Kinetic study of CD34+ cells during peripheral blood stem cell collections

The impact of the separated volume on the yield of CD34+ cells during peripheral blood stem cell collections (PBSCC) remains controversial. We therefore studied the CD34+ cell concentration in the peripheral blood of patients (pts) during PBSCC as well as the total amount of CD34+ cells collected after each blood volume (BV) processed and engraftment data for each cycle of high dose chemotherapy (HD Ctx). A total of 21 PBSCC from 20 patients with different malignancies were analyzed. Stem cells were mobilized by chemotherapy and G-CSF (14 pts) or GM-CSF (6 pts). Samples from the pts peripheral blood and the collection bag were taken after each BV processed and analyzed for CD34+ cells, WBC, platelets (plt), and hemoglobin (Hb). The total volume processed was two to five times the pts calculated BV (mean value 17.4 L, range 9.0-24.0 L). Sixteen pts could be evaluated for engraftment. The mean peripheral blood CD34+ cell count was 116+/-103.5/microl at the start of PBSCC and decreased to 57+/-61.6/microl after processing of four times the pts BV. The mean number of CD34+ cells collected after each BV was 2.3+/-2.4, 5.8+/-5.2, 8.5+/-7.2, and 11.8+/-10.3x10(6) per kg body weight, respectively. The mean plt count decreased by 53+/-40.2/nl, Hb by 1.+/-0.5 g/dl and WBC by 0.+/-6.1/nl after separation of 4 BV. All but two pts reached the target value of 1.5x10(6) CD34+ cells/kg body weight and planned cycle of HD Ctx with 1 PBSCC. All pts engrafted and reached neutrophils>500/microl and plt>20,000/microl at a median of 11 and 13 days, respectively. We could demonstrate, that the yield of CD34+ cells during PBSCC increased continuously with the volume of the separated BV and that up to 5x the patients' BV could be processed safely without serious side effects. Most pts had to undergo only 1 PBSCC to collect sufficient numbers of CD34+ cells to support sequential courses of HD Ctx without delayed engraftment.