Doug Bolgiano

Viability and function of 8-day-stored apheresis platelets.

BACKGROUND: Methods of bacterial detection and pathogen inactivation of platelets (PLTs) may allow extended storage of PLTs as long as PLT quality is maintained.

Signal Transducer and Activator of Transcription 3 (STAT3) Regulates Collagen-Induced Platelet Aggregation Independently of Its Transcription Factor Activity

Background— Platelet hyperactivity induced by inflammation is a known risk factor for atherosclerosis and thrombosis, but its underlying mechanisms remain poorly understood. Methods and Results— The signal transducer and activator of transcription 3 (STAT3) was activated in collagen-stimulated platelets. Activated STAT3 served as a protein scaffold to facilitate the catalytic interaction between the kinase Syk (spleen tyrosine kinase) and the substrate PLC&ggr;2 to enhance collagen-induced calcium mobilization and platelet activation. The same interaction of STAT3 with Syk and PLC&ggr;2 was detected in HEK293 cells transfected with cDNAs for Syk and PLC&ggr;2 and stimulated with interleukin-6. Pharmacological inhibition of STAT3 blocked ≈50% of collagen- and a collagen-related peptide–induced but not thrombin receptor–activating peptide– or ADP-induced aggregation and ≈80% of thrombus formation of human platelets on a collagen matrix. This in vitro phenotype was reproduced in mice infused with STAT3 inhibitors and mice with platelet-specific STAT3 deficiency. By forming a complex with its soluble receptor, the proinflammatory cytokine interleukin-6 enhanced the collagen-induced STAT3 activation in human platelets. Conclusions— These data demonstrate a nontranscriptional activity of STAT3 that facilitates a crosstalk between proinflammatory cytokine and hemostasis/thrombosis signals in platelets. This crosstalk may be responsible for the platelet hyperactivity found in conditions of inflammation.Background —Platelet hyperactivity induced by inflammation is a known risk factor for atherosclerosis and thrombosis, but its underlying mechanisms remain poorly understood. Methods and Results —The signal transducers and activators of transcription 3 (STAT3) was activated in collagen-stimulated platelets. Activated STAT3 served as a protein scaffold to facilitate the catalytic interaction between the kinase Syk and the substrate PLCγ2 to enhance collagen-induced calcium mobilization and platelet activation. The same interaction of STAT3 with Syk and PLCγ2 was also detected in HEK293 cells transfected with cDNAs for Syk and PLCγ2, and stimulated with interleukin-6 (IL-6). Pharmacological inhibition of STAT3 blocked ~50% of collagen- and a collagen-related peptide-, but not TRAP- or ADP-induced aggregation and ~80% of thrombus formation of human platelets on a collagen matrix. This in vitro phenotype was reproduced in mice infused with STAT3 inhibitors and mice with platelet specific STAT3 deficiency. By forming a complex with its soluble receptor, the proinflammatory cytokine IL-6 enhanced the collagen-induced STAT3 activation in human platelets. Conclusions —These data demonstrate a non-transcriptional activity of STAT3 that facilitates a crosstalk between proinflammatory cytokine and hemostasis/thrombosis signals in platelets. This crosstalk may be responsible for platelet hyperactivity found in conditions of inflammation.

Review of In Vivo Studies of Dimethyl Sulfoxide Cryopreserved Platelets

A literature review was conducted to assess the efficacy and safety of dimethyl sulfoxide (DMSO) cryopreserved platelets for potential military use. In vivo DMSO cryopreserved platelet studies published between 1972 and June of 2013 were reviewed. Assessed were the methods of cryopreservation, posttransfusion platelet responses, prevention or control of bleeding, and adverse events. Using the Department of Defenses preferred 6% DMSO cryopreservation method with centrifugation to remove the DMSO plasma before freezing at -65°C and no postthaw wash, mean radiolabeled platelet recoveries in 32 normal subjects were 33% ± 10% (52% ± 12% of the same subjects fresh platelet recoveries), and survivals were 7.5 ± 1.2 days (89% ± 15% of fresh platelet survivals). Using a variety of methods to freeze autologous platelets from 178 normal subjects, mean radiolabeled platelet recoveries were consistently 39% ± 9%, and survivals, 7.4 ± 1.4 days. More than 3000 cryopreserved platelet transfusions were given to 1334 patients. There were 19 hematology/oncology patient studies, and, in 9, mean 1-hour corrected count increments were 11 100 ± 3600 (range, 5700-15 800) after cryopreserved autologous platelet transfusions. In 5 studies, bleeding times improved after transfusion; in 3, there was either no improvement or a variable response. In 4 studies, there was immediate cessation of bleeding after transfusion; in 3 studies, patients being supported only with cryopreserved platelets had no bleeding. In 1 cardiopulmonary bypass study, cryopreserved platelets resulted in significantly less bleeding vs standard platelets. In 3 trauma studies, cryopreserved platelets were hemostatically effective. No significant adverse events were reported in any study. In summary, cryopreserved platelets have platelet recoveries that are about half of fresh platelets, but survivals are only minimally reduced. The platelets appear hemostatically effective and have no significant adverse events.

Factor VIII mutation and desmopressin-responsiveness in 62 patients with mild haemophilia A

Utilization of the synthetic vasopressin analogue (1‐deamino‐8‐D‐arginine‐vasopressin, DDAVP) in treatment of mild haemophilia A (MHA, specific clotting factor VIII activity level 0.05–0.4 IU mL−1) is convenient and effective for many but not all patients. Genetic testing for patients with MHA is increasingly recognized as providing valuable information for patient care beyond informing reproductive decisions, and as more patients are genotyped, mutation data can be utilized to individualize treatment decisions. To determine if genetic information informs response to DDAVP, a retrospective chart review was performed under Institutional Review Board approval to extract patient data with MHA, genetic mutation results, and response to DDAVP challenge. 62 patients met inclusion criteria. Complete responses (C) presented in mean value IU mL−1 (range), were recorded for 32 of 62(52%) subjects: pre 0.19(0.04–0.45) and post 0.78(0.5–1.95); partial responses (P) were recorded for 15 of 62(24%) subjects: pre 0.1(0.06–0.15) and post 0.4(0.3–0.47); responses that were not clinically significant (N) were recorded for 15 of 62(24%) subjects: pre 0.17(0.02–0.34) and post 0.25(0.03–0.44). Subjects (related and unrelated) with the same mutation showed a trend towards a similar response to DDAVP. Eight genotypes were common to two or more subjects (n = 26). Two genotypes were concordant in all subjects [p.Ser2192Ile n = 3(C), p.Ala2220Pro n = 2(P)]. Of mutations in the C1 or C2 domains, 13 of 15(87%) subjects responded to DDAVP [C = 9(60%); P = 4(27%); n = 2(13%)]. Baseline FVIII:C did not predict magnitude of response to DDAVP. Genetic mutation results can assist with predicting DDAVP responsiveness, but baseline FVIII:C may not.

EXTENDED STORAGE OF PLATELET-RICH PLASMA PREPARED PLATELET CONCENTRATES IN PLASMA OR PLASMALYTE

BACKGROUND: Using bacterial detection or pathogen reduction, extended platelet (PLT) storage may be licensed if PLT viability is maintained. The Food and Drug Administration (FDA)s poststorage PLT acceptance guidelines are that autologous stored PLT recoveries and survivals should be 66 and 58% or greater, respectively, of each donors fresh PLT data.

Extended storage of autologous apheresis platelets in plasma.

The purpose of our studies was to determine the effects of extended platelet storage on poststorage platelet viability.

Suppression of FVIII Inhibitor Formation in Hemophilic Mice by Delivery of Transgene Modified Apoptotic Fibroblasts

The development of inhibitory antibodies to factor VIII (FVIII) is currently the most significant complication of FVIII replacement therapy in the management of patients with severe hemophilia A. Immune tolerance protocols for the eradication of inhibitors require daily delivery of intravenous FVIII for at least 6 months and are unsuccessful in 20-40% of treated patients. We hypothesize that tolerance can be induced more efficiently and reliably by delivery of FVIII antigen within autologous apoptotic cells (ACs). In this study, we demonstrated suppression of the T cell and inhibitor responses to FVIII by infusion of FVIII expression vector modified apoptotic syngeneic fibroblasts in both naive and preimmunized hemophilia A mice. ACs without FVIII antigen exerted modest generalized immune suppression mediated by anti-inflammatory signals. However, FVIII expressing apoptotic syngeneic fibroblasts produced much stronger antigen-specific immune suppression. Mice treated with these fibroblasts generated CD4+ T cells that suppressed the immune response to FVIII after adoptive transfer into naive recipients and antigen-specific CD4+CD25+ regulatory T cells (Tregs) that inhibited the proliferation of FVIII responsive effector T cells in vitro. These preclinical results demonstrate the potential for using FVIII vector modified autologous ACs to treat high-titer inhibitors in patients with hemophilia A.

Suppression of the Immune Response to FVIII in Hemophilia A Mice by Transgene Modified Tolerogenic Dendritic Cells

Current methods for eradicating clinically significant inhibitory antibodies to human factor VIII (hFVIII) in patients with hemophilia A rely on repeated delivery of high doses of factor concentrates for a minimum of many months. We hypothesize that tolerance can be induced more efficiently and reliably through hFVIII antigen presentation by tolerogenic dendritic cells (tDCs). In this study, we generated tDCs from hemophilia A mice and modified them with a foamy virus vector expressing a bioengineered hFVIII transgene. Naive and preimmunized mice infused with hFVIII expressing tDCs showed suppression of the T cell and inhibitor responses to recombinant hFVIII (rhFVIII). Treatment with hFVIII expressing tDCs was also associated with a higher percentage of splenocytes demonstrating a regulatory T cell phenotype in immunized mice. Furthermore, CD4(+) T cells harvested from recipients of hFVIII expression vector-modified tDCs were able to mediate antigen-specific immune suppression in naive secondary recipients. We also demonstrated a trend for improved suppression of inhibitor formation by coexpressing interleukin-10 (IL-10) and hFVIII from a bicistronic vector. These preclinical results demonstrate the potential for employing vector modified ex vivo generated tDCs to treat high titer inhibitors in patients with hemophilia A.

Extended storage of buffy coat platelet concentrates in plasma or a platelet additive solution

Platelet (PLT) concentrates (PCs) prepared from whole blood in the United States are made using the PLT‐rich plasma method. The PCs must be made within 8 hours of blood collection and stored for only 5 days. In Europe and Canada, PCs are made using the buffy coat (BC) method from whole blood held overnight at 22°C and storage times may be up to 7 days. Our studies were designed to determine how long BC PLTs can be stored in plasma or Plasmalyte while meeting the FDAs poststorage viability criteria.

Quantitative influence of ABO blood groups on factor VIII and its ratio to von willebrand factor, novel observations from an ARIC study of 11,673 subjects

ABO blood groups are known to influence the plasma level of von Willebrand factor (VWF), but little is known about the relationship between ABO and coagulation factor VIII (FVIII). We analyzed the influence of ABO genotypes on VWF antigen, FVIII activity, and their quantitative relationship in 11,673 participants in the Atherosclerosis Risk in Communities (ARIC) study. VWF, FVIII, and FVIII/VWF levels varied significantly among O, A (A1 and A2), B and AB subjects, and the extent of which varied between Americans of European (EA) and African (AA) descent. We validated a strong influence of ABO blood type on VWF levels (15.2%), but also detected a direct ABO influence on FVIII activity (0.6%) and FVIII/VWF ratio (3.8%) after adjustment for VWF. We determined that FVIII activity changed 0.54% for every 1% change in VWF antigen level. This VWF-FVIII relationship differed between subjects with O and B blood types in EA, AA, and in male, but not female subjects. Variations in FVIII activity were primarily detected at low VWF levels. These new quantitative influences on VWF, FVIII and the FVIII/VWF ratio help understand how ABO genotypes differentially influence VWF, FVIII and their ratio, particularly in racial and gender specific manners.