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A microfluidic model of hemostasis sensitive to platelet function and coagulation.

ABSTRACT: Hemostasis is the process of sealing a vascular injury with a thrombus to arrest bleeding. The type of thrombus that forms depends on the nature of the injury and hemodynamics. There are many models of intravascular thrombus formation whereby blood is exposed to prothrombotic molecules on a solid substrate. However, there are few models of extravascular thrombus formation whereby blood escapes into the extravascular space through a hole in the vessel wall. Here, we describe a microfluidic model of hemostasis that includes vascular, vessel wall, and extravascular compartments. Type I collagen and tissue factor, which support platelet adhesion and initiate coagulation, respectively, were adsorbed to the wall of the injury channel and act synergistically to yield a stable thrombus that stops blood loss into the extravascular compartment in ~7.5 min. Inhibiting factor VIII to mimic hemophilia A results in an unstable thrombus that was unable to close the injury. Treatment with a P2Y12 antagonist to reduce platelet activation prolonged the closure time two-fold compared to controls. Taken together, these data demonstrate a hemostatic model that is sensitive to both coagulation and platelet function and can be used to study coagulopathies and platelet dysfunction that result in excessive blood loss.

SUBMITTER: Schoeman RM

PROVIDER: S-EPMC5435378 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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A microfluidic model of hemostasis sensitive to platelet function and coagulation.

Schoeman R M RM Rana K K Danes N N Lehmann M M Di Paola J A JA Fogelson A L AL Leiderman K K Neeves K B KB

Cellular and molecular bioengineering 20161024 1

Hemostasis is the process of sealing a vascular injury with a thrombus to arrest bleeding. The type of thrombus that forms depends on the nature of the injury and hemodynamics. There are many models of intravascular thrombus formation whereby blood is exposed to prothrombotic molecules on a solid substrate. However, there are few models of extravascular thrombus formation whereby blood escapes into the extravascular space through a hole in the vessel wall. Here, we describe a microfluidic model ...[more]

PMID: 28529666

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Project description:IntroductionTraditional Miao and Dai Chinese medicines have used nicotine-rich leaf tobacco to treat traumatic injuries by promoting hemostasis. While nicotine is known to enhance platelet aggregation, its effects on other platelet functions and underlying mechanisms remain unclear.Methods and resultsThis study aimed to thoroughly investigate nicotine's effects on human platelets and its pharmacological mechanisms, using thromboelastography to assess nicotine's impact on platelet function during coagulation. This study aimed to investigate the functional effects of nicotine on human platelets and elucidate its pharmacological mechanisms. The impact of nicotine on platelet function during the coagulation process was assessed using thromboelastography. Further studies showed that nicotine fully activates washed platelets, promoting aggregation, granule release, adhesion, spreading, and plaque retraction. Concurrently, nicotine was found to enhance the intracellular concentration of calcium ions in platelets ([Ca2+]i). To explore the underlying mechanisms, molecular docking software was employed to identify the platelet membrane receptors PAR1 and PAR4, which exhibited the highest docking scores with nicotine. Intervention with two receptor inhibitors demonstrated that only the PAR4 inhibitor could reverse the stimulatory effects of nicotine on platelet granule release. Through the examination of alterations in the downstream signaling pathways of PAR4 receptors, it was determined that nicotine promo-facilitates the phosphorylation of PI3K, AKT, and ERK1/2 proteins, subsequently contributing to the activation of αIIbβ3 receptors in platelets. Conversely, the application of PAR4 inhibitors was found to reverse these effects.DiscussionIn conclusion, nicotine activates αIIbβ3 receptors and significantly enhances platelet function by promoting the phosphorylation of the platelet PAR4 receptor signaling pathway. These findings suggest the potential utility of nicotine as a hemostatic agent.

Project description:Background: Untreated hypothyroidism is associated with acquired von Willebrand syndrome, and hyperthyroidism is associated with increased thrombosis risk. However, the causal effects of thyroid function on hemostasis, coagulation, and fibrinolysis are unknown. Methods: In a two-sample Mendelian randomization (MR) study with genome-wide association variants, we assessed causality of genetically predicted hypothyroidism (N = 134,641), normal-range thyrotropin (TSH; N = 54,288) and free thyroxine (fT4) (N = 49,269), hyperthyroidism (N = 51,823), and thyroid peroxidase antibody positivity (N = 25,821) on coagulation (activated partial thromboplastin time, von Willebrand factor [VWF], factor VIII [FVIII], prothrombin time, factor VII, fibrinogen) and fibrinolysis (D-dimer, tissue plasminogen activator [TPA], plasminogen activator inhibitor-1) from the CHARGE Hemostasis Consortium (N = 2583-120,246). Inverse-variance-weighted random effects were the main MR analysis followed by sensitivity analyses. Two-sided p < 0.05 was nominally significant, and p < 0.0011[ = 0.05/(5 exposures × 9 outcomes)] was Bonferroni significant for the main MR analysis. Results: Genetically increased TSH was associated with decreased VWF [β(SE) = -0.020(0.006), p = 0.001] and with decreased fibrinogen [β(SE) = -0.008(0.002), p = 0.001]. Genetically increased fT4 was associated with increased VWF [β(SE) = 0.028(0.011), p = 0.012]. Genetically predicted hyperthyroidism was associated with increased VWF [β(SE) = 0.012(0.004), p = 0.006] and increased FVIII [β(SE) = 0.013(0.005), p = 0.007]. Genetically predicted hypothyroidism and hyperthyroidism were associated with decreased TPA [β(SE) = -0.009(0.024), p = 0.024] and increased TPA [β(SE) = 0.022(0.008), p = 0.008], respectively. MR sensitivity analyses showed similar direction but lower precision. Other coagulation and fibrinolytic factors were inconclusive. Conclusions: In the largest genetic studies currently available, genetically increased TSH and fT4 may be associated with decreased and increased synthesis of VWF, respectively. Since Bonferroni correction may be too conservative given the correlation between the analyzed traits, we cannot reject nominal associations of thyroid traits with coagulation or fibrinolytic factors.

Dataset Information

A microfluidic model of hemostasis sensitive to platelet function and coagulation.

Publications

A microfluidic model of hemostasis sensitive to platelet function and coagulation.

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