Spray-dried plasma deficient in high-molecular-weight multimers of von Willebrand factor retains hemostatic properties.

BACKGROUND: Dried plasmas can overcome logistical barriers that prevent fresh frozen plasma (FFP) usage in acute resuscitation, but processing of these products can detrimentally alter the composition. Spray-dried plasma (SpDP) from single units is deficient in high-molecular-weight multimers of von Willebrand factor (vWF), a critical facilitator of platelet adhesion and thrombus formation. We hypothesized that converting high-molecular-weight multimers to smaller-molecular-weight multimers would retain vWF's capacity to mediate platelet adhesion. STUDY DESIGN AND METHODS: SpDP obtained from untreated FFP was reconstituted with glycine-hydrochloric acid (HCl) and glycine (20 mM:50 mM) or pretreated with glycine-HCl (20 mM) or glycine-glycine-HCl (20 mM:50 mM) and reconstituted with water. In vitro hemostatic potential of SpDPs versus FFP or FFP spiked with 70 mM of glycine was evaluated, leading to a more detailed in vitro study of glycine-HCl-glycine (20 mM:50 mM) pretreated SpDP. Plasmas were combined with RBCs and platelets to observe global coagulation response. RESULTS: While vWF-ristocetin cofactor activity is significantly decreased (-41.13%; p < .0001) in SpDP, a model of vWF-mediated platelet adhesion to collagen under flow showed enhanced function (+13%; p < .01). Fewer microparticles, particularly of platelet origin, were observed in SpDP versus FFP (p < .0001). Small but significant differences in thromboelastography results were observed, although SpDP and FFP were within normal ranges. CONCLUSION: Comparable coagulability was observed in FFP and SpDP. The apparent paradox between vWF-ristocetin cofactor assay and vWF-mediated platelet adhesion may be explained by the increase in smaller multimers of vWF in SpDP, producing different outcomes in these assays.

Evaluation of a lyophilized platelet-derived hemostatic product.

BACKGROUND: Current limitations of platelet shelf life to 5 days have led to an increasingly greater demand for hemostatic agents with greater longevity. The objective of this study was to evaluate the function of a lyophilized platelet-derived hemostatic product (thrombosome [TS]) as a potential alternative to fresh platelets. METHODS: Platelets were collected from whole blood from healthy donors. TSs were reconstituted with water and added to various configurations of reassembled whole blood (platelets, plasma, and RBCs); measures included rotational thromboelastometry (ROTEM), optical aggregometry, mitochondrial function, calibrated automated thrombogram, collagen adhesion under flow (shear flow assay), and flow cytometry. RESULTS: In ROTEM, no differences were observed between maximum clot formation values for contact pathway activation thromboelastometry tests with TSs or platelet samples. Significantly decreased aggregation was observed in the TSs versus platelets (p < 0.001 for all agonists). Flow cytometry measures demonstrated significant decreases in glycoprotein Ib expression and increases in phosphatidylserine expression in the TS group (p < 0.01). The calibrated automated thrombogram assay was suggestive (lag time and peak thrombin) that the TSs might have some thrombogenic properties. Measurements of mitochondrial function revealed that TSs had no functional mitochondria. CONCLUSION: In this study, TSs were shown to have nonfunctional mitochondria. ROTEM measures revealed that the TSs had no impact on clot strength. Likewise, compared to platelets, the TSs displayed minimal aggregation, had significantly more phosphatidylserine (measure of activation status), but had the ability to adhere to a collagen surface under flow conditions and contribute to clot formation and induced greater thrombin generation.

Freeze-dried plasma mitigates the dilution effects of a hemoglobin-based oxygen carrier (HBOC-201) in a model of resuscitation for hemorrhage and hemodilution.

BACKGROUND: Hemoglobin-based oxygen carriers (HBOCs) have proven useful for supplementing oxygen delivery when red cells are unavailable; however, HBOCs do not promote hemostasis. The need for prehospital bridges to blood transfusion informed this study which sought to determine the impact of HBOCs on coagulation, with or without cotransfusion of freeze-dried plasma (FDP). METHODS: Treatment was simulated in vitro by replacing whole blood volume (or whole blood prediluted with 25% plasmalyte A as a hemodilution model) with HBOC-201, FDP, or both at ratios of 10% to 50% of original volume. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, complete blood count, viscosity, thromboelastography (TEG), and platelet adhesion to collagen under flow were evaluated. Subsequently, tissue plasminogen activator was added to model hemorrhagic shock effects on fibrinolysis. RESULTS: Substituting blood with HBOC resulted in dose-dependent decreases in fibrinogen and cells, which lengthened PT (+61% at highest dose) and aPTT (+40% at highest dose) and produced TEG parameters consistent with dilutional coagulopathy. While substituting blood with FDP decreased cell counts accordingly, fibrinogen, PT, aPTT, and TEG parameters were not statistically changed. When HBOC and FDP were combined 1:1 for volume replacement, observed HBOC-only detriments were mitigated: PT and aPTT were increased by 17% and 11%, respectively, at the highest doses. In prediluted samples, similar trends were seen with exacerbated differences. Platelet adhesion to collagen was directly affected by hematocrit. Samples containing both HBOC and tissue plasminogen activator were highly susceptible to fibrinolysis. CONCLUSION: A dose equivalent to 1 unit to 2 units each of HBOC-201 and FDP had a modest impact on functional coagulation measures and is reasonable to consider for clinical study as a part of early transfusion intervention. Higher doses may impart hemodilution risks similar to resuscitation with crystalloid or other colloids in coagulation-compromised patients. Further study of HBOC effects on fibrinolysis is also indicated. STUDY TYPE: In vitro laboratory study.

Evaluation of adenosine, lidocaine, and magnesium for enhancement of platelet function during storage.

BACKGROUND: The combination of adenosine, lidocaine, and magnesium (Mg2+) (ALM) has demonstrated cardioprotective and resuscitative properties in models of cardiac arrest and hemorrhagic shock that are linked to reduction of metabolic demand. Platelets play a key role in resuscitation strategies for ATC but suffer from loss of function following storage in part owing to mitochondrial exhaustion. This study evaluates whether ALM also demonstrates protective properties in stored platelet preparations. METHODS: Platelets were tested at (baseline, Day 5, Day 10, and Day 15) at 22°C (room temperature) or 4°C in 100% plasma and platelet additive solution. Adenosine, lidocaine, and magnesium treatment or its individual components (A, L, M, or combinations) were added directly to the minibags at baseline for storage. Measurements consisted of blood gas and chemistry analyses, thromboelastography, impedance aggregometry, and flow cytometry. RESULTS: Blood gas and cell analysis, as well as flow cytometry measures, demonstrated only differences between temperature groups starting at Day 5 (p < 0.05) and no differences between treatment groups. Aggregation response to collagen (A only, M only, and ALM high dose) and thrombin receptor activation peptide (A + M, and ALM high dose) was significantly greater at Day 5 compared to respective 4°C (100% plasma) controls (p < 0.05). Thromboelastography analysis revealed significant preservation of all measures (reaction time, maximum amplitude, and angle) at Day 15 for 4°C-stored samples in 100% plasma in both controls (no ALM) and ALM treatment compared to room temperature (p < 0.05); no differences were observed between the ALM and control groups. CONCLUSIONS: The mechanism of ALM's protective effect remains unclear; key cellular functions may be required to provide protection. In this study, improvements in collagen and thrombin receptor activation peptide aggregation were seen when compared to 4°C-stored plasma samples although no improvements were seen when compared to 4°C-stored platelet additive solution platelets. LEVEL OF EVIDENCE: Therapeutic/care management, level II.