This project proposes to employ intravital video-microscopy and radionuclide imaging to analyze and quantitate the abnormal microvascular flow dynamics of genetic variants of sickle erythrocytes and their propensity to induce vaso-occlusion and microvascular derangement. A secondary objective is to analyze endothelial markers that reflect its injury consequent to the vaso-occlusion, using biochemical and immunological assays. Our hypothesis is that polymer fraction of deoxy HbS in erythrocytes of genetic variants of sickle cell disease (HbSS, HbSC and HbSS Thal) through the effect of MCHC, is the primary determinant of cellular flow dynamics and vaso-occlusion in the microcirculation. This hypothesis will be tested by four experimental approaches: (a) determination of the flow dynamics i.e., flow velocity, flux, transit times, of normal and sickle erythrocytes, and various density-separated and osmotically altered fractions of these cells, flowing through the microcirculation of rat mesentery and cremaster muscle under varying oxygen saturation; (b) determination of the pressure-flow-resistance relationships of a rat hindlimb vascular preparation perfused with normal or sickle erythrocytes, and biochemical and immunological analysis of endothelial markers in the venous effluents that indicate endothelial injury consequent to vaso-occlusion; (c) radionuclide imaging of the kinetics and sites of vaso-occlusion, and the cellular and rheological factors involved, using indium-111 oxine labeled normal or sickle erythrocytes and various density fractions of these cells. These data on the frequency of occlusion at microvascular bifurcations and residence times of the cells at these sites will be supplemented with fluorescent-labeled normal and sickle cells and intravital microscopy; (d) determination of the filterability of the normal and sickle erythrocytes mentioned above flowing through polycarbonate (Nucleopore) filters under varying conditions of oxygen saturation, and pore geometry. These data will be analyzed in terms of pore resistance of a red cell and its transit through the pore. The result of these studies will provide very significant insight into the mechanisms of vaso-occlusive events in sickle cell disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29HL038521-03
Application #
3471230
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1987-04-01
Project End
1992-03-31
Budget Start
1989-04-01
Budget End
1990-03-31
Support Year
3
Fiscal Year
1989
Total Cost
Indirect Cost
Name
George Washington University
Department
Type
Schools of Medicine
DUNS #
City
Washington
State
DC
Country
United States
Zip Code
20052
Ibe, B O; Morris, J; Kurantsin-Mills, J et al. (1997) Sickle erythrocytes induce prostacyclin and thromboxane synthesis by isolated perfused rat lungs. Am J Physiol 272:L597-602
Wick, C E; Loew, M H; Kurantsin-Mills, J (1996) Modeling and simulation of illumination effects for evaluation of microvessels of the conjunctiva. Am J Physiol 271:H1229-39
Ibe, B O; Kurantsin-Mills, J; Raj, J U et al. (1994) Plasma and urinary leukotrienes in sickle cell disease: possible role in the inflammatory process. Eur J Clin Invest 24:57-64
Kurantsin-Mills, J; Ibe, B O; Natta, C L et al. (1994) Elevated urinary levels of thromboxane and prostacyclin metabolities in sickle cell disease reflects activated platelets in the circulation. Br J Haematol 87:580-5
Feriani, M; Kimmel, P L; Kurantsin-Mills, J et al. (1992) Effect of renal replacement therapy on viscosity in end-stage renal disease patients. Am J Kidney Dis 19:131-9
Kurantsin-Mills, J; Ofosu, F A; Safa, T K et al. (1992) Plasma factor VII and thrombin-antithrombin III levels indicate increased tissue factor activity in sickle cell patients. Br J Haematol 81:539-44
Kurantsin-Mills, J; Jacobs, H M; Siegel, R et al. (1989) Indium-111 oxine labeled erythrocytes: cellular distribution and efflux kinetics of the label. Int J Rad Appl Instrum B 16:821-7
Kurantsin-Mills, J; Klug, R K; Lessin, L S (1988) Irreversible erythrocyte volume expansion induced by tellurite. Br J Haematol 70:369-74
Kurantsin-Mills, J; Klug, P P; Lessin, L S (1988) Vaso-occlusion in sickle cell disease: pathophysiology of the microvascular circulation. Am J Pediatr Hematol Oncol 10:357-72