David G. Heidt

Emerging evidence has suggested that the capability of a tumor to grow and propagate is dependent on a small subset of cells within a tumor, termed cancer stem cells. Although data have been provided to support this theory in human blood, brain, and breast cancers, the identity of pancreatic cancer stem cells has not been determined. Using a xenograft model in which primary human pancreatic adenocarcinomas were grown in immunocompromised mice, we identified a highly tumorigenic subpopulation of pancreatic cancer cells expressing the cell surface markers CD44, CD24, and epithelial-specific antigen (ESA). Pancreatic cancer cells with the CD44(+)CD24(+)ESA(+) phenotype (0.2-0.8% of pancreatic cancer cells) had a 100-fold increased tumorigenic potential compared with nontumorigenic cancer cells, with 50% of animals injected with as few as 100 CD44(+)CD24(+)ESA(+) cells forming tumors that were histologically indistinguishable from the human tumors from which they originated. The enhanced ability of CD44(+)CD24(+)ESA(+) pancreatic cancer cells to form tumors was confirmed in an orthotopic pancreatic tail injection model. The CD44(+)CD24(+)ESA(+) pancreatic cancer cells showed the stem cell properties of self-renewal, the ability to produce differentiated progeny, and increased expression of the developmental signaling molecule sonic hedgehog. Identification of pancreatic cancer stem cells and further elucidation of the signaling pathways that regulate their growth and survival may provide novel therapeutic approaches to treat pancreatic cancer, which is notoriously resistant to standard chemotherapy and radiation.

Biliary complications remain a significant problem following liver transplantation in the Model for End-Stage Liver Disease (MELD) era. We hypothesized that donor, recipient, and technical variables may differentially affect anastomotic biliary complications in MELD era liver transplants. We reviewed 256 deceased donor liver transplants after the institution of MELD at our center and evaluated these variables' association with anastomotic biliary complications. The bile leak rate was 18%, and the stricture rate was 23%. Univariate analysis revealed that recipient age, MELD, donor age, and warm ischemia were risk factors for leak, whereas a Roux limb or stent was protective. A bile leak was a risk factor for anastomotic stricture, whereas use of histidine tryptophan ketoglutarate (HTK) versus University of Wisconsin (UW) solution was protective. Additionally, use of a transcystic tube/stent was also protective. Multivariate analysis showed that warm ischemia was the only independent risk factor for a leak, whereas development of a leak was the only independent risk factor for a stricture. HTK versus UW use and transcystic tube/stent use were the only independent protective factors against stricture. Use of an internal stent trended in the multivariate analysis toward being protective against leaks and strictures, but this was not quite statistically significant. This represents one of the first MELD era studies of deceased donor liver transplants evaluating factors affecting the incidence of anastomotic bile leaks and strictures. Donor, recipient, and technical factors appear to differentially affect the incidence of anastomotic biliary complications, with warm ischemia, use of HTK, and use of a stent emerging as the most important variables. Liver Transpl 14:73–80, 2008. © 2007 AASLD.

A strategy is developed in this study for identifying sialylated glycoprotein markers in human cancer serum. This method consists of three steps: lectin affinity selection, a liquid separation and characterization of the glycoprotein markers using mass spectrometry. In this work, we use three different lectins (Wheat Germ Agglutinin, (WGA) Elderberry lectin,(SNA), Maackia amurensis lectin, (MAL)) to extract sialylated glycoproteins from normal and cancer serum. Twelve highly abundant proteins are depleted from the serum using an IgY-12 antibody column. The use of the different lectin columns allows one to monitor the distribution of alpha(2,3) and alpha(2,6) linkage type sialylation in cancer serum vs that in normal samples. Extracted glycoproteins are fractionated using NPS-RP-HPLC followed by SDS-PAGE. Target glycoproteins are characterized further using mass spectrometry to elucidate the carbohydrate structure and glycosylation site. We applied this approach to the analysis of sialylated glycoproteins in pancreatic cancer serum. Approximately 130 sialylated glycoproteins are identified using microLC-MS/MS. Sialylated plasma protease C1 inhibitor is identified to be down-regulated in cancer serum. Changes in glycosylation sites in cancer serum are also observed by glycopeptide mapping using microLC-ESI-TOF-MS where the N83 glycosylation of alpha1-antitrypsin is down regulated. In addition, the glycan structures of the altered proteins are assigned using MALDI-QIT-MS. This strategy offers the ability to quantitatively analyze changes in glycoprotein abundance and detect the extent of glycosylation alteration as well as the carbohydrate structure that correlate with cancer.

As patient survival after orthotopic liver transplantation (OLT) improves, late complications, including late graft failure, more commonly occur and retransplantation (re-OLT) is required more often. Survival after re-OLT is poorer than after primary OLT, and given the organ shortage, it is essential that we optimize our use of scarce donor livers. We sought to identify variables that predict poor outcome after late re-OLT. Among adults who underwent OLT between September 1989 and October 1997, we identified transplant recipients who survived greater than 6 months (n = 964) and analyzed those who required late re-OLT (>/=6 months after primary OLT). We recorded the indication for the initial OLT and interval from OLT to re-OLT. We also analyzed data collected at the time of re-OLT, including age, sex, indications for primary OLT and re-OLT, United Network for Organ Sharing status, preoperative laboratory values (white blood cells, platelets, hemoglobin, albumin, bilirubin, creatinine, and prothrombin time), Child-Pugh-Turcotte score, number of rejection episodes before re-OLT, and interval between OLT and re-OLT. In addition, we analyzed surgical factors (including procedure performed and use of packed red blood cells, fresh frozen plasma, and platelets), postoperative immunosuppression, and donor factors (age, ischemic time). Forty-eight patients (5%) underwent late re-OLT at a median of 557 days (range, 195 to 2,559 days) post-OLT. Survival rates after re-OLT at 90 days, 1 year, and 5 years were 71%, 60%, and 42%, respectively. Patients surviving 90 days or greater after re-OLT had an 85% chance of surviving to 1 year. Sepsis was the leading cause of death (15 of 25 deaths; 60%). Recipient age older than 50 years (P =.04), preoperative creatinine level greater than 2 mg/dL (P =.004), and use of intraoperative blood products (packed red blood cells, P =.001; fresh frozen plasma, P =.002; platelets, P =.004) had significant impacts on survival. Late re-OLT was associated with increased mortality. Careful patient selection, with particular attention to recipient age and renal function, may help improve results and optimize our use of scarce donor livers.