islets were transplanted syngeneically under the renal capsule or into the intraperitoneal cavity and compared with 800 islets in subcutaneous tissue of streptozocin-diabetic mice. Four weeks after transplantation, 14 of 14 under the renal capsule, 4 of 8 in the intraperitoneal site, and 0 of 7 in the subcutaneous tissue site achieved normoglycemia. To create vascularized organoids, we transplanted 800 mouse islets into polyvinyl alcohol (PVA) or polyglycolic acid (PGA) polymers in subcutaneous tissue of streptozocin-diabetic mice either immediately (four in PVA and six in PGA) or 7 days (four in PVA and four in PGA) after implantation. Four weeks after transplantation, the mean blood glucose level and body weight had no change with PVA. However, the mean body weight increased significantly with PGA and 3/10 became normoglycemic. When transplanting 400 islets with PGA polymers intraperitoneally, all animals(n=5) remained hyperglycemic 3 months later. In contrast, four of five recipients transplanted with 800 islets with PGA polymers subcutaneously became normoglycemic. The grafts from successful animals contained numerous revascularized islets containing a substantial amount of insulin. These preliminary results indicate that subcutaneous islet transplantation using PGA polymers can improve the metabolic status and, in some cases, even cure diabetes in streptozocin-diabetic mice.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Human islet transplantation has a high rate of failure, often due to primary nonfunction, which suggests that islets are damaged during the processing of the pancreas. The preparation of human islets for transplantation is still a complex process that requires large teams of surgical and laboratory personnel. To overcome this problem, we have adopted the use of the IBM 2991 COBE cell separator and a metrizamide/Ficoll density medium that is easy to prepare. Twenty-seven pancreatic glands have been processed using the COBE cell separator, 23 of which were purified in metrizamide/Ficoll gradients and 4 in bovine serum albumin gradients. The results show an improvement of recovery and viability in these preparations when compared retrospectively with manual gradients. More importantly, the time required for purification was shortened to one fourth the usual time and total processing time is about half as long. Moreover, a team of two laboratory staff was regularly able to prepare islets for transplantation, reducing the separation time from 7 hr to 3.5 hr. We conclude that the automatic cell separator and metrizamide-based separation medium are useful modifications of current islet purification methods.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

To utilize gene therapy, we required an efficient method to transfect intact islets before their use in transplantation. The biolistic method transforms cells by bombarding them with microprojectiles coated with DNA. Once internalized, the DNA is solubilized and expressed. We used the firefly luciferase gene driven by the human cytomegalovirus immediate early promoter as a reporter construct in freshly isolated BALB/c mouse islets to compare the transfection efficiency using either the biolistic method, lipofection, or recombinant adenoviral infection (n=4 in each case). The biolistic method achieved, on average, a 35-fold higher level of luciferase activity than the lipofection method (mean ± SEM: 42.6±14.2 vs. 1.1±0.2 relative light units (RLU)/islet). Adenoviral infection achieved, on average, a further 25-fold higher level of luciferase activity than the biolistic method (1136.0±542.0 RLU/islet). The average proportion of islets recovered 48 hr after the biolistic blast was 53% (n=20). The average number of dissociated cells found to express the foreign gene product using β-galactosidase as a reporter construct was 3% (n=6). Furthermore, nontransformed and biolistically transformed islets responded similarly to an in vitro glucose challenge (stimulation index of insulin release at 20.0 mM glucose/insulin release at 2.8 mM glucose = 2.8 and 3.0, respectively,P=0.9). Syngeneic, biolistically transfected islets functioned to reverse the diabetic state when transplanted(500 islets) beneath the renal capsule of alloxan-induced diabetic BALB/c recipients (n=7). This methodology can achieve efficient transfection of pancreatic islets while preserving their function and thus holds promise for ex vivo gene therapy of isolated islets prior to transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

We compared the efficacy of using histidine-tryptophan-ketoglurate(HTK) solution with that of University of Wisconsin (UW) solution for heart preservation in an isolated rat heart preparation. Nicorandil (NCR) exerts its action as an ATP-sensitive potassium channel opener at low extracellular potassium concentrations, and HTK solution has a low potassium concentration. Therefore, we also investigated the efficacy of using HTK solution with NCR following 12-hr preservation. Hearts isolated from male Wistar rats were mounted on a Langendorff apparatus to estimate baseline aortic flow (AF), coronary flow (CF), cardiac output (CO), heart rate (HR), systolic pressure(SP), aortic mean pressure, and the rate-pressure product (RPP). The hearts were divided into four groups: group 1, 8-hr storage in UW solution; groups 2 and 3, 8- or 12-hr storage in HTK solution, respectively; and group 4, 12-hr storage in HTK solution with NCR. They were arrested and stored at 4 °C in each preservation solution. Following storage, they were reperfused and postpreservative function was measured to assess cardiac functional recovery. Concentrations of creatine phosphokinase, troponin-T, and lactate in the coronary perfusate were measured. Frozen tissue samples from groups 3 and 4 were analyzed for adenylate content and cGMP. The myocardial water content was also measured. The recovery of AF, CF, CO, SP, and RPP in group 2 was significantly improved compared with that in group 1(P<0.05). The recovery of AF, CF, CO and HR in group 4 was significantly better than that in group 3(P<0.05). Creatine phosphokinase leakage in group 2 and troponin-T leakage in group 4 were significantly reduced(P<0.05 vs. groups 1 and 3, respectively). Total adenine nucleotides and the adenylate energy charge in group 4 were well sustained (P<0.05 vs. group 3). These results suggest that HTK solution is more effective than UW solution for cardiac preservation, and that NCR provides still better protection.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Patients undergoing primary cadaveric kidney transplantation were followed for 1 year as part of a phase II, multicenter, open-label concentration-ranging trial of FK506 and cyclosporine. One hundred twenty patients were randomly assigned to a cyclosporine-based regimen or one of three FK506-based regimens designed to achieve low (5-14 ng/ml), medium (15-25 ng/ml), or high (26-40 ng/ml) trough whole blood levels. Corresponding initial doses of FK506 were 0.2, 0.3, or 0.4 mg/kg/day, respectively. Patients with toxicity to FK506 had their target concentration reduced by lowering the dose of FK506. Ninety-two patients completed a 1-year follow-up to determine patient and graft survival and long-term safety. At 1-year, the patient survival rate was 98% for FK506 and 92% for cyclosporine, and the graft survival rate was 93% and 89% in the FK506 and cyclosporine groups, respectively. The incidence of acute rejection was significantly lower (14% FK506, 32% cyclosporine,P=0.048) at day 42 after transplantation. However, the incidence of rejection episodes requiring treatment at 1 year was similar in both groups (33% for FK506 and 32% for cyclosporine). Nephrotoxicity occurred with a similar frequency with FK506 and cyclosporine, but the incidence of neurotoxic events and the incidence of new insulin use were higher among FK506-treated patients. The target range of whole blood levels that optimizes efficacy and minimizes toxicity seems to be 5-15 ng/ml. The corresponding recommended initial dose of FK506 for kidney transplant recipients is 0.2 mg/kg/day. These results indicate that the efficacy and safety of FK506 were comparable to that for cyclosporine for primary immunosuppression in patients undergoing cadaveric kidney transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

We studied multiple determinants of graft survival at a single center and the effects of nonimmunologic graft loss on transplant survival. This retrospective study examined the results of 589 cadaver donor transplants performed between 1986 and 1992. Graft survival rates were calculated using Kaplan-Meier estimates for both overall graft survival (all causes of graft loss) and immunologic graft survival (function lost due to acute or chronic rejection and noncompliance). Cadaver graft survival was significantly poorer with an increasing degree of DR mismatch (P=0.02). An analysis of pretransplant variables showed graft loss risk was highest with greater DR mismatches, two B-antigen mismatch, higher donor serum creatinine, and younger recipient age. After transplantation, acute rejection was the most significant factor associated with long-term graft survival. Our data demonstrate a significant advantage for zero DR and one DR mismatch cadaver donor transplants, with excellent immunologic graft survival. This study suggests that a combination of immediate graft function, prevention of acute rejection by appropriate early immunosuppressive therapy, and acceptable DR match enhances cadaveric graft survival.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Alloantibody frequently appears during the immune response to alloantigens in renal transplant recipients. We studied whether the presence of antibody against donor class I antigens correlated with the clinical and pathologic features of acute rejection episodes. We identified patients who had (1) clinical evidence of acute rejection, (2) a renal biopsy showing pathologic features of acute rejection, defined by the Banff criteria, and (3) pre- and posttransplant sera screened against donor T cells. We divided these patients into those with or without donor-specific alloantibody reactive with donor T cells. Of 44 patients with biopsy-proven rejection, 20 were antibody negative (Ab-R) and 24 were antibody positive (Ab+R). The biopsies from Ab+R patients had a higher incidence of severe vasculitis(P=0.0009) and glomerulitis(P=0.01). Fibrin thrombi in the glomeruli and/or vessels, fibrinoid necrosis, and dilatation of peritubular capillaries were also more frequent in the Ab+R group. Infarction was present in biopsy specimens from 9/24 Ab+R patients versus none in the Ab-R group(P=0.002). The Ab+R biopsy specimens more often had polymorphonuclear leukocytes in the peritubular capillaries(P=0.003). In contrast, specimens of Ab-R patients showed tubulitis more often than the specimens of Ab+R patients: moderate and severe tubulitis was present in 19/20 (95%) Ab-R patients versus 12/24 (50%) Ab+R patients (P=0.002). Graft loss was increased in Ab+R patients, particularly in the first 3 months (12/24 compared with 3/20,P=0.025). Thus, during biopsy-proven acute rejection episodes, anti-class I antibody correlates with severe vascular lesions, glomerulitis, and infarction, whereas more severe tubulitis predominates in rejection episodes without antibody.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

This study investigated whether serial daily measurements of serum C-reactive protein (sCRP) in 187 renal allograft recipients could help discriminate episodes of renal dysfunction due to rejection or cyclosporine(CsA) nephrotoxicity and help adjust immunosuppression in the early posttransplant period.Excellent primary graft function was associated with an initial peak of sCRP on day 2 after transplant (median, 29 μg/ml; range, 4->200μg/ml) with a return to <20 μg/ml in all patients by day 5 (median, 7μg/ml; range, 2-19 μg/ml). Stable graft function (mean creatinine, 155μg/ml) was accompanied by a median sCRP of 4 μg/ml (range, 1-19μg/ml). In 30 episodes of rejection responsive to methylprednisolone, sCRP was initially significantly raised to a median of 49 μg/ml(P<0.001) but fell rapidly in response to treatment to a median of 11 μg/ml and continued to fall. In 19 episodes of rejection unresponsive to methylprednisolone, median initial sCRP levels were significantly higher (P<0.001) at 119 μg/ml and were still at a median of 77 μg/ml at the end of the treatment. Twenty-four patients in whom renal dysfunction was associated with CsA nephrotoxicity showed no increase in sCRP concentrations; median sCRP concentrations remained at <5 μg/ml throughout the episodes. A similar pattern was seen in patients with acute tubular necrosis.Serial sCRP measurements provide economical and reproducible evidence of immune activation, help discriminate renal dysfunction due to CsA nephrotoxicity or rejection, and allow appropriate modification of immunosuppressive therapy.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Renal function impairment is common after solid organ transplantation, due to the nephrotoxicity of cyclosporine. Moreover, in patients with severe respiratory failure, renal function is often impaired. This renal function impairment may predispose patients to further renal function impairment after lung transplantation. Therefore, renal hemodynamics were measured in 44 patients before lung transplantation and 1, 6, 12, 18, 24, and 30 months after transplantation. After transplantation, a decline in renal function occurred, with a progressive fall in glomerular filtration rate (GFR) of 33±4% at 12 months and 42±9% at 30 months. Effective renal blood flow fell by 22±5% at 12 months and remained stable thereafter. Changes in effective renal plasma flow (ERPF) were less pronounced than those of effective renal blood flow, due to a fall in hematocrit after transplantation. Blood pressure and renal vascular resistance increased significantly, consistent with the effects of cyclosporine. Prior to transplantation, renal function impairment with intense renal vasoconstriction had been found in a subset of the patients. Remarkably, the decrease in renal function after transplantation was less pronounced in patients with renal function impairment prior to transplantation, as indicated by significant negative correlations between pretransplantation GFR and the percentage change in GFR after transplantation, and pretransplantation ERPF and the percentage change in ERPF after transplantation. This suggests that the net course of renal hemodynamics after lung transplantation is the result of the opposed effects of cyclosporine nephrotoxicity and the favorable effects of the normalization of respiratory status. In conclusion, after lung transplantation a decline in renal function occurs that is less pronounced in patients with renal function impairment and intense renal vasoconstriction prior to transplantation. Such a renal function impairment, therefore, should not be considered a contraindication to lung transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

It is our experience that warm dissection in the porta hepatis as well as extensive organ mobilization during combined pancreas-liver procurements may cause posttransplant dysfunction of the liver. To avoid this, we recently utilized a rapid en bloc procurement technique with minimal warm dissection and division of the liver and pancreas ex vivo.Fifteen procurements were performed using this rapid en bloc technique; seventeen procurements involved extensive dissection followed by sequential in situ procurement of the liver and pancreas grafts. The control group consisted of 15 age-matched patients who received livers when no pancreas was harvested. Dissection time was 157±13 min (mean ± SEM) in the in situ group, 78±3 min in the en bloc group(P<0.02), and 51±6 min in the liver only group(P<0.02). There was no difference in donor age, cold ischemia time, or recipient United Network for Organ Sharing status. Pancreata obtained using the en bloc technique all had immediate function and there were no episodes of acute pancreatitis.Early liver graft function, as assessed by lactate dehydrogenase, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, and total bilirubin levels, was significantly lower in the en bloc and liver only group when compared with the in situ group. The total hospital stay was also significantly lower in these groups.We conclude that the rapid en bloc technique decreases operative time during the donor operation. Procurement-related injury to the liver graft is minimized without compromising pancreas graft function.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID