Genetic mechanisms of age regulation of blood coagulation: factor IX model

Understanding Solid-Based Platelet-Rich Fibrin Matrices in Oral and Maxillofacial Surgery: An Integrative Review of the Critical Protocol Factors and Their Influence on the Final Product

Platelet-rich fibrin (PRF) is a second-generation platelet concentrate whose use in clinical practice has been widely disseminated. This has led to the development of several commercial protocols, creating great confusion as to the terminology and implications of each of them. This integrative review aims to identify the critical factors of each of the phases of the solid-based PRF matrix protocol and their possible influence on their macro- and microscopic characteristics. An electronic search of the MEDLINE database (via PubMed), Web of Science, Scopus, LILACS, and OpenGrey was carried out. The search was temporarily restricted from 2001 to 2022. After searching, 43 studies were included that met the established criteria. There were numerous factors to consider in the PRF protocol, such as the material of the blood collection tubes, the duration of phlebotomy, the parameters related to blood centrifugation, the time from centrifugation to dehydration of the fibrin clots and their dehydration into membranes, as well as the time to clinical use. These factors influenced the macro- and microscopic characteristics of the PRF and its physical properties, so knowledge of these factors allows for the production of optimised PRF by combining the protocols and materials.

Bleeding phenotype in nonsevere hemophilia by International Society on Thrombosis and Haemostasis bleeding assessment tool, bleeding frequency, and the joint status

Background

Although the phenotype of severe hemophilia has been well studied, there are still knowledge gaps in nonsevere hemophilia.

Objectives

The objective of this study was to characterize the clinical bleeding phenotype in nonsevere hemophilia and its association with different factor VIII/IX assessments.

Methods

This was a cross-sectional, multicenter study to investigate the bleeding phenotype in adults with nonsevere hemophilia by the number of bleeding and joint bleeding in the past 5 years, a joint score, and the International Society on Thrombosis and Haemostasis bleeding assessment tool (ISTH-BAT). Factor levels were analyzed by 1-stage (lowest in history and at study inclusion) and chromogenic assay (at study inclusion). Patients were enrolled between March 2015 and May 2019.

Results

Of the 111 patients (86 with mild and 25 with moderate hemophilia), 57 patients (54.8%) reported any bleeding and 24 (23.1%) any joint bleeding in the past 5 years. A joint score ≥1 was found in 44 patients (41.9%), an ISTH-BAT ≥4 in 100 patients (90.1%), and an ISTH-BAT joint item ≥1 in 50 patients (45.0%). Within the ISTH-BAT, muscle and joint bleeds showed the largest difference between mild and moderate hemophilia. The lowest factor VIII/IX level in patients' history was best associated with bleeding outcomes. Factor was inversely associated with joint bleeds (incidence rate ratio 0.88; 95% CI, 0.79-0.98), joint score, and ISTH-BAT (odds ratios from proportional odds ordinal logistic regression 0.92; 95% CI, 0.87-0.97; and 0.89; 95% CI, 0.86-0.93, respectively).

Conclusion

The occurrence of joint bleeding differentiated persons with mild and moderate hemophilia. The ISTH-BAT and lowest factor in patients' history provided valuable information of the bleeding phenotype in nonsevere hemophilia.

Genome-Wide DNA Methylation Profile Indicates Potential Epigenetic Regulation of Aging in the Rhesus Macaque Thymus

We analyzed whole-genome bisulfite sequencing (WGBS) and RNA sequencing data of two young (1 year old) and two adult (9 years old) rhesus macaques (Macaca mulatta) to characterize the genomic DNA methylation profile of the thymus and explore the molecular mechanism of age-related changes in the thymus. Combining the two-omics data, we identified correlations between DNA methylation and gene expression and found that DNA methylation played an essential role in the functional changes of the aging thymus, especially in immunity and coagulation. The hypomethylation levels of C3 and C5AR2 and the hypermethylation level of C7 may lead to the high expressions of these genes in adult rhesus macaque thymuses, thus activating the classical complement pathway and the alternative pathway and enhancing their innate immune function. Adult thymuses had an enhanced coagulation pathway, which may have resulted from the hypomethylation and upregulated expressions of seven coagulation-promoting factor genes (F13A1, CLEC4D, CLEC4E, FCN3, PDGFRA, FGF2 and FGF7) and the hypomethylation and low expression of CPB2 to inhibit the degradation of blood clots. Furthermore, the functional decline in differentiation, activation and maturation of T cells in adult thymuses was also closely related to the changes in methylation levels and gene expression levels of T cell development genes (CD3G, GAD2, ADAMDEC1 and LCK) and the thymogenic hormone gene TMPO. A comparison of the age-related methylated genes among four mammal species revealed that most of the epigenetic clocks were species-specific. Furthermore, based on the genomic landscape of allele-specific DNA methylation, we identified several age-related clustered sequence-dependent allele-specific DNA methylated (cS-ASM) genes. Overall, these DNA methylation patterns may also help to assist with understanding the mechanisms of the aging thymus with the epigenome.

Identification of zebrafish ortholog for human coagulation factor IX and its age-dependent expression

BACKGROUND

Coagulation factor IX (FIX) is a serine protease zymogen involved in the intrinsic blood coagulation pathway, and its deficiency causes hemophilia B. Zebrafish has three f9 genes, and the ortholog to human F9 is unknown.

OBJECTIVE

To identify the zebrafish ortholog to F9 using sequence analysis and piggyback knockdown technology.

METHODS

Gene and protein sequence analysis for three f9 genes, f9a, f9b, and f9l, present in the zebrafish genome was performed. In vivo and in vitro assays after knockdown of each gene and immunodepletion using specific antibodies were carried out.

RESULTS

Sequence analysis revealed that f9a and f9b are similar to human F9, whereas f9l is similar to human F10. RNA analysis showed an age-dependent increase in expression of all three genes. Zebrafish f9a gene knockdown and Fixa immunodepletion prolonged kinetic partial thromboplastin time (kPTT), whereas f9l knockdown and Fixl immunodepletion prolonged kPTT, kinetic prothrombin time, and kinetic Russell viper venom activation time. Laser-assisted venous thrombosis increased time to occlusion after f9a and f9l knockdown and antibody inhibition of Fixa and Fixl. Further, analysis of plasma proteins by mass spectrometry and immunohistochemistry detected all three proteins.

CONCLUSIONS

Our findings suggest that zebrafish f9a has functional activity similar to human F9. Fixl is functionally similar to Fx. The age-dependent increases of these factors are comparable to those observed in mice and humans. Thus, the zebrafish model could be used to study factors involved in increasing f9a expression during aging. It could also be used to test whether normal human Factor IX and Factor IX Leyden promoter work in zebrafish background.

Primary and secondary haemostasis changes related to aging

Life expectancy has increased in many countries as a result the world's population is aging. The projections indicate that the proportion of the elderly in a few decades will increase significantly. Aging carries with it a series of physiological changes; one of them is an imbalance in the hemostatic system. Thus the levels or activity of various proteins involved, such as most coagulation factors, natural anticoagulants and the fibrinolytic system are altered so that the hemostatic balance leans toward thrombosis. Also, platelet activity suggests a state of abnormal activation (P-selectin, beta thromboglobulin and platelet factor). In this review we will systematically examine the alterations in the hemostatic components that occur during aging. Therefore, understanding these hemostatic changes could contribute to developing strategies for the proper management of health in old age.

Coagulation factors and antithrombin levels in young and elderly subjects in Pakistani population

Aging is associated with increased levels of coagulation factors and decrease in natural anticoagulant factors. This strongly supports that age-related hypercoagulable state occurs in elderly. This study aimed to measure the plasma levels of coagulation factors and anticoagulant levels in young and elderly to observe the effect of age on haemostatic system. Ninety healthy individuals, both men and women were divided into two groups on the basis of age. Group I included participants of less than 40 years of age, whereas, group II comprised of participants more than 60 years of age. Fibrinogen activity was assessed by using Clauss technique. Coagulation factor VII, and factor VIII activity by corresponding one stage assay based on prothrombin time and activated partial thromboplastin time. Antithrombin III was measured by the chromogenic method. Our results showed that significantly increased levels of fibrinogen (P = 0.001) were observed in the elderly population as compared to young. Higher fibrinogen levels in younger women than men and comparatively higher level than other races was observed in our local population. Increase in factor VII levels (P = 0.05) was also observed in the elderly group. This increase was statistically significant with age in women (P = 0.03). Factor VIII rose with age in both sexes (P = 0.001). Higher antithrombin activity was observed in the younger group whereas the older group demonstrated significantly lower antithrombin activity (P = 0.001). We conclude that considerable effects of age and sex are observed on coagulation factors and naturally occurring inhibitors.

Intrinsic clotting factors in dependency of age, sex, body mass index, and oral contraceptives: definition and risk of elevated clotting factor levels

Elevated clotting factors have been demonstrated to be a risk factor for venous thromboembolism (VTE). The aim of our study was to investigate the impact of age, sex, body mass index, and oral contraceptives on the clotting factor activities of factors VIII, IX, XI, and XII and their impact on the cutoff definition and risk of VTE associated with elevated clotting factors. Factor VIII, IX, XI, and XII activities were measured in 499 blood donors and 286 patients with VTE. Age and body mass index predicted significantly and independently the clotting factor activities of factors VIII, IX, and XI, whereas use of oral contraceptives predicted factor IX, XI, and XII levels. Percentiles of clotting factor activities, which are often used for the cutoff definition of elevated clotting factors, varied due to the effect of age, body mass index, and oral contraceptives. The adjusted odds ratios for VTE were 10.3 [95% confidence interval (CI) 5.1-20.7], 6.1 (95% CI 3.1-12.0), and 3.3 (95% CI 1.9-5.8) for elevated factors VIII, IX, and XI, respectively. Furthermore, our study demonstrates for the first time that elevated factor XII is associated with an increased risk of VTE (adjusted odds ratio 2.9, 95% CI 1.6-5.3).

The hemostatic system through aging and menopause

The process of aging is accompanied by several modifications in the hemostatic system at different levels (blood coagulation, fibrinolysis, platelet activity, vascular endothelium). These changes may explain the higher incidence of arterial and venous thrombosis in the elderly compared to young people. Genetic and environmental factors modulate in different combinations the expression of proteins involved in the hemostatic process. Among the latter, diet and smoking habits play an important role, as well as physical exercise and, for women, hormonal status. A gradual and progressive development of a low-grade inflammatory state (clearly demonstrated in the elderly) is also an important factor that influences hemostasis during aging. In spite of the fact that the increased hypercoagulable state observed with aging may account for the higher incidence of thrombosis in the elderly, the finding of a similar pattern of coagulation activation in healthy centenarians suggests that a hypercoagulable state is compatible with health and longevity. Taking also into consideration that no laboratory parameters of hemostasis are predictive of thrombosis on an individual basis, a physician's behavior towards aging patients (e.g. prescription of hormonal replacement therapy to a woman during menopause) should not be affected by laboratory tests, but mainly by a patient's clinical history and the presence of strong risk factors for thrombosis other than age (e.g. diabetes mellitus, arterial hypertension, dyslipidemia, obesity, smoking).

Does Ginkgo biloba Special Extract EGb??761?? Provide Additional Effects on Coagulation and Bleeding when Added to Acetylsalicylic Acid 500mg Daily?

OBJECTIVE

The aim of this study was to determine whether Ginkgo biloba special extract EGb 761 amplifies the known effects of acetylsalicylic acid (ASA) on platelet aggregation, bleeding time or other coagulation parameters in healthy subjects.

METHODS

In a double-blind, double-dummy procedure, 50 healthy male subjects (20-44 years) were randomly allocated in equal numbers to one of two possible treatment sequences, i.e. ASA followed by ASA + EGb 761 or ASA + EGb 761 followed by ASA. Each treatment lasted 7 days; the washout period between treatments was 3 weeks. Study medication was taken twice daily (ASA group: ASA 500 mg tablet + placebo-coated tablet in the morning and placebo tablet + placebo-coated tablet in the evening; ASA + EGb 761 group: ASA 500 mg tablet + EGb 761 120 mg-coated tablet in the morning and placebo tablet + EGb 761 120 mg-coated tablet in the evening), resulting in a daily dose of ASA 500 mg in the ASA group and 500 mg ASA + 240 mg EGb 761 in the ASA + EGb 761 group. Bleeding time, coagulation parameters and platelet activity in response to various agonists were determined. In addition, adverse events, laboratory variables and vital signs were measured. The primary variable bleeding time was assessed in confirmatory analysis, all other variables were evaluated descriptively. The coagulation variables were analysed by ANOVA under the crossover model.

RESULTS

ASA given alone clearly prolonged bleeding time. ASA and the combination of ASA + EGb 761 exerted quite similar effects on all coagulation parameters measured, including bleeding time (ASA alone: 4.1 min before therapy, 6.2 min after therapy; ASA + EGb 761: 4.2 min before therapy, 6.3 min after therapy; ratio of means: 1.01, 90% CI 0.86, 1.19) and agonist-induced platelet aggregation (collagen-induced platelet aggregation - ASA: 84.5% before therapy, 81.0% after therapy; ASA + EGb 761: 86.6% before therapy, 81.0% after therapy; ratio of means: 1.00, 90% CI 0.95, 1.05; adenosine diphosphate-induced platelet aggregation - ASA: 72.6% before therapy, 47.2% after therapy; ASA + EGb 761: 71.7% before therapy, 44.8% after therapy; ratio of means: 0.95, 90% CI 0.85, 1.06). Both treatments were well tolerated, and both the number and nature of adverse events in the two groups were similar.

CONCLUSIONS

Our findings suggest that co-administration of ASA and EGb 761 does not constitute a safety risk, including in an elderly patient population undergoing treatment with EGb 761.

Rheological analyses of coagulation of blood from different individuals with special reference to procoagulant activity of erythrocytes

In our previous papers, we reported that factor IX (FIX), when activated by erythrocyte membranes, causes coagulation. We have identified and characterized the FIX-activating enzyme located in normal human erythrocyte membranes. In this paper, to examine physiological and pathological significances of procoagulant activity of erythrocytes, coagulation of blood obtained from different individuals was analyzed by means of a rheological technique. In more than 65% of subjects including normals and patients, the initiation of coagulation seemed to be governed by erythrocytes. Coagulation of whole blood and platelet-free plasma supplemented with erythrocytes had a tendency to occur rapidly in the elderly. It was suggested that the concentration of FIX-activating enzyme on erythrocyte membranes for aged donors was somewhat higher than that for young ages. Propagation reactions on erythrocyte membranes (i.e. factor X activation leading to thrombin generation after FIX activation) was slower than that on platelet membranes. Moreover, the propagation reaction on erythrocyte membranes was greatly dependent on individuals, whereas that on platelet membranes was not so much. Our study demonstrates that the activation of FIX by erythrocytes and subsequent propagation reaction on platelet membranes may be important for initiating and controlling blood coagulation reactions.

Elevated Clotting Factor Levels and Venous Thrombosis

Increased plasma levels of fibrinogen, factor VIII (FVIII), factor IX (FIX), factor XI (FXI) and prothrombin all were reported to be independent risk factors of venous thromboembolism (VTE). However there is only limited information on the molecular basis of these plasma phenotypes. In addition some of these plasma phenotypes may form clusters, which may point to defects in common pathways affecting biosynthesis or clearance. Uncertainties as to what should be considered the cut-off for an elevated plasma level and in some cases (FIX, FXI) the lack of published confirmatory and/or prospective studies, have delayed the incorporation of these parameters in thrombophilia screening procedures.

Zebrafish: a genetic model for hemostasis and thrombosis

Here we review the zebrafish hemostatic system, its relevance to mammalian hemostasis, and its efficacy as a vertebrate genetic model to further the understanding of hemostasis and thrombosis.

Influence of a 7-day treatment with Ginkgo biloba special extract EGb 761 on bleeding time and coagulation

During recent years, several case reports have been published in which the authors have voiced their suspicion of a causal relationship between hemorrhagic complications and the intake of Ginkgo biloba preparations. Therefore, a trial was conducted to investigate the influence of Ginkgo biloba special extract EGb 761 on hemostasiological parameters. Fifty healthy, male volunteers underwent 7 days of crossover treatment with 2 x 120 mg/day EGb 761 and placebo in randomized sequence. Between the two treatment phases, a washout-period of at least 3 weeks was inserted. The study's main outcome measures were bleeding time, coagulation parameters, platelet activity in response to various agonists and platelet morphology. The equivalence of the two treatments was analyzed by computing the 90% Fieller confidence intervals for the ratio between the means of the pre-post treatment differences for EGb 761 and placebo, respectively. Treatment safety was investigated by clinical laboratory and vital signs assessment and by adverse events monitoring. Among the 29 coagulation and bleeding parameters assessed, none showed any evidence of an inhibition of blood coagulation and platelet aggregation through EGb 761. Furthermore, the study did not reveal any evidence to substantiate a causal relationship between the administration of EGb 761 and hemorrhagic complications. As regards treatment tolerability, there were no interpretable differences between EGb 761 and placebo except for a slight increase of gastrointestinal complaints during administration of the herbal extract.

Polymorphisms in coagulation factor genes and their impact on arterial and venous thrombosis

Arterial and venous thromboses, with their clinical manifestations such as stroke, myocardial infarction (MI), or pulmonary embolism, are the major causes of death in developed countries. Several studies in twins and siblings have shown that genetic factors contribute significantly to the development of these diseases. Since the advent of molecular genetics in medicine, it has been a focus of interest to elucidate the role of mutations in various candidate genes and their impact on hemostatic disorders such as arterial and venous thromboses. In this article, we review the current knowledge of the contribution of polymorphisms in coagulation factors to the development of thrombotic diseases. We show that in arterial thrombosis, results are controversial. Only for factor XIII 34Leu a protective effect on the development of myocardial infarction has been demonstrated in several studies. No other single polymorphism in a coagulation factor could be confirmed as a relevant risk factor, although there is evidence for a role of factor V Arg506Gln, factor VII Arg353Gln, and vWF Thr789Ala polymorphisms in patient subgroups. Further studies will be necessary to confirm the value of testing for genetic polymorphisms in arterial thrombosis. A large body of data is available on the role of factor V Arg506Gln and the prothrombin G20210A mutation in venous thrombosis. Some papers already recommend diagnosis and treatment strategies. We will discuss these recent publications on venous thrombosis in our review.

Vascular complications and gene therapy

For gene therapy, the last few years have been an exciting period. Encouraging results from several successful gene therapy trials were reported. Children born with a life-threatening immune system disorder, severe combined immune deficiency (SCID), were cured after receiving gene therapy for replacement of their defective adenosine deaminase (ADA) gene. Gene therapy successes related to vascular complications were also reported. The first human gene therapy trial for a blood-vessel disorder was performed successfully, in which copies of an angiogenic gene, the vascular endothelial growth factor (VEGF) gene, were directly delivered to the area surrounding the diseased artery of the leg of a patient with peripheral artery disease. Within a few days, this stimulated the growth of new blood vessels around the blockage in the ailing blood vessel and helped avoid amputation. In 1998, a patient with genetically small arteries became the first to receive VEGF gene therapy in the heart. Multiple copies of a plasmid with the VEGF gene were delivered into the damaged area of the heart, and a few days later angiogenesis ensued that helped bypass the blocked vessel, with markedly reduced chest pain in the patient. Gene therapy is becoming a reality and, more importantly, it appears to be safe and does not require supplementary immuno-suppressing drugs. Gene therapy seems to have begun delivering on its promises.