Method of freezing red blood cells

A method of freezing red blood cells comprising the steps of centrifuging a standard donor unit of 450 ml of blood to remove plasma and platelets and to achieve a red blood cell Packed Cell Volume of not less than 90%, occupying a volume of substantially 200 ml, introducing the red blood cells into a freezing bag containing substantially 35 ml of 40% w/v HES solution, wherein said HES has an average molecular weight in the range of 150,000 to 200,000, positioning the freezing bag in a frame having two parallel curved plates adapted to move slightly normal to one another while remaining parallel, and of placing the freezing frame in liquid nitrogen and leaving it there without shaking until the mixture of HES and red blood cells has frozen.

A method of freezing red blood cells that remain, on thawing therefrom, suitable for therapeutic transfusion, wherein said method comprises preparing a freezing mixture itself comprising red blood cells and hydroxyethyl starch, said preparation comprising the steps of isolating from blood a volume of red blood cells that are substantially free of plasma and platelets, contacting said cells, so isolated, with hydroxyethyl starch and then freezing said mixture in liquid nitrogen, and wherein said red blood cells are not contacted, once isolated, with additional plasma prior to freezing.

A method of freezing red blood cells so that said cells remain suitable for transfusion, wherein said method comprises preparing a freezing mixture itself comprising red blood cells and hydroxyethyl starch, said preparation comprising the steps of isolating from blood a volume of red blood cells that are substantially free of platelets and, contacting said cells, so isolated, with hydroxyethyl starch, and then freezing said mixture in liquid nitrogen, and wherein the concentration of hydroxyethyl starch in the extracellular fluid of said frozen mixture is about 25% (w/v).

A method of freezing red blood cells in liquid nitrogen so that said cells remain suitable for transfusion, said method comprising first preparing a freezing mixture itself comprising red blood cells and hydroxyethyl starch molecules, wherein the cryoprotective capability of said starch molecules is affected adversely by the presence of plasma, and wherein the amount of plasma in contact with said red blood cells or said starch molecules is limited prior to freezing said mixture, and then freezing said mixture, said limitation being accomplished by not adding additional plasma to said cells or said molecules.

A cryoprotecting cell freezing unit consisting essentially of a fluid in which red blood cells are present to a Packed Cell Volume of greater than about 75%, and hydroxyethyl starch is present in the fluid external to said cells at about 25% (w/v), such that said hydroxytheyl starch is present at from about 5% to 7% (w/v) of the freezing unit.

A method of preparing, for transfusion, red blood cells from a patient stored in a frozen state, wherein said method comprises first isolating red blood cells from blood so that they are substantially free of plasma and platelets, mixing hydroxyethyl starch with said cells, freezing said mixture for storage, and then thawing said mixture prior to transfusion into said patient, wherein also said plasma is recovered separately for storage, and wherein said red blood cells, so isolated, are not contacted with said plasma until after thawing of said mixture.

A method of freezing red blood cells so that said cells remain on thawing therefrom suitable for transfusion, wherein said method comprises preparing a freezing mixture itself comprising red blood cells and hydroxyethyl starch, said preparation comprising the steps of isolating from blood volume of red blood cells that are substantially free of platelets, and contacting said cells, so isolated, with hydroxyethyl starch, and then freezing said mixture in liquid nitrogen, and wherein the concentration of hydroxyethyl starch in the freezing mixture is no more than 7% (w/v).

A cryoprotecting cell freezing unit suitable for transfusion consisting essentially of a fluid containing the red blood cells from a standard donor unit, and containing hydroxyethyl starch in said fluid external to said cells wherein said cells therein have, after freezing of said unit and thawing thereof, a recovery means on thaw of about 99% or higher.

A cryoprotecting cell freezing unit consisting essentially of a fluid containing the red blood cells from a standard donor unit, and containing hydroxyethyl starch in said fluid external to said cells wherein said unit provides after freezing of said unit, and half an hour after the thawing thereof, a yield of saline stable cells of bout 91% or higher.

A cryoprotecting cell freezing unit consisting essentially of a fluid containing the red blood cells from a standard donor unit, and containing an extracellular cryoprotectant in said fluid external to said cells wherein said cells therein have, after freezing of said unit and thawing thereof, a recovery mean on thaw of about 99% or higher, and a yield of saline stable cells, at half an hour after the thawing thereof, of about 91% or higher.