Cell processing protocol for allogeneic peripheral blood stem cells mobilized by granulocyte colony-stimulating...

Area of Science:

• Hematology
• Immunology
• Stem Cell Transplantation

Background:

• Peripheral blood stem cell (PBSC) autografts are well-documented, but allograft applications are less explored.
• Restoration of hematopoiesis using allogeneic PBSCs requires efficient stem cell mobilization and T-cell depletion.

Purpose of the Study:

• To investigate the feasibility of mobilizing PBSCs using recombinant human granulocyte colony-stimulating factor (G-CSF) in healthy donors.
• To evaluate different methods for bulk T-cell depletion from apheresis-harvested PBSCs.

Main Methods:

• Nine healthy donors received G-CSF (5 or 2 micrograms/kg/d) for 5 days to mobilize PBSCs.
• Serial blood counts and hematopoietic progenitor cells (CFU-GM) were monitored.
• PBSCs were collected via apheresis, and T-cell depletion was attempted using L-phenylalanine methyl ester (PME), anti-CD5/CD8 monoclonal antibodies, or neuraminidase-treated sheep red blood cells (SRBC).

Main Results:

• G-CSF administration led to a plateau in white blood cell counts and a significant increase in circulating CFU-GM levels.
• The 5 micrograms/kg/d G-CSF dose yielded higher CFU-GM counts (4.6 x 10^6) compared to the 2 micrograms/kg/d dose (1.8 x 10^6).
• PME-based cell lysis was effective for initial cell processing, but T-cell depletion (99.5%) and hematopoietic progenitor cell recovery (7.5%) were suboptimal.

Conclusions:

• G-CSF is effective in mobilizing PBSCs with increased hematopoietic progenitor cells for potential allograft use.
• Current T-cell depletion strategies require significant improvement to achieve adequate T-cell removal while preserving stem cell function.
• Further research is necessary to optimize T-cell depletion protocols for clinical application in allogeneic PBSC transplantation.