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

R. L. Sparrow, H. Komodromou, E. Tippett, T. Georgakopoulos, W. Xu

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15 Citations (Scopus)


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 SYTO16bright 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/SYTO16dim 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.

Original languageEnglish
Pages (from-to)61-67
Number of pages7
JournalBone Marrow Transplantation
Issue number1
Publication statusPublished - Jul 2006
Externally publishedYes


  • Apoptosis
  • CD34
  • CD62L
  • Cord blood
  • Cryopreservation
  • SYTO 16

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