A. O. Gaber

Glomerulosclerosis as a determinant of posttransplant function of older donor renal allografts

Transplantation of kidneys from older donors is being advocated to expand the organ donor pool. However, the prevalence of atherosclerosis and age-induced renal structural alterations account for the variable function of allografts procured from these older donors. Pretransplant biopsies are sometimes used to evaluate kidneys from older donors, but to date there are no defined criteria correlating the extent of structural alterations in these kidneys to subsequent function. We investigated the effect of glomerulosclerosis, a marker for nephrosclerosis, on graft outcome. Sixty-five baseline biopsies of kidney allografts were retrospectively analyzed to identify a referent point of glomerulosclerosis that correlated with inferior graft outcome. Age and death from non-traumatic cerebrovascular injuries were the main correlates for donor glomerulosclerosis (P<0.001). Allografts with poor function at 6 months defined as serum creatinine >2.5 mg/dl (n=13) or nephrectomy (n=4) had a mean of 20% glomerulosclerosis at the time of implantation compared with only 2% sclerosis in allografts with good function (P<0.05). Delayed graft function occurred in 22% and 33% of recipients with no glomerulosclerosis and those with less than 20% glomerulosclerosis, respectively. In contrast, patients receiving kidneys with >20% sclerosis had an 87% incidence of delayed function (P<0.05). Moreover, graft loss occurred in 7% of recipients of kidneys with less than 20% sclerosis and in 38% of recipients with >20% sclerosis (P<0.04). Measurements of serum creatinine in the donors did not distinguish the different degrees of glomerulosclerosis found on biopsy. Our data indicate that donor glomerulosclerosis greater than 20% increases the risk of delayed graft function and poor outcome of transplanted kidneys. Therefore, we advocate the use of routine biopsies of kidneys from older (>50 yrs) donors and those donors with nontraumatic cerebrovascular accidents, despite seemingly normal preprocurement serum creatinine.

Improvement in autonomic and gastric function following pancreas-kidney versus kidney-alone transplantation and the correlation with quality of life.

We conducted a series of studies to document changes in autonomic and gastrointestinal function following pancreas-kidney and kidney-alone transplantation, define how autonomic function is associated with quality of life, and identify how transplantation alters the quality of life of diabetic transplant recipients.Uremic type I diabetic patients receiving combined pancreas-kidney (n=23) or kidney-alone (n=16) transplants completed pre- and 12-month-posttransplant evaluation of vasomotor function (total capillary pulse amplitude, capillary vasoconstriction response to cold, capillary response to postural adjustments), cardiac function (R-R interval variation, valsalva ratio), overall autonomic function (total autonomic score, autonomic index), gastric function (cutaneous electroga-

A comparison of media supplement methods for the extended culture of human islet tissue

BACKGROUND The preservation of sufficient quantities of islets for human transplantation has proven to be a tenacious problem for researchers and transplant programs. Beyond the variables associated with islet procurement, there is the problem of tissue storage before transplantation. Cryopreservation has been adopted as a method for long-term islet storage that allows for recovery of viable tissue. However, there is significant tissue loss during the process and the possibility that long-term viability may be compromised. An alternate method of prolonged culture at 24 degrees C was initially introduced as a means of reducing islet antigenicity. Although successful in the short term, prolonged culture with serum-based media has also resulted in a significant loss of tissue. In this study, we report the successful use of an ITS+ Premix-supplemented serum-free media for prolonged islet culture and its comparison to fetal bovine serum-supplemented media and to cryopreservation. METHODS Pancreata were procured from cadaveric organ donors, and islets were isolated using our own modification of the automated method of Ricordi. Aliquots from a series of human islet isolations were cultured in parallel in (A) CMRL + ITS (serum-free media; SFM) or (B) CMRL +10% fetal bovine serum (standard media) and compared with cryopreserved and thawed tissue. RESULTS Our results show that SFM allows for the long-term culture of islet tissue. For time points up to 2 months, islets cultured in SFM showed recovery ratios greater than those for standard serum-supple. mented media. At 1 week and 1 month, islet recovery ratios were greater for SFM-cultured islets than for cryopreserved tissue. Viability studies confirmed that the SFM-cultured islets were able to respond to glucose stimulation (stimulation index 0.8-21.2). Additionally, in vivo results using cultured islets in a patient demonstrated good islet function, with a 1-month stimulation index of 4.02 in response to an intravenous glucose tolerance test. CONCLUSION We conclude that this culture modification represents a method by which functional islet tissue can be maintained in long-term culture and successfully transplanted.

Polyomavirus in kidney and kidney-pancreas transplant recipients

Abstract: Purpose. To report the incidence and clinical characteristics of polyomavirus (PV) nephritis in kidney (KTX) and kidney–pancreas transplant (KPTX) recipients.

Kidney-pancreas transplantation: The effect of portal versus systemic venous drainage of the pancreas on the lipoprotein composition

We have previously shown that both kidney-alone and combined kidney-pancreas transplantation lower VLDL and IDL apoB while increasing LDL apoB, apoA-I, and HDL free cholesterol (FC). In this report, we analyze the lipoproteins of 31 patients who have undergone combined kidney-pancreas transplantation. Systemic venous drainage of the pancreas was utilized in 20 of these patients while 11 had portal venous drainage. Six lipoprotein subfractions (VLDL, IDL, LDL, HDL-L, HDL-M, HDL-D) were isolated by rapid gradient ultracentrifugation using a fixed-angle rotor. The apolipoprotein (by reverse-phase HPLC) and lipid (by enzymatic assays) composition of each subfraction was determined. After three months, there were few group differences. However, the portal group had substantial reductions in VLDL apoB at both six (-50% vs. +1%) and twelve months (-57% vs. +149%, P = .042) while the systemic group had increases in VLDL apoB. Similar differences were seen in IDL apoB (six months: -38% vs. +13%; twelve months: -61% vs. +56%, P = .008). LDL apoB increased in both groups at six months (portal: +7%; systemic: +30%) but fell in the portal group at twelve months (-17% vs. +41%, P = .0007). IDL triglyceride, cholesterol ester, phospholipids, and free cholesterol also fell by 19% to 47% in the portal group while they rose by 8% to 44% in the systemic patients, six and twelve months after surgery (P < .05). In addition, the VLDL and LDL free cholesterol to phospholipid ratios (FC/PL) fell (improved) by 16% to 26% in the portal patients while they rose by 9% to 28% in the systemic subjects during this time (P < .04). Finally, there were substantial improvements in the LDL composition of the portal patients compared to the systemic patients at six (PL/apoB: +23% vs. -16%, P = .005; CE/apoB: +14% vs. -14%, P = .037) and twelve months (PL/apoB: +39% vs. -13%, P = .011; CE/apoB: +41% vs. -15%, P = .011). These data indicate that portal drainage of the transplanted pancreas reduced the number of VLDL, IDL, and LDL particles, reduced the total mass of IDL (by 35%), and normalized the VLDL and LDL particle composition. These improvements were not seen in the patients who received systemic drainage of their pancreas. HDL-M also improved in the portal patients (TG: -29% vs. +12%, P = .025) (PL: +22% vs. -5%, P = .014) (total mass: +16% vs. +0.2%, P = .044) but not in the systemic patients six months after surgery. These results suggest that portal venous drainage of the pancreas leads to greater improvements in the lipoprotein composition of IDDM patients than does systemic drainage.

Conversion to sirolimus in solid organ transplantation: a Single-Center experience

BACKGROUND Calcineurin inhibitors are associated with adverse events, including nephrotoxicity and diabetes that might reduce the benefits of long-term graft survival. We report our experience in converting kidney (K), kidney-pancreas (KP), pancreas (P), and (L) recipients from a calcineurin inhibitor/mycophenolate mofetil (MMF)/prednisone dose-induced nephrotoxicity (K = 9, KP = 5, P = 1, L = 5), hemolytic uremic syndrome (HUS) (K = 7, KP = 5), chronic allograft nephropathy (K = 12, L = 1), and glucose intolerance (K = 9, KP = 6, P = 2, L = 2). METHODS The conversion protocol consisted of an abrupt discontinuation of the calcineurin inhibitor with sirolimus (8-12 mg, PO loading dose) initiated 24-72 hours after stopping the calcineurin inhibitor. Sirolimus was titrated to target trough levels of 12-16 ng/mL. Daclizumab 2 mg/kg IV was given to all KP and P recipients on days 0 and 14 postconversion. RESULTS Resolution of HUS occurred in 12 of 12 patients (100%) with a drop in serum creatinine from 3.3 +/- 1.5 to 1.8 +/- 0.9 mg/dL (P =.04). Sirolimus conversion due to nephrotoxicity, HUS, and chronic allograft nephropathy improved serum creatinine from 2.9 +/- 1.4 to 2.2 +/- 0.9 mg/dL (P =.01). Eleven of 19 patients (58%) resolved glucose intolerance. Two patients suffered rejection due to noncompliance. Increases in cholesterol (208 +/- 70 to 243 +/- 77 mg/dL, P <.05) and triglycerides (232 +/- 145 to 265 +/- 148 mg/dL, P = NS), and minimal reduction in platelet values (243 +/- 85 to 237 +/- 85, P = NS) occurred. CONCLUSIONS These data suggest that a calcineurin inhibitor-free immunosuppressive regimen with sirolimus, mycophenolate mofetil, and steroids preserves graft function in patients with clinical indications warranting calcineurin inhibitor discontinuation.

Utility of standardized histological classification in the management of acute rejection

BACKGROUND Standardized histological grading of transplant kidney biopsies has become a primary criterion for diagnosis of rejection in immunosuppression clinical trials. METHODS A consortium of 19 transplant centers from North America, Europe, and Australia convened in 1995 to examine kidney transplant rejection. Data from the 1995 Efficacy Endpoints Conference were examined for frequency of adoption of Banff schema. Biopsy grading was correlated with clinical parameters of rejection and therapy response. RESULTS Histological confirmation of rejection episodes occurred in 73% of 953 cases, with Banff criteria adoption increasing in frequency between 1992 and 1995. Banff grading significantly correlated with clinical rejection severity (rejection creatinine: grade I, 2.8+/-0.2 mg/dl; grade II, 3.5+/-0.2 mg/dl; grade III, 4.1+/-0.3 mg/dl; P < 0.001), although nadir creatinines were similar. Response rates of Banff grades I and II to steroid therapy were not different, but only 42% of grade III rejections responded to steroids (P < 0.003. Banff grading also correlated with postrejection creatinine, day 15: grade I, 2.2+/-0.2 mg/dl; grade II, 3.0+/-0.2 mg/dl; grade III, 3.8+/-0.4 mg/dl (P < 0.001), and day 30: grade I, 2.1+/-0.1 mg/dl; grade II, 2.2+/-0.2 mg/dl; grade III, 2.7+/-0.2 mg/dl (P < 0.06). Banff grade III correlated with reduced graft survival at 1 year: grade I, 86%; grade II, 88%; grade III, 70% (P < 0.01). CONCLUSIONS This multicenter review of rejection severity confirms that standardized histologic classifications such as the Banff schema provide a reliable means for stratifying patient risk of treatment success or failure. These data support the use of Banff criteria in clinical trial design.

Co-Expression of Vascular Endothelial Growth Factor and Interleukin-1 Receptor Antagonist Improves Human Islet Survival and Function

PurposeEx vivo gene therapy approaches can improve the outcome of islet transplantation for treating type I diabetes. We have previously shown the improvement in islet function and vascularization following ex vivo transfection for human vascular endothelial growth factor (hVEGF) gene expression. In this study, we tested the hypothesis that co-expression of two genes, which target different challenges faced by islets post-transplantation, supplement each other to improve the survival and function of islets. We determined whether there is an additive effect of hVEGF and human interleukin-1 receptor antagonist (hIL-1Ra) gene expression in human islets.Materials and MethodsHuman islets were co-infected with adenoviral vectors encoding hVEGF and hIL-1Ra. Islets were then incubated with a cocktail of inflammatory cytokines (IL-1β+TNFα+IFNγ), and islet viability and function were determined. In vivo function was evaluated by transplanting islets under the kidney capsules of streptozotocin-induced non-obese diabetic severe combined immunodeficient (NOD-SCID) mice.ResultsInfection of human islets with Adv-hVEGF and/or Adv-hIL-1Ra inhibited expression of inducible nitric oxide synthase (iNOS), decreased the production of nitric oxide (NO), and prevented the loss of in vitro glucose-stimulated insulin response and viability. Moreover, co-expression of hVEGF and hIL-1Ra reduced the blood glucose level of mice, and increased the level of blood insulin and c-peptide upon glucose challenge.ConclusionsOur results indicated that co-expression of genes that target different insults to transplanted islets can improve the outcome of islet transplantation better than either gene alone.

Glucose stimulation of cytochrome C reduction and oxygen consumption as assessment of human islet quality

Background. An in vitro method to assess human islets could prevent transplantation of nonviable islets and facilitate the optimization of islet preparation. We hypothesize that glucose-stimulated cytochrome c reduction and oxygen consumption by human islets can be used as predictors of transplant success. Methods. Isolated human islets were obtained from research-grade pancreata. Using a previously developed islet flow culture system, the response of cytochrome c reduction and oxygen consumption to glucose was compared to the ability of islets transplanted into nondiabetic NOD-SCID mice to secrete C-peptide in response to a glucose tolerance test conducted 7 days following transplant (n=10). Results. In vitro responses by human islets were qualitatively similar to those seen in rat islets: glucose increased both oxygen consumption and cytochrome c reduction. However, the responses were smaller in magnitude and quite variable. Scatter plots of C-peptide and quantiles for ln(C-peptide) indicated that 12 ng/ml could be used as threshold of transplant success with which to evaluate the diagnostic potential of cytochrome c and oxygen consumption. Data was analyzed by generating receiver operating curves and the area under the curve was 0.889 (95% CI: 0.645–1.000) and 0.738 (95% CI: 0.413–1.000) for cytochrome c reuction and oxygen consumption respectively (1 indicates absolute predictive capability and 0.5 indicates no predictive capability). Conclusions. The detection of glucose-stimulated cytochrome c reduction and oxygen consumption may have utility as criteria for the assessment of human islet quality.

Intermediate-Term Graft Loss After Renal Transplantation is Associated With Both Donor-Specific Antibody and Acute Rejection

Background Renal transplant recipients with de novo DSA (dDSA) experience higher rates of rejection and worse graft survival than dDSA-free recipients. This study presents a single-center review of dDSA monitoring in a large, multi-ethnic cohort of renal transplant recipients. Methods The authors performed a nested case-control study of adult kidney and kidney-pancreas recipients from July 2007 through July 2011. Cases were defined as dDSA-positive whereas controls were all DSA-negative transplant recipients. DSA were determined at 1, 3, 6, 9, and 12 months posttransplant, and every 6 months thereafter. Results Of 503 recipients in the analysis, 24% developed a dDSA, of whom 73% had dDSA against DQ antigen. Median time to dDSA was 6.1 months (range 0.2–44.6 months). After multivariate analysis, African American race, kidney-pancreas recipient, and increasing numbers of human leukocyte antigen mismatches were independent risk factors for dDSA. Recipients with dDSA were more likely to suffer an acute rejection (AR) (35% vs. 10%, P<0.001), an antibody-mediated AR (16% vs. 0.3%, P<0.001), an AR ascribed to noncompliance (8% vs. 2%, P=0.001), and a recurrent AR (6% vs. 1%, P=0.002) than dDSA-negative recipients. At a median follow-up of 31 months, the death-censored actuarial graft survival of dDSA recipients was worse than the DSA-free cohort (P=0.002). Yet, for AR-free recipients, there was no difference in graft survival between cohorts (P=0.66). Conclusions Development of dDSA was associated with an increased incidence of graft loss, yet the detrimental effect of dDSA was limited in the intermediate term to recipients with AR.