Faculty Bibliography

Cynomolgus monkeys are often used in preclinical transplantation research. Performing liver transplantation in cynomolgus monkeys is challenging because they poorly tolerate portal vein clamping during the anhepatic phase. Finding an alternative to portal vein clamping is necessary before preclinical liver transplant models can be performed with reliable outcomes. We used 3 different techniques to perform 5 liver transplants in male cynomolgus macaques (weight, 7.4-10.8 kg; mismatched for MHC I and II; matched for ABO). In procedure A, we clamped the portal vein briefly, as in human transplants, as well as the superior mesentery artery to minimize congestion at the expense of temporary ischemia (n = 2). In procedure B, we performed a temporary portocaval shunt with extracorporeal venovenous bypass (n = 1). For procedure C, we developed an H-shunt system (modified portocaval shunt) with extracorporeal bypass (n = 2). Postoperative immunosuppression comprised cyclosporine A, mycophenolate mofetil, and steroids. Recipients in procedure A developed hemodynamic instability and were euthanized within 2 d. The recipient that underwent procedure B was euthanized within 11 d due to inferior vena caval thrombosis. The H-shunt in procedure C led to minimal PV congestion during the anhepatic phase, and both recipients reached the 21-d survival endpoint with good graft function. Our novel H-shunt bypass system resulted in successful liver transplantation in cynomolgus macaques, with long-term posttransplant survival possible. This technical innovation makes possible the use of cynomolgus monkeys for preclinical liver transplant tolerance models.

In islet transplantation, in addition to immunologic and ischemic factors, the diabetic/hyperglycemic state of the recipient has been proposed, although not yet validated, as a possible cause of islet toxicity, contributing to islet loss during the engraftment period. Using a miniature swine model of islet transplantation, we have now assessed the effect of a persistent state of hyperglycemia on islet engraftment and subsequent function. An islet-kidney (IK) model previously described by our laboratory was utilized. Three experimental donor animals underwent total pancreatectomy and autologous islet transplantation underneath the renal capsule to prepare an IK at a load of ≤1,000 islet equivalents (IE)/kg donor weight, leading to a chronic diabetic state during the engraftment period (fasting blood glucose >250 mg/dL). Three control donor animals underwent partial pancreatectomy (sufficient to maintain normoglycemia during islet engraftment period) and IK preparation. As in vivo functional readout for islet engraftment, the IKs were transplanted across an immunologic minor or class I mismatch barrier into diabetic, nephrectomized recipients at an islet load of ∼4,500 IE/kg recipient weight. A 12-d course of cyclosporine was administered for tolerance induction. All experimental donors became diabetic and showed signs of end organ injury, while control donors maintained normoglycemia. All recipients of IK from both experimental and control donors achieved glycemic control over long-term follow-up, with reversal of diabetic nephropathy and with similar glucose tolerance tests. In this preclinical, large animal model, neither islet engraftment nor subsequent long-term islet function after transplantation appear to be affected by the diabetic state.

OBJECTIVE:Marginal livers (ML) have been used to expand the donor pool. National utilization of MLs is variable, and in some centers, they are never used. We examined the outcomes of MLs in the largest single center series of MLs used to date and compared outcomes to standard (SL) and living donor (LD) livers. METHODS:Analysis of a prospectively maintained database of all liver transplants performed at our institution from 1998 to 2016. ML grafts were defined as livers from donors >70, livers discarded regionally and shared nationally, livers with cold ischemic time >12 hours, livers from hepatitis C virus positive donors, livers from donation after cardiac death donors, livers with >30% steatosis, and livers split between 2 recipients. RESULTS:A total of 2050 liver transplant recipients were studied, of these 960 (46.8%) received ML grafts. ML recipients were more likely to have lower MELDs and have hepatocellular carcinoma. Most MLs used were from organs turned down regionally and shared nationally (69%) or donors >70 (22%). Survival of patients receiving MLs did not significantly differ from patients receiving SL grafts (P = 0.08). ML and SL recipients had worse survival than LDs (P < 0.01). Despite nearly half of our recipients receiving MLs, overall survival was significantly better than national survival over the same time period (P = 0.04). Waitlist mortality was significantly lower in our series compared with national results (19% vs 24.0%, P < 0.0001). CONCLUSIONS:Outcomes of recipients of ML grafts are comparable to SL transplants. Despite liberal use of these grafts, we have been able to successfully reduce waitlist mortality while exceeding national post-transplant survival metrics.

OBJECTIVE:We sought to develop a "Model Of Recurrence After Liver transplant" (MORAL) for hepatocellular carcinoma (HCC). BACKGROUND:The Milan criteria are used to allocate livers to patients with HCC requiring liver transplantation (LT) but do not include objective measures of tumor biology. Biological markers including the neutrophil-lymphocyte ratio (NLR) and alpha-fetoprotein (AFP) have been associated with recurrence risk. METHODS:Prospective cohort study of adults undergoing LT for HCC between January 2001 and December 2012. RESULTS:A total of 339 patients were included. On multivariable Cox regression analysis, 3 preoperatively available factors were independent predictors of worse recurrence-free survival (RFS), namely, an NLR ≥ 5 (P < 0.0001, hazard ratio, HR: 6.2), AFP > 200 (P < 0.0001, HR: 3.8), and Size >3 cm (P < 0.001, HR: 3.2). The Pre-MORAL score was constructed from the hazard ratios and assigning patients points in an additive fashion, with a minimum of 0 points (no factors) and a maximum of 13 points (all 3 factors). The highest risk patients in the Pre-MORAL had a 5-year RFS of 17.9% compared with 98.6% for the low risk group (P < 0.0001). The post-MORAL was constructed similarly using the 4 postoperatively available independent predictors of worse RFS, grade 4 HCC's (P < 0.0001, HR: 5.6), vascular invasion (P = 0.019, HR: 2.0), size >3 cm (P < 0.0001, HR: 3.2) and number >3 (P = 0.048, HR: 1.8). The pre- and post-MORAL were superior to Milan at predicting recurrence with c-statistics of 0.82 and 0.87, compared with 0.63, respectively. We then combined the scores to produce a combo-MORAL, with a c-statistic of 0.91 for predicting recurrence. CONCLUSIONS:The MORAL score provides a simple, highly accurate tool for predicting recurrence and risk-stratification pre- and postoperatively.

Maturation and migration to lymph nodes (LNs) constitutes a central paradigm in conventional dendritic cell (cDC) biology but remains poorly defined in humans. Using our organ donor tissue resource, we analyzed cDC subset distribution, maturation, and migration in mucosal tissues (lungs, intestines), associated lymph nodes (LNs), and other lymphoid sites from 78 individuals ranging from less than 1 year to 93 years of age. The distribution of cDC1 (CD141hiCD13hi) and cDC2 (Sirp-alpha+CD1c+) subsets was a function of tissue site and was conserved between donors. We identified cDC2 as the major mature (HLA-DRhi) subset in LNs with the highest frequency in lung-draining LNs. Mature cDC2 in mucosal-draining LNs expressed tissue-specific markers derived from the paired mucosal site, reflecting their tissue-migratory origin. These distribution and maturation patterns were largely maintained throughout life, with site-specific variations. Our findings provide evidence for localized DC tissue surveillance and reveal a lifelong division of labor between DC subsets, with cDC2 functioning as guardians of the mucosa.

A paradigm in transplantation states that graft-infiltrating T cells are largely non-alloreactive "bystander" cells. However, the origin and specificity of allograft T cells over time has not been investigated in detail in animals or humans. Here, we use polychromatic flow cytometry and high throughput TCR sequencing of serial biopsies to show that gut-resident T cell turnover kinetics in human intestinal allografts are correlated with the balance between intra-graft host-vs-graft (HvG) and graft-vs-host (GvH) reactivities and with clinical outcomes. In the absence of rejection, donor T cells were enriched for GvH-reactive clones that persisted long-term in the graft. Early expansion of GvH clones in the graft correlated with rapid replacement of donor APCs by the recipient. Rejection was associated with transient infiltration by blood-like recipient CD28+ NKG2D^Hi CD8+ alpha beta T cells, marked predominance of HvG clones, and accelerated T cell turnover in the graft. Ultimately, these recipient T cells acquired a steady state tissue-resident phenotype, but regained CD28 expression during rejections. Increased ratios of GvH to HvG clones were seen in non-rejectors, potentially mitigating the constant threat of rejection posed by HvG clones persisting within the tissue-resident graft T cell population.

By preserving part of the native liver, auxiliary partial orthotopic liver transplantation (APOLT) provides the advantage of potential immunosuppression (ISP) withdrawal if the native liver recovers but has had limited acceptance, especially in the United States, due to technical complications and low rates of native liver regeneration. No previous study has evaluated APOLT specifically for preadolescent children with fulminant hepatic failure (FHF). This population might benefit especially based on greater capacity for liver regeneration. Data from 13 preadolescent children who underwent APOLT were compared to 13 matched controls who underwent orthotopic liver transplantation (OLT) for FHF from 1996 to 2013. There were no significant differences in patient demographics or survival between the 2 groups. However, all surviving OLT recipients (10/13) remain on ISP, while all but 1 surviving APOLT recipient (12/13) showed native liver regeneration, and the first 10 recipients (76.9%) are currently off ISP with 2 additional patients currently weaning. In our experience, APOLT produced excellent survival and high rates of native liver regeneration in preadolescent children with FHF. This represents the largest series to date to report such outcomes. Liberating these children from lifelong ISP without the downside of increased surgical morbidity makes APOLT an attractive alternative. In conclusion, we therefore propose that, with the availability of technical expertise and with the technical modifications above, APOLT for FHF should be strongly considered for preteenage children with FHF.

It is unclear how the immune response in early life becomes appropriately stimulated to provide protection while also avoiding excessive activation as a result of diverse new antigens. T cells are integral to adaptive immunity; mouse studies indicate that tissue localization of T cell subsets is important for both protective immunity and immunoregulation. In humans, however, the early development and function of T cells in tissues remain unexplored. We present here an analysis of lymphoid and mucosal tissue T cells derived from pediatric organ donors in the first two years of life, as compared to adult organ donors, revealing early compartmentalization of T cell differentiation and regulation. Whereas adult tissues contain a predominance of memory T cells, in pediatric blood and tissues the main subset consists of naive recent thymic emigrants, with effector memory T cells (T(EM)) found only in the lungs and small intestine. Additionally, regulatory T (T(reg)) cells comprise a high proportion (30-40%) of CD4(+) T cells in pediatric tissues but are present at much lower frequencies (1-10%) in adult tissues. Pediatric tissue T(reg) cells suppress endogenous T cell activation, and early T cell functionality is confined to the mucosal sites that have the lowest T(reg):T(EM) cell ratios, which suggests control in situ of immune responses in early life.