Superiority of portal venous drainage over systemic venous drainage in pancreas transplantation: a retrospective study.

OBJECTIVE: To compare portal and systemic venous drainage of pancreas transplants and demonstrate an immunologic and survival superiority of portal venous drainage. SUMMARY BACKGROUND DATA: Traditionally, solitary pancreas transplants have been performed using systemic venous and bladder drainage, but more recently, the advantages of enteric drainage have been well documented. Although physiologic benefits for portal venous drainage have been described, the impact of portal venous drainage, especially with solitary pancreas transplants, has yet to be determined. METHODS: Since August 1995, 280 pancreas transplants with enteric duct drainage were analyzed. One hundred and seventeen were simultaneous pancreas and kidney (SPK), 63 with systemic venous drainage (SV) and 54 with portal venous drainage (PV). The remainder were solitary transplants; 97 pancreas after kidney (PAK; 42 SV and 55 PV) and 66 transplants alone (PTA; 26 SV and 40 PV). Immunosuppressive therapy was equivalent for both groups. RESULTS: The groups were similar with respect to recipient characteristics and HLA matching. Thirty-six month graft survival for all transplants was 79% for PV and 65% for SV (P =.008). By category, SPK graft survival was 74% for PV and 76% for SV, PAK graft survival was 70% for PV and 56% for SV, and PTA graft survival was 84% for PV and 50% for SV. The rate of at least one rejection episode was also significantly higher in the SV group. At 36 months, for all pancreas transplants, the rejection rate was 21% for PV and 52% for SV (P <.0001). For SPK, rejection rates were 9% for PV and 45% for SV. For PAK, rejection rates were 16% for PV and 65% for SV, and for PTA 36% for PV and 51% for SV. The rejection rates for kidneys following SPK were also lower in the PV group (26% versus 43% for SV). Furthermore, the grades of rejection were milder in PV for all transplants (P =.017). By multivariate analysis, portal venous drainage was the only parameter that significantly affected rejection. CONCLUSION: Graft survival and rejection is superior for PV. These clinical findings are consistent with published reports of experimentally induced portal tolerance and strongly argue that PV drainage should be the procedure of choice for pancreas transplantation.

A high panel-reactive antibody rescue protocol for cross-match-positive live donor kidney transplants.

BACKGROUND: Alloimmunization can present a virtually insurmountable barrier to kidney transplantation. Past protocols to desensitize patients using plasmapheresis and cyclophosphamide have not been broadly applied because of the fear of complications, including high rates of immunologic failure. METHODS: Fifteen patients with a positive donor-recipient cross-match were desensitized with plasmapheresis to permit live donor (LD) transplantation under newer maintenance immunosuppressants. Pretransplant the patients received plasmapheresis three times weekly for a planned maximum of six treatments, plus intravenous hyperimmune globulin, tacrolimus, mycophenolate mofetil, and prednisone. Patients who were successfully desensitized and received transplants were given 10 days of OKT3 postoperatively. RESULTS: Eleven of the 15 patients became anti-human globulin cross-match-negative after one to five plasmapheresis treatments and underwent LD transplantation. Relatively low initial titers of donor-specific antibody were predictive of successful attainment of a negative cross-match. Few side effects and rejection episodes were observed. All transplant patients remain dialysis-free after 3-26 months of follow-up. CONCLUSION: A positive cross-match is not necessarily a contraindication to LD transplantation, especially for patients with low donor-specific alloantibody titers.

Increased rates of donation with laparoscopic donor nephrectomy.

OBJECTIVE: To examine the impact of laparoscopic nephrectomy and recipient education on the proportion of kidney recipients who could identify a potential live donor, and on the live donor (LD) transplantation rate. SUMMARY BACKGROUND DATA: Laparoscopic donor nephrectomy (LDN) results in less postoperative surgical pain, a shorter hospital stay, and quicker recovery than the standard open donor nephrectomy (ODN). The authors hypothesized that the availability of this less invasive surgical technique would enhance the willingness of family and friends to donate. METHODS: The study population consisted of 3,298 end-stage renal disease patients referred for kidney transplant evaluation between November 1991 and February 2000, divided into three groups. The first group received no formal LD education and had only ODN available. The second group received formal education about the LD process and had only ODN available. The third group had both formal LD education and LDN available. Records were examined to determine what proportion of each group had any potential donors tissue-typed, and the rate at which they received an LD transplant. RESULTS: Before LDN availability and formal LD education, only 35.1% of referrals found a potential donor, and only 12.2% received an LD transplant within 3 years. Institution of a formal education program increased the volunteer rate to 39.0%, and 16.5% received an LD transplant. When LDN became available, 50% of patients were able to find at least one potential donor, and within 3 years 24.7% received an LD transplant. Regression analysis indicated that availability of LDN was independently associated with a 1.9 relative risk of receiving an LD transplant. Kaplan-Meier death-censored 1- and 3-year graft survival rates for ODN transplants were 95.8% and 90.6%, versus 97.5% and 94. 8% for LDN. CONCLUSIONS: The availability of LDN and an LD family education program has doubled the live donor transplantation rate, and outcomes remain excellent.

Simultaneous pancreas-kidney (SPK) and pancreas living-donor kidney (SPLK) transplantation at the University of Maryland.

The evolution of enteric and portal venous drainage, better immunosuppression, and better patient care has elevated pancreas transplantation with dramatically improved results. At our center, long-term graft survival and rejection has significantly improved with portal venous drainage, which has become our gold standard. This improvement is exemplified by the excellent one-year patient and graft survival rates for SPLK transplants. SPLK has proven to be an ideal approach in uremic Type 1 diabetic patients with living donors and should become the procedure of choice for that population. Moreover, the improved monitoring of rejection has allowed a similar success of pancreas transplantation alone in non-uremic patients with brittle diabetes. The treatment of diabetes mellitus has room for great improvement, however, and there is no question that islet transplantation, xenotransplantation, and the pursuit of immunologic tolerance will play an extremely important role in that endeavor.

The shrinking renal replacement therapy "break-even" point.

BACKGROUND: This study examines the current cost of live donor (LD) transplantation at our institution, and compares it with that of dialysis. METHODS: The study population consisted of 184 consecutive adult recipients of laparoscopically procured LD kidney transplants. Cost-containment measures instituted during this series included elimination of routine postoperative antilymphocyte induction and an accelerated discharge clinical pathway with planned discharge of the recipient on postoperative day (POD) 2. Costs of the transplants to Medicare were estimated from hospital charges, readmission rates, and immunosuppressant usage. These were compared with published costs of dialysis to Medicare in terms of a fiscal transplant-dialysis break-even point. RESULTS: Kaplan-Meier patient and graft survival rates at 1 year were 97 and 93%, respectively. Among patients followed for at least 90 days and treated with no induction and either cyclosporine-mycophenolate mofetil or tacrolimus-mycophenolate mofetil, acute rejection rates were low (27.6 and 13.9%, respectively). In the last 124 patients, 32.3% were discharged by POD 3 and 71.8% by POD 6, with corresponding mean transplant hospital charges (excluding organ acquisition) of $11,873 and $17,350, respectively. The 30-day readmission rate for patients discharged on the accelerated pathway by POD 3 was only 16%. The least expensive subgroup in the present study (30% of patients) was that of patients discharged by POD 6 and not readmitted during the first year; the break-even point with dialysis costs was calculated as 1.7 years after the transplant. CONCLUSIONS: The cost of LD transplants can be safely reduced by elimination of routine postoperative anti-lymphocyte immune induction and by an early discharge clinical pathway. Uncomplicated LD kidney transplants, meaning those with a short length of stay in the hospital after transplantation and no need for readmission within the first year, accrue savings over dialysis within 2 years.

Kidney transplantation at the University of Maryland.

1. The number of kidney transplants performed at the University of Maryland increased yearly from 51 in 1991 to 285 in 1998. Over the past 3 years, the increase in the number of kidney transplants can be ascribed almost exclusively to a marked increase in living donor transplants, from 49 cases in 1995 to 130 cases in 1998; a 160% increase. The increase in our frequency of living-donor kidney transplantation can be attributed to a formal family education program and the availability of the laparoscopic technique for kidney removal. 2. In addition to the availability of the laparoscopic technique, a number of special programs has allowed an increased number of living donor kidney transplants. This includes a special protocol for transplantation of Epstein-Barr virus negative recipients, a protocol for transplantation of patients who have a positive crossmatch with a living donor, as well as, the simultaneous living donor kidney/cadaver pancreas "SPK(LRD/PTA)" program. 3. The one-year graft and patient survival for the entire program was 87.0% and 94.5%, respectively. However, the more recent graft survival rates have markedly increased; Since August 1995, the one-year graft and patient survival was 89.8% and 95.8%, respectively. 4. Improvement in immunosuppression has lead to dramatic improvement in the success rates in living-donor kidney transplants. Despite the omission of antibody-based induction therapy, the one-year graft survival rate using a mycophenolate mofetil/tacrolimus-based immunosuppression protocol was 96.4%. The one-year rejection rate was 8% in Caucasian patients and 14% in African-American patients in this subgroup of living-donor kidney transplant recipients. 5. The data demonstrate that the use of the living-donor transplant option is grossly underutilized. Estimates are presented that more than 11,000 living-donor kidney transplants should be possible in the US yearly.

National Transplantation Pregnancy Registry: analysis of pregnancy outcomes in female liver transplant recipients.

Outcomes from 48 pregnancies in 34 female liver transplant recipients were analyzed. Data were collected via interviews, questionnaires, and hospital records. All recipients were treated with cyclosporine-based immunosuppression except 2 patients treated with FK506 and 2 treated with no immunosuppression. The age at conception was 26.1 +/- 5.9 years (mean +/- SD) with a transplant interval (time from transplantation to conception) of 2.9 +/- 2.5 years. There were 49 outcomes (1 set of twins): miscarriage 9 (18%), therapeutic abortion 4 (8%), and live birth 36 (74%). No stillbirths or ectopic pregnancies were reported. Of the 36 live births, the gestational age was 36.9 +/- 3.5 weeks, the birthweight was 2,604 +/- 698 grams, 39% were premature (< 37 weeks), and 31% had low birthweight (< 2,500 grams). No birth defects or neonatal deaths (< 28 days) were reported. The newborn complication rate was 17% (n = 6), 5% in premature infants. The incidence of drug-treated hypertension was 46%; pre-eclampsia 21%; infectious complications 26%; and Caesarean section 47%. Recipients with hypertension had a higher proportion of premature infants (71%) than normotensive patients (38%) (P = .04 by Fisher's exact test). Acute rejection was diagnosed in 6 pregnancies, 2 of which were ended by therapeutic abortion. Four recipients who continued their pregnancies were treated with increased immunosuppression for rejection, and all delivered livebirths. There were two grafts lost within 6 months of pregnancy. The only maternal death occurred in a patient who required retransplantation for recurrent C hepatitis 3 months afte therapeutic abortion and died 6 months later. The other recipient with graft loss was successfully retransplanted for chronic rejection 6 months after delivery. We draw the following conclusions: (1) female liver transplant recipients can safely undergo pregnancy, although there is a high rate of premature and low birthweight infants; (2) pregnancies in this population should be considered high-risk and require close monitoring of liver function; and (3) altered graft function during pregnancy should be thoroughly investigated.

Collagenase lot selection and purification for adipose tissue digestion.

Crude Clostridial collagenase (CCC) remains the most widely used enzyme for the digestion of tissues prior to cell isolation and culture. CCC contains numerous components in addition to specific collagenases and proteases. A chronic problem associated with CCC is significant lot variability which occurs with respect to the ability of different lots of CCC to digest tissue. We have evaluated numerous commercially available samples of CCC for their ability to digest human liposuction-derived SC fat. Digestion capacity was evaluated as the ability to release endothelial cells from fat as well as the ability of isolated cells to adhere to tissue culture plastic. A significant variation in digestion efficacy between lots of collagenase was observed. We subsequently purified CCC using a partial purification method with dialysis and centrifugation as well as a complete purification, using liquid chromatography, to remove all nonspecific proteases. While partially purified collagenase retained digestion capacity, pure collagenase exhibited reduced digestion capacity. Maximum digestion was achieved with pure collagenase when trypsin was added. The use of completely purified collagenase with trypsin is advantageous where all components in the enzyme digestion mixture must be known.

Variables affecting birthweight and graft survival in 197 pregnancies in cyclosporine-treated female kidney transplant recipients.

Outcomes from 197 pregnancies in 141 female kidney transplant recipients were analyzed from data collected via questionnaires, hospital records, and phone interviews. All recipients were maintained on cyclosporine (CsA) before and during pregnancy. Of the livebirths, 54% were premature (< 37 wk) and 50% were low-birthweight (LBW) (< 2500 g). The incidence of recipient drug-treated hypertension (HTN) was 56%; preeclampsia, 29%; infections and complications 22%; and rejection during pregnancy and up to 3 mo. post delivery (rej.), 11%. Graft loss within 2 years of delivery occurred in 9% of recipients (GrL < 2). No recipients reported a pregnancy after a postpregnancy graft loss. Mean serum creatinine was reported before, during, and after pregnancy. Mean cyclosporine doses were similar in recipients during and after pregnancy. Data were analyzed by logistic regression using SAS. Outcomes included prematurity, LBW, rej., and GrL < 2. In a case-controlled study comparing a recipient group with graft dysfunction during pregnancy vs. a group with good graft function, there was a trend toward lower mean prepregnancy CsA doses (in mg/kg) in the graft dysfunction group. A decline in recipient graft function during pregnancy is associated with lower newborn birthweights and lower maternal graft survival in cyclosporine treated female kidney recipients. Pregnancy-related infections and complications are associated with rejection and graft loss in this population. Close monitoring of CsA dosing and serum creatinine levels during pregnancy and immediately postpartum is recommended as CsA dosage adjustment may be required.

Endothelial cell transplantation onto polymeric arteriovenous grafts evaluated using a canine model.

Prosthetic arteriovenous grafts (AVG) placed for hemodialysis access fail in humans due to the thrombogenicity of the flow surface and development of cellular intimal hyperplasia, particularly at the venous anastomosis. The poor patency rates of prosthetic AVG result in significant morbidity and mortality in dialysis patients. Consequently, investigators have been evaluating methods to improve the patency of prosthetic grafts by examining endothelial cell transplantation as a means of creating an antithrombogenic lining on artificial polymers. A canine model was developed to study the effects of cell transplantation of autologous, fat-derived microvessel endothelial cells (MVEC) onto the luminal surface of expanded polytetrafluoroethylene (ePTFE) grafts. Microvessel endothelial cells were isolated from falciform ligament fat, with each dog receiving its own endothelial cells. Isolated cells were subsequently placed into the lumen of the graft (4 mm by 20 cm ePTFE). The graft lumen was pressurized to 5 pounds per square inch (psi) resulting in the partial denucleation of the graft, due to the flow of buffer into the interstices of the graft, and the forced deposition of cells onto the luminal surface. Animals were maintained on aspirin and persantine during the implant phase. During the implant phase, grafts were evaluated by both duplex ultrasound and magnetic resonance angiography (MRA). At explant, gross observation of the sodded grafts revealed a glistening white flow surface with no evidence of thrombosis. Morphologic and scanning electron microscopic evaluations revealed the presence of a cellular lining on the luminal flow surface that exhibited characteristics of antithrombogenic endothelial cells. Midgraft samples were evaluated by immunocytochemistry and indicated that cells on the luminal surface react positively with antibodies to von Willebrand factor. Results from this study demonstrate that the canine model provides an excellent method of studying the effects of MVEC sodding on the thrombogenicity and hyperplastic response of prosthetic arteriovenous graft.

Liposuction-derived human fat used for vascular graft sodding contains endothelial cells and not mesothelial cells as the major cell type.

PURPOSE: Endothelial cell transplantation has been suggested as a method to improve the patency of prosthetic grafts used for vascular reconstruction. A major technical concern of all cell transplantation studies has been the purity of cells in the primary isolate used for subsequent transplantation. Accordingly we have evaluated the cellular constituents of liposuction-derived human fat with immunocytochemistry and scanning electron microscopy. METHODS: Samples of liposuction-derived human fat were processed for immunohistochemistry and subsequently stained for the presence of von Willebrand factor (vWF), alpha-smooth muscle cell actin, cytokeratin (peptide 18), and the endothelial cell-specific marker EN4. We also performed histochemistry studies on the cells derived from this fat after collagenase dispersion of the liposuction far. RESULTS: Immunohistochemistry revealed that 86.1% of the cells in intact, liposuction-derived fat express vWF, whereas 5.7% of the cells exhibited alpha-smooth muscle cell actin, and 1.0% expressed the mesothelial cell-related antigen, cytokeratin peptide 18. Expression of EN4 was found in 89.6% of the cells counted in intact far. After digestion of fat with collagenase and centrifugal separation of adipocytes from vascular and stromal cells, the expression of vWF, alpha-smooth muscle cell actin, and cytokeratin was 77.5%, 5.8%, and 2.1%, respectively. EN4 expression was observed in 74.6% of the isolated cells. Thus most cells present in liposuction-derived fat, even before tissue digestion and cell isolation, were characterized as endothelium. Although other cells common to mesodermally derived tissue were identified (e.g., adipocytes, smooth muscle cells, and mesothelium), they represented a minor fraction of the total cells present. On isolation, the number of cells expressing vWF- and EN4-specific antigens was less than that observed in intact fat. CONCLUSIONS: This finding suggests that a portion of cells reacting with antibodies in situ lose vWF and EN4 staining during the isolation procedure. Unlike omentum, liposuction-derived fat predominantly contains adipocytes and endothelial cells. On digestion of liposuction-derived fat and separation of cells, vascular endothelial cells represent the major cellular component.

National transplantation Pregnancy Registry--outcomes of 154 pregnancies in cyclosporine-treated female kidney transplant recipients.

Outcomes of pregnancies from 115 female kidney transplant recipients maintained on cyclosporine before and during pregnancy were obtained from questionnaires, hospital records, and telephone interviews. The mean age of conception was 29 years with a mean transplant interval of 2.2 years. There were 156 outcomes (2 sets of twins): ectopic 1%, therapeutic abortion 12%, miscarriage 16%, stillborn 2.6%, live birth 68.6%. The incidence of prematurity (< 37 weeks) was 56%, and that of low birthweight (< 2500 g) 49.5%. Complications occurred in 21.7% of newborns, but with only 1 neonatal death. Liveborn infants had a mean gestational age of 35.6 weeks (term 37-42 weeks) and a mean birthweight of 2407 g. The incidence of drug-treated hypertension prior to pregnancy was 51.7%; of diabetes prior to pregnancy, 11.7%; of preeclampsia, 24.8%; and of rejection during pregnancy or within 3 months postdelivery 14.5%. When infants born to women with or without a given risk factor were compared, mothers with pregnancy drug-treated hypertension had significantly lower-birth-weight infants (2250 vs. 2603 g, P = 0.028 by Wilcoxon). Similarly, mothers with prepregnancy creatinine > or = 1.5 mg/dl had smaller infants (2090 vs. 2505 g, P = 0.031 by Wilcoxon). There was a trend toward lower birth-weight in infants of diabetic recipients. Of 107 recipients interviewed, 12(11%) experienced graft loss, 8 associated with graft dysfunction or rejection during pregnancy. There was 1 graft loss during pregnancy due to rejection and 8 grafts were lost within 2 years of the pregnancy. There was one maternal death 4.3 years postpregnancy. For the 8 recipients who lost their graft within 2 years of pregnancy, outcomes included 1 miscarriage and 7 live births. The 7 live births had a mean gestational age of 35.7 weeks and a mean birth-weight of 2194 g. Five of 8 recipients who had graft loss within 2 years of pregnancy were in the drug-treated hypertensive group. Prepregnancy factors that appear to increase the risk to the newborn of a female kidney transplant recipient include maternal drug-treated hypertension, diabetes, and serum creatinine > or = 1.5 mg/dl. More data are needed before specific prepregnancy predictors for maternal graft loss can be determined in this population.

Microvascular endothelial cell sodding of ePTFE vascular grafts: improved patency and stability of the cellular lining.

Small diameter (< 6 mm) synthetic vascular grafts fail at a clinically unacceptable rate due in large part to their inherent thrombogenicity. The development of a new cellular lining on synthetic vascular grafts would most likely improve the patency rates observed for these grafts in small diameter positions. We have evaluated the use of endothelial cell transplantation to accelerate the formation of a cell lining using microvascular endothelial cells derived from canine falciform ligament fat. This source of fat is histologically similar to human liposuction fat and was isolated using a collagenase digestion technique identical to methods used for human liposuction fat microvessel endothelial cell isolation. The isolated fat endothelial cells were sodded onto 4 mm ePTFE grafts using pressure to force the cells onto the luminal surface. This pressure sodding method permitted cell deposition in less then 3 min. Sodded and control (non-cell-treated) grafts were implanted as interpositional paired grafts using end-to-end anastomoses in the carotid arteries of mixed breed dogs. Each dog therefore received a sodded graft on one side and a control graft on the contralateral side. After 12 weeks of implantation all control grafts were occluded while 86% of the cell-sodded grafts remained patent. Statistical evaluation of the data revealed a significant improvement in patency of cell sodded grafts (McNemar's chi 2 P = .02). Morphological evaluation of grafts explanted at 5, 12, 26, and 52 weeks following implantation revealed the presence of a cell lining on sodded grafts which remained stable for a period of at least one year. This new cell lining exhibited morphologic characteristics of a nonthrombogenic endothelial cell lining. The development of this new intima, evaluated 5 weeks-1 year after implantation, was not associated with a progressive intimal hyperplasia. From these data we conclude that microvessel endothelial cells derived from canine falciform ligament fat can be rapidly isolated using an operating room compatible method. Cell deposition on synthetic grafts is subsequently accelerated using a pressure sodding technique. A cellular lining forms on the inner surface and is associated with a statistically significant improvement in the function of sodded grafts in a canine carotid artery model.

Serum amino acids following human orthotopic liver transplantation.

Our findings indicate that serum amino acid changes after OLT are complex and influenced by multiple factors including sepsis and use of parenteral hyperalimentation with exogenous amino acids. Additional factors which may influence the rate of normalization of amino acids after OLT include the presence of malnutrition (frequently observed before OLT) and the extent of pretransplant portal-systemic shunting. Our results demonstrate that the presence of septic complications and the use of CPN are important determinants of the postoperative levels of several amino acids, including the BCAA/AAA ratio. Our logistic regression model using the BCAA/AAA ratio predicted the occurrence of sepsis after OLT 77% of the time. Prospective assessment and validation of this model is under way.