Intra-apheresis Cycling to Improve the Clinical Efficacy of Peripheral Blood Stem Cell Donations

Peripheral blood stem cell (PBSC) donation is the primary procedure used to collect haemopoietic stem cells (HSCs) for transplantation in individuals with haematological malignancies. More than 90,000 HSC transplants take place globally each year, and there is an increasing need to guarantee HSC mobilisation, improve tolerability to apheresis, and optimise immune reconstitution. Currently, mobilisation of HSCs depends upon pharmacological agents, with donors inactive during their subsequent apheresis. A successful yield of HSCs is not always achieved, and greater efficiency of collection procedures would improve the donors' safety and experience, along with the overall functioning of apheresis departments. The mobilisation of immune cells during bouts of exercise has been increasingly studied over the past 40 years. Exercise enriches peripheral blood with HSCs and immune cells such as cytolytic natural killer cells, and these may impact upon collection efficiency and patient outcomes following transplantation. Using exercise in conjunction with routine pharmaceutical agents may meet these needs. This article describes the impact of exercise on the quantity and engraftment potential of HSCs. Given that PBSC collections take on average 3-4 h per day per donor, and often consecutive days to complete, particular attention is paid to adopting interval exercise in this setting. Moreover, practical and safety considerations for allogeneic and autologous donors are discussed. 'Intra-apheresis cycling' is proposed as a feasible adjunctive strategy to evoke clinically significant improvements in the quality of the immune graft. Further research is needed to validate this concept in conjunction with routine mobilisation agents.