Abstract: The present invention relates a method for the enumeration of mammalian cell micronuclei, while distinguishing micronuclei from the chromatin of dead and dying cells. The method utilizes differential staining of chromatin from dead and dying cells, to distinguish the chromatin from micronuclei and nuclei that can be detected based upon fluorescent emission and light scatter following exposure to an excitatory light source. Counting of micronuclei events relative to the number of nuclei can be used to assess the DNA-damaging potential of a chemical agent, the DNA-damaging potential of a physical agent, the effects of an agent which can modify endogenously-induced DNA damage, and the effects of an agent which can modify exogenously-induced DNA damage. Kits for practicing the invention are also disclosed.

Abstract: A single laser flow cytometric method for the enumeration of micronuclei in erythrocyte populations, wherein a sample of peripheral blood or bone marrow is obtained and the cell populations in the sample are fixed. Reticulocytes in the fixed samples are treated simultaneously with RNAse and with a fluorescent labeled antibody having binding specificity for a surface marker for erythroblasts/reticulocytes. The erythrocyte populations are then stained with a nucleic acid stain which stains DNA representing micronuclei, if present. The stained and/or labelled erythrocyte populations are then exposed to a laser beam of appropriate excitation wavelength for both the nucleic acid staining dye and the fluorescent label to produce fluorescent emission. The fluorescent emission and light scatter produced by the erythrocyte populations are detected by the flow cytometer from which is calculated the number of specific erythrocyte populations in said sample.

Abstract: Disclosed are a composition for the lyophilization of mammalian red blood cells comprising a hydrophilic polymer, a carbohydrate, and an organic solvent; and a method of using the composition to lyophilize red blood cells comprising mixing red blood cells with the composition, freezing the mixture, and drying the mixture by removing water by sublimation. Also disclosed are red blood cells lyophilized according to this method for lyophilization, and a method for reconstituting the lyophilized red blood cells. In particular, the composition used to lyophilize the red blood cells comprises a mixture of a hydrophilic polymer ranging from 1,450-20,000 Daltons at 5-50% w/v, a mono- or disaccharide or a mixture thereof from 0.01-0.2M and an organic solvent such as a primary alcohol, a secondary alcohol, dimethyl sulfoxide or combinations thereof at 0.5-20% v/v.