Research InterestsPlatelet Physiology and Thrombosis; Platelet Immunology and Maternal Immune Response to Fetal Antigens
AcceptingFellows, Graduates, Summer Students
Department of Laboratory Medicine and Pathobiology
Department of Medicine, and Department of Physiology, University of Toronto
Scientist of Canadian Blood Services Centre for Innovation
Platform Director for Hematology, Cancer and Immunological Diseases, St. Michael's Hospital
1) Platelet Physiology and Thrombosis:
Thrombotic diseases such as heart attack and stroke are the leading causes of mortality and mobility worldwide. Dr. Ni and his colleagues established an intravital microscopy thrombosis model at Harvard to study thrombus formation in real-time in live mice. Through direct monitoring of platelet adhesion and aggregation in vivo, Dr. Ni was the first to observe that platelet aggregation and thrombus formation still occurs in mice lacking both von Willebrand factor (VWF) and fibrinogen (Fg). This surprising discovery challenged the established theory of thrombosis that required VWF and Fg for thrombus formation. This finding suggested that other unidentified molecule(s) may also be involved in thrombosis and hemostasis and may provide novel targets for anti-thrombotic therapies. Dr. Ni's team is in the process of identifying these mystery molecules at St. Michael's Hospital using several state-of-the-art techniques such as proteomics and confocal intravital microscopy.
2) Platelet Immunology and Maternal Immune Response to Fetal Antigens:
Dr. Ni’s laboratory recently published two important papers in Blood investigating: 1) How ITP mediated by anti-b3 integrin and anti-GPIba antibodies differ, finding that these two antibody specificities may respond to therapy differently. This has important implications for human ITP and potential screening of patients in order to successfully treat this disease. 2) Dr. Ni’s laboratory also established the first animal model of fetal and neonatal alloimmune thrombocytopenia (FNAITP), and characterized the disease and its response to intravenous immunoglobulin G (IVIG) therapy. Currently, the laboratory is studying the molecular and cellular basis for ITP, and the maternal immune responses to fetal platelet antigens, and the roles of anti-angiogenesis and apoptosis in the patho-progression of FNAITP.
Publications and Awards
SAMPLE PUBLICATIONS AND ABSTRACTS
Yang H, Reheman A, Chen P, Hynes R.O., Freedman J, Wagner D.D., and Ni H. Fibrinogen and von Willebrand factor-independent platelet aggregation in vitro and in vivo. Journal of Thrombosis and Haemostasis. 2006 October, 4: 2230-2237
Webster, M.L., Sayeh, E., Crow, M., Chen, P., Neiswandt, B., Freedman, J., and Ni H. Relative efficacy of intravenous immunoglobulin G in ameliorating thrombocytopenia induced by anti-platelet GPIIbIIIa versus GPIb alpha antibodies. Blood. 2006 Aug 1;108(3):943-946.
Ni, H., Chen, P., Spring, C., Sayeh, E., Semple, J.W., Lazarus, A.H., Hynes, R.O., and Freedman, J. A novel murine model of fetal and neonatal alloimmune thrombocytopenia: response to intravenous IgG therapy. Blood. 2006 Apr 1;107(7):2976-2983
Reheman A, Gross P, Yang H, Chen P, Allen D, Leytin V, Freedman J, Ni H. Vitronectin stabilizes thrombi and vessel occlusion but plays a dual role in platelet aggregation. Journal of Thrombosis and Haemostasis. 2005 May;3(5):875-83.
Ni H, Yuen PS, Papalia JM, Trevithick JE, Sakai T, Fässler R, Hynes RO, Wagner DD. Plasma fibronectin promotes thrombus growth and stability in injured arterioles. Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2415-9.