The problem of limited availability of biological replacements for diseased vessels and organs is exacerbated by the failure of most prosthetic implants and organ substitutes due to repeated thrombo-embolic events. The mechanism which underlie the deposition of thrombotic masses on biomaterial surfaces is poorly understood. The objective of the present proposal is to investigate the influence of vascular surfaces on the deposition of platelets and fibrin on selected prosthetic surfaces. A tubular perfusion chamber has been developed for mounting the materials immediately downstream of injured vascular surfaces exposing the composite substrates to blood in an ex vivo perfusion system. Blood from both swine and human subjects will be utilized to investigate the specific mechanisms which are important in determining the deposition of thrombotic material on the biomaterial surface. Evaluation of the surface deposits will be performed by several techniques. In swine, III-In labelled platelets will be injected and the quantity of deposited radioactivity determined. In swine and humans, morphometric analysis of epoxy embedded semi-thin sections will be utilized to quantify platelet and fibrin deposits. The thrombotic deposits will be evaluated for several exposure times, axial positions from the proximal surface and wall shear rates, such that the full physiological range of flow conditions is investigated (wall shear rates from 50-5000 sec-1). Variation of proximal (vascular) and distal (biomaterial) surfaces and the condition of the blood will utilized to explore the mechanisms of platelet and fibrin deposition on the prosthetic surface. Various components of the vessel wall, including, subendothelium and its modifications, collagen, and tissue factor will be utilized as the activating proximal surface. Blood from patients and animal models with various bleeding disorders will be utilized to investigate the importance of von Willebrand factor, platelet glycoproteins Ib and IIb-IIIa, platelet released products and the relative importance of the Factor XI, coagulation and the tissue factor, Factor VII, IX pathways. Antibodies of VWF, and glycoproteins Ib and IIb-IIIa will also be employed and compared to results obtained with the corresponding naturally occurring deficiency. The mechanisms of growth of thrombotic deposits will also be investigated in nonstreamline (recirculation) flow by appropriately modifying the perfusion chambers and a theory for particle deposition will be developed.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL038933-06
Application #
3355421
Study Section
Surgery and Bioengineering Study Section (SB)
Project Start
1987-09-30
Project End
1994-09-29
Budget Start
1991-09-30
Budget End
1994-09-29
Support Year
6
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Memphis
Department
Type
Schools of Engineering
DUNS #
City
Memphis
State
TN
Country
United States
Zip Code
38152
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Yun, Y H; Turitto, V T; Daigle, K P et al. (1996) Initial hemocompatibility studies of titanium and zirconium alloys: prekallikrein activation, fibrinogen adsorption, and their correlation with surface electrochemical properties. J Biomed Mater Res 32:77-85
Lewis, G; Newman, J; Katz, W (1995) Characterization of biomedical polymer surface interaction with human factor Xa. Biomed Mater Eng 5:65-82
Badimon, J J; Weng, D; Chesebro, J H et al. (1994) Platelet deposition induced by severely damaged vessel wall is inhibited by a boroarginine synthetic peptide with antithrombin activity. Thromb Haemost 71:511-6
Slack, S M; Jennings, L K; Turitto, V T (1994) Platelet size distribution measurements as indicators of shear stress-induced platelet aggregation. Ann Biomed Eng 22:653-9
Lewis, G (1994) Use of enzyme-linked immunosorbent assay (ELISA) for detection and quantification of monoclonal antibodies. Biomed Mater Eng 4:363-7
Meyer, B J; Badimon, J J; Mailhac, A et al. (1994) Inhibition of growth of thrombus on fresh mural thrombus. Targeting optimal therapy. Circulation 90:2432-8
Fernandez-Ortiz, A; Badimon, J J; Falk, E et al. (1994) Characterization of the relative thrombogenicity of atherosclerotic plaque components: implications for consequences of plaque rupture. J Am Coll Cardiol 23:1562-9
Mailhac, A; Badimon, J J; Fallon, J T et al. (1994) Effect of an eccentric severe stenosis on fibrin(ogen) deposition on severely damaged vessel wall in arterial thrombosis. Relative contribution of fibrin(ogen) and platelets. Circulation 90:988-96

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