Benjamin Samstein

Validation of a current definition of early allograft dysfunction in liver transplant recipients and analysis of risk factors

Translational studies in liver transplantation often require an endpoint of graft function or dysfunction beyond graft loss. Prior definitions of early allograft dysfunction (EAD) vary, and none have been validated in a large multicenter population in the Model for End‐Stage Liver Disease (MELD) era. We examined an updated definition of EAD to validate previously used criteria, and correlated this definition with graft and patient outcome. We performed a cohort study of 300 deceased donor liver transplants at 3 U.S. programs. EAD was defined as the presence of one or more of the following previously defined postoperative laboratory analyses reflective of liver injury and function: bilirubin ≥10mg/dL on day 7, international normalized ratio ≥1.6 on day 7, and alanine or aspartate aminotransferases >2000 IU/L within the first 7 days. To assess predictive validity, the EAD definition was tested for association with graft and patient survival. Risk factors for EAD were assessed using multivariable logistic regression. Overall incidence of EAD was 23.2%. Most grafts met the definition with increased bilirubin at day 7 or high levels of aminotransferases. Of recipients meeting the EAD definition, 18.8% died, as opposed to 1.8% of recipients without EAD (relative risk = 10.7 [95% confidence interval: 3.6, 31.9] P < 0.0001). More recipients with EAD lost their grafts (26.1%) than recipients with no EAD (3.5%) (relative risk = 7.4 [95% confidence interval: 3.4, 16.3] P < 0.0001). Donor age and MELD score were significant EAD risk factors in a multivariate model. In summary a simple definition of EAD using objective posttransplant criteria identified a 23% incidence, and was highly associated with graft loss and patient mortality, validating previously published criteria. This definition can be used as an endpoint in translational studies aiming to identify mechanistic pathways leading to a subgroup of liver grafts with clinical expression of suboptimal function. Liver Transpl 16:943‐949, 2010.

The Ngal reporter mouse detects the response of the kidney to injury in real time

Many proteins have been proposed to act as surrogate markers of organ damage, yet for many candidates the essential biomarker characteristics that link the protein to the injured organ have not yet been described. We generated an Ngal reporter mouse by inserting a double-fusion reporter gene encoding luciferase-2 and mCherry (Luc2-mC) into the Ngal (Lcn2) locus. The Ngal-Luc2-mC reporter accurately recapitulated the endogenous message and illuminated injuries in vivo in real time. In the kidney, Ngal-Luc2-mC imaging showed a sensitive, rapid, dose-dependent, reversible, and organ- and cell-specific relationship with tubular stress, which correlated with the level of urinary Ngal (uNgal). Unexpectedly, specific cells of the distal nephron were the source of uNgal. Cells isolated from Ngal-Luc2-mC mice also revealed both the onset and the resolution of the injury, and the actions of NF-κB inhibitors and antibiotics during infection. Thus, imaging of Ngal-Luc2-mC mice and cells identified injurious and reparative agents that affect kidney damage.

Survival Outcomes Following Liver Transplantation (SOFT) Score: A Novel Method to Predict Patient Survival Following Liver Transplantation

It is critical to balance waitlist mortality against posttransplant mortality.

Complications of Living Donor Hepatic Lobectomy—A Comprehensive Report

A wider application of living donor liver transplantation is limited by donor morbidity concerns. An observational cohort of 760 living donors accepted for surgery and enrolled in the Adult‐to‐Adult Living Donor Liver Transplantation cohort study provides a comprehensive assessment of incidence, severity and natural history of living liver donation (LLD) complications. Donor morbidity (assessed by 29 specific complications), predictors, time from donation to complications and time from complication onset to resolution were measured outcomes over a 12‐year period. Out of the 760 donor procedures, 20 were aborted and 740 were completed. Forty percent of donors had complications (557 complications among 296 donors), mostly Clavien grades 1 and 2. Most severe counted by complication category; grade 1 (minor, n = 232); grade 2 (possibly life‐threatening, n = 269); grade 3 (residual disability, n = 5) and grade 4 (leading to death, n = 3). Hernias (7%) and psychological complications (3%) occurred >1 year postdonation. Complications risk increased with transfusion requirement, intraoperative hypotension and predonation serum bilirubin, but did not decline with the increased center experience with LLD. The probability of complication resolution within 1 year was overall 95%, but only 75% for hernias and 42% for psychological complications. This report comprehensively quantifies LLD complication risk and should inform decision making by potential donors and their caregivers.

Urinary-Cell mRNA Profile and Acute Cellular Rejection in Kidney Allografts

BACKGROUND The standard test for the diagnosis of acute rejection in kidney transplants is the renal biopsy. Noninvasive tests would be preferable. METHODS We prospectively collected 4300 urine specimens from 485 kidney-graft recipients from day 3 through month 12 after transplantation. Messenger RNA (mRNA) levels were measured in urinary cells and correlated with allograft-rejection status with the use of logistic regression. RESULTS A three-gene signature of 18S ribosomal (rRNA)-normalized measures of CD3ε mRNA and interferon-inducible protein 10 (IP-10) mRNA, and 18S rRNA discriminated between biopsy specimens showing acute cellular rejection and those not showing rejection (area under the curve [AUC], 0.85; 95% confidence interval [CI], 0.78 to 0.91; P<0.001 by receiver-operating-characteristic curve analysis). The cross-validation estimate of the AUC was 0.83 by bootstrap resampling, and the Hosmer-Lemeshow test indicated good fit (P=0.77). In an external-validation data set, the AUC was 0.74 (95% CI, 0.61 to 0.86; P<0.001) and did not differ significantly from the AUC in our primary data set (P=0.13). The signature distinguished acute cellular rejection from acute antibody-mediated rejection and borderline rejection (AUC, 0.78; 95% CI, 0.68 to 0.89; P<0.001). It also distinguished patients who received anti-interleukin-2 receptor antibodies from those who received T-cell-depleting antibodies (P<0.001) and was diagnostic of acute cellular rejection in both groups. Urinary tract infection did not affect the signature (P=0.69). The average trajectory of the signature in repeated urine samples remained below the diagnostic threshold for acute cellular rejection in the group of patients with no rejection, but in the group with rejection, there was a sharp rise during the weeks before the biopsy showing rejection (P<0.001). CONCLUSIONS A molecular signature of CD3ε mRNA, IP-10 mRNA, and 18S rRNA levels in urinary cells appears to be diagnostic and prognostic of acute cellular rejection in kidney allografts. (Funded by the National Institutes of Health and others.).

Hypothermic Machine Preservation Facilitates Successful Transplantation of “Orphan” Extended Criteria Donor Livers

Hypothermic machine preservation (HMP) remains investigational in clinical liver transplantation. It is widely used to preserve kidneys for transplantation with improved results over static cold storage (SCS). At our center, we have used HMP in 31 adults receiving extended criteria donor (ECD) livers declined by the originating United Network for Organ Sharing region (“orphan livers”). These cases were compared to ECD SCS cases in a matched cohort study design. Livers were matched for donor age, recipient age, cold ischemic time, donor risk index and Model for End‐Stage Liver Disease (MELD) score. HMP was performed for 3–7 h at 4–8°C using our previously published protocol. Early allograft dysfunction rates were 19% in the HMP group versus 30% in the control group (p = 0.384). One‐year patient survival was 84% in the HMP group versus 80% in the SCS group (p = NS). Post hoc analysis revealed significantly less biliary complications in the HMP group versus the SCS group (4 vs. 13, p = 0.016). Mean hospital stay was significantly shorter in the HMP group (13.64 ± 10.9 vs. 20.14 ± 11.12 days in the SCS group, p = 0.001). HMP provided safe and reliable preservation in orphan livers transplanted at our center.

Hypothermic Machine Preservation Reduces Molecular Markers of Ischemia/Reperfusion Injury in Human Liver Transplantation

Hypothermic machine perfusion (HMP) is in its infancy in clinical liver transplantation. Potential benefits include diminished preservation injury (PI) and improved graft function. Molecular data to date has been limited to extrapolation of animal studies. We analyzed liver tissue and serum collected during our Phase 1 trial of liver HMP. Grafts preserved with HMP were compared to static cold stored (SCS) transplant controls. Reverse transcription polymerase chain reaction (RT‐PCR), immunohistochemistry and transmission electron microscopy (TEM) were performed on liver biopsies. Expression of inflammatory cytokines, adhesion molecules and chemokines, oxidation markers, apoptosis and acute phase proteins and the levels of CD68 positive macrophages in tissue sections were evaluated. RT‐PCR of reperfusion biopsy samples in the SCS group showed high expression of inflammatory cytokines, adhesion molecules and chemokines, oxidative markers and acute phase proteins. This upregulation was significantly attenuated in livers that were preserved by HMP. Immunofluorescence showed larger numbers of CD68 positive macrophages in the SCS group when compared to the HMP group. TEM samples also revealed ultrastructural damage in the SCS group that was not seen in the HMP group. HMP significantly reduced proinflammatory cytokine expression, relieving the downstream activation of adhesion molecules and migration of leukocytes, including neutrophils and macrophages when compared to SCS controls.

Standing the test of time: Outcomes of a decade of prioritizing patients with hepatocellular carcinoma, results of the UNOS natural geographic experiment

Priority is given to patients with hepatocellular carcinoma (HCC) to receive liver transplants, potentially causing significant regional disparities in organ access and possibly outcomes in this population. Our aim was to assess these disparities by comparing outcomes in long waiting time regions (LWTR, regions 5 and 9) and short waiting time regions (SWTR regions 3 and 10) by analyzing the United Network for Organ Sharing (UNOS) database. We analyzed 6,160 HCC patients who received exception points in regions 3, 5, 9, and 10 from 2002 to 2012. Data from regions 5 and 9 were combined and compared to data from regions 3 and 10. Survival was studied in three patient cohorts: an intent‐to‐treat cohort, a posttransplant cohort, and a cohort examining overall survival in transplanted patients only (survival from listing to last posttransplant follow‐up). Multivariate analysis and log‐rank testing were used to analyze the data. Median time on the list in the LWTR was 7.6 months compared to 1.6 months for SWTR, with a significantly higher incidence of death on the waiting list in LWTR than in SWTR (8.4% versus 1.6%, P < 0.0001). Patients in the LWTR were more likely to receive loco‐regional therapy, to have T3 tumors at listing, and to receive expanded‐criteria donor (ECD) or donation after cardiac death (DCD) grafts than patients in the SWTR (P < 0.0001 for all). Survival was significantly better in the LWTR compared to the SWTR in all three cohorts (P < 0.0001 for all three survival points). Being listed/transplanted in an SWTR was an independent predictor of poor patient survival on multivariate analysis (P < 0.0001, hazard ratio = 1.545, 95% confidence interval 1.375‐1.736). Conclusion: This study provides evidence that expediting patients with HCC to transplant at too fast a rate may adversely affect patient outcomes. (Hepatology 2014;60:1956–1961)

Kidneys at Higher Risk of Discard: Expanding the Role of Dual Kidney Transplantation

Half of the recovered expanded criteria donor (ECD) kidneys are discarded in the United States. A new kidney allocation system offers kidneys at higher risk of discard, Kidney Donor Profile Index (KDPI) > 85%, to a wider geographic area to promote broader sharing and expedite utilization. Dual kidney transplantation (DKT) based on the KDPI is a potential option to streamline allocation of kidneys which otherwise would have been discarded. To assess the clinical utility of the KDPI in kidneys at higher risk of discard, we analyzed the OPTN/UNOS Registry that included the deceased donor kidneys recovered between 2002 and 2012. The primary outcomes were allograft survival, patient survival and discard rate based on different KDPI categories (<80%, 80–90% and >90%). Kidneys with KDPI > 90% were associated with increased odds of discard (OR = 1.99, 95% CI 1.74–2.29) compared to ones with KDPI < 80%. DKTs of KDPI > 90% were associated with lower overall allograft failure (HR = 0.74, 95% CI 0.62–0.89) and better patient survival (HR = 0.79, 95% CI 0.64–0.98) compared to single ECD kidneys with KDPI > 90%. Kidneys at higher risk of discard may be offered in the up‐front allocation system as a DKT. Further modeling and simulation studies are required to determine a reasonable KDPI cutoff percentile.

Totally Laparoscopic Full Left Hepatectomy for Living Donor Liver Transplantation in Adolescents and Adults

In recent years different minimal access strategies have been designed in order to perform living donor liver surgery for adult recipients with less morbidity. Techniques involve shortening the length of the incision with or without previous laparoscopic mobilization of the liver. Herein we present two cases of totally laparoscopic living donor left hepatectomy, with and without removal of the middle hepatic vein, respectively. We describe in detail the anatomical and technical aspects of the procedure focusing on relevant points to enhance safety.