Standardizing stem cell enumeration: A methodological comparison of single and dual flow cytometry platforms

Area of Science:

• Hematology
• Immunology
• Laboratory Medicine

Background:

• Flow cytometry is crucial for stem cell enumeration, with single platform (SP) and dual platform (DP) methods being commonly used.
• Previous studies have yielded conflicting results regarding the comparative performance of SP and DP methods for CD34+ cell enumeration.

Purpose of the Study:

• To evaluate and compare the variations between SP and DP flow cytometry methods for CD34+ stem cell enumeration using a modified workflow.
• To assess the clinical acceptability of observed variations in CD34+ cell counts and viability between the two methods.

Main Methods:

• Analysis of 54 fresh and thawed specimens, including mobilized peripheral blood, apheresis products, and umbilical cord blood.
• Enumeration of absolute viable CD34+ cells and CD34+ viability using both SP and DP flow cytometry methods.
• Statistical analysis to determine concordance and variations between the methods for CD34+ counts and viable white blood cell (WBC) counts.

Main Results:

• High concordance was observed between SP and DP methods for absolute viable CD34+ counts and CD34+ viability in both fresh and thawed specimens.
• Comparable viable WBC counts were found in thawed specimens, with a modest variation in fresh specimens, primarily influenced by umbilical cord blood.
• Median variations in absolute viable CD34+ counts were clinically acceptable (2.4% for fresh, 1.4% for thawed samples).

Conclusions:

• Both SP and DP flow cytometry methods demonstrate high concordance for enumerating viable CD34+ cells and assessing CD34+ viability.
• The DP method offers greater gating flexibility, requires fewer resources, and is more cost-effective, making it a practical alternative.
• Observed variations in WBC counts did not impact CD34+ enumeration and remained within clinically acceptable limits.