title: [The optimizing conditions in sorting of side population in Hep-2].
abstract: OBJECTIVE
  To investigate the optimizing conditions in isolation of the side population in laryngeal carcinoma cell line Hep-2.
  
  
  METHODS
  Single-cell suspension cells were detached from the culture flask with trypsin EDTA, at a concentration of 1 x 10(6) cells/ml. (1) The trail Samples were incubated with Hoechst33342 at a concentration of 5 microg/ml, 9 microg/ml, 10 microg/ml, 11 microg/ml for 90 minutes. (2) They were incubated with Hoechst for 50, 70, 90, 110, 130 min in water bath individually. (3) The single-cell suspension were incubated Hoechst in water bath and in thermostat each. (4) The two different density of cells were harvested, which were 100% and 70%, and then di gest into single-cell suspension. Once incubation finished, suspended in phosphate buffered saline (PBS), then test SP% by flow cytometry. Among all groups,Verapamil hydrochloride was added to the control samples, incubated at 37 degrees C for 30 minutes, the other condition were keep the same with their trial groups.
  
  
  RESULTS
  (1) The percentage of Hoechst-negative cells in trial group was (39.96 +/- 0.24)%, (26.23 +/- 0.39)%. (18.79 +/- 0.02)%, (19.01 +/- 0.14)% at the concentration of 5 microg/ml, 9 microg/ml, 10 microg/ml, 11 microg/ml respectively, when the PI-positive cells were (30.45 +/- 0.63)%, (49.9 +/- 0.42)%, (50.12 +/- 0.68)%, (64.16 +/- 0.39)% separately. (2) Varying the duration of staining incubation showed that there was a typical FACS pattern and SP% was constant when the incubation was at least 90 min. (3) Compare to water bath, SP% was more than in thermostat, the SP% was (18.67 +/- 0.45)%, (22.6 +/- 0.50)% respectively; (4) Cell density is also responsible for SP%. The low density the cell is, the less in SP%. SPSS13.0 was used in statistical analysis, the groups were compared using t-Test. P < 0.05 was considered statistically significant.
  
  
  CONCLUSIONS
  The optimum concentration and duration of incubation of Hoechst33342 in isolation of the side population cells in laryngeal carcinoma cell line Hep-2 is 10 microg/ml and 90 min. Incubated in water bath is better than in thermostat. The best staining cell density is around 80%-90%.
authors.forename: Feng
authors.initials: F
authors.lastname: Yu
authors.forename: Maomao
authors.initials: M
authors.lastname: Ai
mesh_terms: D002452:Cell Count; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D006801:Humans; D007822:Laryngeal Neoplasms / Q000473:pathology*; D014411:Neoplastic Stem Cells / Q000166:cytology*; D058985:Side-Population Cells / Q000166:cytology*