Peritoneal cavity B-1 cells are believed to produce IgM natural Abs. We have used α1,3-galactosyltransferase-deficient (GalT−/−) mice, which, like humans, produce IgM natural Abs against the carbohydrate epitope Galα1,3Gal (Gal), to demonstrate that peritoneal cavity B-1b cells with anti-Gal receptors produce anti-Gal IgM Abs only after LPS stimulation. Likewise, peritoneal cavity cells of GalT−/− and wild-type mice do not produce IgM Abs of other specificities without LPS stimulation. Development of Ab-secreting capacity is associated with loss of CD11b/CD18 (Mac-1) expression. In contrast, there are large numbers of cells producing anti-Gal and other IgM Abs in fresh splenocyte preparations from GalT−/− and (for non-Gal specificities) wild-type mice. These cells are Mac-1− but otherwise B-1b-like in their phenotype. We therefore hypothesized a pathway wherein peritoneal cavity B cells migrate into the spleen after activation in vivo and lose Mac-1 expression to become IgM Ab-producing cells. Consistent with this possibility, splenectomy reduced anti-Gal Ab production after immunization of GalT−/− mice with Gal-positive rabbit RBC. Furthermore, splenectomized B6 GalT−/−, Ig μ-chain mutant (μ−/−) (both Gal- and B cell-deficient) mice produced less anti-Gal IgM than nonsplenectomized controls after adoptive transfer of peritoneal cavity cells from B6 GalT−/− mice. When sorted GalT−/− Mac-1+ peritoneal cavity B cells were adoptively transferred to B6 GalT−/−, μ−/− mice, IgM Abs including anti-Gal appeared, and IgM-producing and Mac1− B cells were present in the spleen 5 wk after transfer. These findings demonstrate that peritoneal cavity Mac-1+ B-1 cells are precursors of Mac-1− splenic IgM Ab-secreting cells.

Percutaneous transhepatic portal access avoids surgery, but is rarely associated with bleeding or portal venous thrombosis. We herein report our large, single-center experience of percutaneous islet implantation, and evaluate risk factors of portal vein thrombosis and graft function. Prospective data was collected on 268 intraportal islet transplants (122 subjects). A portal venous Doppler ultrasound was obtained on Days 1 and 7 days posttransplant. Therapeutic heparinization, complete ablation of the portal catheter tract with Avitene paste, and limiting packed cell volume to < 5 ml completely prevented any portal thrombosis in the most recent 101 islet transplant procedures over the past 5 years. In the previous cumulative experience, partial thrombosis did not affect islet function. Standard liver volume correlated negatively (r=−0.257, P<0.001), and packed cell volume correlated positively with portal pressure rise (r=0.463, P<0.001). Overall, partial portal thrombosis occurred after 10 procedures (overall incidence 3.7%, most recent 101 patient incidence 0%). There were no cases of complete thrombosis, and no patient developed sequelae of portal hypertension. In conclusion, portal thrombosis is a preventable complication in clinical islet transplantation, provided therapeutic anticoagulation is maintained, and packed cell volume is limited to <5 ml.

The development of calcineurin inhibitors (CNIs) led to marked improvements in patient and graft survival after liver transplantation (LTx). We have been left, however, with a dependence on immunosuppressive agents with nephrotoxicity, neurotoxicity, adverse impacts on cardiac risk profile, and risk for malignancy. These challenges need to be met against a dominance of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC) as indications for liver transplant. Unmet needs for immunosuppression (IS) in LTx include: (1) Effective drugs that avoid CNIs toxicities. (2) Agents without adverse impact on HCV recurrence. (3) Compounds that minimize risk of HCC recurrence. New immunosuppressives will need to address the above needs while supporting patient and graft survival equivalent to those achievable with CNIs, ideally without important new toxicities. Two new classes of agents are currently in advanced clinical development: belatacept, and the mammalian target of rapamycin inhibitors (m-TORi). This manuscript will review evidence for a role for m-TORi in LTx in a range of clinical scenarios including patients with CNI nephrotoxicity or neurotoxicity, patients at risk of (or with) HCV recurrence, and patients at risk of HCC recurrence.

Human hepatocyte transplantation is an alternative treatment for acute liver failure and liver diseases involving enzyme deficiencies. Although it has been successfully applied in selected recipients, both isolation and transplantation outcomes have the potential to be improved by better donor selection. This study assessed the impact of various donor variables on isolation outcomes (yield and viability) and posttransplant engraftment, using the SCID/Alb-uPA (severe combined immunodeficient/urokinase type plasminogen activator under the control of an albumin promoter) human liver chimeric mouse model. Human hepatocytes were obtained from 90 human liver donor specimens and were transplanted into 3942 mice. Multivariate analysis revealed improved viability with younger donors (P ¼ 0.038) as well as with shorter warm ischemic time (P ¼ 0.012). Hepatocyte engraftment, assessed by the posttransplant level of serum human a1-antitrypsin, was improved with shorter warm ischemia time. Hepatocytes isolated from older donors (!60 years) had lower viability and posttransplant engraftment (P 0.01). In conclusion, the selection of young donors (<60 years) and rapid liver specimen retrieval, allowing for shorter warm ischemia time, are key determinants for the success of both the isolation of high viability human hepatocytes and their subsequent posttransplantation capacity for engraftment and expansion. Liver Transpl 16:974-982,

Mixed xenogeneic chimerism induces T-and B-cell tolerance in mice receiving T-cell-depleted rat bone marrow cells (BMC)following nonmyeloablative conditioning that includes ab and cd T cell and Natural killer (NK) cell-depleting mAbs. NK-cell depletion is essential to permit marrow engraftment, but NK-cell tolerance has not been previously assessed in mixed xenogeneic chimeras. We assessed NK-cell tolerance in rat → mouse mixed xenogeneic chimeras using in vivo 125 I-5iodo-2-deoxyuridine assays. Additional rapid marrow rejection mechanisms resulted in a requirement for 10-fold more rat than ß2 microglobulin knockout (ß2M −/− ) (MHC class I-deficient) mouse BMC to achieve engraftment in NK-cell-depleted mice. Both 12-week mixed xenogeneic chimeras and conditioned controls showed reduced resistance to engraftment of ß2M −/− mouse and rat BMC. While conditioned control mice recovered NK-cell-mediated resistance to ß2M −/− and rat BMC by 16 weeks, mixed chimeras lacked resistance to either, similar to NK-cell-deficient Ly49A transgenic mice. Thus, global NK-cell unresponsiveness is induced by mixed xenogeneic chimerism. Our data suggest that NK-cell anergy is induced by interactions with xenogeneic hematopoietic cells that express activating but not inhibitory ligands for recipient NK cells.

Patient: Male, 60Final Diagnosis: Hepatocellular carcinomaSymptoms: NoneMedication: —Clinical Procedure: HepatectomySpecialty: SurgeryObjective:Unusual clinical courseBackground:Carbon dioxide (CO2) is believed to be the safest gas for laparoscopic surgery, which is a standard procedure. We experienced severe cerebral infarction caused by paradoxical CO2 embolism during laparoscopic liver resection with injury of the hepatic vessels despite the absence of a right-to-left systemic shunt.Case Report:A 60-year-old man was diagnosed with hepatocellular carcinoma in the right hepatic lobe secondary to alcoholic liver disease. We planned the laparoscopy-assisted liver resection. During the surgery, the root of the right hepatic vein was injured. A 1.5-cm hole was accidentally made in the right hepatic vein, while mobilizing the right hepatic lobe laparoscopically. End-tidal CO2 dropped from 39 to 15.5 mmHg, and systemic blood pressure dropped from 121 to 45 mmHg, returning to normal with the administration of inotropes. The transesophageal echocardiography revealed numerous bubbles in the left atrium and ventricle. The Bispectral Index monitoring system showed low brain activity, suggesting cerebral infarction due to paradoxical gas embolism. The hepatectomy was completed by conversion to open laparotomy. The patient went into a coma and suffered quadriplegia after surgery, despite the cooling of his head and the administration of Thiamylal. Brain MRI revealed cerebral infarction in the broad area of the cerebral cortex right side predominantly, with poor blood flow confirmed by the brain perfusion single-photon emission CT. Rehabilitation was gradually achieved with Botox injections.Conclusions:Cerebral infarction by paradoxical gas embolism is a rare complication in laparoscopic surgery, but it is important to be aware of the risk and to be prepared to treat it.

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Non-purified IAT has a higher risk for acute portal pressure rise than allogeneic islet transplantation, and the rise is associated with the packed cell volume and the number of transplanted cells. Minimization of packed cell volume and cautious monitoring of portal pressure are important to avoid potential complications of portal hypertension.