Arguments against the Requirement of a Biological License Application for Human Pancreatic Islets: The Position Statement of the Islets for US Collaborative Presented during the FDA Advisory Committee Meeting

The Food and Drug Administration (FDA) has been regulating human islets for allotransplantation as a biologic drug in the US. Consequently, the requirement of a biological license application (BLA) approval before clinical use of islet transplantation as a standard of care procedure has stalled the development of the field for the last 20 years. Herein, we provide our commentary to the multiple FDA’s position papers and guidance for industry arguing that BLA requirement has been inappropriately applied to allogeneic islets, which was delivered to the FDA Cellular, Tissue and Gene Therapies Advisory Committee on 15 April 2021. We provided evidence that BLA requirement and drug related regulations are inadequate in reassuring islet product quality and potency as well as patient safety and clinical outcomes. As leaders in the field of transplantation and endocrinology under the “Islets for US Collaborative” designation, we examined the current regulatory status of islet transplantation in the US and identified several anticipated negative consequences of the BLA approval. In our commentary we also offer an alternative pathway for islet transplantation under the regulatory framework for organ transplantation, which would address deficiencies of in current system.

The demise of islet allotransplantation in the United States: A call for an urgent regulatory update

Islet allotransplantation in the United States (US) is facing an imminent demise. Despite nearly three decades of progress in the field, an archaic regulatory framework has stymied US clinical practice. Current regulations do not reflect the state-of-the-art in clinical or technical practices. In the US, islets are considered biologic drugs and "more than minimally manipulated" human cell and tissue products (HCT/Ps). In contrast, across the world, human islets are appropriately defined as "minimally manipulated tissue" and not regulated as a drug, which has led to islet allotransplantation (allo-ITx) becoming a standard-of-care procedure for selected patients with type 1 diabetes mellitus. This regulatory distinction impedes patient access to islets for transplantation in the US. As a result only 11 patients underwent allo-ITx in the US between 2016 and 2019, and all as investigational procedures in the settings of a clinical trials. Herein, we describe the current regulations pertaining to islet transplantation in the United States. We explore the progress which has been made in the field and demonstrate why the regulatory framework must be updated to both better reflect our current clinical practice and to deal with upcoming challenges. We propose specific updates to current regulations which are required for the renaissance of ethical, safe, effective, and affordable allo-ITx in the United States.

Efficacy and safety of bleselumab in kidney transplant recipients: A phase 2, randomized, open-label, noninferiority study

This study assessed the efficacy and safety of the anti-CD40 monoclonal antibody bleselumab (ASKP1240) in de novo kidney transplant recipients over 36 months posttransplant. Transplant recipients were randomized (1:1:1) to standard of care (SoC: 0.1 mg/kg per day immediate-release tacrolimus [IR-TAC]; target minimum blood concentration [C_trough ] 4-11 ng/mL plus 1 g mycophenolate mofetil [MMF] twice daily) or bleselumab (200 mg on days 0/7/14/28/42/56/70/90, and monthly thereafter) plus either MMF or IR-TAC (0.1 mg/kg per day; target C_trough 4-11 ng/mL days 0-30, then 2-5 ng/mL). All received basiliximab induction (20 mg pretransplant and on days 3-5 posttransplant) and corticosteroids. One hundred thirty-eight transplant recipients received ≥1 dose of study drug (SoC [n = 48]; bleselumab + MMF [n = 46]; bleselumab + IR-TAC [n = 44]). For the primary endpoint (incidence of biopsy-proven acute rejection [BPAR] at 6 months), bleselumab + IR-TAC was noninferior to SoC (difference 2.8%; 95% confidence interval [CI] -8.1% to 13.8%), and bleselumab + MMF did not demonstrate noninferiority to SoC (difference 30.7%; 95% CI 15.2%-46.2%). BPAR incidence slightly increased through month 36 in all groups, with bleselumab + IR-TAC continuing to demonstrate noninferiority to SoC. Bleselumab had a favorable benefit-risk ratio. Most treatment-emergent adverse events were as expected for kidney transplant recipients (ClinicalTrials.gov NCT01780844).

Oxygen Perfusion (Persufflation) of Human Pancreata Enhances Insulin Secretion and Attenuates Islet Proinflammatory Signaling

BACKGROUND

All human islets used in research and for the clinical treatment of diabetes are subject to ischemic damage during pancreas procurement, preservation, and islet isolation. A major factor influencing islet function is exposure of pancreata to cold ischemia during unavoidable windows of preservation by static cold storage (SCS). Improved preservation methods may prevent this functional deterioration. In the present study, we investigated whether pancreas preservation by gaseous oxygen perfusion (persufflation) better preserved islet function versus SCS.

METHODS

Human pancreata were preserved by SCS or by persufflation in combination with SCS. Islets were subsequently isolated, and preparations in each group matched for SCS or total preservation time were compared using dynamic glucose-stimulated insulin secretion as a measure of β-cell function and RNA sequencing to elucidate transcriptomic changes.

RESULTS

Persufflated pancreata had reduced SCS time, which resulted in islets with higher glucose-stimulated insulin secretion compared to islets from SCS only pancreata. RNA sequencing of islets from persufflated pancreata identified reduced inflammatory and greater metabolic gene expression, consistent with expectations of reducing cold ischemic exposure. Portions of these transcriptional responses were not associated with time spent in SCS and were attributable to pancreatic reoxygenation. Furthermore, persufflation extended the total preservation time by 50% without any detectable decline in islet function or viability.

CONCLUSIONS

These data demonstrate that pancreas preservation by persufflation rather than SCS before islet isolation reduces inflammatory responses and promotes metabolic pathways in human islets, which results in improved β cell function.

Variability in assessing for BK viremia: whole blood is not reliable and plasma is not above reproach - a retrospective analysis

Polyomavirus nephropathy (PVN) is a major complication of kidney transplantation. Most reports describe polyomavirus viremia either precedes or is detectable at the time of diagnosis of PVN. This association is the basis of current screening recommendations. We retrospectively reviewed the PCR results of blood and urine samples from 29 kidney transplant recipients with biopsy-proven PVN. Biopsies were performed for a rise in serum creatinine or persistent high-level BK viruria. All biopsies showed polyoma virus large T-antigen expression in tubular epithelium using immunohistochemistry. All had viruria preceding or at the time of biopsy (range, 5.2 × 10⁴ to >25 × 10⁶ BKV DNA copies/ml). Twenty (69%) had viremia ranging from 2.5 × 10³ to 4.3 × 10⁶ copies/ml at the time of the biopsy. Via blood BK PCR assay, nine (31%) had no BK viremia detected either preceding or at the time of the biopsy. In five recipients where sufficient specimen permitted, additional plasma BK assessment revealed positive detection of viremia. A comparative analysis of assays from two centres was performed with spiked samples. BK DNA may not be detected in the blood of some kidney transplant recipients with histologically confirmed PVN. This may reflect limitation of whole blood as opposed to plasma-based BK DNA assessment.

The role of extended criteria donors in liver transplantation for nonalcoholic steatohepatitis

BACKGROUND

Nonalcoholic steatohepatitis is expected to become the leading indication for liver transplantation. Use of extended criteria donors (ECD) may help with donor allocation in these patients. The objective of this study was to determine the use of ECDs in patients with nonalcoholic steatohepatitis undergoing liver transplantation to stimulate a liver-specific predictive model for ECD use.

METHODS

The United Network for Organ Sharing database was used to identify patients undergoing liver transplantation for nonalcoholic steatohepatitis (2002-2014). Cox hazards models were created using (1) United Network for Organ Sharing ECD criteria (based on kidney allocation), (2) individual donor characteristics (age, sex, race, cause of death, body mass index, cold ischemic time), and (3) the Kidney Donor Profile Index (KDPI) to examine the effect of ECDs on mortality and graft failure.

RESULTS

A total of 4,387 patients underwent liver transplantation for nonalcoholic steatohepatitis; 1,359 (30.9%) patients received an ECD. Transplantation with ECD livers had comparable patient survival (hazard ratio [HR] 1.06, 95% confidence interval [CI] 0.91-1.23) between donor types but an increased risk of graft failure (HR 1.18, 95% CI 1.03-1.36) compared to standard donors. Individual characteristics did not affect patient survival or graft failure. A 10% increase in KDPI was associated with a 28% increase in patient mortality (HR 1.28, 95% CI 1.02-1.60) and 45% increase in graft failure (HR 1.45, 95% CI 1.18-1.80).

CONCLUSION

Based on the current United Network for Organ Sharing definition, ECDs in nonalcoholic steatohepatitis were associated with similar overall survival but increased risk of graft failure. Given the shortage of organs, creation of an easily calculated, liver-specific model similar to the KDPI may help risk stratify patients and improve organ allocation.

Higher risk of kidney graft failure in the presence of anti-angiotensin II type-1 receptor antibodies

Reports have associated non-HLA antibodies, specifically those against angiotensin II type-1 receptor (AT1R), with antibody-mediated kidney graft rejection. However, association of anti-AT1R with graft failure had not been demonstrated. We tested anti-AT1R and donor-specific HLA antibodies (DSA) in pre- and posttransplant sera from 351 consecutive kidney recipients: 134 with biopsy-proven rejection and/or lesions (abnormal biopsy group [ABG]) and 217 control group (CG) patients. The ABG's rate of anti-AT1R was significantly higher than the CG's (18% vs. 6%, p < 0.001). Moreover, 79% of ABG patients with anti-AT1R lost their grafts (vs. 0%, CG), anti-AT1R levels in 58% of those failed grafts increasing posttransplant. With anti-AT1R detectable before DSA, time to graft failure was 31 months-but 63 months with DSA detectable before anti-AT1R. Patients with both anti-AT1R and DSA had lower graft survival than those with DSA alone (log-rank p = 0.007). Multivariate analysis showed that de novo anti-AT1R was an independent predictor of graft failure in the ABG, alone (HR: 6.6), and in the entire population (HR: 5.4). In conclusion, this study found significant association of anti-AT1R with graft failure. Further study is needed to establish causality between anti-AT1R and graft failure and, thus, the importance of routine anti-AT1R monitoring and therapeutic targeting.

Incidence and impact of de novo donor-specific alloantibody in primary renal allografts

BACKGROUND

To date, limited information is available describing the incidence and impact of de novo donor-specific anti-human leukocyte antigen (HLA) antibodies (dnDSA) in the primary renal transplant patient. This report details the dnDSA incidence and actual 3-year post-dnDSA graft outcomes.

METHODS

The study includes 189 consecutive nonsensitized, non-HLA-identical patients who received a primary kidney transplant between March 1999 and March 2006. Protocol testing for DSA via LABScreen single antigen beads (One Lambda) was done before transplantation and at 1, 3, 6, 9, and 12 months after transplantation then annually and when clinically indicated.

RESULTS

Of 189 patients, 47 (25%) developed dnDSA within 10 years. The 5-year posttransplantation cumulative incidence was 20%, with the largest proportion of patients developing dnDSA in the first posttransplantation year (11%). Young patients (18-35 years old at transplantation), deceased-donor transplant recipients, pretransplantation HLA (non-DSA)-positive patients, and patients with a DQ mismatch were the most likely to develop dnDSA. From DSA appearance, 9% of patients lost their graft at 1 year. Actual 3-year death-censored post-dnDSA graft loss was 24%.

CONCLUSION

We conclude that 11% of the patients without detectable DSA at transplantation will have detectable DSA at 1 year, and over the next 4 years, the incidence of dnDSA will increase to 20%. After dnDSA development, 24% of the patients will fail within 3 years. Given these findings, future trials are warranted to determine if treatment of dnDSA-positive patients can prevent allograft failure.

Novel biomarker combination predicts long-term allograft outcome

Donor specific human leukocyte antigen (HLA) antibodies (DSA) are a significant cause of allograft failure. However, it has been reported that some DSA negative patients still experience allograft failure. In addition, some DSA positive patients maintain good graft function for >20 years. These findings suggest that while DSA is a cause of failure, it is not the sole risk factor for graft dysfunction and that the presence of DSA alone may not predict the time course of graft failure. Here, we report the predictive value of a proprietary panel of four biomarkers in long-term renal allograft outcome. A total of 310 consecutive patients, who received kidney transplants between 1999 and 2012, were included in this study. Recipient sera was tested for HLA antibodies and biomarkers at 3, 6, 12, 24, and 36 months post-transplant. HLA antibodies were identified using Labscreen single antigen beads. The biomarker combination (BMC) test consisted of a proprietary panel of 4 biomarkers and was performed using Luminex. Sera were defined as positive when any one of the 4 biomarkers became detectable. Sera of normal healthy people were used as negative controls. Graft survival analyses were performed and compared between different patient groups based on the positivity of DSA and BMC. Our results indicate that 57% of DSA negative patients and 54% of DSA positive patients had detectable biomarkers. There was no significant difference in BMC positive patients between the DSA positive and negative groups, which suggests that presence of BMC is not associated with HLA DSA. DSA positive patients had a 10% lower 10-year graft survival rate than patients without DSA, while BMC positive patients had a 25% lower 10-year graft survival rate than patients without detectable BMC. When DSA negative patients were divided into two groups based on the positivity of BMC, BMC positive patients had a 20% lower 10-year graft survival rate compared to BMC negative patients (p<0.05). Similarly, when DSA positive patients were divided into two groups based on the positivity of BMC, BMC positive patients had a 30% lower 10-year graft survival rate compared to BMC negative patients (p<0.01). When both DSA and BMC testing results were considered, DSA and BMC double positive patients had the lowest and double negative patients had the highest graft survival rates. The survival rates for the BMC alone and DSA alone positive groups were in between (p<0.001). Multivariate Cox models confirmed that BMC was an independent risk factor for graft failure, with a higher hazard ratio than DSA (BMC=2.60 versus DSA=1.64). In conclusion, serum BMC is an independent predictor of graft failure. BMC was more significantly associated with graft failure than DSA. In combination with DSA, BMC better predicted graft outcome than DSA or BMC alone.

Reuse of a previously transplanted kidney: does success come with a price?

Longer wait times for deceased donor kidney transplant have prompted newer initiatives to expedite the process. Reuse of a previously transplanted kidney might be appropriate in certain circumstances. However, one must also consider the unique issues that may arise after such transplants. We describe our experience in one such case where the donor kidney had lesions of focal and segmental glomerulosclerosis and signs of alloreactivity (positive C4d staining) prior to transplantation and the recipient developed ganciclovir-resistant cytomegalovirus (CMV) infection, which was perhaps transmitted from the donor. Despite the challenges, the allograft function remained stable 5 years after reuse.

A report of the epidemiology of de novo donor-specific anti-HLA antibodies (DSA) in "low-risk" renal transplant recipients

The donor specific anti-HLA antibody (DSA) has been increasingly recognized as the major cause of allograft loss. Despite this, no published reports exist describing the true epidemiology of de novo DSA.Here we describe the epidemiology of DSA based on the results of one of the longest running antibody study in consecutive renal transplant recipients. The study includes 224 non-sensitized, non-HLA-identical patients who received a primary kidney transplant between 3/1999-3/2006. Protocol testing for DSA was done pre-transplant, at 1, 3, 6, 9, and 12 months, and then annually. DSA was tested using single antigen beads. Data from the East Carolina University transplant cohort indicate that the prevalence of DSA in the first year post-transplant is 12.1 cases per 100. The average annual incidence of DSA is 4.7 per 100 cases, per year. The highest incidence of DSA was in the first year post transplant. Although deceased donors and African-Americans have a higher incidence rate of DSA than the comparator living donors and non-African American groups, respectively, these factors were not associated with DSA onset. The one factor found to be predictive of DSA was DQ mismatch (p = 0.036). Based on these epidemiologic findings in combination with previous reports showing DSA is a cause of allograft failure, it seems reasonable that at least annual testing should be done even in "low-risk" transplant patients, because every year a new 5% of patients will develop DSA.

Liver and vascularized posterior rectus sheath fascia composite tissue allotransplantation

Abdominal wall closure in pediatric solid organ recipients may be confounded by donor size discrepancy and structural insults from previous surgery. Here we describe the novel use of vascularized donor abdominal wall posterior rectus sheath fascia, as a composite tissue allotransplant (CTA), to achieve abdominal wall closure in a liver and double kidney pediatric recipient who could not be closed primarily due to donor/recipient size mismatch. The posterior rectus sheath fascia was procured in continuity with the liver and falciform ligament. Blood supply was achieved using the single hepatic artery anastomosis as part of the standard liver transplantation procedure. Specimens of posterior rectus sheath fascia taken on postoperative days 3 and 30 showed no signs of acute rejection. The patient succumbed to an overwhelming fungal infection on day 51, with no signs of intraabdominal involvement. The patient received no additional immunosuppression in conjunction with the posterior rectus sheath fascia allotransplant.

Changing attitudes toward influenza vaccination in U.S. Kidney transplant programs over the past decade

BACKGROUND AND OBJECTIVES

Influenza infection in transplant recipients is often associated with significant morbidity. Surveys were conducted in 1999 and 2009 to find out if the influenza vaccination practices in the U.S. transplant programs had changed over the past 10 years.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In 1999, a survey of the 217 United Network for Organ Sharing-certified kidney and kidney-pancreas transplant centers in the U.S. was conducted regarding their influenza vaccination practice patterns. A decade later, a second similar survey of 239 transplant programs was carried out.

RESULTS

The 2009 respondents, compared with 1999, were more likely to recommend vaccination for kidney (94.5% versus 84.4%, P = 0.02) and kidney-pancreas recipients (76.8% versus 48.5%, P < 0.001), family members of transplant recipients (52.5% versus 21.0%, P < 0.001), and medical staff caring for transplant patients (79.6% versus 40.7%, P < 0.001). Physicians and other members of the transplant team were more likely to have been vaccinated in 2009 compared with 1999 (84.2% versus 62.3% of physicians, P < 0.001 and 91.2% versus 50.3% of nonphysicians, P < 0.001).

CONCLUSIONS

Our study suggests a greater adoption of the Centers for Disease Control and Prevention influenza vaccination guidelines by U.S. transplant programs in vaccinating solid-organ transplant recipients, close family contacts, and healthcare workers.

Acute humoral rejection in an ABO compatible combined liver-kidney transplant--the kidney is not always protected

Combined liver-kidney transplantation has become a common practice for the treatment of patients with concurrent end-stage renal disease and end-stage liver disease. Liver transplantation in the setting of multiorgan transplantation is thought to have a protective effect against humoral rejection even when a positive crossmatch is obtained prior to surgery. In most centers, a pre liver-kidney transplant crossmatch is rarely performed because of the known immunoprotective effect of the liver allograft. In this report, a case of acute humoral rejection in the kidney allograft after a combined liver-kidney transplant is described. Although humoral rejection was treated using plasmapheresis, intravenous immunoglobulin and rituximab, the kidney required 3 months to recover function and finally progressed to chronic allograft nephropathy. A heightened index of suspicion for acute humoral rejection of the renal allograft is necessary when performing combined liver-kidney transplants to highly sensitized patients due to previous organ transplants.

Changes in pediatric renal transplantation after implementation of the revised deceased donor kidney allocation policy

In October 2005, the United Network for Organ Sharing (UNOS) implemented a revised allocation policy requiring that renal allografts from young deceased donors (DDs) (<35 years old) be offered preferentially to pediatric patients (<18 years old). In this study, we compare the pre- and postpolicy quarterly pediatric transplant statistics from 2000 to 2008. The mean number of pediatric renal transplants with young DDs increased after policy implementation from 62.8 to 133 per quarter (p < 0.001), reflecting a change in the proportion of all transplants from young DDs during the study period from 0.33 to 0.63 (p < 0.001). The mean number of pediatric renal transplants from old DDs (> or =35 years old) decreased from 22.4 to 2.6 per quarter (p < 0.001). The proportion of all pediatric renal transplants from living donors decreased from 0.55 to 0.35 (p < 0.001). The proportion from young DDs with five or six mismatched human leukocyte antigen (HLA) loci increased from 0.16 to 0.36 (p < 0.001) while those with 0 to 4 HLA mismatches increased from 0.18 to 0.27 (p < 0.001). Revision of UNOS policy has increased the number of pediatric renal transplants with allografts from young DDs, while increasing HLA-mismatched allografts and decreasing the number from living donors.

Probabilistic risk assessment of accidental ABO-incompatible thoracic organ transplantation before and after 2003

BACKGROUND

A widely reported ABO-mismatch accident in March of 2003 raised concerns about the reliability of the transplantation system. Because this type of failure is rare and significant, we performed a probabilistic risk assessment (PRA) of the donor-recipient matching processes for thoracic organ transplantation.

METHODS

A probabilistic risk assessment was performed.

RESULTS

The likelihood of accidental incompatible implantation was already low in 2003. The PRA model indicates that the likelihood of such an event was 1.38x10 per donated organ. This estimate correlates closely with the observed rate of these accidents. Based on this model, process changes put in place shortly after the accident reduced the probability to approximately 3.08x10 and changes put in place in October 2004 further reduced the probability to approximately 2.22x10 per organ donated.

CONCLUSIONS

The observed and predicted likelihoods of accidental incompatible thoracic organ transplantation are comparable. These likelihoods are several orders of magnitude smaller than other hazards associated with solid organ transplantation. The PRA model indicates that changes that followed the March 2003 accident further reduced the likelihood of accidental incompatible implantation by roughly two orders of magnitude. Quantitative estimates from PRA can be used to assess risks in healthcare and to gauge the impact of system changes on these risks.

Case report: robot-assisted laparoscopic pyeloureterostomy in a transplanted kidney with ureteral stricture

Ureteral obstruction secondary to ischemia is the most common urologic complication of kidney transplantation. Although endoscopic management has shown satisfactory short-term success rates, surgical repair is considered the definitive therapy. To our knowledge, this procedure has been performed only through open surgery. We present a minimally invasive approach for reconstruction of a ureteral stricture in a renal transplant patient using the Da Vinci robotic system.

Implications of Immunohistochemical Detection of C4d along Peritubular Capillaries in Late Acute Renal Allograft Rejection

BACKGROUND

Immunohistochemical detection of the C4d complement product along peritubular capillaries (PC) may indicate humoral rejection of renal allografts. We examined the frequency of PC C4d expression in renal-allograft biopsies with acute rejection (AR) arising more than 6 months after transplantation and the impact of this finding.

METHODS

C4d was detected by immunoperoxidase in 2-micron paraffin sections of consecutive biopsies obtained over a 3-year period. The extent was classified as diffuse (> or =50% PC C4d+), focal (<50% C4d+), and negative (C4d-). Clinical data were obtained by retrospective chart review. Fifty-five AR episodes with Banff 97 types 1A (n = 13), 1B (n = 26), 2A (n = 11), 2B (n = 3), and 3 (n = 2) met inclusion criteria.

RESULTS

PC C4d expression was diffuse in 23 (42%), focal in 9 (16%), and negative in 23 (42%) biopsies. AR episodes with focal and diffuse C4d expression had higher proportionate elevation of serum creatinine at biopsy and 4 weeks after diagnosis (P< or =0.05). Biopsies with diffuse PC C4d had interstitial hemorrhage (56.5%) and plasmacytic infiltrates (52%) more frequently than C4d- biopsies (22% and 16%), P = 0.02, but had no other distinctive histologic features. Graft loss was greater in diffuse (65%) compared with focal C4d+ (33%) and C4d- (33%) groups 1 year after diagnosis, P = 0.03. Other clinical and pathologic parameters did not differ significantly, including treatment received for AR.

CONCLUSION

Evidence of acute cellular with occult humoral rejection is identified in more than 40% of late AR episodes. Late acute humoral rejection may be associated with interstitial hemorrhage and plasma cells and contributes significantly to graft loss.

RENAL TOLERANCE TO PROLONGED WARM ISCHEMIA TIME IN A LAPAROSCOPIC VERSUS OPEN SURGERY PORCINE MODEL

PURPOSE

To our knowledge the effects of renal warm ischemia (WI) during laparoscopic vs open surgery have not been investigated. Decreased renal blood flow during pneumoperitoneum may precondition the kidney to tolerate longer WI time. Traditionally 30 minutes has defined the limit of renal WI time in open surgery. However, recent reports show renal function recovery at WI times of 45 to 120 minutes. We assessed renal function recovery after prolonged WI during laparoscopic vs open surgery in a solitary kidney porcine model.

MATERIALS AND METHODS

A total of 32 female farm pigs underwent right laparoscopic nephrectomy to create a single kidney model. At 12 days later the animals were randomized into open and laparoscopic groups, each with 4 subgroups, namely 30, 60 and 90 minutes of WI, and a 90-minute control. Serum creatinine and the glomerular filtration rate were assessed preoperatively and on postoperative days 1, 3, 8 and 15.

RESULTS

There was no statistical difference in renal function between the laparoscopic and open groups. Although the early decrease in renal function (72 hours) was highest in the 60 and 90-minute WI groups, by postoperative day 15 this difference was not statistically significant. Postoperative day 15 glomerular filtration rate and serum creatinine values were not significantly different from baseline in any of the WI groups.

CONCLUSIONS

We found no difference in renal function recovery when comparing laparoscopic and open WI. Although WI up to 90 minutes resulted in initial renal dysfunction, by 2 weeks postoperatively function normalized. Our results indicate that in a single kidney porcine model the renal unit can fully recover from WI times of up to 90 minutes.

A reliable method for isolation of viable porcine islet cells

HYPOTHESIS

Mechanical injury and oxidative stress caused by reoxygenation of isolated porcine islet cells result in their unresponsiveness to glucose stimulation.

DESIGN

Adult pigs (weighing 25-30 kg) were anesthetized, and following intra-arterial infusion of ice-cold University of Wisconsin solution, a complete pancreatectomy was performed. The pancreatic duct was cannulated for infusion of digestion medium containing collagenase type P, 1.5 mg/mL; deoxyribonuclease I, 10 000 U; and a water-soluble analogue of vitamin E (Trolox), 1 mmol/L. After 20-minute incubations on ice, and at 37 degrees C, the pancreas was hand shaken for 1 minute, followed by filtration and separation on an automatic cell separator (COBE 2991). Islet cells, identified by dithizone staining, were perifused at 37 degrees C.

RESULTS

The mean +/- SEM yield of intact purified islet cells (50-200 microm in diameter), and mostly present in clusters, was 2398 +/- 143 cells per gram (n = 12). Glucose stimulation caused a significant increase in biphasic insulin secretion in the perifusion experiments.

CONCLUSION

We have developed a simple, reproducible, and reliable procedure for isolating intact and viable porcine islet cells suitable for xenotransplantation.

Bile acids in xenogeneic ex-vivo liver perfusion: function of xenoperfused livers and compatibility with human bile salts and porcine livers

BACKGROUND

In recent years, hepatic support systems using xenogeneic cells have been developed to support patients in fulminant hepatic failure. The extent to which xenogeneic hepatocytes metabolize and excrete human organic anions is unclear. In these studies we examined the ability of the ex vivo porcine liver to clear human bile acids during extracorporeal liver perfusion (ELP).

METHODS

Four patients with fulminant hepatic failure underwent extracorporeal liver perfusion with 9 porcine livers. The venovenous circuit was designed as previously described (NEJM,1994,331:234) as were the immunologic features (Transplantation 1994,58:1162). Bile from the porcine liver and serum samples were collected hourly during perfusion. Three bile acids (glycocholic, glycodeoxycholic, taurodeoxycholic acid) were selected as markers for human bile and three (glycohyocholic, glycohyodeoxycholic, and glyco-3alpha-hydroxy-6-oxo-5beta-cholanoic acid) for markers of pig bile. Bile acids from both serum and bile were processed and analyzed through high performance liquid chromatography. The Students' t test was used for statistical analysis.

RESULTS

The mean duration of perfusions was 4.1+/-1.5 hr. The mean total bile acid clearance from serum (243+/-44 micromol/h) was similar to the total bile acid biliary excretion (286+/-84 micromol/hr, P = 0.06). After 1 hr of perfusion, bile samples demonstrated a predominance of pig bile salts (65%). After 3 hr of perfusion, human bile acids made up 85% of total biliary bile acids. Pig bile acids appeared in patients' sera after 1 hr of perfusion, and after 3 hr, 35% of serum bile salts were pig-specific.

CONCLUSIONS

Porcine livers perfused with human blood can clear the serum of potentially toxic human bile acids and excrete them into bile. Simultaneously, the percentage of pig-specific bile acids in patient serum increases during xenogeneic perfusion for unknown reasons. The relative hepatic uptake of bile acid from serum is similar to bile acid excretion in bile. Further development of systems using porcine livers or hepatocytes is warranted.

Storage and microencapsulation of islets for transplantation

Microencapsulation is an effective means of immunoisolation for pancreatic islet transplants. However, the process of isolating, purifying, encapsulating, and transplanting islets in a single day is labor intensive and difficult for routine use. There is an apparent need for reliable methods of islet storage, and cryopreservation has emerged as an attractive system of islet banking. While studies have shown that cryopreserved islets are viable when tested unencapsulated after thawing, it is not clear if the combination of freezing and encapsulation would affect islet function. The purpose of the present study was to determine the in vitro function of cryopreserved islets following thawing and microencapsulation. Islets were isolated from the pancreata of Sprague-Dawley rats and cryopreserved under liquid nitrogen for either 1 week or 1 month, following an overnight culture at 37 degrees C. Upon thawing, the islets were tested either unencapsulated or after encapsulation in polylysine-alginate membrane. In all experiments islets were preperifused for 1 h at 37 degrees C with a modified Krebs-Ringer bicarbonate buffer containing 3.3 mM (60 mg/dl) glucose and maintained at pH 7.4 by continuous gassing with 95% air/5% CO2. Following basal effluent sample collection on ice, the glucose concentration was raised to 16.7 mM (300 mg/dl). It was found that, within 10 min of high glucose stimulation, an average of twofold increase in insulin secretion (p < 0.01) was obtained in islets within or without microcapsules. We conclude that islets cryopreserved for 1 month prior to thawing and microencapsulation retained functional viability as determined in in vitro experiments.

P-Selectin mediates reperfusion injury through neutrophil and platelet sequestration in the warm ischemic mouse liver

Hepatic damage following ischemia-reperfusion injury involves polymorphonuclear leukocytes (PMN) and platelet sequestration, however the mechanisms of adhesion remain elusive. In this study, using gene-targeted deficient mice, we evaluated P-selectin and its contribution to PMN and platelet adhesion in hepatic damage. In an in vivo warm ischemia model, hepatic injury was assessed by serum transaminase levels, survival, PMN adhesion by histological analysis, and platelet sequestration by immunostaining. Serum transaminase levels were strikingly reduced (by up to threefold) in the P-selectin deficient mice, particularly at 90 minutes of ischemia, when compared with wild-type controls. PMN adhesion and platelet sequestration was also significantly decreased in P-selectin deficient mice following 90 minutes of partial ischemia. Animal survival was significantly improved after 75 minutes of total hepatic ischemia in P-selectin deficient mice when compared with wild-type mice. Survival was also achieved after 90 minutes of ischemia in the mutant mice whereas none of the wild-type animals survived. These data show that P-selectin plays a critical role in PMN and platelet adhesion following ischemia-reperfusion injury to the liver.

L-selectin and ICAM-1 mediate reperfusion injury and neutrophil adhesion in the warm ischemic mouse liver

Leukocytes recruited during ischemia-reperfusion to the liver are important mediators of injury. However, the mechanisms of leukocyte adhesion and the role of adhesion receptors in hepatic vasculature remain elusive. L-selectin may critically contribute to injury, priming adhesion for later action of intercellular adhesion molecule-1 (ICAM-1). Paired experiments were performed using mutant mice (L-selectin -/-, ICAM-1 -/-, and L-selectin/ICAM-1 -/-) and wild-type mice (C57BL/6) to investigate leukocyte adhesion in the ischemic liver. Leukocyte adhesion and infiltration were assessed histologically. Aspartate aminotransferase levels were significantly reduced (2- to 3-fold) in mutant vs. wild-type mice in most groups but most significantly after 90 min of partial hepatic ischemia. Leukocyte adhesion was significantly reduced in all mutant mice. Areas of microcirculatory failure, visualized by intravital microscopy, were prevalent in wild-type but virtually absent in L-selectin-deficient mice. After total hepatic ischemia for 75 or 90 min, survival was better in mutant L-selectin and L-selectin/ICAM-1 mice vs. wild-type mice and ICAM-1 mutants. In conclusion, L-selectin is critical in the pathogenesis of hepatic ischemia-reperfusion injury. Poor sinusoidal perfusion due to leukocyte adhesion and clot formation is a factor of injury and appears to involve L-selectin and ICAM-1 receptors.

A new and simple technique of total hepatic ischemia in the mouse

BACKGROUND

A model of total hepatic ischemia is currently not available in mice. Models described in rats using portosystemic shunts to achieve total ischemia have been notoriously difficult. In mice, the problem is compounded further when using this type of technique because of the small size of the animal. A new technique is described combining partial hepatectomy with clamping of the remnant liver.

METHODS

A partial (30%) hepatectomy is performed with resection of the caudate, right lateral, and quadrate lobes, and papillary process. Vascular microclamps are placed across the pedicles of the median and left lateral lobe at the level of the hilum to achieve total ischemia. Spontaneous portocaval shunts through caudate branches and collateral vessels prevent mesenteric congestion. Animals were studied for survival.

RESULTS

The procedure consistently took less than 30 min (25+/-2 min), and no bleeding of the resected tissue was observed. Evidence for total hepatic ischemia and spontaneous shunts was demonstrated by the use of an intraportal dye. All animals survived 60 min of ischemia, whereas all died after 90 min of ischemia.

CONCLUSION

This is a technically simple and rapid procedure to perform. In the current environment of multiple knockout mice and bioreagents that are available, a model of this type is essential.

The role of antibodies in acute vascular rejection of pig-to-baboon cardiac transplants

Long-term success in xenotransplantation is currently hampered by acute vascular rejection. The inciting cause of acute vascular rejection is not yet known; however, a variety of observations suggest that the humoral immune response of the recipient against the donor may be involved in the pathogenesis of this process. Using a pig-to-baboon heterotopic cardiac transplant model, we examined the role of antibodies in the development of acute vascular rejection. After transplantation into baboons, hearts from transgenic pigs expressing human decay-accelerating factor and CD59 underwent acute vascular rejection leading to graft failure within 5 d; the histology was characterized by endothelial injury and fibrin thrombi. Hearts from the transgenic pigs transplanted into baboons whose circulating antibodies were depleted using antiimmunoglobulin columns (Therasorb, Unterschleisshein, Germany) did not undergo acute vascular rejection in five of six cases. Biopsies from the xenotransplants in Ig-depleted baboons revealed little or no IgM or IgG, and no histologic evidence of acute vascular rejection in the five cases. Complement activity in the baboons was within the normal range during the period of xenograft survival. In one case, acute vascular rejection of a xenotransplant occurred in a baboon in which the level of antidonor antibody rose after Ig depletion was discontinued. This study provides evidence that antibodies play a significant role in the pathogenesis of acute vascular rejection, and suggests that acute vascular rejection might be prevented or treated by therapies aimed at the humoral immune response to porcine antigens.

Optimization of the microencapsulated islet for transplantation

BACKGROUND

Microencapsulation of isolated islets is a good method for providing protection against immunologic reactions to the cells in both allogeneic and xenogenic grafts. Current methods of microencapsulation require chelation of the alginate-calcium core, which solubilizes the structural support of the capsules and may adversely affect durability. The purpose of the present study was to determine the in vitro response to glucose stimulation, of microencapsulated islets that have not been subjected to chelation.

MATERIALS AND METHODS

Using an air-jet-syringe-pump droplet generator, islets isolated from male Sprague-Dawley rats were encapsulated in alginate, followed by washes with poly-L-lysine, saline, and a second coat of alginate. Different groups of the microencapsulated islets were then tested for response to high glucose perifusion, before or after chelation, and the responses were compared with those of unencapsulated islets.

RESULTS

Chelated microencapsulated islets showed a normal biphasic insulin response to stimulation with 16.7 mM (300 mg%). Thus, insulin secretion increased from a mean +/- SEM basal rate of 3005 +/- 645 to a stimulated rate of 5165 +/- 1030 pg/min (P < 0.05, n = 6) in the first phase, comparable to results obtained with the unencapsulated islets. In contrast, unchelated microencapsulated islets did not respond to stimulation with 16.7 mM glucose. However, after a 24-h culture of these unchelated microcapsules, a small but significant response was observed.

CONCLUSIONS

Although culturing unchelated microcapsules of islets may enhance their function, chelation of the microcapsular core is essential for optimal function of the enclosed islets.

Liver transplantation complicated by misplaced TIPS in the portal vein

OBJECTIVE

The purpose of this study was to determine the incidence and complications related to transjugular intrahepatic portosystemic shunt (TIPS) stents found in the portal vein at the time of an orthotopic liver transplantation.

BACKGROUND

Transjugular intrahepatic portosystemic shunts are frequently used in patients with end-stage liver disease as a bridge to liver transplantation. The incidence of finding the metal stent outside of the liver parenchyma at the time of transplantation is reported as high as 30%. Most cases that have been detailed involve stents misplaced in the vena cava with various outcomes. Almost no data are available regarding stents misplaced into the portal vein.

METHODS AND RESULTS

We report our experience with four patients with whom a TIPS stent was found misplaced in the portal vein at the time of liver transplantation, including one patient with a stent extending into the superior mesenteric vein. This patient required extensive venous reconstruction using a retropancreatic "pant" donor-iliac vein graft. The three other patients were transplanted without the need for extensive venous reconstruction. There was no significant difference in operative times for this group of patients, but there was a significant increase in the requirement for blood transfusion. In a follow-up period ranging from 6 months to 2 years, all patients remained alive and had normal portal venous flow and functioning allografts. Most misplaced stents were placed in patients with small cirrhotic livers and by radiologists with minimal experience with the procedure.

CONCLUSIONS

Misplaced TIPS in the portal vein before liver transplantation is a more frequent complication than previously reported; however, it does not represent major technical difficulty if a clamp can be placed proximally on the portal vein. In the case of a stent extending below the spleno-mesenteric confluence, interposition grafts such as a donor-iliac vein graft are necessary for venous reconstruction. The experience of the radiologist is critical to prevent this complication.

Evidence that ursodeoxycholic acid prevents steroid-resistant rejection in adult liver transplantation

Steroid-resistant rejection continues to be a serious problem in liver transplantation. Since ursodeoxycholic acid (UDCA) is beneficial in several cholestatic disorders and possesses in vitro immunomodulatory and immunosuppressive effects, we have tested in a pilot study the effects of adjuvant UDCA in the prevention of steroid-resistant rejection. Fifty consecutive liver transplant patients were treated with a standard cyclosporine immunosuppressive regimen. Treatment with UDCA (10 mg/kg/d) was initiated in each patient who developed biopsy-proven rejection or biochemical evidence of cholestasis. Clinical and laboratory features were monitored for evidence of rejection. Data were analyzed after at least a 10-month follow-up period was available in each patient. Seven patients died during the study period, all within 4 wk of surgery. No evidence of rejection was documented in these patients. Twenty three of the 43 survivors 53% (23/43) developed an episode of rejection, and UDCA was initiated in each of them. Only one patient had a second episode of rejection, which responded to intravenous methylprednisolone therapy; no patient required antilymphocyte therapy. There was no evidence of toxicity for UDCA. These data suggest that UDCA can be given safely following OLT and may contribute to prevention of steroid-resistant rejection in liver transplant recipients.

Prospects for xenotransplantation of the liver

Because of the tremendous success of clinical transplantation of the liver and other organs in the last three decades, the demand for organs for transplantation has risen sharply and there is now a substantial shortage. The utilization of organs from other species, xenotransplantation, is increasingly viewed as a potential solution to this problem. The major limitation to xenotransplantation is the formidable immunological barriers that prevent the successful transplantation of non-human organs into human recipients. Here we review current knowledge about the immunology of xenotransplantation and the limited clinical and experimental experience in xenotransplantation of the liver.

Quality of life after treatment for pancreatitis

OBJECTIVE

The authors evaluated the morbidity, mortality, and quality of life after pancreatic debridement for necrosis and compared these values to those for quality of life after elective medical and surgical management for chronic pancreatitis.

SUMMARY BACKGROUND DATA

Quality of life after pancreatic debridement for necrosis has received little attention. Although quality of life after other pancreatic surgery has been evaluated and is though to be good, management of patients with pancreatic necrosis can be labor intensive and require extraordinary resources. Therefore, further evaluation of the quality of life achieved after treatment is appropriate.

METHODS

Forty patients (group 1) underwent operative debridement for necrosis between 1986 and 1994. Medical records of these patients were reviewed for morbidity, mortality, and in-hospital costs. Follow-up of quality of life was assessed by the Short Form-36 Health Survey. Patients in group 2 (n = 89) underwent medical management of chronic pancreatitis. Group 3 included 47 patients who underwent elective operations for ductal abnormalities. The Short Form-36 Health Surveys were administered to all three groups and compared statistically.

RESULTS

Mortality and morbidity from pancreatic debridement was 18% and 77%, respectively. Quality-of-life evaluations in groups 1 through 3 and age-matched controls were statistically similar.

CONCLUSIONS

Pancreatic debridement for necrosis requires intense application of resources and is associated with a high mortality and morbidity. Long-term follow-up shows good quality of life for patients who survive this morbid disease. This study supports the continued aggressive approach to the management of pancreatic necrosis, given that long-term outcome about quality of life is good.

Kidney sharing by centers of the South-Eastern Organ Procurement Foundation

1. SEOPF centers historically have shared kidneys at a higher rate than the rest of the United States. 2. SEOPF centers transplanted better-matched kidneys than the rest of the nation despite transplanting a significantly larger percentage of "hard-to-match" black recipients. 3. Within SEOPF centers, a shared kidney was almost twice as likely to be a good match (zero-3 HLA antigen mismatches) as was a local kidney. 4. Within SEOPF centers, well-matched kidneys (zero-3 HLA antigen mismatches) had significantly better graft survival than did poorly-matched (4-6 HLA antigen mismatches) kidneys. 5. SEOPF centers had one-, 2- and 3-year graft survival rates comparable to those of the rest of the nation. 6. SEOPF centers have proven the efficiency of ROP trays in predicting final crossmatch results for shared kidneys. 7. The SEOPF High Grade Match (HGM) algorithm has been successful in transplanting highly sensitized (current PRA > 40%) recipients. 8. The use of ROP trays in well-matched, highly sensitized recipients resulted in improved kidney availability. 9. Graft survival of HGM recipients was comparable to that of non-HGM recipients. 10. Despite longer cold ischemia times for HGM kidneys, there was no increased incidence of delayed graft function in these kidneys. 11. The HGM program accounted for 8.1% of the participating centers' activity and, thus, has not adversely impacted the majority of the centers' other patients. 12. The one- and 2-year graft survival data for HGM transplants were in accordance with the expected rates and were not statistically different from those of non-HGM transplants.

Immunoglobulin prevents complement-mediated hyperacute rejection in swine-to-primate xenotransplantation

Immunoglobulins regulate the complement system by activating complement on foreign surfaces and diverting reactive complement proteins away from autologous cell surfaces. Based on this model, we explored the ability of Ig to balance complement activation versus control in a pig-to-primate cardiac xenotransplantation model in which the binding of xenoreactive antibodies of the recipient to graft blood vessels and the activation of complement cause hyperacute rejection. Human IgG added to human serum caused a dose-dependent decrease in deposition of iC3b, cytotoxicity, and heparan sulfate release when the serum was incubated with porcine endothelial cells. This decrease was not caused by alteration in antibody binding or consumption of complement but presumably reflected decreased formation of C3 convertase on the endothelial cells. Infusion of purified human IgG into nonhuman primates prevented hyperacute rejection of porcine hearts transplanted into the primates. As expected, the transplants contained deposits of recipient Ig and C1q but not other complement components. The inhibition of complement on endothelial cell surfaces and in the xenotransplantation model supports the idea that IgG regulates the classical complement pathway and supports therapeutic use of that agent in humoral-mediated disease.

The humoral immune response in humans following cross-perfusion of porcine organs

A major question in xenotransplantation is the nature of the humoral response that would occur following the transplantation of a xenogeneic organ into an immunosuppressed recipient as such a response could mediate delayed types of injury to the graft. To begin to address this issue we characterized the changes in the properties of xenoreactive antibodies occurring in patients exposed to porcine organs under conditions simulating transplantation. In two patients whose blood had been cross-perfused through porcine livers as a treatment for hepatic failure, the titer of xenoreactive IgM increased by four-fold and the titer of xenoreactive IgG increased by sixty-fold within ten days after perfusion procedures. The xenoreactive IgM and IgG antibodies were specific for Gal alpha 1-3Gal based on binding to porcine endothelial cells and bovine thyroglobulin, which express this determinant, and on the decrease in binding following treatment of porcine endothelial cells or bovine thyroglobulin with alpha-galactosidase. The sequential addition to endothelial cells of amounts of serum known to saturate antibody-binding sites obtained before and ten days after perfusion of porcine organs revealed no increase in binding of IgM above the level observed with serum obtained before perfusion, suggesting that new determinants were not identified. Moreover, the functional avidity of binding to porcine endothelial cells of IgM in serum obtained before and ten days after perfusion of porcine organs was unchanged. Even at later times, the presence of newly elicited antibodies against porcine aortic endothelial cell targets was not detected. Thus, exposure to porcine antigens in a vascularized organ results in increases in the levels of xenoreactive IgM and IgG antibodies--however, these antibodies exhibit properties similar to natural antibodies.

Identification of selective immunoglobulin a deficiency by renal biopsy

We report three cases of selective immunoglobulin A (IgA) deficiency in which lack of direct immunofluorescent staining for IgA on renal biopsy specimens contributed to the diagnosis. In two patients, one with systemic lupus erythematosus and the other having asthma with nephrotic syndrome, the diagnosis of IgA deficiency was suggested by the complete absence of IgA on the renal biopsy. In the third patient, a renal transplant recipient, initial biopsies demonstrated donor-derived IgA, which disappeared on subsequent biopsies. The diagnosis of IgA deficiency was confirmed in all three patients by serologic quantification of IgA.