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World J Stem Cells. Apr 26, 2010; 2(2): 18-23
Published online Apr 26, 2010. doi: 10.4252/wjsc.v2.i2.18
Hematopoietic stem cells in research and clinical applications: The “CD34 issue”
Zoran Ivanovic
Zoran Ivanovic, Etablissement Français du Sang Aquitaine-Limousin, Place Amélie Raba Léon, BP24, 33035 Bordeaux Cedex, France
Author contributions: Ivanovic Z solely contributed to this paper.
Correspondence to: Zoran Ivanovic, MD, PhD, Etablissement Français du Sang Aquitaine-Limousin, Place Amélie Raba Léon, BP24, 33035 Bordeaux Cedex, France. zoran.ivanovic@efs.sante.fr
Telephone: +33-5-56908383 Fax: +33-5-56908384
Received: February 8, 2010
Revised: March 10, 2010
Accepted: March 17, 2010
Published online: April 26, 2010
Abstract

In this paper, experimental findings concerning the kinetics of hematopoietic reconstitution are compared to corresponding clinical data. Although not clearly apparent, the transplantation practice seems to confirm the basic proposals of experimental hematology concerning hematopoietic reconstitution resulting from successive waves of repopulation stemming from different subpopulations of progenitor and stem cells. One of the “first rate” parameters in clinical transplantations in hematology; i.e. the CD34+ positive cell dose, has been discussed with respect to the functional heterogeneity and variability of cell populations endowed by expression of CD34. This parameter is useful only if the relative proportion of stem and progenitor cells in the CD34+ cell population is more or less maintained in a series of patients or donors. This proportion could vary with respect to the source, pathology, treatment, processing procedure, the graft ex vivo treatment and so on. Therefore, a universal dose of CD34+ cells cannot be defined. In addition, to avoid further confusion, the CD34+ cells should not be named “stem cells” or “progenitor cells” since these denominations only concern functionally characterized cell entities.

Keywords: Hematopoietic progenitors; Transplantation; Hematopoietic stem cells; Hematopoietic reconstitution; Granulocytopenia; CD34+; Functional stem cell definition; Immunophenotype