Juan Echeverri

Mechanism of hard-nanomaterial clearance by the liver

The liver and spleen are major biological barriers to translating nanomedicines because they sequester the majority of administered nanomaterials and prevent delivery to diseased tissue. Here we examined the blood clearance mechanism of administered hard nanomaterials in relation to blood flow dynamics, organ microarchitecture, and cellular phenotype. We found that nanomaterial velocity reduces 1000-fold as they enter and traverse the liver, leading to 7.5 times more nanomaterial interaction with hepatic cells relative to peripheral cells. In the liver, Kupffer cells (84.8%±6.4%), hepatic B cells (81.5±9.3%), and liver sinusoidal endothelial cells (64.6±13.7%) interacted with administered PEGylated quantum dots but splenic macrophages took up less (25.4±10.1%) due to differences in phenotype. The uptake patterns were similar for two other nanomaterial types and five different surface chemistries. Potential new strategies to overcome off-target nanomaterial accumulation may involve manipulating intra-organ flow dynamics and modulating cellular phenotype to alter hepatic cell interaction.

Normothermic ex vivo liver perfusion using steen solution as perfusate for human liver transplantation: First North American results.

The European trial investigating normothermic ex vivo liver perfusion (NEVLP) as a preservation technique for liver transplantation (LT) uses gelofusine, a non–US Food and Drug Administration–approved, bovine‐derived, gelatin‐based perfusion solution. We report a safety and feasibility clinical NEVLP trial with human albumin–based Steen solution. Transplant outcomes of 10 human liver grafts that were perfused on the Metra device at 37 °C with Steen solution, plus 3 units of erythrocytes were compared with a matched historical control group of 30 grafts using cold storage (CS) as the preservation technique. Ten liver grafts were perfused for 480 minutes (340‐580 minutes). All livers cleared lactate (final lactate 1.46 mmol/L; 0.56‐1.74 mmol/L) and produced bile (61 mL; 14‐146 mL) during perfusion. No technical problems occurred during perfusion, and all NEVLP‐preserved grafts functioned well after LT. NEVLP versus CS had lower aspartate aminotransferase and alanine aminotransferase values on postoperative days 1‐3 without reaching significance. No difference in postoperative graft function between NEVLP and CS grafts was detected as measured by day 7 international normalized ratio (1.1 [1‐1.56] versus 1.1 [1‐1.3]; P = 0.5) and bilirubin (1.5; 1‐7.7 mg/dL versus 2.78; 0.4‐15 mg/dL; P = 0.5). No difference was found in the duration of intensive care unit stay (median, 1 versus 2 days; range, 0‐8 versus 0‐23 days; P = 0.5) and posttransplant hospital stay (median, 11 versus 13 days; range, 8‐17 versus 7‐89 days; P = 0.23). Major complications (Dindo‐Clavien ≥ 3b) occurred in 1 patient in the NEVLP group (10%) compared with 7 (23%) patients in the CS group (P = 0.5). No graft loss or patient death was observed in either group. Liver preservation with normothermic ex vivo perfusion with the Metra device using Steen solution is safe and results in comparable outcomes to CS after LT. Using US Food and Drug Administration–approved Steen solution will avoid a potential regulatory barrier in North America. Liver Transplantation 22 1501–1508 2016 AASLD.

Eight-Hour Continuous Normothermic Ex Vivo Kidney Perfusion Is a Safe Preservation Technique for Kidney Transplantation: A New Opportunity for the Storage, Assessment, and Repair of Kidney Grafts.

Background Hypothermic kidney storage causes preservation injury and is poorly tolerated by renal grafts. We investigated whether static cold storage (SCS) can be safely replaced with a novel technique of pressure-controlled normothermic ex vivo kidney perfusion (NEVKP) in heart-beating donor kidney transplantation. Methods Right kidneys were removed from 30 kg Yorkshire pigs in a model of heart-beating donation and either preserved in cold histidine-tryptophan-ketoglutarate solution for 8 hours (n = 5), or subjected to 8 hours of pressure-controlled NEVKP (n = 5) followed by renal heterotopic autotransplantation. Results During NEVKP, physiologic perfusion conditions were maintained with low intrarenal resistance and normal electrolyte and pH parameters. Aspartate aminotransferase and lactate dehydrogenase as injury markers were below the detectable analyzer range (<4 and <100 U/L, respectively). Perfusate lactate concentration decreased from baseline until the end of perfusion (10.38 ± 0.76 mmol/L vs 1.22 ± 0.26 mmol/L; P < 0.001). Posttransplantation, animals transplanted with NEVKP versus SCS grafts demonstrated similar serum creatinine peak levels (NEVKP, 2.0 ± 0.5 vs SCS 2.7 ± 0.7 mg/dL; P = 0.11) and creatinine clearance on day 10 (NEVKP, 65.9 ± 18.8 mL/min vs SCS 61.2 ± 15.6 mL/min; P = 0.74). After 10 days of follow-up, animals transplanted with NEVKP grafts had serum creatinine and blood urea nitrogen values comparable to their basal levels (P = 0.49 and P = 0.59), whereas animals transplanted with SCS grafts had persistently elevated serum creatinine and blood urea nitrogen when compared with basal levels (P = 0.01 and P = 0.03). Conclusions Continuous pressure-controlled NEVKP is feasible and safe in good quality heart-beating donor kidney grafts. It maintains a physiologic environment and excellent graft function ex vivo during preservation without causing graft injury.

Anti‐inflammatory signaling during ex vivo liver perfusion improves the preservation of pig liver grafts before transplantation

Normothermic ex vivo liver perfusion (NEVLP) improves graft preservation by avoiding cold ischemia injury. We investigated whether the protective effects of NEVLP can be further improved by applying strategies targeted on reducing the activation of proinflammatory cytokines during perfusion. Livers retrieved under heart‐beating conditions were perfused for 4 hours. Following the preservation period, a pig liver transplantation was performed. In group 1 (n = 5), anti‐inflammatory strategies (alprostadil, n‐acetylcysteine, carbon monoxide, sevoflurane, and subnormothermic temperature [33°C]) were applied. This was compared with a perfused control group (group 2) where livers (n = 5) were perfused at 37°C without anti‐inflammatory agents, similar to the setup used in current European clinical trials, and to a control group preserved with static cold storage (group 3). During 3‐day follow‐up, markers of reperfusion injury, bile duct injury, and liver function were examined. Aspartate aminotransferase (AST) levels during perfusion were significantly lower in the study versus control group at 1 hour (52 ± 6 versus 162 ± 86 U/L; P = 0.01), 2 hours (43 ± 5 versus 191 ± 111 U/L; P = 0.008), and 3 hours (24 ± 16 versus 218 ± 121 U/L; P = 0.009). During perfusion, group 1 versus group 2 had reduced interleukin (IL) 6, tumor necrosis factor α, and galactosidase levels and increased IL10 levels. After transplantation, group 1 had lower AST peak levels compared with group 2 and group 3 (1400 ± 653 versus 2097 ± 1071 versus 1747 ± 842 U/L; P = 0.47) without reaching significance. Bilirubin levels were significantly lower in group 1 versus group 2 at day 1 (3.6 ± 1.5 versus 6.60 ± 1.5 μmol/L; P = 0.02) and 3 (2 ± 1.1 versus 9.7 ± 7.6 μmol/L; P = 0.01). A trend toward decreased hyaluronic acid, as a marker of improved endothelial cell function, was observed at 1, 3, and 5 hours after reperfusion in group 1 versus group 2. Only 1 early death occurred in each group (80% survival). In conclusion, addition of anti‐inflammatory strategies further improves warm perfused preservation. Liver Transplantation 22 1573–1583 2016 AASLD.

Continuous Normothermic Ex Vivo Kidney Perfusion Improves Graft Function in Donation After Circulatory Death Pig Kidney Transplantation.

Background Donation after circulatory death (DCD) is current clinical practice to increase the donor pool. Deleterious effects on renal graft function are described for hypothermic preservation. Therefore, current research focuses on investigating alternative preservation techniques, such as normothermic perfusion. Methods We compared continuous pressure-controlled normothermic ex vivo kidney perfusion (NEVKP) with static cold storage (SCS) in a porcine model of DCD autotransplantation. After 30 minutes of warm ischemia, right kidneys were removed from 30-kg Yorkshire pigs and preserved with 8-hour NEVKP or in 4°C histidine-tryptophan-ketoglutarate solution (SCS), followed by kidney autotransplantation. Results Throughout NEVKP, electrolytes and pH values were maintained. Intrarenal resistance decreased over the course of perfusion (0 hour, 1.6 ± 0.51 mm per minute vs 7 hours, 0.34 ± 0.05 mm Hg/mL per minute, P = 0.005). Perfusate lactate concentration also decreased (0 hour, 10.5 ± 0.8 vs 7 hours, 1.4 ± 0.3 mmol/L, P < 0.001). Cellular injury markers lactate dehydrogenase and aspartate aminotransferase were persistently low (lactate dehydrogenase < 100 U/L, below analyzer range; aspartate aminotransferase 0 hour, 15.6 ± 9.3 U/L vs 7 hours, 24.8 ± 14.6 U/L, P = 0.298). After autotransplantation, renal grafts preserved with NEVKP demonstrated lower serum creatinine on days 1 to 7 (P < 0.05) and lower peak values (NEVKP, 5.5 ± 1.7 mg/dL vs SCS, 11.1 ± 2.1 mg/dL, P = 0.002). The creatinine clearance on day 4 was increased in NEVKP-preserved kidneys (NEVKP, 39 ± 6.4 vs SCS, 18 ± 10.6 mL/min; P = 0.012). Serum neutrophil gelatinase-associated lipocalin at day 3 was lower in the NEVKP group (1267 ± 372 vs 2697 ± 1145 ng/mL, P = 0.029). Conclusions Continuous pressure-controlled NEVKP improves renal function in DCD kidney transplantation. Normothermic ex vivo kidney perfusion might help to decrease posttransplant delayed graft function rates and to increase the donor pool.

Continuous Normothermic Ex Vivo Kidney Perfusion Is Superior to Brief Normothermic Perfusion Following Static Cold Storage in Donation After Circulatory Death Pig Kidney Transplantation.

Hypothermic preservation is known to cause renal graft injury, especially in donation after circulatory death (DCD) kidney transplantation. We investigated the impact of cold storage (SCS) versus short periods of normothermic ex vivo kidney perfusion (NEVKP) after SCS versus prolonged, continuous NEVKP with near avoidance of SCS on kidney function after transplantation. Following 30 min of warm ischemia, kidneys were removed from 30‐kg Yorkshire pigs and preserved for 16 h with (A) 16 h SCS, (B) 15 h SCS + 1 h NEVKP, (C) 8 h SCS + 8 h NEVKP, and (D) 16 h NEVKP. After contralateral kidney resection, grafts were autotransplanted and pigs followed up for 8 days. Perfusate injury markers such as aspartate aminotransferase and lactate dehydrogenase remained low; lactate decreased significantly until end of perfusion in groups C and D (p < 0.001 and p = 0.002). Grafts in group D demonstrated significantly lower serum creatinine peak when compared to all other groups (p < 0.001) and 24‐h creatinine clearance at day 3 after surgery was significantly higher (63.4 ± 19.0 mL/min) versus all other groups (p < 0.001). Histological assessment on day 8 demonstrated fewer apoptotic cells in group D (p = 0.008). In conclusion, prolonged, continuous NEVKP provides superior short‐term outcomes following DCD kidney transplantation versus SCS or short additional NEVKP following SCS.

Liver transplantation for cholangiocarcinoma: Current status and new insights

Cholangiocarcinoma is a malignant tumor of the biliary system that can be classified into intrahepatic (iCCA), perihiliar (phCCA) and distal. Initial experiences with orthotopic liver transplantation (OLT) for patients with iCCA and phCCA had very poor results and this treatment strategy was abandoned. In the last decade, thanks to a strict selection process and a neoadjuvant chemoradiation protocol, the results of OLT for patients with non-resectable phCCA have been shown to be excellent and this strategy has been extended worldwide in selected transplant centers. Intrahepatic cholangiocarcinoma is a growing disease in most countries and can be diagnosed both in cirrhotic and in non-cirrhotic livers. Even though OLT is contraindicated in most centers, recent investigations analyzing patients that were transplanted with a misdiagnosis of HCC and were found to have an iCCA have shown encouraging results. There is some information suggesting that patients with early stages of the disease could benefit from OLT. In this review we analyze the current state-of-the-art of OLT for cholangiocarcinoma as well as the new insights and future perspectives.

Inducing Hepatitis C Virus Resistance After Pig Liver Transplantation -”A Proof of Concept of Liver Graft Modification Using Warm Ex Vivo Perfusion”

Normothermic ex vivo liver perfusion (NEVLP) offers the potential to optimize graft function prior to liver transplantation (LT). Hepatitis C virus (HCV) is dependent on the presence of miRNA(microRNA)‐122. Miravirsen, a locked‐nucleic acid oligonucleotide, sequesters miR‐122 and inhibits HCV replication. The aim of this study was to assess the efficacy of delivering miravirsen during NEVLP to inhibit miR‐122 function in a pig LT model. Pig livers were treated with miravirsen during NEVLP or cold storage (CS). Miravirsen absorption, miR‐122 sequestration, and miR‐122 target gene derepression were determined before and after LT. The effect of miravirsen treatment on HCV infection of hepatoma cells was also assessed. NEVLP improved miravirsen uptake versus CS. Significant miR‐122 sequestration and miR‐122 target gene derepression were seen with NEVLP but not with CS. In vitro data confirmed miravirsen suppression of HCV replication after established infection and prevented HCV infection with pretreatment of cells, analogous to the pretreatment of grafts in the transplant setting. In conclusion, miravirsen delivery during NEVLP is a potential strategy to prevent HCV reinfection after LT. This is the first large‐animal study to provide “proof of concept” for using NEVLP to modify and optimize liver grafts for transplantation.

Small-for-size syndrome in live donor liver transplantation-Pathways of injury and therapeutic strategies.

Due to the severe organ shortage and the increasing gap between the supply and demand for donor grafts, live donor liver transplantation (LDLT) has become an accepted and alternative technique for the expansion of the donor pool. However, donor safety and good recipient outcomes must be balanced regarding risk stratification and decision‐making within this patient population. Small‐for‐size syndrome (SFSS) is one of the complications encountered after LDLT, thus increasing the burden of optimizing donor graft selection and effective treatments during its occurrence. A graft‐to‐recipient weight ratio (GRWR) <0.8 predisposes the graft to SFSS. However, other factors may induce this complication even without a graft‐to‐patient size mismatch. Several strategies to prevent this complication include portal vein flow and liver outflow modulation, as well as pharmacological treatment. Also, as an entity with a multifactorial etiology, outcomes vary between right‐lobe, left‐lobe, and posterior‐lobe donation among series encountered in the literature. In this review, we analyze the pathophysiology and classification of this complication, the state‐of‐the‐art on management of SFSS, and the outcomes regarding the best treatment strategy on this patient population.

Management of "very early" hepatocellular carcinoma on cirrhotic patients.

Due to the advances in screening of cirrhotic patients, hepatocellular carcinoma (HCC) is being diagnosed in earlier stages. For this reason the number of patients diagnosed of very early HCC (single tumors ≤ 2 cm) is continuously increasing. Once a patient has been diagnosed with this condition, treatment strategies include liver resection, local therapies or liver transplantation. The decision on which therapy should the patient undergo depends on the general patients performance status and liver disease. Anyway, even in patients with similar conditions, the best treatment offer is debatable. In this review we analyze the state of the art on the management of very early HCC on cirrhotic patients to address the best treatment strategy for this patient population.