Erhard Seifried

Mutations in VKORC1 cause warfarin resistance and multiple coagulation factor deficiency type 2

Coumarin derivatives such as warfarin represent the therapy of choice for the long-term treatment and prevention of thromboembolic events. Coumarins target blood coagulation by inhibiting the vitamin K epoxide reductase multiprotein complex (VKOR). This complex recycles vitamin K 2,3-epoxide to vitamin K hydroquinone, a cofactor that is essential for the post-translational γ-carboxylation of several blood coagulation factors. Despite extensive efforts, the components of the VKOR complex have not been identified. The complex has been proposed to be involved in two heritable human diseases: combined deficiency of vitamin-K-dependent clotting factors type 2 (VKCFD2; Online Mendelian Inheritance in Man (OMIM) 607473), and resistance to coumarin-type anticoagulant drugs (warfarin resistance, WR; OMIM 122700). Here we identify, by using linkage information from three species, the gene vitamin K epoxide reductase complex subunit 1 (VKORC1), which encodes a small transmembrane protein of the endoplasmic reticulum. VKORC1 contains missense mutations in both human disorders and in a warfarin-resistant rat strain. Overexpression of wild-type VKORC1, but not VKORC1 carrying the VKCFD2 mutation, leads to a marked increase in VKOR activity, which is sensitive to warfarin inhibition.

VKORC1 haplotypes and their impact on the inter-individual and inter-ethnical variability of oral anticoagulation.

In order to elucidate the role of VCORC1 sequence variants in warfarin sensitivity, we established a complete SNP map of the VKORC1 gene locus in 200 blood donors from Western Germany. Nearly all of the genetic variability of the VKORC1 gene in Europeans is reflected by three main haplotypes. Recently described polymorphisms associated with low warfarin dose requirement (dbSNP:rs9934438; dbSNP:rs17878363) were found in complete linkage disequilibrium with the VKORC1*2 haplotype. In two patient cohorts of European origin with either increased coumarin sensitivity (n= 14) or partial coumarin resistance (n=36) the VKORC1*2 frequency varied highly significant between the two groups and also when compared to 200 blood donor controls (coumarin sensitive 96%, coumarin resistant 7%, controls 42%) thus demonstrating a strong association between these two phenotypes and the VKORC1 haplotype (p = 1.6 x 10(-8) for coumarin sensitive and p = 1.9 x 10(-8) for coumarin resistant). Analysis of database derived VKORC1 genotypes of African Americans and Chinese revealed that haplotype frequencies in these populations differ significantly from the European sample (for VKORC1*2: Europeans 42%, Chinese 95%, African Americans 14%). These observations suggest VKORC1 as principal genetic modulator of the ethnic differences in warfarin response. Since hereditary pharmacodynamic (VKORC1) and pharmacokinetic (CYP2C9) factors account for up to 50% of the inter-individual variability of the warfarin response, these genetic markers may serve as clinically relevant predictors of warfarin dosing in future studies.

Feasibility and efficacy of routine PCR screening of blood donations for hepatitis C virus, hepatitis B virus, and HIV-1 in a blood-bank setting

BACKGROUND Despite sensitive antibody-based blood-donor screening, a residual risk of transfusion-transmitted viral infections exists. Only direct monitoring by sensitive nucleic-acid tests would provide data accurately to measure the risk and to assess risk-reduction procedures. We investigated the feasibility and efficacy of routine screening of donors for hepatitis C virus (HCV), hepatitis B virus (HBV), and HIV-1 by PCR. METHODS For PCR testing, individual donor plasma samples were pooled (96x100 microL) overnight by two automatic pipetting machines. Viruses were concentrated by centrifugation and nucleic acids were extracted. HCV PCR was done on the Cobas Amplicor system (Hoffmann-La Roche, Mannheim, Germany). HBV and HIV-1 sequences were amplified by single (non-nested) in-house PCRs and detected by agarose-gel electrophoresis. Detection limits were 1000-5000 genome equivalents/mL in the donor blood. FINDINGS PCR testing was done in parallel to antibody screening with a maximum throughput of 3000 samples in 7-8 h. Positive samples were identified 1-2 days later. 111 of 373,423 donations (107 of 4500 pools) were PCR and antibody/antigen-confirmed positive. We found one HCV PCR-positive antibody-negative donation with normal alanine aminotransferase and one HCV PCR-positive donation with an elevated alanine aminotransferase (100 IU), which was negative in the AxSYM 2.0 and Matrix 1.0, but positive after control in the Abbott Prism test (Abbott GmbH, Wiesbaden, Germany). INTERPRETATION PCR is a suitable and fast blood-donor screening procedure and contributes to a reduction in viral transmission by transfusion of blood components. In our selected donor population, the yield of detected contaminated donations from donors in the time window in which they are highly infectious but do not have any symptoms or detectable antigen and antibody concentrations (diagnostic window), confirms theoretical estimates.

Transcoronary Transplantation of Functionally Competent BMCs Is Associated With a Decrease in Natriuretic Peptide Serum Levels and Improved Survival of Patients With Chronic Postinfarction Heart Failure: Results of the TOPCARE-CHD Registry

Although intracoronary administration of bone marrow–derived mononuclear progenitor cells (BMCs) may be associated with improved cardiac function in patients with chronic postinfarction heart failure, the impact on prognosis and clinical outcome of these patients is unknown. To identify potential predictors for a favorable clinical outcome, we assessed natriuretic peptide serum levels as objective markers of heart failure and the occurrence of cardiac death in relation to functional capacity of the infused cells in a consecutive series of 121 patients with chronic ischemic heart disease treated with intracoronary infusion of BMCs. Our analyses show that both N-terminal pro–brain natriuretic peptide (NT-proBNP) and N-terminal pro–atrial natriuretic peptide (NT-proANP) serum levels were significantly reduced in patients with established postinfarction heart failure 3 months after transcoronary progenitor cell administration. NT-proBNP serum levels greater than or equal to median (735 pg/mL) at baseline and a high number of infused progenitor cells with colony-forming capacity were the only independent predictors of a favorable response 3 months after intracoronary administration of BMCs. During extended clinical follow-up (577±442 days), a total of 14 deaths occurred in the overall patient population. Kaplan–Meier curves for both all cause and cardiac mortality showed that patients receiving a higher number of colony-forming cells were significantly less likely to die than those patients receiving low numbers of colony-forming cells (P=0.01). Most importantly, infusion of a high number of cells with colony-forming capacity was associated with a complete abrogation of increased mortality in patients with elevated NT-proBNP serum levels (≥735 pg/mL; median) at baseline (P<0.001). Taken together, our results show that patients with objective evidence of postinfarction heart failure demonstrate a significant reduction of both NT-proBNP and NT-proANP serum levels within 3 months following intracoronary infusion of BMCs. Importantly, infusion of progenitor cells with a high functional capacity is associated with a significantly lower mortality during further follow-up.

Adoptive transfer and selective reconstitution of streptamer-selected cytomegalovirus-specific CD8+ T cells leads to virus clearance in patients after allogeneic peripheral blood stem cell transplantation

BACKGROUND: Cytomegalovirus (CMV) disease constitutes a serious complication after allogeneic stem cell transplantation. For the clearance of CMV, CD8+ T cells are pivotal.

Cellular immunotherapy of malignancies using the clonal natural killer cell line NK-92.

For years activated natural killer (A-NK) cells have been explored with respect to their efficacy in anticancer therapy, but, except for some anectdotal reports, no clear clinical benefit has been shown. However, as the understanding about the interactions of NK cells and tumor cells advances, the use of A-NK cells might be revisited with more sophisticated approaches that pay tribute to mechanisms which allow tumor cells to escape immune surveillance. Here the highly cytotoxic NK cell line NK-92 seems to be an attractive alternative for use in adoptive immunotherapy, because it was shown to exhibit substantial antitumor activity against a wide range of malignancies in vitro as well as in xenografted SCID mice. NK-92 cells are characterized by an almost complete lack of killer cell immunglobulin-like receptors (KIRs) yet conserved ability to perforin and granzyme B-mediated cytolytic activity, which make them unique among the few established NK and T cell-like cell lines. NK-92 is the only natural killer cell line that has entered clinical trials. Here we discuss the current status of development of this cell line for adoptive immunotherapy (AIT) of malignancies and review our first clinical experience in patients with advanced cancer who have received repeated transfusions of irradiated NK-92 in a phase I/II trial. Also we discuss issues that address safety aspects of immunotherapy with clonal cell lines and describe further manipulations, which hold the potential of significantly improving the clinical outcome of AIT with NK-92.

Bacterial contamination of platelet concentrates: results of a prospective multicenter study comparing pooled whole blood-derived platelets and apheresis platelets.

BACKGROUND: The GERMS Group initiated a prospective multicenter study to assess prevalence and nature of bacterial contamination of pooled buffy‐coat platelet concentrates (PPCs) and apheresis platelet concentrates (APCs) by routine screening with a bacterial culture system.

Experience of German Red Cross blood donor services with nucleic acid testing: results of screening more than 30 million blood donations for human immunodeficiency virus‐1, hepatitis C virus, and hepatitis B virus

BACKGROUND: The risk of transfusion‐transmitted human immunodeficiency virus‐1 (HIV‐1), hepatitis C virus (HCV), and hepatitis B virus (HBV) infections is predominantly attributable to donations given during the early stage of infection when diagnostic tests may fail. In 1997, nucleic acid amplification technique (NAT)‐testing was introduced at the German Red Cross (GRC) blood donor services to reduce this diagnostic window period (WP).

NAT for HBV and anti-HBc testing increase blood safety

BACKGROUND: Routine HBV PCR screening of blood donations to our institutes was introduced in January 1997 to complete the NAT screening program for transfusion‐relevant viruses. Testing was successively extended to customer transfusion services with a total of 1,300,000 samples tested per year.

In vitro differentiation of human mesenchymal stem cells to epithelial lineage

Our study examined whether human bone marrow‐derived MSCs are able to differentiate, in vitro, into functional epithelial‐like cells. MSCs were isolated from the sternum of 8 patients with different hematological disorders. The surface phenotype of these cells was characterized.To induce epithelial differentiation, MSCs were cultured using Epidermal Growth Factor, Keratinocyte Growth Factor, Hepatocyte Growth Factor and Insulin‐like growth Factor‐II. Differentiated cells were further characterized both morphologically and functionally by their capacity to express markers with specificity for epithelial lineage. The expression of cytokeratin 19 was assessed by immunocytochemistry, and cytokeratin 18 was evaluated by quantitative RT‐PCR (Taq‐man). The data demonstrate that human MSCs isolated from human bone marrow can differentiate into epithelial‐like cells and may thus serve as a cell source for tissue engineering and cell therapy of epithelial tissue.