title: Therapeutic relevance of CD34 cell dose in blood cell transplantation for cancer therapy.
abstract: OBJECTIVE
  To review recent advances in peripheral-blood progenitor-cell (PBPC) transplantation in order to define the optimal cell dose required for autologous and allogeneic transplantation.
  
  
  METHODS
  A search of MEDLINE was conducted to identify relevant publications. Their bibliographies were also used to identify further articles and abstracts for critical review.
  
  
  RESULTS
  The CD34(+) cell content of a graft is regarded as an accurate predictor of engraftment success. Postchemotherapy autologous PBPC transplantation with >/= 5 x 10(6) CD34(+) cells/kg body weight leads to more rapid engraftment than does transplantation of lower cell doses. Further increases in transplant cell dose further accelerate platelet but not neutrophil engraftment. Evidence that long-term hematopoietic recovery may be more accurately predicted by the subpopulation of primitive progenitors transplanted suggests that the content of CD34(+)CD33(-) and long-term culture-initiating cells in cell collection samples may be important for predicting successful engraftment, particularly in patients with poor mobilization. Allogeneic transplantation has been limited by concerns regarding graft-versus-host disease and the use of hematopoietic growth factors in donors. The risk of graft rejection and engraftment failure after HLA-mismatched allogeneic transplantation may be overcome by intensive chemoradiotherapy and the infusion of large numbers of T cell-depleted hematopoietic stem cells.
  
  
  CONCLUSIONS
  An optimal cell dose of >/= 8 x 10(6) CD34(+) cells/kg seems to be recommended for autologous PBPC transplantation. This dose facilitates the administration of scheduled chemotherapy on time and reduces the demand for other supportive therapies. A combination of growth factors may enable patients with poor mobilization to achieve a collection sufficient to allow transplantation. The optimum PBPC dose for allogeneic transplantation remains to be defined.
authors.affiliation: Falck Division of Medical Oncology, Department of Hematology and Oncology, Ospedale Niguarda Ca' Granda, Milan, Italy. salvatore.siena@tin.it
authors.forename: S
authors.initials: S
authors.lastname: Siena
authors.forename: R
authors.initials: R
authors.lastname: Schiavo
authors.forename: P
authors.initials: P
authors.lastname: Pedrazzoli
authors.forename: C
authors.initials: C
authors.lastname: Carlo-Stella
mesh_terms: D018952:Antigens, CD34; D019650:Hematopoietic Stem Cell Mobilization; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D006801:Humans; D009369:Neoplasms / Q000276:immunology / Q000628:therapy; D010641:Phenotype; D014181:Transplantation Immunology; D014182:Transplantation, Autologous; D014184:Transplantation, Homologous
chemical_list: D018952:Antigens, CD34