Peripheral blood stem cell collection: The interaction of technology, procedure, and biological factors

Centrifugal technology, continuous flow and discontinuous flow, has served as the technology platform for extracting cell concentrates of interest fro m peripheral blood (PB) for patient therapy for the past 35-40 yr. Models f or procedure outcome exist for collection of normal donor (ND) platelet and granulocyte concentrates that integrate: (1) biological variables (pre-pro cedure PB cell concentration, the total circulating quantity of cells, dono r/patient blood volume (BV)), (2) device efficiency, and (3) procedure para meters such as total blood processed (TBP), and in the case of cytoreductio ns - the volume collected. (cf. Hester J, Kellogg R, Mulzet A, et al., Bloo d (54) (1979) 254; Hester J, Ventura G, J Clin Apheresis (4) (1988) 188.) T o date, no predictive CD34+ yield algorithm integrating these three variabl es has been formulated that could be applied prospectively for individual N D or patients (PT). There are economic, toxicity and statistical comparison benefits to be derived from generating such an algorithm. A small pilot study is presented with a brief review of current publication s that suggest the circulating quantity of CD34+ cells available to be coll ected and the quantity mobilized during leukapheresis are the major contrib uting factors to CD34+ yield, somewhat obscuring the role of the total bloo d processed (TBP). Intraprocedure CD34+ cell mobilization, incompletely cha racterized to date, appears to be a dynamic nonlinear process, as the harve sted yield does not rise proportionally as the fraction of BV processed inc reases. And, like the pre-procedure PB CD34+ concentration and total circul ating quantity, CD34+ mobilization during leukapherrsis probably relates to prior treatment. and the priming regimen. Studies that provide: (1) separa te analyses of PT populations divided according to chemotherapy toxicity fa ctors; (2) design and implementation of optimal priming regimens with respe ct to dose 'intensity' of both growth factors and chemotherapy; and (3) sta ndardization of laboratory assays of CD34+ enumeration seem essential to ge nerating a predictive algorithm. (C) 2000 Elsevier Science Ltd. All rights reserved.