Hematopoietic  Progenitor  Cells  (HPC)  Novel  parameter  in  Hematology  Analyzer  

 

                                                                                                                                                                                                                   Kanchan  Jeswani                                      Product  Manager  -­‐  Hematology                                              Transasia  Bio-­‐Medicals  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  Bio-­‐Medicals  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   colony-­‐stimulating   factor   (G-­‐CSF)  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).    

                                                                             The   investigators   found   a   strong   correlation   between   the   numbers   of  HPCs   and   CD34+   cells.   The   expected  total  number  of  HPCs  in  the  final  product  was  estimated  from  HPCs  in  pre  apheresis  peripheral  blood  (PB)  or  mid  apheresis  product.  This  count  was  found  to  correlate  well  with  the  total  number  of  CD34+  cells  in  the  final  products.   Moreover,   the   change   in   HPCs   in   PB   closely   resembled   that   of   CD34+   cells   during   mobilization.  Further,  studies  using  immunomagnetic  beads  suggested  that  majority  of  CD34+  cells  existed  in  HPCs,  and  vice  versa.      

             Figure  1-­‐    No  HPC  detected                    

                 Figure  2  –  HPC  detected      Conclusion    

• The  Sysmex  XN  analyzer  can  carry  out  an  HPC  enumeration  without  the  use  of  monoclonal  antibodies  • Sensitivity   of   flagging   of   blasts   is   enhanced   in   the  WPC   channel   of   the   instrument.   It   gives   a   clear  

demarcation  between  the  blasts  and  the  abnormal  lymphocytes.  • The   total   number   of   HPCs   in   the   final   products,   as  well   as   from  pre   apheresis   PB   and   intermediate  

products  during  apheresis,  can  be  used  to  predict  the  final  amount  of  collected  CD34+  cells.    • The  detection  and  number  of  HPC  in  the  peripheral  blood  could  possibly  provide  a  standard  and  rapid  

alternative  for  predicting  the  yield  of  stem  cells  collected  by  apheresis.  • HPCs  may  also  be  a  good   indicator  to  know  the  optimal  timing  for  collection  of  the  peripheral  blood  

stem  cells.  • The  HPC  count  can  thus  be  a  useful  potential  parameter  in  optimizing  timing  for  CD34+  enumeration  

prior  to  leukapheresis.  

   References:  

1. Bali  Medical  Journal  (Bali  Med.  J.)  2014,  Volume  3,  Number  3:  112-­‐115\P-­‐ISSN.2089-­‐1180,  E-­‐ISSN.2302-­‐2914  www.balimedicaljournal.org  or  www.ojs.  unud.ac.id  112                            HEMATOPOIETIC  PROGENITOR  CELLS  AS  A  PREDICTIVE  OF  CD34+  ENUMERATION  PRIOR  TO  PERIPHERAL  BLOOD  STEM  CELLS  HARVESTING  1Zefarina  Zulkafli,  2Rapiaah  Mustaffa,  and  2Shafini  Mohammed  Yusoff  

2. Hemopoietic   Progenitor   Cell   (HPC)   Enumeration:   A   Comparitive   Study   between   Flow   Cytometry   and   Sysmex   XE-­‐2100  Hematology  Analyzer-­‐  Salem  H.  Khalil,  Barbara  GengJournal of Appplied Hematology 2010

3. http://www.bloodjournal.org/content/122/21/2032November 15, 2013; Blood: 122 (21) 4. December 27, 2013, in the International Journal of Laboratory Hematology