Collection of autologous peripheral blood stem cells in steady state

Cells normally present in the circulation are capable of providing sustained haematopoietic function in a manner similar to cells normally present in the bone marrow, when transplanted to an autologous or allogeneic recipient. The function of these circulating cells is not known, but they may serve as a reservoir of haematopoietic stem cells which can migrate via the blood stream to sites of need when called upon, thereby providing a protective role. In the past, these cells were collected from the blood during steady-state marrow function to serve as both autologous and allogeneic graft products for transplantation. While this application has since been abandoned in favour of mobilized blood stem-cell transplantation, laboratory investigation of non-mobilized circulating stem cells will be needed if a full understanding of their purpose and function is to be learned.