Integration of biological, procedural, apheresis principles of peripheral blood stem cell transplantation programs

Collection and use of peripheral blood stem cells have rapidly replaced harvesting of pelvic bone marrow for transplant protocols. The mobilization of progenitor populations into the peripheral blood by chemotherapy and/or cytokine stimulation of marrow hematopoietic production has made it possible, in general, to collect larger quantities of progenitor populations than obtained in a single harvest of marrow. Technological advances through flow cytometry and generation of monoclonal antibodies to identify CD34 antigen expression on cells has provided a rapid means of assessing leukapheresis products for the presence of progenitor populations and has largely replaced the laborious 14 day culture assays' to measure colony forming units. Unlike apheresis platelet collection, where the yields are predictable through integration of donor biological variability, total volume of blood processed, and machine efficiency, CD34+ cell yields are not predictable. This has led to great diversity in stem cell collection procedures. Analyses of the same variables used to predict platelet yields, if applied to CD34+ cell collection, might lead to useful algorithms for development of standardized guidelines for stem cell collection.