When activated on or in the vicinity of cells, complement usually causes loss of function and sometimes cell death. Yet the liver, which produces large amounts of complement proteins, clears activators of complement and activated complexes from portal blood without obvious injury or impaired function. We asked whether and to what extent hepatocytes resist injury and loss of function mediated by exposure to complement. Using cells isolated from porcine livers as a model system, we found that, in contrast to endothelial cells, hepatocytes profoundly resist complement-mediated lysis and exhibit normal synthetic and conjugative functions when complement is activated on their surface. The resistance of hepatocytes to complement-mediated injury was not a function of cell surface control of the complement cascade but rather an intrinsic resistance of the cells dependent on the PI3K/Akt pathway. The resistance of hepatocytes to complement might be exploited in developing approaches to the treatment of hepatic failure or more broadly to the treatment of complement-mediated disease.

Summary Background & Objective The factor VIII (FVIII) B domain shares very little amino acid homology to other known proteins and is not directly necessary for procoagulant activity. Despite this, missense mutations within the B domain have been reported in patients with hemophilia A. Given that the B domain is dispensable for secretion and function of FVIII, we hypothesized that these mutations should not be causative of hemophilia A in these patients. Methods Plasmid vectors containing B domain missense mutations that were reported to be associated with moderate/severe hemophilia A (T751S, D826E, V993L, H1047Y, T1353A, N1441K, L1462P, E1579D, A1591S, P1641L and S1669L) were analyzed for their effect on synthesis and secretion compared to FVIII wild-type (WT) following transient transfection into COS-1 and CHO cells in vitro. Further, H1047Y, N1441K and E1579D mutants were expressed in vivo in a hemophilia A mouse model by hydrodynamic tail-vein injection. Results FVIII activity and antigen levels for all mutants expressed into the conditioned media of COS-1 and CHO cells were similar to FVIII WT. Also, plasma expression of these mutants was similar to FVIII WT in hemophilia A mice. An in vivo tail clip bleeding assay also demonstrated that blood loss from hemophilia A mice expressing FVIII WT, H1047Y, N1441K and E1579D were similar. Conclusion We conclude that most missense mutations within the FVIII B domain would be unlikely to lead to severe hemophilia A and that the majority of such missense mutations represent polymorphisms or non-pathologic mutations.

Immunotherapy and vaccination for cancer or infection are generally approached by administration of antigen or stimulation of antigen-presenting cells or both. These measures may fail if the treated individual lacks T cells specific for the immunogen(s). We tested another strategy-the generation of new T cells from hematopoietic stem cells that might be used for adoptive immunotherapy. To test this concept, we introduced T cell-depleted human bone marrow cells into fetal swine and tested the swine for human T cells at various times after birth. Human T cells were detected in the thymus and blood of the treated swine. These cells were generated de novo as they contained human T cell receptor excision circles not present in the T cell-depleted bone marrow. The human T cells were highly diverse and included novel specificities capable of responding to antigen presented by human antigen-presenting cells. Our findings constitute a first step in a new promising approach to immunotherapy in which tumor-or virus-specific T cell clones lacking in an individual might be generated in a surrogate host from hematopoietic stem cells of the individual to be treated.

We demonstrate that transduction of adipocytes with a simian immunodeficiency virus agm TYO1 (SIVagm)-based lentiviral vector carrying the human coagulation factor VIII gene (SIVhFVIII) resulted in expression of the human FVIII transgene in vitro and in db/db mice in vivo. Cultured human adipocytes were transduced with the SIVagm vector carrying the GFP gene in a dose-dependent manner and transduction of adipocytes with SIVhFVIII resulted in efficient expression of human coagulation factor VIII (hFVIII; 320739.8 ng/10 6 adipocytes/24 h) in vitro. Based upon successful transduction of adipocytes by SIV vectors carrying the lacZ gene in vivo in mice, the adipose tissue of db/db mice was transduced with SIVhFVIII. There was a transient appearance of human FVIII in mouse plasma (maximum 1.8 ng/ml) on day 11 after the injection. Transcripts of human FVIII transgene and human FVIII antigen also were detected in the adipose tissue by RT-PCR and immunofluorescence, respectively, on day 14. Emergence of anti-human FVIII antibodies 14 days after the injection of SIVhFVIII may explain the disappearance of human FVIII from the circulation. These results suggest that transduction of the adipocytes with vectors carrying the human FVIII gene may be potentially applicable for gene therapy of hemophilia A.