Collection and Recruitment of CD34+ Cells During Large-Volume Leukapheresis

Abstract

Although sufficient progenitor cells for hematopoietic rescue following high-dose therapy may be obtained in a single leukapheresis, the majority of patients require multiple procedures. In an attempt to minimize the number of leukapheresis and maximize collection efficiency, we undertook large-volume leukapheresis in 17 patients with a variety of hematologic malignancies. Twenty-four procedures were performed over a 6-h period, with a mean of 21 L of blood processed. By employing a modified collection set, three separate 2-h collection bags were analyzed for a number of variables. CD34+ cells are collected at a steady rate throughout the procedure, with no evidence of exhaustion of progenitor cells. There was evidence of progenitor cell recruitment, with 1.4-fold more CD34+ cells in the collected product than were present in the blood at the beginning of the procedure. Initiation of leukapheresis was based on the blood CD34+ count, and this value was strongly correlated with the number of CD34+ cells in the collected product. The procedure is safe and relatively simple and minimizes the number of leukaphereses required to collect adequate progenitors for autologous transplantation.

Large volume leukapheresis: Efficacy and safety of processing patient’s total blood volume six times

“…Our results confirm that CD34+ cells were collected at a steady rate throughout the LVL [9,19,26,30]. The lowest CD34+ cell yield and collection efficiency were observed at the very beginning of LVL, which can be explained by the time required to establish interface, and by a dilution effect in the first collection bag, caused by the automated filling with saline [19,29,31].…”

“…The lowest CD34+ cell yield and collection efficiency were observed at the very beginning of LVL, which can be explained by the time required to establish interface, and by a dilution effect in the first collection bag, caused by the automated filling with saline [19,29,31]. In the remaining collection period, the CD34+ cell yield and collection efficiency were stable, without any time-dependent changes, as Bojanic,16 observed by others [9,10]. Furthermore, the MNC purity remained constant during LVL, confirming that enhanced blood volume processing doesn't affect the product quality in terms of higher granulocyte contamination during the final stages of apheresis [19].…”

“…Higher CD34+ cell yield harvested by processing a larger volume of blood was explained with a steady recruitment of PBSCs during leukapheresis [8,9,18,19]. In our study, threefold more CD34+ cells were collected than were present in blood before leukapheresis.…”

“…The optimal study design would be to compare products collected during the same procedure at different time, which was done in this study, and differences caused by interindividual variability were excluded. Studies of kinetics of PBSC enrichment during LVL showed variable results [3,[8][9][10][19][20][21][22][23][24][25][26][27][28][29][30][31], which could be consequence of difference in volumes of processed blood. Therefore, processed blood volume in our study was standardized and strictly related to the patient's TBV.…”

“…CD34+ cell collection efficiency [6,7] and recruitment factor [8][9][10] for the various cell populations were calculated as previously described.…”