Use of the Hematopoietic Progenitor Cell Parameter on the Sysmex SE-9500TMas a Screening Tool for Circulating Hematopoietic Precursors in Pediatrics

Abstract

In the field of hematopoietic progenitor cell therapy there is the need for a rapid and inexpensive screening tool for quantification of hematopoietic precursors. Currently the surrogate measures of the hematopoietic stem cell that are used in clinical practice are the hematopoietic colony forming unit or quantitation of CD34+ cells. The hematopoietic progenitor cell (HPC) parameter that runs on the platform of the SE-9500 has been developed to provide a rapid screening test for hematopoietic precursors that is comparable to CD34+ cell quantitation. The advantages of this assay are that it is a rapid, low-complexity and inexpensive test that easily fits into the routine clinical laboratory flow. We evaluated the HPC measurement and compared it to the other measurements of hematopoiesis in the clinical pediatric setting. Umbilical cord blood HPC correlated well with total nucleated cell count (r = 0.6), CD34 quantitation (r= 0.62), and colony forming units (r = 0.86). There were no detectable HPC in peripheral blood once outside the newborn period. With growth factor mobilization there was an increase in HPC detected in peripheral blood ranging from 0 to 800 HPC/µl on the day of planned stem cell apheresis. We found a linear correlation between the day of apheresis peripheral blood CD34 count and the HPC measurement. Furthermore, using either measure we were able to predict the number days of collection that would be required to reach a target hematopoietic collection (usually 5 × 10⁶ CD34/kg). In the pediatric setting the HPC measurement appears to be a useful adjunct to care – especially as a screening tool for stem cell mobilization and collection.