Pancreaticoduodenal Grafts Research Articles

Exocrine drainage in vascularized pancreas transplantation in the new millennium

The history of vascularized pancreas transplantation largely parallels developments in immunosuppression and technical refinements in transplant surgery. From the late-1980s to 1995, most pancreas transplants were whole organ pancreatic grafts with insulin delivery to the iliac vein and diversion of the pancreatic ductal secretions to the urinary bladder (systemic-bladder technique). The advent of bladder drainage revolutionized the safety and improved the success of pancreas transplantation. However, starting in 1995, a seismic change occurred from bladder to bowel exocrine drainage coincident with improvements in immunosuppression, preservation techniques, diagnostic monitoring, general medical care, and the success and frequency of enteric conversion. In the new millennium, pancreas transplants are performed predominantly as pancreatico-duodenal grafts with enteric diversion of the pancreatic ductal secretions coupled with iliac vein provision of insulin (systemic-enteric technique) although the systemic-bladder technique endures as a preferred alternative in selected cases. In the early 1990s, a novel technique of venous drainage into the superior mesenteric vein combined with bowel exocrine diversion (portal-enteric technique) was designed and subsequently refined over the next ≥ 20 years to re-create the natural physiology of the pancreas with first-pass hepatic processing of insulin. Enteric drainage usually refers to jejunal or ileal diversion of the exocrine secretions either with a primary enteric anastomosis or with an additional Roux limb. The portal-enteric technique has spawned a number of newer and revisited techniques of enteric exocrine drainage including duodenal or gastric diversion. Reports in the literature suggest no differences in pancreas transplant outcomes irrespective of type of either venous or exocrine diversion. The purpose of this review is to examine the literature on exocrine drainage in the new millennium (the purported "enteric drainage" era) with special attention to technical variations and nuances in vascularized pancreas transplantation that have been proposed and studied in this time period.

Regeneration of β Cells in the Native Pancreata After Syngeneic and Allogeneic Pancreas Transplantations in Spontaneously Type 2 Diabetic Torii Rats

Background We previously demonstrated that syngeneic pancreas transplantation has a potential to reverse diabetes even in a rat model of type 2 diabetes mellitus, namely Spontaneously Diabetic Torii (SDT; RT1 a). The onset of diabetes was significantly delayed in the pancreas transplant recipients. We speculated that perfect diabetic control achieved by pancreas transplantation showed a beneficial effect on the native pancreata & recipients. Materials and Methods Twenty-five-week-old diabetic SDT rats were divided into 3 groups: untreated controls and syngeneic and allogeneic transplant recipients. We transplanted pancreaticoduodenal grafts from nondiabetic 10-week-old SDT rats and from 10-week-old allogeneic Dark Agouti (DA; RT1 a) rats using daily administration of FK506. Results Untreated SDT rats showed disappearance of pancreatic and duodenal homeobox-1 (PDX-1) expression in the pancreas and a marked decrease in β-cell mass. Among syngeneic and allogeneic pancreas transplant recipients, islet-like cell clusters were found in the native pancreata. The β-cell mass at 40 weeks of age was significantly increased in the native pancreata of recipients compared with age-matched controls. Interestingly, we observed the reexpression of PDX-1 in the nuclei of islet-like cell clusters. Conclusions Our results indicated the benefits of avoiding glucose toxicity by pancreas transplantation which induced PDX-1 expression in the native pancreata of type 2 diabetic recipients, resulting in regeneration of β cells in the native pancreata.

Development of donor-specific immunoregulatory T-cells after local CTLA4Ig gene transfer to pancreatic allograft.

CTLA4Ig gene transfer directly to graft tissue might have the potential to avoid the need for systemic immunosuppression. In our previous studies of bio-breeding (BB) rats, local adenovirus-mediated CTLA4Ig gene transfer protected the pancreas from autoimmune and alloimmune responses. This study investigated the potency of local CD28/B7 costimulatory blockade for induction of donor-specific tolerance and further examined the existing mechanisms. Brown Norway (BN; RT1)-pancreaticoduodenal grafts transfected with Ad.CTLA4Ig via intraarterial ex vivo perfusion were transplanted into streptozotocin-induced diabetic Lewis (LEW; RT1) rats. Ad.CTLA4Ig transduced grafts combined with a short course of FK506 resulted in indefinitely prolonged survival (>156 days vs. 19.5 days with FK506 alone). CTLA4Ig was predominantly expressed in grafts on day 4. The expression was gradually diminished and was only slightly detectable at day >100. The proliferative responses against BN antigen were remarkably enhanced among recipients with rejected grafts, but the T-cells from tolerant recipients (>100 days) showed poor cytotoxic responses. On adoptive transfer assay, the splenic T-cells of tolerant recipients were able to suppress the rejection of BN, but not third-party Wistar Furth (WF; RT1) hearts in irradiated (480 cGy) LEW recipients. The percentage of CD4CD25 splenic T-cells was significantly increased in tolerant recipients (13.53 +/- 4.06% vs. 6.06 +/- 0.56% in naive rats). CTLA4Ig gene transfer to the pancreaticoduodenal allograft combined with a short course of FK506 induces donor-specific tolerance. The mechanism of maintaining tolerance could be explained by development of splenic T suppressor cells.

Proliferation of donor-derived NKR-P1 +TCRαβ + (NKT) cells in the nonrecurrent spontaneous diabetic BB rats transplanted with pancreaticoduodenal grafts of Wistar-Furth donors

Proliferation of donor-derived NKR-P1 +TCRαβ + (NKT) cells in the nonrecurrent spontaneous diabetic BB rats transplanted with pancreaticoduodenal grafts of Wistar-Furth donors

A COMPOSITE GRAFT OF ISLET PLUS DONOR LYMPH NODE CELLS COULD NOT INDUCE DONOR SPECIFIC TOLERANCE IN A "LOW RESPONDER" RAT COMBINATION WITH CLASS I MHC DISPARITY

408 We previously reported that WF(RT1U) pancreas transplantation, but not islet transplantation protected recurrence of IDDM by anti-ICAM-1/LFA-1 mAbs in diabetic prone BB rats (RT1U). We have recently reported that class I MHC disparate PVG.R1 (RT1.A'B'D'C') pancreaticoduodenal grafts could be rejected in diabetic PVG (RT1.A'B'D'C') recipients by streptozotocin, while PVG.R1 liver, heart, and kidney grafts could survive indefinitely without immunosuppression. Purpose: This study was to examine that passenger leukocytes have a potencial to induce donor specific tolerance or not, in this "low responder" combination with MHC class I disparity. Materials and Methods: PTx was performed using a modification of S. Lee's method. Approximately overnight cultured 1500 islets were implanted into the subcapsular space of left kidney. Rejection was confirmed by hyperglycemic relapse over 300 mg/dl and by histological examination. PVG recipients were divided into the following 6 groups. Mixed lymphocyte reaction (MLR) and limiting dilution assay to estimate frequencies of IL-2 producing helper (fThp) and cytotoxic (fTcp) T cell precursors to PVG.R1 alloantigens were adopted for cellular immuity.□Flow cytometoric analysis (FACS) to detect antidonor antibodies was performed. Results: Only one case was rejected within 57 days in PTx (n=7) and 3 cases were rejected in ITx (n=7) within 26, 20, 19 days post grafting. Tolerant rats which PTx or ITx grafts survived more than 100 days, were challenged with donor (R1) and 3rd party (BUF) skin grafts to examine the alloantigen specificity. PTx rats rejected BUF skin grafts within 15 days, but interestingly accepted R1 skin (>100 days). Tolerant ITx rats (group 2) rejected both R1 and BUF skin grafts in 13 and 10 days, respectively. Tolerant ITx rats□(group 3.4) transplanted copmosite graft of islet plus with donor R1 ileoceacal lymph node cells, however, are prolonged only donor R1 skin than ITx (group 2). Tolerant ITx rats (group 5) transplanted copmosite graft of islet plus with BUF ileoceacal lymph node cells, however, are prolonged only donor R1 skin than ITx (group 2). Tolerant ITx rats (group 6) transplanted copmosite graft OF islet plus R1 spleen cells, however, are prolonged only donor R1 skin but could not induced tolerance. Conclusion: Donor specific tolerance was obtained by PTx, but not ITx. Immunoreguratory passenger leukocytes might be necessary for the induction of tolerance in ITx in this combination. It was not necessary for donor ileocecal lymph node to prolong graft survivals. (Table)Table

Prevention of autoimmune recurrence and rejection by adenovirus-mediated CTLA4Ig gene transfer to the pancreatic graft in BB rat.

Type 1 diabetes is the result of a selective destruction of pancreatic islets by autoreactive T-cells. Therefore, in the context of islet or pancreas transplantation, newly transplanted beta-cells are threatened by both recurrent autoimmune and alloimmune responses in recipients with type 1 diabetes. In the present study, using spontaneously diabetic BB rats, we demonstrate that whereas isolated islets are susceptible to autoimmune recurrence and rejection, pancreaticoduodenal grafts are resistant to these biological processes. This resistance is mediated by lymphohematopoietic cells transplanted with the graft, since inactivation of these passenger cells by irradiation uniformly rendered the pancreaticoduodenal grafts susceptible to recurrent autoimmunity. We further studied the impact of local immunomodulation on autoimmune recurrence and rejection by ex vivo adenovirus-mediated CTLA4Ig gene transfer to pancreaticoduodenal grafts. Syngeneic DR-BB pancreaticoduodenal grafts transduced with AdmCTLA4Ig were rescued from recurrent autoimmunity. In fully histoincompatible LEW-->BB transplants, in which rejection and recurrence should be able to act synergistically, AdmCTLA4Ig transduced LEW-pancreaticoduodenal allografts enjoyed markedly prolonged survival in diabetic BB recipients. In situ reverse transcription-polymerase chain reaction revealed that transferred CTLA4Ig gene was strongly expressed in both endocrine and exocrine tissues on day 3. These results indicate the potential utility of local CD28-B7 costimulatory blockade for prevention of alloimmune and autoimmune destruction of pancreatic grafts in type 1 diabetic hosts.

Significant role of intragraft lymphoid tissues in preventing insulin-dependent diabetes mellitus recurrence in whole pancreaticoduodenal transplantation.

Graft recurrence of insulin-dependent diabetes mellitus (IDDM) was examined. Islet transplantation or pancreas-alone transplantation excluding the duodenum and peripancreatic lymph nodes was compared with whole pancreaticoduodenal transplantation. A Wistar Furth (WF; RT1(u), RT6.2) to major histocompatibility complex (MHC)-compatible diabetes-prone (DP; RT1(u), RT6.1 gene carrier)-biobreeding (BB) rat transplantation model was used. Only DP recipients that had been transplanted with whole pancreaticoduodenal grafts were free from IDDM recurrence (>60 days postgrafting) when treated with anti-intercellular adhesion moluecule-1 (ICAM)-1/leukocyte function-associated antigen-1 (LFA-1) monoclonal antibodies (mAbs). In the spleen cells of the DP rats that had accepted pancreatic grafts (60 days postgrafting), flow cytometric analysis showed that NKR-P1(+)TCRalphabeta(+) (NKT) cells had proliferated markedly, with the proportion of 12.8 +/- 1.7% in the total splenic T cells, most of which (86.2%) were derived from the donor (RT6.2(+)). By enzyme-linked immunonosorbent assay (ELISA), serum interferon gamma (IFN-gamma) was not detected (<13 pg/ml) in all rats. However, interleukin-4 (IL-4) was detected as 158.8 +/- 28.0 pg/ml in the nonrecurrent DP recipients. These data suggested that to prevent IDDM recurrence in the pancreatic graft, the lymphocytes in the pancreaticoduodenal grafts are necessary. Also, the donor-derived NKT cells might have some immunoregulatory functions with a Th2 deviation.

Significant role of intragraft lymphoid tissues in preventing insulin‐dependent diabetes mellitus recurrence in whole pancreaticoduodenal transplantation

Graft recurrence of insulin-dependent diabetes mellitus (IDDM) was examined. Islet transplantation or pancreas-alone transplantation excluding the duodenum and peripancreatic lymph nodes was compared with whole pancreaticoduodenal transplantation. A Wistar Furth (WF; RT1u, RT6.2) to major histocompatibility complex (MHC)-compatible diabetes-prone (DP; RT1u, RT6.1 gene carrier)-biobreeding (BB) rat transplantation model was used. Only DP recipients that had been transplanted with whole pancreaticoduodenal grafts were free from IDDM recurrence (>60 days postgrafting) when treated with anti-intercellular adhesion moluecule-1 (ICAM)-1/leukocyte function-associated antigen-1 (LFA-1) monoclonal antibodies (mAbs). In the spleen cells of the DP rats that had accepted pancreatic grafts (60 days postgrafting), flow cytometric analysis showed that NKR-P1+TCRαβ+ (NKT) cells had proliferated markedly, with the proportion of 12.8 ± 1.7% in the total splenic T cells, most of which (86.2%) were derived from the donor (RT6.2+). By enzyme-linked immunonosorbent assay (ELISA), serum interferon gamma (IFN-γ) was not detected (<13 pg/ml) in all rats. However, interleukin-4 (IL-4) was detected as 158.8 ± 28.0 pg/ml in the nonrecurrent DP recipients. These data suggested that to prevent IDDM recurrence in the pancreatic graft, the lymphocytes in the pancreaticoduodenal grafts are necessary. Also, the donor-derived NKT cells might have some immunoregulatory functions with a Th2 deviation. © 1999 Wiley-Liss, Inc. MICROSURGERY 19:338–343 1999

Conversion from bladder to enteric drainage after pancreaticoduodenal transplantations

Background: Bladder drainage is the most common technique for managing the exocrine secretions of pancreaticoduodenal grafts. However, bladder drainage can cause urinary, pancreatic, and metabolic complications that may require conversion to enteric drainage. With enteric drainage, urinary amylase levels cannot be monitored as a marker for rejection. After enteric conversion, rejection is the major cause of graft loss. Timing the conversion to reduce immunologic graft loss would greatly improve patient and graft survival rates. Our study was designed to assess the incidence of, indications for, and complications of converting from bladder to enteric drainage after pancreaticoduodenal transplantations. Methods: We retrospectively reviewed our experience with 80 recipients who underwent enteric conversion. We studied the recipient category, the interval from transplantation to conversion, the interval from the last rejection episode to conversion, the indications for conversion, the type of enteric drainage at conversion (loop versus Roux-en-Y), the results of the conversion, and postconversion complications. Results: The major indications for conversion were metabolic acidosis (n = 26, 33%), recurrent urinary tract infections (UTIs) (n = 16, 20%), reflux pancreatitis (n = 15, 19%), and hematuria (n = 12, 15%). For most recipients, their symptoms resolved after conversion (n = 76, 95%). The cumulative probability of undergoing conversion was 13% at 12 months, 21% at 36 months, and 25% at 60 months. Of the recipients with surgical complications after conversion (n = 12, 15%), one lost his graft as a result of pancreatitis. Overall, of the 80 recipients who underwent conversion, 12 (15%) lost their graft, most due to rejection (n = 8, 75%). Immunologic graft loss was highest for recipients of pancreas transplants alone who underwent conversion ≤6 months after transplantation or ≤1 year after their last rejection episode. Conclusions: Enteric conversion is safe and therapeutic in recipients with complications related to the exocrine secretions of bladder-drained pancreas grafts. After conversion, rejection accounted for 75% of the grafts lost. However, waiting at least 1 year after the last rejection episode significantly reduced immunologic graft loss. (Surgery 1998;124:883-93.)

Conversion from bladder to enteric drainage after pancreaticoduodenal transplantations

<h2>Abstract</h2> <b>Background:</b> Bladder drainage is the most common technique for managing the exocrine secretions of pancreaticoduodenal grafts. However, bladder drainage can cause urinary, pancreatic, and metabolic complications that may require conversion to enteric drainage. With enteric drainage, urinary amylase levels cannot be monitored as a marker for rejection. After enteric conversion, rejection is the major cause of graft loss. Timing the conversion to reduce immunologic graft loss would greatly improve patient and graft survival rates. Our study was designed to assess the incidence of, indications for, and complications of converting from bladder to enteric drainage after pancreaticoduodenal transplantations. <b>Methods:</b> We retrospectively reviewed our experience with 80 recipients who underwent enteric conversion. We studied the recipient category, the interval from transplantation to conversion, the interval from the last rejection episode to conversion, the indications for conversion, the type of enteric drainage at conversion (loop versus Roux-en-Y), the results of the conversion, and postconversion complications. <b>Results:</b> The major indications for conversion were metabolic acidosis (n = 26, 33%), recurrent urinary tract infections (UTIs) (n = 16, 20%), reflux pancreatitis (n = 15, 19%), and hematuria (n = 12, 15%). For most recipients, their symptoms resolved after conversion (n = 76, 95%). The cumulative probability of undergoing conversion was 13% at 12 months, 21% at 36 months, and 25% at 60 months. Of the recipients with surgical complications after conversion (n = 12, 15%), one lost his graft as a result of pancreatitis. Overall, of the 80 recipients who underwent conversion, 12 (15%) lost their graft, most due to rejection (n = 8, 75%). Immunologic graft loss was highest for recipients of pancreas transplants alone who underwent conversion ≤6 months after transplantation or ≤1 year after their last rejection episode. <b>Conclusions:</b> Enteric conversion is safe and therapeutic in recipients with complications related to the exocrine secretions of bladder-drained pancreas grafts. After conversion, rejection accounted for 75% of the grafts lost. However, waiting at least 1 year after the last rejection episode significantly reduced immunologic graft loss. (Surgery 1998;124:883-93.)

Autoimmune Recurrence in the Pancreatic Allografts: Chimerism by the NKT Immunoregulatory Cells

156 Introduction: Insulin dependent diabetes mellitus (IDDM) is the result of selective destruction of pancreatic β cells by autoreactive T lymphocytes. In animal models of diabetes (BB rats and NOD mice), isolated islet transplants are highly susceptible to autoimmune destruction. This process is also suspected to play a major role in the disappointing outcome of most human islet transplants. However, in contrast to isolated islets, whole pancreatic grafts demonstrate prolonged correction of hyperglycemia in autoimmune diabetic DP (diabetes prone)-BB rat recipients. In the present study, we have sought to examine the basis of the resistance of whole pancreatic grafts to autoimmune damage utilizing the DP-BB rat pancreas transplantation model. Methods: Whole pancreaticoduodenal grafts were recovered from diabetes resistant (DR)-BB (RT1u, RT6.1) or WF (RT1u, RT6.2) rat donors and transplanted into diabetic DP-BB recipients (RT1u). DP-BB rats have severe T lymphocytopenia with almost complete defect of RT6 alloantigen positive (RT6+) T cells (1.9%), whereas DR-BB or WF rats have normal composition of RT6+ immunoregulatory T cells (40.9% and 47.6%, respectively). Results: As expected diabetic DP-BB rat recipients of DR-BB or WF grafts remained normoglycemic indefinitely (MST >100 days, n=6 and >100 days, n=6, respectively). FACS analysis revealed that the normoglycemic DP-BB recipients of DR-BB or WF pancreatic grafts had restoration of RT6+ T cells, whereas these population were deficient in untransplanted DP-BB rats (27.2% and 3.1%, respectively vs. 1.8%). This suggested a role of donor RT6+ T cell chimerism in protection of pancreatic grafts from recurrent autoimmunity. Double staining of lymphoid cells from naive diabetic DP-BB and pancreas transplanted DP-BB rats utilizing monoclonal antibodies specific for αβ T-cell receptors and NKR-P1 natural killer (NK)-cell receptors revealed that pancreas transplanted DP-BB rats had a significant cell population which expressed both receptors (NKT cells) (7.8% and 9.3%, respectively, vs. 1.1%). To confirm the crucial role of donor chimeric cells in protection from autoimmune damage, a cohort of diabetic DP-BB rats received whole DR-BB or WF pancreatic grafts that were irradiated (1000 rad) prior to transplantation to deplete their passenger leukocytes. In these recipients, despite an initial restoration of normoglycemia, there was a consistent recurrence of IDDM at 15.2 days (n=6) and 17.6 days (n=7), respectively. Histological assessment of the pancreatic grafts revealed mononuclear infiltration of the islets (insulitis) with sparing of the exocrine tissues. Importantly, FACS analysis revealed that DP-BB recipients of irradiated grafts did not exhibit donor chimerism for RT6+ T or NKT cell populations. Conclusion: We have established a consistent model of recurrent autoimmunity in whole pancreaticoduodenal grafts in the BB model of autoimmune diabetes. A protective role of donor chimerism has been demonstrated, in particular NKT cells for the prevention of recurrent autoimmune attack on the β cells. Interestingly, NKT cells have been found to produce IL-4 and enhance the polarization of the immune response to Th2 pathway. These studies argue in favor of the augmentation of donor chimerism in islet or pancreas transplant recipients with highly selected population of immunoregulatory lymphocytes.

Neutrophil elastase enhances intercellular adhesion molecule-1 expression.

Elastase released from activated neutrophils is an important mediator of inflammatory tissue damage. We investigated the effect of human neutrophil elastase (NE) inhibitor (ONO-5046) on reperfusion injury after pancreaticoduodenal transplantation in rats by measuring the expression of intercellular adhesion molecule-1 (ICAM-1). Additional in vitro experiments were conducted to investigate the effect of NE on ICAM-1 mRNA transcription in a rat endothelial cell line (WK-5) and human umbilical vein endothelial cells (HUVEC). In an in vivo experiment, male Wistar rats were transplanted with syngeneic pancreaticoduodenal grafts. An NE inhibitor, ONO-5046, was injected intravenously 5 min before vascular clamping and immediately after reperfusion at a dose of 10 mg/kg. ICAM-1 expression was determined by immunostaining and Northern analysis. In in vitro experiments, the effects of NE and chemical agents on ICAM-1 mRNA transcripts were determined in WK-5 cells and HUVEC. Pretreatment with ONO-5046 decreased ICAM-1 immunostaining in the pancreatic graft and inhibited the increase in ICAM-1 mRNA levels in grafts after reperfusion. ICAM-1 mRNA levels in WK-5 cells and HUVEC showed stimulation by NE, while ONO-5046 inhibited this increase. Calcium ionophore (A23187) augmented NE stimulation of ICAM-1 mRNA levels in these cells. In contrast, a phospholipase C inhibitor (U73122) blunted NE induction of ICAM-1 mRNA, and either calcium chelator (TMB-8) or a nuclear factor-kappa B inhibitor (pyrrolidine dithiocarbamate) completely inhibited induction. These results indicate that NE stimulates ICAM-1 expression in pancreatic grafts via intracellular Ca2+ influx and a phospholipase C signal transduction.

Neutrophil elastase inhibitor (ONO-5046) decreases cytokine-induced neutrophil chemoattractant after reperfusion of pancreaticoduodenal transplantation in rats.

The protective effects of a neutrophil elastase inhibitor (ONO-5046) on reperfusion injury following pancreaticoduodenal transplantation in rats were studied by measuring serum concentrations of cytokine-induced neutrophil chemoattractant (CINC). Male Wistar rats were transplanted with syngeneic pancreaticoduodenal grafts. ONO-5046 was injected intravenously 5 min before vascular clamping and immediately after reperfusion at a dose of 10 mg/kg. No significant differences were observed in the peak serum concentrations of amylase between the groups treated with and treated without ONO-5046. The serum lipase concentrations in the untreated animals increased and peaked 3 hr after reperfusion. ONO-5046 significantly decreased the peak serum lipase concentration. The serum CINC concentrations, which were determined by enzyme-linked immunosorbent assay, increased and peaked 3 hr after reperfusion, decreasing gradually thereafter. However, pretreatment with ONO-5046 significantly inhibited the rise in serum CINC concentrations after reperfusion. Expression of CICN transcripts in the pancrease grafts was evaluated by Northern blot analysis and peaked 3 hr after reperfusion in untreated animals. Pretreatment with ONO-5046 also significantly inhibited the expression of CINC mRNA transcripts in the graft. ONO-5046 significantly decreased the number of neutrophils accumulated in the pancreas graft 24 hr after transplantation. In vitro CINC production by peritoneal macrophages was increased by neutrophil elastase in dose-dependent fashion. However, ONO-5046 decreased CINC production by peritoneal macrophages in response to neutrophil elastase. These results suggest that ONO-5046 prevents early neutrophil accumulation in the pancreas following ischemia/reperfusion of pancreaticoduodenal transplantation.

The blood flow in pancreatico-duodenal grafts in rats: inhibition of nitric oxide synthase preferentially decreases islet blood flow

In this study normoglycemic inbred Wistar-Furth rats were implanted with a syngeneic pancreatico-duodenal graft, i.e. a denervated pancreas. The blood flow to the intact native pancreas and to the transplanted gland was measured with a microsphere technique in anesthetized rats 2 weeks after transplantation. The animals were given an intravenous injection with saline alone, N G-nitro- l-arginine (25 mg/kg body weight) or sodium nitroprusside (10 μg/kg body weight) 10 min before blood flow measurements. Administration of N G-nitro- l-arginine increased mean arterial blood pressure and caused a pronounced decrease in whole pancreatic blood flow in both the native and transplanted gland. The islet blood flow was more markedly decreased by N G-nitro- l-arginine in both the native and transplanted pancreas, and constituted about 4% of whole pancreatic blood flow compared with 10% in the control animals. Sodium nitroprusside markedly decreased mean arterial blood pressure, but did not affect pancreatic or islet blood flow in any of the glands. It is concluded that inhibition of nitric oxide synthase causes a preferential decrease in islet blood flow both in the native pancreas and in the transplanted pancreas. This suggests that nitric oxide which affects islet blood flow is mainly endothelial-derived, and does not emanate from external nervous fibers.

EVIDENCE OF ALLOREACTIVE T SUPPRESSOR CELLS IN THE MAINTENANCE PHASE OF SPONTANEOUS TOLERANCE AFTER ORTHOTOPIC LIVER TRANSPLANTATION IN THE RAT

In the DA-->PVG rat strain combination liver allografts are spontaneously tolerated and induce a state of systemic tolerance towards donor antigens. Thirty long-term (> 100 days)-surviving liver recipients in this strain combination were used to study humoral and cellular mechanisms of tolerance in the maintenance phase after liver transplantation. In the popliteal lymph node assay splenocytes of liver grafted or native PVG rats displayed a similar proliferative response in (DAxPVG)F1 hybrid rats, indicating an unaffected capacity of these cells to mount graft-versus-host reactions. Using adoptive transfer assays T-splenocytes (1x10(7) cells, MRC Ox 19+, MRC Ox12-, CD 5) of long-term-surviving liver recipients were able to suppress the rejection of DA hearts (donor-specific), of DA and AO kidney grafts in irradiated (300 cGy) PVG recipients. Serum of long-term-surviving liver recipients was able to suppress the rejection of semiallogeneic (DAxPVG)F1 heart grafts after double injection of 1 ml serum, while fully allogeneic DA heart as well as skin and pancreaticoduodenal grafts were resistant to passive enhancement. The results confirm the development of spontaneous tolerance after liver grafting in the DA-->PVG strain combination, and the demonstration of T cells with suppressive capacity in adoptive transfer experiments indicates a role for T suppressor cells in the maintenance phase of spontaneous tolerance after liver grafting.

EVIDENCE OF ALLOREACTIVE T SUPPRESSOR CELLS IN THE MAINTENANCE PHASE OF SPONTANEOUS TOLERANCE AFTER ORTHOTOPIC LIVER TRANSPLANTATION IN THE RAT

In the DA→PVG rat strain combination liver allografts are spontaneously tolerated and induce a state of systemic tolerance towards donor antigens. Thirty long-term (>100 days)-surviving liver recipients in this strain combination were used to study humoral and cellular mechanisms of tolerance in the maintenance phase after liver transplantation. In the popliteal lymph node assay splenocytes of liver grafted or native PVG rats displayed a similar prolif-erative response in (DA×PVG)F1 hybrid rats, indicating an unaffected capacity of these cells to mount graft-versus-host reactions. Using adoptive transfer assays T-splenocytes (1×107 cells, MRC O× 19+, MRC O×12-, CD 5) of long-term-surviving liver recipients were able to suppress the rejection of DA hearts (donor-specific), of DA and AO kidney grafts in irradiated (300 cGy) PVG recipients. Serum of long-term-surviving liver recipients was able to suppress the rejection of semiallogeneic (DA×PVG)F1 heart grafts after double injection of 1 ml serum, while fully allogeneic DA heart as well as skin and pancreaticoduodenal grafts were resistant to passive enhancement. The results confirm the development of spontaneous tolerance after liver grafting in the DA×PVG strain combination, and the demonstration of T cells with suppressive capacity in adoptive transfer experiments indicates a role for T suppressor cells in the maintenance phase of spontaneous tolerance after liver grafting.

Effects of cyclosporin A on the blood flow of the native and transplanted rat pancreas and duodenum.

The aim of the present study was to evaluate the effects of cyclosporin A (CyA) on the blood perfusion of the transplanted pancreas. For this purpose syngeneic pancreaticoduodenal transplantations were performed in Wistar-Furth rats. After nephrectomy the graft was anastomosed using a nonsuturing cuff technique to the left renal vessels. Beginning 7 days after transplantation and then continuing for 2 weeks, CyA (15 mg/kg body weight) or vehicle was given p.o. once daily, 6 days a week. The serum CyA concentrations were greater than 600 ng/ml at all points in time tested. Intraperitoneal glucose tolerance tests were normal in CyA-treated animals after 12 days, but the pancreatic insulin concentration was decreased to the same extent in the native and transplanted pancreas. A microsphere technique was used to measure the blood perfusion of the pancreaticoduodenal graft, the native pancreas and duodenum, and remaining kidney 14 days after starting the CyA treatment. The renal blood flow was markedly decreased by CyA when compared with the control animals. In rats given vehicle alone, pancreatic, islet, and duodenal blood flows were higher in the graft than in the corresponding native organs. However, in rats given CyA, hyperperfusion of the graft was not observed. We conclude that the administration of CyA prevents the transplantation-induced blood flow increase seen in pancreaticoduodenal grafts of vehicle-treated rats. These observations may reflect graft denervation.

Effects of cyclosporin A on the blood flow of the native and transplanted rat pancreas and duodenum

Abstract The aim of the present study was to evaluate the effects of cyclosporin A (CyA) on the blood perfusion of the transplanted pancreas. For this purpose syngeneic pancreaticoduodenal transplantations were performed in Wistar-Furth rats. After nephrectomy the graft was anastomosed using a nonsuturing cuff technique to the left renal vessels. Beginning 7 days after transplantation and then continuing for 2 weeks, CyA (15 mg/kg body weight) or vehicle was given p.o. once daily, 6 days a week. The serum CyA concentrations were greater than 600 ng/ml at all points in time tested. Intraperitoneal glucose tolerance tests were normal in CyA-treated animals after 12 days, but the pancreatic insulin concentration was decreased to the same extent in the native and transplanted pancreas. A microsphere technique was used to measure the blood perfusion of the pancreaticoduodenal graft, the native pancreas and duodenum, and remaining kidney 14 days after starting the CyA treatment. The renal blood flow was markedly decreased by CyA when compared with the control animals. In rats given vehicle alone, pancreatic, islet, and duodenal blood flows were higher in the graft than in the corresponding native organs. However, in rats given CyA, hyperperfusion of the graft was not observed. We conclude that the administration of CyA prevents the transplantation-induced blood flow increase seen in pancreaticoduodenal grafts of vehicle-treated rats. These observations may reflect graft denervation.

Pancreatic flush injury in combined pancreas-liver recovery.

The function of pancreatic grafts harvested from six pancreas-liver (PL) donors was compared to that of nine pancreas-alone (PA) donors. All donors had comparable physiological parameters. Pancreas and liver were flushed in situ with 4C Collins solution and the portal vein was vented immediately. The pancreaticoduodenal grafts were reflushed and stored in Collins solution (three PA and two PL), silica gel-filtered plasma (six PA and two PL), or University of Wisconsin solution (two PL). Later they were revascularized by the iliac vessels and drained into the bladder. All pancreas recipients were insulin-dependent. Serum glucose, amylase, lipase, blood urea nitrogen (BUN), creatinine, protein, albumin, and urine amylase, bicarbonate and pH were monitored for 12 days. Data were analyzed using the Mann-Whitney U-test and Fischer's exact test. The PL grafts received a significantly higher aortic flush volume (5983 cc vs 1622 cc, P = 0.001) than those in the other group. Recipients of PL grafts had higher serum amylase (335 vs 250 IU/l) and lipase (1048 vs 424 IU/l), significantly lower levels of urine bicarbonate (11.2 vs 27.1 mEq/l, P = 0.01), pH (6.8 vs 7.3, P = 0.04), and amylase (9202 vs 19,981 IU/l, P = 0.05) than those in the PA group.(ABSTRACT TRUNCATED AT 250 WORDS)

Pancreatic islet blood flow after syngeneic pancreaticoduodenal transplantation in rats. Differences between the blood perfusion of the native and the transplanted gland.

Inbred male Sprague-Dawley rats were transplanted with syngeneic pancreaticoduodenal grafts. Diabetes was induced in some of the recipient animals by an i.v. injection of streptozotocin one week before transplantation, while the remaining control rats were untreated, and thus had both an intact native and a transplanted pancreas. The left kidney of the recipient was removed and its blood vessels were used for the graft vascular anastomosis. The graft duodenum was sutured end-to-side to the ileum of the recipient. Two weeks after transplantation the rates of blood flow through both the native and transplanted pancreas and duodenum were measured. The blood perfusion of the whole pancreas and the islets was higher in the tx than in the native gland, although no difference was seen with regard to the duodenum. Administration of glucose to control animals had no effect on either native or tx whole pancreatic or intestinal blood flow. However, the islet blood flow through the native pancreas was increased in response to glucose, while that of the tx gland remained unchanged. The combined data show that the blood flow of a tx pancreas is slightly higher than that of the native organ, and that the response of the islet blood perfusion to glucose administration differs between the native and tx pancreas. This suggests that islets in the tx pancreas 14 days after transplantation are not subject to the same blood flow regulatory mechanisms as native islets.