title: Effects of hemoglobin vesicles on resting and agonist-stimulated human platelets in vitro.
abstract: Hemoglobin vesicles (HbV) are artificial oxygen carriers that encapsulate a concentrated hemoglobin (Hb) solution with a phospholipid bilayer membrane. The oxygen transporting ability of HbV in vivo has been demonstrated by the transfusion of HbV into hemorrhagic shock rodent models. However, the compatibility of HbV with human blood cells must be evaluated. Preincubation of platelets with concentrations of 20% or 40% HbV had no effect on the binding of PAC-1, a monoclonal antibody that detects activation-dependent conformational changes in alphaIIbbeta3 on platelets, or the surface expression of CD62P in whole blood. ADP-induced increases in PAC-1 binding were significantly enhanced by exposing the platelets to concentrations of either 20% or 40% HbV, whereas the ADP-induced increases in CD62P expression were not affected by HbV treatment at either concentration. Preincubation of platelet-rich plasma (PRP) with HbV minimally reduced the spontaneous release of TXB2 and RANTES, but did not significantly affect the formation of TXB2 or the release of RANTES and beta-TG in platelets stimulated with ADP. Similarly, preincubation of PRP with HbV minimally reduced the spontaneous release of RANTES but did not significantly affect the formation of TXB2 or the release of RANTES and beta-TG in platelets stimulated with collagen, although collagen-induced serotonin release tended to decrease with HbV pretreatment. These data suggest that the exposure of human platelets to high concentrations of HbV (up to 40%) in vitro did not cause platelet activation and did not adversely affect the formation and secretion of prothrombotic substances or proinflammatory substances triggered by platelet agonists, although one of the earliest events in ADP-induced platelet activation was slightly potentiated by HbV pretreatment at the doses tested. Taken together, these results imply that HbV, at concentrations of up to 40%, do not have any aberrant interactions with either unstimulated or agonist-induced platelets.
authors.affiliation: Japanese Red Cross, Hokkaido Red Cross Blood Center, Sapporo, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Wakamoto
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Fujihara
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Miki
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Azuma
authors.forename: Hisami
authors.initials: H
authors.lastname: Ikeda
authors.forename: Shinji
authors.initials: S
authors.lastname: Takeoka
authors.forename: Eishun
authors.initials: E
authors.lastname: Tsuchida
mesh_terms: D015415:Biomarkers / Q000032:analysis; D001792:Blood Platelets / Q000187:drug effects*; D018946:Chemokine CCL5 / Q000032:analysis; D016503:Drug Delivery Systems / Q000009:adverse effects; D006454:Hemoglobins / Q000008:administration & dosage*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced; D008081:Liposomes / Q000009:adverse effects / Q000627:therapeutic use*; D019007:P-Selectin / Q000032:analysis; D010743:Phospholipids / Q000009:adverse effects / Q000627:therapeutic use; D015539:Platelet Activation / Q000187:drug effects; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000737:chemistry; D019851:Thrombophilia / Q000139:chemically induced; D013929:Thromboxane B2 / Q000032:analysis
chemical_list: D015415:Biomarkers; D018946:Chemokine CCL5; D006454:Hemoglobins; D008081:Liposomes; D019007:P-Selectin; D010743:Phospholipids; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D013929:Thromboxane B2