Collection of Peripheral Blood Stem Cells Using G-CSF and Plerixafor in Normal Volunteers

Hematopoietic stem cells that have been mobilized from the bone marrow into the peripheral circulation are readily collected by apheresis, and may be used for several purposes. They are used for allogeneic and autologous transplantation and are often manipulated in various ways depending on the goal of the transplant. Gene therapy for immunodeficiencies relies on the collection of these cells. Traditionally, mobilization has been done using granulocyte colony stimulating factor (G-CSF). However not all patients or normal donors respond to GCSF alone. Plerixafor, a recently Food and Drug Administration (FDA) approved drug, has a unique mode of action distinct from that of GCSF, but also results in mobilization of peripheral blood progenitors into the circulation, allowing their collection by standard apheresis. The quality of these cells for transduction using viral vectors in anticipation of gene therapy uses has not been thoroughly assessed, and there are theoretical considerations why vectors that use various envelopes for cell binding may be affected by the use of this CXCR4 antagonist. In order to be able to assess the transduction and engraftment of these cells in murine models, we will perform collection and mobilization on 5 healthy volunteers at the NIH Clinical Center using the FDA approved medications G-CSF and plerixafor.