The phenotypic profile of CD34‐positive peripheral blood stem cells in different mobilization regimens

Abstract

Summary. The type of regimen used might result in mobilization of phenotypically and functionally different CD34 1 cells. We compared the phenotype of CD34 1 cells in leukapheresis products of three homogeneous groups: I, healthy individuals treated with granulocyte colony-stimulating factor (G-CSF) alone (n 13); II, patients mobilized with G-CSF following chemotherapy (n 16); and III, patients mobilized with G-CSF after high-dose chemotherapeutic pretreatment (n 24). Multiparameter flow cytometry was performed for CD341 subpopulation analysis and focused on adhesion molecules, differentiation markers and megakaryocytic markers relevant for stem cell homing, with special reference to the importance of L-selectin expression. Regimens I and II led to higher numbers of mobilized CD34 subpopulations that were also positive for L-selectin, there was no significant difference between the three regimens. A similar approach for the megakaryocytic CD34 1 population resulted in an even worse quality of regimen III: 5´1% of CD34 1 being CD41 1 /L-selectin 1 compared with 9´2% and 8´9% in regimens I and II respectively. We concluded that the phenotypes of the CD34 1 cells in the G-CSF (group I) and G-CSF±chemotherapy (group II) regimens are similar, whereas the phenotype of the CD34 1 cells mobilized in the high-dose regimen (group III) displayed features that might negatively influence homing of the cells. Future studies will be directed towards regimens that will lead to the mobilization of a higher amount of CD34 1 cells with a phenotypically favourable phenotype.

CD34+ cell adhesion molecule profiles differ between patients mobilized with granulocyte–colony‐stimulating factor alone and chemotherapy followed by granulocyte–colony‐stimulating factor

“…Chemotherapy received before the mobilization regimen has been reported to result in adhesion molecule down regulation 6 . This observation suggested the hypothesis that down regulation in adhesion molecule profiles might be a mechanism involved in the superiority of chemotherapy plus growth factor mobilization.…”

“…The mechanism(s) underlying this difference is unknown. The observations that mobilized CD34+ cells show down regulation of several adhesion molecules 1 and that chemotherapy administered before the mobilization regimen may result in adhesion molecule down regulation 6 suggested the possibility that a similar mechanism might contribute to the superiority of chemotherapy plus growth factor mobilization regimens. In addition, differing adhesion molecule profiles related to mobilization regimen, if present, might affect engraftment.…”

Bioequivalence of two recombinant granulocyte colony-stimulating factor formulations in healthy male volunteers

“…Increments in circulating leukocytes were exclusively due to ANC since other lineages did not have variations. The circulating CD34+ cell count increment has been suggested to be an adequate variable that measures stem cell mobilization [30][31][32][33]. The compared formulations did not differ significantly with respect to this variable either.…”