AGGREGATES OF RED BLOOD CELLS, AND AGGREGATES OF PLATELETS UNDER ZERO GRAVITY: EXPERIMENT ON NASA SPACE SHUTTLE "DISCOVERY" STS 51-C, JANUARY l985

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The aim of experiment "ARC" on the space shuttle "Discovery STS 51-C, was to define effect of zero gravity on kinetics and morphology of aggregation of red cells in blood obtained from patients suffering from ischaemic heart disease, colon cancer, insulin-dependent diabetes, hyperlipidaemia, IgG and IgM papa-proteins. Space-rated automated slit-capillary photo-viscometer contained a motorized infusion pump capable of handling eight different blood samples. Two cameras and a microscope allowed micro and macrophotography, and total of 500 photographs was obtained in space; and equivalent number on the ground, in the Kennedy Space Center, where a duplicate ground photo-viscometer was present. Identical blood samples have been used in the ground experiments. The slit had a gap of 12.5 microns (micrometers). Blood was anticoagulated with EDTA and adjusted to haematocrit of 0.30 using native plasma. Samples were kept at -5°C prior to the experiment, and at 25°C during experiment; duration of experiment was 91/2 hours. The same computer program was used in both instruments. Photography was carried out at set intervals up to six minutes from the moment of stasis. There was a drastic difference between aggregation on the ground and at zero gravity. Blood from patients was greatly sludged on the ground, but normal rouleaux were formed under zero gravity. Also, aggregates uikder zero g were much smaller. However, red cell shape was not changed. Blood samples from normal donors, which showed normal rouleaux on the ground, exhibited random swarm pattern under zero gravity. Platelets, which tended to aggregate on the ground, and tended to accummulate at the slit entrance, remained monodisperse under zero gravity and no pseudopodia have been noted; under zero g platelet moved through the slit. Subject to future confirmation, it is suggested that zero gravity affects cell-to-cell interaction, and probably causes a modification of the cell membrane. If this is true, a new vista opens in the studies of immunology and oncology under zero gravity.