Australasian CD34+ quality assurance program and rationale for the clinical utility of the single-platform method for CD34+ cell enumeration

Flow cytometric CD34+ stem cell enumeration: Lessons from nine years' external quality assessment within the Benelux countries

“…Third, single platform methodologies avoid inaccuracies by rounding up or down low percentages of CD34þ cells in dual platform techniques used for calculations of absolute CD34þ cell counts. Our current analysis of 9 years' experience with EQA for CD34þ cell counting confirms and extends the studies by Barnett et al, 2000;Chang et al, 2004;. Furthermore, it shows that the implementation of single platform methodology is highly effective in reducing between-laboratory variability of this assay.…”

“…It is well known that dual-platform techniques are associated with higher variability than single platform techniques (29,37,44). First, single platform technologies bypass the denominator issue, i.e., the percentage CD34þ cells should be reported as a proportion of leukocytes, total nucleated cells, or total events scattering above a FSC threshold.…”

Assessment of cord blood unit characteristics on the day of transplant: comparison with data issued by cord blood banks

“…In addition to the effect of thawing and washing, this most probably accounts for the high discrepancy between our results and those issued by CBBs. Nevertheless, we used the standard dual‐platform ISHAGE protocol for all CB units processed 13 and have recently moved to the single‐platform ISHAGE method that was proven to be more reproducible from one center to another 20,28 . Although recognized as more accurate, the single‐platform CD34+ cell enumeration method has not yielded unacceptable differences with the dual‐platform method in our hands (data not shown).…”

“…We invariably noted, however, lower TNC counts and doses than reported by CBBs (Table 2). One must be aware that, as different automated cell counters are used by different centers, discrepancies in TNC counts can be expected at times, 20 which we have noted for some units. Moreover, the thawing and washing procedure is known to induce a loss in TNC because of its nature 12 and the presence of nucleated RBCs that hemolyze during thawing 8 .…”

Ten Years of External Quality Control for Cellular Therapy Products in France

“…The single-platform methods are also relevant for the measurement of CD34+ cells in the thawed products where the sample brittleness makes the double-platform use more delicate (without beads) as well as for products from bone marrow because of the presence of erythroblasts (which are CD45 negative cells). Thus, external control results contribute to develop the use of standardized tools by showing their superiority as it confirms by several publications (Barnett et al, 2000 ;Gratama et al, 2003 ;Chang et al, 2004). Indeed, whereas single-platform methods were used only by 30% of French producers of HSC in 2000, there are now 75%.…”