Development of a fully humanised model for understanding platelet function
Lead Research Organisation:
University of Reading
Department Name: Sch of Biological Sciences
Abstract
Platelets are small cells in the blood which, when activated, play a critical role in the prevention of excessive bleeding at sites of injury. Conversely, inappropriate platelet activation can block the blood supply to the heart and brain resulting in life threatening heart attacks or strokes and contribute to an estimated 40% of cardiovascular deaths.
Current therapy in the prevention of heart attacks and strokes is based on drugs which suppress normal platelet function. While effective in approximately two thirds of patients, the remainder succumb to a second heart attack or stroke. As anti-platelet drugs suppress normal platelet function they can also have the undesirable side effect of nuisance bleeding, which can in some cases become a serious complication for patients. Therefore, an understanding of the molecular mechanisms governing platelet activation and function and how platelets interact with a damaged blood vessel wall is needed to understand how platelets impact health and disease and for the identification of new and improved drug targets. It is not ethical to study these events directly in people and platelet research is currently heavily reliant on the use of genetically altered mouse models to understand how proteins or specific protein domains play a role in platelet function. However, mouse models are not always a suitable alternative to investigate human platelet function and a model of the human blood vessel is needed.
This project will, for the first time, bring together a model to replicate the human blood vessel with a method that will allow human platelets to be modified. This will enable new drug targets to be studied and tested using human tissue, reducing and replacing the use of animals in cardiovascular research.
Current therapy in the prevention of heart attacks and strokes is based on drugs which suppress normal platelet function. While effective in approximately two thirds of patients, the remainder succumb to a second heart attack or stroke. As anti-platelet drugs suppress normal platelet function they can also have the undesirable side effect of nuisance bleeding, which can in some cases become a serious complication for patients. Therefore, an understanding of the molecular mechanisms governing platelet activation and function and how platelets interact with a damaged blood vessel wall is needed to understand how platelets impact health and disease and for the identification of new and improved drug targets. It is not ethical to study these events directly in people and platelet research is currently heavily reliant on the use of genetically altered mouse models to understand how proteins or specific protein domains play a role in platelet function. However, mouse models are not always a suitable alternative to investigate human platelet function and a model of the human blood vessel is needed.
This project will, for the first time, bring together a model to replicate the human blood vessel with a method that will allow human platelets to be modified. This will enable new drug targets to be studied and tested using human tissue, reducing and replacing the use of animals in cardiovascular research.
Technical Summary
Platelets are small cells in the blood which, when activated, play a critical role in the prevention of excessive bleeding at sites of injury. Conversely, abnormal platelet behaviour can lead to a thrombotic event resulting in a heart attack or stroke. Understanding the molecular mechanisms governing platelet activation and function is fundamental to determining how platelets impact health and disease and to the identification of new and improved drug targets.
Platelets lack a cell nucleus meaning that standard molecular biology methods, used to study biological processes in nucleated cells, cannot be used. This limitation has resulted in the greater use of animals, particularly genetically modified mouse models, where genes of interest are disrupted so that platelets deficient in protein can be studied. There has also been an increase in the number of mouse models which express fluorescent imaging probes that are used to follow biological processes in real time. However, research carried out using mouse platelets do not always translate well to human and this has resulted in an increased number of humanised mouse models to tackle this problem.
Thrombus formation is a complex process which involves changes to the endothelial cell lining of the blood vessels in addition to the circulating blood. To recreate the complexity of this process we propose a route to an animal free approach to support thrombosis research. Protein knockdown in human platelets will be achieved using antibody mediated protein depletion. Antibodies against therapeutically relevant targets will be delivered directly into the cytoplasm of human platelets by fusogenic liposomes. Blood reconstituted with modified platelets will be perfused over a microfluidic 'vessel on a chip' device. This fully humanised system will remove the need to used genetically modified mice to investigate thrombus formation.
Platelets lack a cell nucleus meaning that standard molecular biology methods, used to study biological processes in nucleated cells, cannot be used. This limitation has resulted in the greater use of animals, particularly genetically modified mouse models, where genes of interest are disrupted so that platelets deficient in protein can be studied. There has also been an increase in the number of mouse models which express fluorescent imaging probes that are used to follow biological processes in real time. However, research carried out using mouse platelets do not always translate well to human and this has resulted in an increased number of humanised mouse models to tackle this problem.
Thrombus formation is a complex process which involves changes to the endothelial cell lining of the blood vessels in addition to the circulating blood. To recreate the complexity of this process we propose a route to an animal free approach to support thrombosis research. Protein knockdown in human platelets will be achieved using antibody mediated protein depletion. Antibodies against therapeutically relevant targets will be delivered directly into the cytoplasm of human platelets by fusogenic liposomes. Blood reconstituted with modified platelets will be perfused over a microfluidic 'vessel on a chip' device. This fully humanised system will remove the need to used genetically modified mice to investigate thrombus formation.
