Analysis of shear stress-induced von Willebrand factor and platelet damage from ventricular assist devices
Lead Research Organisation:
Swansea University
Department Name: Institute of Life Science Medical School
Abstract
A ventricular assist device (VAD) supports heart function in people with heart failure. VADs pumps blood from the heart to various parts of the body. Although heart failure can be treated with VADs, bleeding remains a serious complication of long-term VAD use. Acquired von Willebrand Disease (aVWD) is due to the breakdown of high molecular weight (HMW) von Willebrand factor (vWF) multimers. vWF circulating in blood is cleaved by ADAMTS13 metalloprotease under high shear stress. HMW vWF multimers are required for platelet aggregation, which is critical for blood clotting. This study will investigate the loss of HMW vWF from blood under shear stress. Therefore, the hypothesis of this project is that inhibition of ADAMTS13 can restore HMW vWF multimers and vWF function. This hypothesis will be tested by using the following three aims:
1. To analyse the effect of ADAMTS13 inhibition on the levels and activity of HMW vWF multimers in blood. The loss of HMW multimers and activity of vWF exposed to shear stress will be analysed in the presence or absence of ADAMTS13 inhibitors. Blood will be analysed by immunoblotting and platelet aggregation, flow cytometry and confocal microscopy.
2. To study the levels and activity of HMW vWF multimers in blood passed through a VAD in vitro or by cardiopulmonary bypass (CPB) circuit. The vWF HMW multimers and activity in plasma of blood of healthy volunteers passed through a VAD or heart patients passed through CPB circuit during bypass surgery will be assessed by immunoblotting and platelet aggregation. This is to determine if mechanical shear stress differentially affects blood from healthy volunteers and heart failure patients. Since it is impossible to obtain 2000 mL of blood, which is required to pump through a VAD in vitro, we will be using blood obtained during bypass surgery in this study.
3. To analyse the levels of vWF HMW multimers and activity in plasma of patients and sheep implanted with a VAD. The plasma samples obtained from a VAD implanted sheep (Calon Cardio Technology Ltd/Catholic Univ. of Leuven) and human patients (from HDZ-NRW) will be used to assess the HMW multimer levels (by immunoblotting) and the activity (by platelet aggregation) of vWF. This analysis will be useful to study the effect of shear stress-induced ADAMTS13 HMV vWF multimers loss in real physiological conditions.
Significance: Heart failure is the UK's biggest killer. Since the availability of heart donors for transplantation has declined, VAD implantation has become an option for bridge to transplantation or destination therapy. Therefore, it becomes pertinent to understand the consequences of long-term VAD usage on the quality of life of patients. Acquired von Willebrand syndrome, a bleeding disorder, is common in VAD implanted patients. The proposed research will, therefore, be useful in the development of lower blood damage VADs.
The proposed project is within Clinical Devices of EPSRC research topic. The research will be beneficial in designing VADs with less side-effects highlighting the translation to healthcare applications. The project will advantage the development of new healthcare solutions that comes under the Developing Future Therapies grand challenge of the theme.
1. To analyse the effect of ADAMTS13 inhibition on the levels and activity of HMW vWF multimers in blood. The loss of HMW multimers and activity of vWF exposed to shear stress will be analysed in the presence or absence of ADAMTS13 inhibitors. Blood will be analysed by immunoblotting and platelet aggregation, flow cytometry and confocal microscopy.
2. To study the levels and activity of HMW vWF multimers in blood passed through a VAD in vitro or by cardiopulmonary bypass (CPB) circuit. The vWF HMW multimers and activity in plasma of blood of healthy volunteers passed through a VAD or heart patients passed through CPB circuit during bypass surgery will be assessed by immunoblotting and platelet aggregation. This is to determine if mechanical shear stress differentially affects blood from healthy volunteers and heart failure patients. Since it is impossible to obtain 2000 mL of blood, which is required to pump through a VAD in vitro, we will be using blood obtained during bypass surgery in this study.
3. To analyse the levels of vWF HMW multimers and activity in plasma of patients and sheep implanted with a VAD. The plasma samples obtained from a VAD implanted sheep (Calon Cardio Technology Ltd/Catholic Univ. of Leuven) and human patients (from HDZ-NRW) will be used to assess the HMW multimer levels (by immunoblotting) and the activity (by platelet aggregation) of vWF. This analysis will be useful to study the effect of shear stress-induced ADAMTS13 HMV vWF multimers loss in real physiological conditions.
Significance: Heart failure is the UK's biggest killer. Since the availability of heart donors for transplantation has declined, VAD implantation has become an option for bridge to transplantation or destination therapy. Therefore, it becomes pertinent to understand the consequences of long-term VAD usage on the quality of life of patients. Acquired von Willebrand syndrome, a bleeding disorder, is common in VAD implanted patients. The proposed research will, therefore, be useful in the development of lower blood damage VADs.
The proposed project is within Clinical Devices of EPSRC research topic. The research will be beneficial in designing VADs with less side-effects highlighting the translation to healthcare applications. The project will advantage the development of new healthcare solutions that comes under the Developing Future Therapies grand challenge of the theme.