Project description:CD34+ hematopoietic stem and progenitor cells were isolated immunomagnetically from patients with multiple myeloma during chemotherapy and G-CSF-induced mobilization. Patients received either unconjugated G-CSF (n=9) or polyethylenglykol (PEG)-conjugated G-CSF (n=7). From each patient only one sample was analyzed. Total RNA was extracted, reversely transcribed, in vitro transcribed and labelled and hybridized to Affymetrix HG Focus Arrays according to manufacturer's instructions. Following quality control and normalization 9 samples of G-CSF-mobilized CD34+ cells were compared with 7 samples of PEG-G-CSF-mobilized cells were compared by significance analysis of microarrays (SAM). The aim was to figure out transcriptional differences resulting from various pharmacokinetics of the same drug (G-CSF: fluctuating serum levels; PEG-G-CSF: continously high serum levels). Peripheral blood stem and progenitor cells (PBSC) are widely used for autologous and allogeneic hematopoietic stem cell transplantation. PBSC can be mobilized into the peripheral blood using cytokines, cytotoxic chemotherapy or a combination of both. Granulocyte colony stimulating factor (G-CSF) has become the most commonly administered cytokine for PBSC mobilization because of its high potency and lack of serious toxicity. Recently, a modified form of recombinant human G-CSF has been introduced. This new compound is pegylated G-CSF (Peg-G-CSF) which possesses a substantially longer half-life than the unconjugated drug because of its reduced renal excretion and therefore provides the basis for continuous G-CSF serum-levels after a single injection. The use of Peg-G-CSF in patients who had received a cytotoxic chemotherapy was accompanied by mobilization kinetics different from those observed in patients who had received unconjugated G-CSF. In particular, more rapid leukocyte recovery and occurrence of CD34-positive cells in the peripheral blood was seen. These findings are presumably related to the more even and continuously high serum level of G-CSF maintained by Peg-G-CSF. Using microarray technology and functional assays, we examined whether pegylation of G-CSF and its different pharmacokinetics results in addition to an earlier leucocyte recovery in transcriptional and functional changes in CD34+ cells obtained from patients who had received either G-CSF or Peg-G-CSF following a standard cytotoxic chemotherapy for PBSC mobilisation. CD34+ hematopoietic stem and progenitor cells were isolated immunomagnetically from patients with multiple myeloma during chemotherapy and G-CSF-induced mobilization. Patients received either unconjugated G-CSF (n=9) or polyethylenglykol (PEG)-conjugated G-CSF (n=7). Total RNA was extracted, reversely transcribed, in vitro transcribed and labelled and hybridized to Affymetrix HG Focus Arrays. Following quality control and normalization differentially expressed genes were identified by significance analysis of microarrays (SAM). Comparing both groups 339 genes were significantly differentially expressed (q value <5%; fold change > 1.2). Peg-G-CSF-mobilized CD34+ cells showed an expression pattern of more early progenitor cells as early stem cell markers such as HOX genes were higher expressed and differentiation-associated genes were lower expressed in comparison with G-CSF-mobilized cells. Moreover, Peg-G-CSF-mobilized CD34+ cells had a greater expression level of cell-cycle-promoting genes suggesting a greater cycle activity of these cells. In conclusion, despite the similar active drug component different pharmacokinetics of Peg-G-CSF and G-CSF result in distinct molecular phenotypes reflecting different functional characteristics.

Project description:Peripheral blood stem and progenitor cells (PBSC) are widely used for autologous and allogeneic hematopoietic stem cell transplantation. PBSC can be mobilized into the peripheral blood using cytokines, cytotoxic chemotherapy or a combination of both. Granulocyte colony stimulating factor (G-CSF) has become the most commonly administered cytokine for PBSC mobilization because of its high potency and lack of serious toxicity. Recently, a modified form of recombinant human G-CSF has been introduced. This new compound is pegylated G-CSF (Peg-G-CSF) which possesses a substantially longer half-life than the unconjugated drug because of its reduced renal excretion and therefore provides the basis for continuous G-CSF serum-levels after a single injection. The use of Peg-G-CSF in patients who had received a cytotoxic chemotherapy was accompanied by mobilization kinetics different from those observed in patients who had received unconjugated G-CSF. In particular, more rapid leukocyte recovery and occurrence of CD34-positive cells in the peripheral blood was seen. These findings are presumably related to the more even and continuously high serum level of G-CSF maintained by Peg-G-CSF. Using microarray technology and functional assays, we examined whether pegylation of G-CSF and its different pharmacokinetics results in addition to an earlier leucocyte recovery in transcriptional and functional changes in CD34+ cells obtained from patients who had received either G-CSF or Peg-G-CSF following a standard cytotoxic chemotherapy for PBSC mobilisation. CD34+ hematopoietic stem and progenitor cells were isolated immunomagnetically from patients with multiple myeloma during chemotherapy and G-CSF-induced mobilization. Patients received either unconjugated G-CSF (n=9) or polyethylenglykol (PEG)-conjugated G-CSF (n=7). Total RNA was extracted, reversely transcribed, in vitro transcribed and labelled and hybridized to Affymetrix HG Focus Arrays. Following quality control and normalization differentially expressed genes were identified by significance analysis of microarrays (SAM). Comparing both groups 339 genes were significantly differentially expressed (q value <5%; fold change > 1.2). Peg-G-CSF-mobilized CD34+ cells showed an expression pattern of more early progenitor cells as early stem cell markers such as HOX genes were higher expressed and differentiation-associated genes were lower expressed in comparison with G-CSF-mobilized cells. Moreover, Peg-G-CSF-mobilized CD34+ cells had a greater expression level of cell-cycle-promoting genes suggesting a greater cycle activity of these cells. In conclusion, despite the similar active drug component different pharmacokinetics of Peg-G-CSF and G-CSF result in distinct molecular phenotypes reflecting different functional characteristics. Keywords: ordered

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