Establishment and optimization of a flow cytometric method for evaluation of viability of CD34+ cells after cryopreservation and comparison with trypan blue exclusion staining

BACKGROUND: Trypan blue exclusion staining is probably the most frequently applied method (Method I) for assessment of viability in peripheral blood progenitor cell grafts after cryopreservation. Alternatively, a flow cytometry–based method (Method II) was established and optimized. STUDY DESIGN AND METHODS: In a first series of 22 autologous apheresis products, the influence of duration of antibody staining and red cell (RBC) lysis on viability was investigated. In a second series of 21 autologous and 1 allogeneic apheresis products, the effect of omitting the RBC lysis was evaluated. On the basis of the results of the first two series, 155 autologous and 57 allogeneic apheresis products were analyzed with Method I and the now optimized Method II. RESULTS: Halving the incubation times did not influence the viability of CD45+ or CD34+ cells. Omission of RBC lysis resulted in a significantly (p = 0.022) increased median viability of CD45+ cells (75.8% vs. 71.0%) without any influence on CD34+ cells. In the third series, the median viability of CD34+ cells (96.9%) was significantly (p