Patients with multiple myeloma (MM) are at increased risk of venous thromboembolism. Therefore, adequate laboratory control of hemostasis and subsequent adjustments of anticoagulant therapy are necessary. We studied hemostasis changes using thromboelastography (TEG), thrombin generation test (TGT) and thrombodynamics (TD) in primary MM patients (PMMpt, n=25) and patients in remission (RMMpt, n=34) during blood stem cell (BSC) mobilization. TD and TEG reveal hypercoagulability in PMMpt (*p<0.05) in relation to healthy volunteers. There was no difference in any of the tests between PMMpt and RMMpt. We detected no heparin effect in 22% of patients one day after the onset of the prophylactic heparin treatment (500 IU/h) during BSC mobilization; tests shifted toward the hypercoagulability in 75% of patients one day after cyclophosphamide (4 g/m2) chemotherapy. Global hemostasis tests were in good agreement with each other, revealed hypercoagulability and heparin "resistance" in patients with MM and may be useful for therapy individualization.

BackgroundHeparin therapy and prophylaxis may be accompanied by bleeding and thrombotic complications due to individual responses to treatment. Dosage control based on standard laboratory assays poorly reflects the effect of the therapy. The aim of our work was to compare the heparin sensitivity of new thrombodynamics (TD) assay with sensitivity of other standard and global coagulation tests available to date.Study population and methodsA total of 296 patients with high risk of venous thromboembolism (deep vein thrombosis (DVT), early postoperative period, hemoblastosis) were enrolled in the study. We used a case-crossover design to evaluate the sensitivity of new thrombodynamics assay (TD) to the hemostatic state before and after unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) therapy/prophylaxis and to compare it with the activated partial thromboplastin time (APTT), anti-Xa activity test, thrombin generation test (TGT) and thromboelastography (TEG). A receiver operating characteristic (ROC) curve analysis was used to evaluate changes before and after heparin prophylaxis and therapy. Blood was sampled before heparin injection, at the time of maximal blood heparin concentration and before the next injection.ResultsHypercoagulation before the start of heparin treatment was detected by TD, TGT and TEG but not by APTT. The area under the ROC curve (AUC) was maximal for TD and anti-Xa, intermediate for TGT and TEG and minimal for APTT.ConclusionsThese results indicate that TD has a high sensitivity to the effects of UFH and LMWH after both prophylactic and therapeutic regimes and may be used for heparin monitoring.

Fibrinolysis is a cascade of proteolytic reactions occurring in blood and soft tissues, which functions to disintegrate fibrin clots when they are no more needed. In order to elucidate its regulation in space and time, fibrinolysis was investigated using an in vitro reaction-diffusion experimental model of blood clot formation and dissolution. Clotting was activated by a surface with immobilized tissue factor in a thin layer of recalcified blood plasma supplemented with tissue plasminogen activator (TPA), urokinase plasminogen activator or streptokinase. Formation and dissolution of fibrin clot was monitored by videomicroscopy. Computer systems biology model of clot formation and lysis was developed for data analysis and experimental planning. Fibrin clot front propagated in space from tissue factor, followed by a front of clot dissolution propagating from the same source. Velocity of lysis front propagation linearly depended on the velocity clotting front propagation (correlation r2 = 0.91). Computer model revealed that fibrin formation was indeed the rate-limiting step in the fibrinolysis front propagation. The phenomenon of two fronts which switched the state of blood plasma from liquid to solid and then back to liquid did not depend on the fibrinolysis activator. Interestingly, TPA at high concentrations began to increase lysis onset time and to decrease lysis propagation velocity, presumably due to plasminogen depletion. Spatially non-uniform lysis occurred simultaneously with clot formation and detached the clot from the procoagulant surface. These patterns of spatial fibrinolysis provide insights into its regulation and might explain clinical phenomena associated with thrombolytic therapy.

Background: Patients (pts) with multiple myeloma (MM) have an increased risk of thrombosis. Previous studies have shown that 3.7–4.6% of pts undergoing peripheral blood stem cell (PBSC) mobilization developed thrombotic complications. Aims: The aim of the study was to investigate the blood coagulation status in MM pts during PBSC mobilization. Methods: 20 pts: 12 males, 8 females at the age of 27 – 64 years (median 53) were included in the study. After bortezomib-containig induction therapy 5 of them achieved CR, 11 – VGPR and 6 – PR. PBSC mobilization was performed by using cyclophosphamide (CY, 4g/m2) and granulocyte colony-stimulating factor (G-CSF, 5mcg/kg/day). A central venous catheter (CVC) was placed on the day before CY administration and heparin-sulphate continuous infusion (500 IU/hour) as thromboprophylaxis was started. Subcutaneous injections of G-CSF were administrated when WBS decreased less 1 x 109/l. The procedures of stem cell collection were carried out when the number PB CD 34+ cells exceeded 10 x 103/ml. Hemostasis analysis was performed 5 times, namely before (point 0) and 24 hours after heparin administration (point 1), the next day after CY infusion (point 2), before G-CSF administration (point 3) and on the day of PBSC collection (point 4). Condition of hemostasis was assessed by the results of activated partial thromboplasin time (APTT, normal rate: 25 – 38 sec) and thrombin generation test, namely by using endogenous thrombin potential (ETP, normal rate: 760 – 1450 nM*min) in every point. Hypercoagulation was considered in cases when APTT < 25 sec and ETP > 1450 nM*min. And hypocoagulation was estimated by data APTT > 38 sec and ETP < 760 nM*min. Time series analysis performed using TIMESERIES procedure in SAS 9.3 (SAS Institute Inc. Cary, NC). Significance level of alpha was set at 0.05. Results: Before heparin administration (point 0) APTT evaluation showed normal coagulation in 18 pts (90%) and hypocoagulation in 2 pts (mean 34 sec, 95% CI 32 – 36 sec) (Figure 1). ETP was normal in 14 pts and increased in 6 cases (mean 1441 nM*min, 95% CI 1304 – 1578 nM*min) (Figure 2). Pts in CR demonstrated no significant difference in coagulation status compared to pts in VGPR or PR. On the next day after CVC incorporation and starting thromboprophylaxis (point 1), APTT and ETP have significantly changed (p < 0,05) to hypocoagulability in response to heparin infusion: mean data APTT became 38 sec (95% CI 36 – 41 sec) and mean ETP - 938 nM*min (95% CI 801 – 1074 nM*min). On the next day after CY administration (point 2) APTT was statistically significantly decreased (p < 0.05) reaching 35 sec (95% CI 34 – 36 sec). ETP had also changed but to a lesser degree, the mean was 1079 nM*min (95% CI 929 – 1229 nM*min). Hemostasis at point 3 was characterized by APTT mean 38 sec (95% CI 37 – 40 sec) and ETP mean 1057 nM*min (95% CI 911 – 1203 nM * min). On the day of PBSC collection mean values of measured parameters have not changed as compared to the previous point: APTT was 40 sec (95% CI 37 – 43 sec) and ETP was 1046 nM*min (95% CI 916 – 1176 nM*min) (Table 1). Thrombotic events were diagnosed in 2 cases of the total of 20 pts. There were two females, 54 and 56 years, both in CR MM. The first pt developed CVC-associated thrombosis. She had additional risk factors such as obesity (BMI – 44) and heterozygous MTHFR polymorphism. The second pt demonstrated acute violation of cerebral circulation which arose due to occlusion of the right internal carotid artery. She was a hard smoker and heterozygous FV Leiden polymorphism. Having confirmed thrombotic complications, the dose of heparin had been increased. Besides, folic acid was administrated for the first pt and combination of aspirin and pentoxifilline for the second. PBSC collection was successful for both pts. Summary: The results of our study identify latent hypercoagulation status in 30% pts of confirmed by elevated ETP. Those changes were registered despite of achievement CR or PR MM. Thrombotic complications have developed in 10% from our group. Notably, one should consider individual risk factors for each pt. Figure 1 Figure 1. Figure 2 Figure 2. Table 1. Measurements data of parameters of hemostasis Measuring point Mean APTT (95% CI) Mean ETP (95% CI) 0 33.6 (31.2-35.9)* 1441.1 (1304.3-1577.9)* 1 38.6 (35.7-41.6)* 937.6 (801.3-1074.0)* 2 35.2 (33.9-36.5)* 1079.0 (928.8-1229.2)* 3 38.1 (36.7-39.5) 1057.2 (911.4-1203.1) 4 39.6 (36.5-42.8) 1046.2 (916.0-1176.3) * Means in the same column are significantly different (P<0.05) Disclosures No relevant conflicts of interest to declare.