Alterations of hemostatic parameters in the early development of allogeneic hematopoietic stem cell transplantation-related complications

Thrombotic events are common and potentially fatal complications in patients receiving hematopoietic stem cell transplantation (HSCT). Early diagnosis is crucial but remains controversial. In this study, we investigated the early alterations of hemostatic parameters in allogeneic HSCT recipients and determined their potential diagnostic values in transplantation-related thrombotic complications and other post-HSCT events. Results from 107 patients with allogeneic HSCT showed higher levels of plasma plasminogen activator inhibitor-1 (PAI-1), fibrinogen, and tissue-plasminogen activator (t-PA) and a lower level of plasma protein C after transplantation. No change was found for prothrombin time, antithrombin III, d-dimer, and activated partial thromboplastin time following HSCT. Transplantation-related complications (TRCs) in HSCT patients were defined as thrombotic (n = 8), acute graft-versus-host disease (aGVHD, n = 45), and infectious (n = 38). All patients with TRCs, especially the patients with thrombotic complications, presented significant increases in the mean and maximum levels of PAI-1 during the observation period. Similarly, a high maximum t-PA level was found in the thrombotic group. In contrast, apparent lower levels of mean and minimum protein C were observed in the TRC patients, especially in the aGVHD group. Therefore, the hemostatic imbalance in the early phase of HSCT, reflecting prothrombotic state and endothelial injury due to the conditioning therapy or TRCs, might be useful in the differential diagnosis of the thrombotic complication from other TRCs

Revised diagnosis and severity criteria for sinusoidal obstruction syndrome/veno-occlusive disease in adult patients : a new classification from the European Society for Blood and Marrow Transplantation

Sinusoidal obstruction syndrome, also known as veno-occlusive disease (SOS/VOD), is a potentially life threatening complication that can develop after hematopoietic cell transplantation. Although SOS/VOD progressively resolves within a few weeks in most patients, the most severe forms result in multi-organ dysfunction and are associated with a high mortality rate (480%). Therefore, careful attention must be paid to allow an early detection of SOS/VOD, particularly as drugs have now proven to be effective and licensed for its treatment. Unfortunately, current criteria lack sensitivity and specificity, making early identification and severity assessment of SOS/VOD difficult. The aim of this work is to propose a new definition for diagnosis, and a severity-grading system for SOS/VOD in adult patients, on behalf of the European Society for Blood and Marrow Transplantation.Peer reviewe

The factor V HR2 haplotype and the risk of venous thrombosis: a meta-analysis

Background and Objectives: A complex haplotype of factor V gene (FV HR2) has been recently reported. FVHR2 possesses decreased co-factor activity to APC in the degradation of FVIIIa, and an increased ratio of the more procoagulant isoform FV1 compared to FV2. Contrasting results on whether the haplotype induces a significant risk of venous thromboembolism (VTE) have been reported. Design and Methods: It has been surmised that FVHR2 enhances the risk of VTE carried by FV Leiden. We carried out a meta-analysis of the reported studies on the role of HR2 haplotype in inducing a risk of VTE and the influence of the polymorphism on the risk carried by patients with FV Leiden. Results: Eight studies were analyzed for the estimation of the risk of VTE. A total of 338 out of 2,696 cases (12.5%; range 7.8 to 18.5%) and 885 out of 7,710 controls (11.5%; range 8.1 to 12.1%) were HR2 positive. The odds ratio for VTE associated with HR2 haplotype was not statistically significant (OR 1.15; 95% C.I. 0.98-1.36). The OR for the association between FV Leiden and FV HR2 and the risk of VTE in cases and controls was largely heterogeneous as to OR and 95% C.I. and no statistical significant difference was observed. Interpretation and Conclusions: The data from the present meta-analysis suggests that FVHR2 could be a very mild prothrombotic factor. The association of FV Leiden and HR2 haplotype seems not to increase significantly the risk of VTE carried by isolated heterozygosity for FV Leiden. However, well-designed clinical studies are needed to clarify this issue definitely

RESISTANCE TO ACTIVATED PROTEIN-C IN 9 THROMBOPHILIC FAMILIES - INTERFERENCE IN A PROTEIN-S FUNCTIONAL ASSAY

Nine thrombophilic patients who had had previous diagnoses of functional protein S deficiency were reinvestigated. The functional protein S assays gave dose-response curves that were not parallel to those of the reference plasma. The same pattern was true for approximately half of the first-degree relatives of the propositi. When protein S was extracted from the plasma of the patients by immunoabsorption, it had a normal ratio of functional activity to immunologic concentration. Restriction fragment length polymorphism analysis, informative in one family, showed no linkage between the protein S gene marker and the abnormal behavior of the protein S functional assay. All the propositi and 23/36 first-degree relatives were resistant to the prolongation of activated partial thromboplastin time induced by activated protein C. Furthermore, there was striking concordance in all patients and relatives between the abnormal pattern of the protein S functional assay and resistance to activated protein C. We conclude that a plasma-based functional protein S assay is sensitive to activated protein C resistance and this may lead to spuriously low results in the assay. In agreement with the results of others, this study indicates that resistance to activated protein C is a frequent hemostatic defect in selected thrombophilic population

A factor V genetic component differing from factor V R506Q contributes to the activated protein C resistance phenotype

Factor V gene polymorphisms were investigated to detect components that may contribute to the activated protein C (APC) resistance phenotype in patients with venous thromboembolism. A specific factor V gene haplotype (HR2) was defined by six polymorphisms and its frequency was found to be similar in normal subjects coming from Italy (0.08), India (0.1), and Somalia (0.08), indicating that it was originated by ancestral mutational events. The relationship between the distribution of normalized APC ratios obtained with the functional assay and haplotype frequency was analyzed in patients heterozygous for factor V R506Q (factor V Leiden). The HR2 haplotype was significantly more frequent in patients with ratios below the 15th percentile than in those with higher ratios or in normal controls. Moreover, the study of 10 patients with APC resistance in the absence of the factor V R506Q mutation showed a 50-fold higher frequency of HR2 homozygotes. The HR2 haplotype was associated with significantly lower APC ratios both in patients with venous thromboembolism and in age- and sex-matched controls. However, the two groups showed similar HR2 haplotype frequencies. Plasma mixing experiments showed that an artificially created double heterozygote for the factor V R506Q mutation and the HR2 haplotype had an APC ratio lower than that expected for a simple R506Q heterozygote. Time-course experiments evaluating the decay of factor V in plasma showed the normal stability of the molecule encoded by the factor V gene marked by the HR2 haplotype, which ruled out the presence of a pseudo-homozygous APC resistance mechanism. Our results provide new insights into the presence of factor V genetic components other than the factor V R506Q that are able to contribute to the APC resistance phenotype in patients with venous thromboembolis

A proteomic analysis of changes in prothrombin and plasma proteins associated with the G20210A mutation.

The G-->A mutation at position 20210 of the prothrombin gene, localized in the 3'-polyadenylation untranslated region of the mRNA, is a recognized genetic risk factor for venous thromboembolism. The mechanism by which this base change confers an increased risk of thrombosis compared to noncarriers is undefined. Studies on the mRNA suggest enhanced cleavage site recognition and a change in the location of the 3'-cleavage/polyadenylation reaction, but no defined model has been proposed. The present study, based on proteomic investigation by two-dimensional gel electrophoresis and electrospray ionization (ESI) tandem mass spectrometry (MS/MS) protein identification, suggests that the G20210A mutation is associated with increased glycosylation of prothrombin, which confers greater stability to the protein. Additionally, proteomic investigation of pooled plasma showed that expression levels of six spots, three of them identified by ESI MS/MS, were altered in subjects carrying the mutation, suggesting a possible cooperative effect in the thrombotic risk increment induced by the mutation