Hematopoietic Progenitor Cells (HPC) Novel parameter in Hematology Analyzer Kanchan Jeswani Product Manager Hematology Transasia BioMedicals Ltd. Peripheral blood stem cells (PBSC) are increasingly used to restore hematopoiesis as an alternative to bone marrow transplantation. It is important to determine the precise time for HSCs (hematopoietic stem cells) to be collected for a reliable, rapid and successful hematological recovery. HPC and HSC express high levels of the cell surface glycoprotein,adhesion receptor CD34. The levels of CD34 expression decreases with cell maturation and differentiation. Expression of CD34+ is thus a defininghallmark for hematopoietic stem cells (HSCs) andprogenitor cells (HPCs) in bone marrow (BM), peripheral blood (PB) and cord blood. An accurate quantification of circulating CD34+ stem cells is important to decide the optimal time for collection. Flow cytometric enumeration of CD34+is the standard method of counting. The International Society of Hematotherapyand Graft Engineering (ISHAGE) gating strategy isused for CD34+ cell detection. An alternate method for quantification of circulating HSC minimizes the number of CD34 determination, thus saving important resources. Since the introduction of the HPC software in 1997 in the high end Sysmex analyers, many studies of HPC determination versus CD34+ cell enumeration have been performed. The HPC parameter serves as an inexpensive and fast alternative for quantification of the circulating HSC Cells. Sysmex Corporation, Japan offers the latest and best technology in hematology analyzers. Marketed in India, exclusively by Transasia BioMedicals Ltd., Sysmex offers a whole range of systems ranging from 3 to 6 Part Differential Analyzers. Infact the newly launched Sysmex XN series is equipped with a White Precursor Cell (WPC) channel to differentiate abnormal lymphocytes and blasts by using the optical detection system and Fluoroscence flow cytometry. A study (published in December, 2013, in the International Journal of Laboratory Hematology) conducted by the scientists at the National Cancer Center Hospital (Tokyo, Japan) concluded that the HPC count obtained on a Sysmex XN analyzer correlates accurately with the enumerated CD34 cells. Cells expressing the CD34+ and hematopoietic progenitor cells (HPCs) were compared in 76 granulocyte colonystimulating factor (GCSF) mobilized blood or apheresis samples taken from 18 healthy donors and 6 patients undergoing autologous PBSCT. CD34+ cells were isolated using MACS magnetic cell separation kits (MiltenyiBiotec – BergischGladbach, Germany).