title: Apoptotic lymphocytes and CD34+ cells in cryopreserved cord blood detected by the fluorescent vital dye SYTO 16 and correlation with loss of L-selectin (CD62L) expression.
abstract: Discrimination between live and apoptotic cells is important for accurate determination of viable CD34(+) cells in hematopoietic stem cell transplant products. SYTO16 is a sensitive fluorescent dye for discriminating live from apoptotic leukocytes. The incidence of apoptotic leukocytes in paired samples of fresh and cryopreserved-thawed cord blood (CB) was determined by the SYTO16/7-AAD flow cytometric assay. Cell migration and expression of the cell homing molecule L-selectin (CD62L) was determined in relation to SYTO16 staining. SYTO16 detected significant proportions of apoptotic lymphocytes and CD34(+) cells in fresh and thawed CB buffy-coat samples that were not detected by 7-AAD. Compared to fresh CB, the proportion of apoptotic lymphocytes and CD34(+) cells significantly increased following thawing. Significantly higher proportions of live SYTO16(bright) lymphocytes and CD34(+) cells were found in the migrated cell population compared to the non-migrated population. Significantly fewer lymphocytes and CD34(+) cells expressed CD62L following thawing. Absence of CD62L expression was strongly correlated with apoptotic/SYTO16(dim) lymphocytes and CD34(+) cells. Cryopreserved-thawed CB contains significant proportions of apoptotic lymphocytes and CD34(+) cells that are not detected by 7-AAD. SYTO16 offers a sensitive method for discrimination of live from apoptotic leukocytes and assists in accurate assessment of CB quality and suitability for use in clinical transplantation.
authors.affiliation: Research Unit, Australian Red Cross Blood Service, Melbourne, Victoria, Australia. rsparrow@arcbs.redcross.org.au
authors.forename: R L
authors.initials: RL
authors.lastname: Sparrow
authors.forename: H
authors.initials: H
authors.lastname: Komodromou
authors.forename: E
authors.initials: E
authors.lastname: Tippett
authors.forename: T
authors.initials: T
authors.lastname: Georgakopoulos
authors.forename: W
authors.initials: W
authors.lastname: Xu
mesh_terms: D018952:Antigens, CD34 / Q000096:biosynthesis*; D017209:Apoptosis / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D015925:Cryopreservation / Q000379:methods*; D005312:Fetal Blood / Q000166:cytology*; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D019041:L-Selectin / Q000096:biosynthesis*; D008214:Lymphocytes / Q000166:cytology* / Q000502:physiology; D008856:Microscopy, Fluorescence / Q000379:methods; D013194:Staining and Labeling
chemical_list: D018952:Antigens, CD34; D005456:Fluorescent Dyes; D019041:L-Selectin