Functional and ultrastructural status of platelets prepared by the Celltrifuge

Cryopreservation of human platelets and bone marrow and peripheral blood totipotential mononuclear stem cells

Human platelets in sufficient numbers for a therapeutic transfusion can be collected for preservation either by pooling ABO- and Rh-compatible platelets or by apheresis procedures using mechanical cell-separating machines. Human platelets have been frozen successfully with 5 or 6% dimethyl sulfoxide (DMSO) and stored at -150 or -180 degrees C, respectively. Platelets frozen with 5% DMSO have been stored at -150 degrees C for at least 3 years, and platelets frozen with 6% DMSO have been stored at -80 degrees C for at least 2 years. Approximately 95% of the DMSO usually is removed by washing the platelets after thawing, and the residual DMSO produces no untoward effects. Washed platelets resuspended in plasma can be stored at room temperature for 6 to 8 hr before transfusion. Platelets thus frozen have freeze-thaw-wash recovery values of about 80%. In vivo survival values are only about 50% those seen with fresh platelets, and it is necessary to transfuse twice as many to achieve comparable results. Studies have shown that these platelets have satisfactory circulation, reduce clinical bleeding, and shorten the prolonged bleeding times associated with thrombocytopenia. Studies are now being made on human bone marrow and peripheral blood, from which totipotential cells devoid of immunocompetent cells can be isolated and frozen.