Peripheral Blood Stem Cell Collection and Engraftment Kinetics in Pediatric Patients

Yoon, Won Sang; Kook, Hoon; Kim, Chan Jong; Park, Anna; Ryang, Dong Wook; Hwang, Tai Ju

Abstract

PURPOSE: Peripheral blood stem cell transplantation (PBSCT) has recently been used to rescue from myelosuppression following high-dose chemo-radiotherapy in patients with leukemia and solid tumor. Nevertheless, few data are still available on PBSC collection in pediatric patients, owing to technical problems. The time of stem cell harvest and the mobilization regimen may play important roles in terms of achieving adequate numbers of stem cells by leukapheresis. In this study, we analyse; 1) the technical aspects of leukapheresis as to feasibility and safety, 2) the optimal timing for PBSC collection after cytokine-based mobilizing regimens, 3) the engraftment kinetics. Method: A total of 93 leukapheresis was performed 22 children by Fenwall CS 3000 continuous cell separator, of whom 15 children weighed less than 25 kg. To mobilize hematopoietic stem cells into circulation, hematopoietic growth factor plus chemotherapy were used. Nineteen patients underwent autologous peripheral blood stem cell transplantation.
RESULTS
The mean body weight was 25.3 kg (range: 10 to 56 kg). A total of 3 to 12 L of blood was processed (mean 265.4 65.9 mL/kg) for 2.5 to 5 hours (mean 3.15 hours). Extracorporeal line was primed with packed red blood cells below 25 kg. Serious morbidity was not noted. Each apheresis products contained a mean of 2.41 1.63x108 mononuclear cells/kg, 2.83 3.40x106 CD34 cells/kg, 9.30 10.3x104 colony forming unit (CFU-GM)/kg, respectively. Absolute neutrophil count (r=0.38, P<0.01) and CD34 cell count (r=0.65, P<0.001) on the day of leukapheresis seemed to predict the CFU-GM count collected in leukapheresis. A significant statistical correlation between the number of infused CFU-GM and the time to achieve an absolute neutrophil count of greater than 500/mm3 (P<0.01) was found.
CONCLUSION
Leukapheresis for PBSCT seemed to be feasible and reliable in pediatric patients, conferring no major additional risks than adult patients, only if red cells are primed in extracorporeal line for small children. Absolute neutrophil count and CD34 cell number seemed to predict the timing of leukapheresis. In the PBSCT patient, engraftment was influenced by the infused CFU-GM count and bone marrow environment.