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Peripheral blood stem cell transplantation in young children: experience with harvesting, mobilization and
M Kletzel1, R Longino, A W Rademaker
1Department of Pediatrics, The Children's Memorial Hospital, Northwestern University School of Medicine, Chicago, Illinois 60614, USA. mkletzel@anima.nums.nwu.edu
Insights
Collecting peripheral blood stem cells (PBSC) is feasible and safe in young children for transplantation. Optimal timing for PBSC collection is during white blood cell (WBC) recovery, around 1.0 x 10(9)/l, ensuring prompt engraftment.
Area of Science:
- Pediatric Hematology
- Stem Cell Transplantation
- Oncology
Background:
- Peripheral blood stem cell (PBSC) transplantation is a critical treatment for pediatric cancers.
- Mobilization and collection of PBSC in young children (<25 kg) present unique challenges.
- Assessing optimal timing and feasibility is crucial for successful engraftment.
Purpose of the Study:
- To determine the feasibility of harvesting PBSC in young children.
- To assess the optimal timing for PBSC collection post-mobilization.
- To evaluate the safety and efficacy of PBSC transplantation in this cohort.
Main Methods:
- Thirteen children (<25 kg) with recurrent solid tumors/leukemia received chemotherapy and rhG-CSF for stem cell mobilization.
- Cytaphereses were performed via central venous line (CVL) during marrow recovery (WBC >0.5 x 10(9)/l).
- Phereses were grouped by WBC count (Group I: <1.0, Group II: 1.0-3.0, Group III: >3.0 x 10(9)/l) and analyzed for cell content and tumor contamination.
Main Results:
- No significant differences in CD34+ cells, CFU-GM, or BFU-E were found across WBC groups.
- Higher mononuclear cell (MNC) yields were observed in Groups II and III compared to Group I (p<0.001).
- All patients achieved prompt and durable engraftment (WBC and platelets); no tumor contamination detected in neuroblastoma patients.
Conclusions:
- PBSC collection is feasible and safe in young children using a CVL after chemotherapy and G-CSF mobilization.
- Optimal cytapheresis occurs when peripheral WBC count approaches 1.0 x 10(9)/l.
- Successful engraftment supports the use of PBSC transplantation in this pediatric population.
Abstract:
The purpose of this study was to determine the feasibility and assess optimal timing of harvesting peripheral blood stem cells (PBSC) for transplantation in young children. Thirteen children with body weight less than 25 kg, mean age of 3.9 years (1-9 yrs) who had recurrent solid tumors and leukemia were given tumor specific chemotherapy followed by i.v. rhG-CSF (5 microg/kg/d) for stem cell mobilization. Cytaphereses were done through a central venous line (CVL) during the marrow recovery phase (WBC >0.5 x 10(9)/l). The phereses were analyzed separately and assigned to three groups depending on the WBC at the time of the pheresis: Group I (WBC <1.0 x 10(9)/l), Group II [WBC in the range 1.0-3.0 x 10(9)/l] and Group III (WBC >3.0 x 10(9)/l). Samples from each harvest were assayed for cell count, CFU-GM, BFU-E, CD34+ cell count, and tumor cell immunocytology in patients with neuroblastoma (NBL). A median of 3.2 x 10(8) mononuclear cells per kg (MNC/kg), [mean 2.8 x 10(8) MNC/kg, standard error of the mean (SEM) +/- 0.74 (1.1-4.7)] were infused following myeloablative therapy. 78 phereses were performed in 13 children with a median weight of 18 kg (10-25 kg). A median of 5 phereses were performed per patient. There were no significant differences in the percentage and number of CD34+ cells, CFU-GM or BFU-E colonies assayed by plating 0.5 x 10(5) cells. Differences could be found in the total number of MNC (p<0.008) and the number of MNC/kg (p<0.001) between Groups II and III. No tumor cell contamination was detected in the NBL patients by immunocytology. All patients were rescued with PBSC and achieved sustained white cell engraftment (ANC >0.5 x 10(9)/l) at a median of 13.5 d (10-25 d) and platelet engraftment (untransfused platelet count >20.0 x 10(9)/l) at a median of 29 d (12-63 d). The only toxicity encountered during the phereses was thrombocytopenia in 4 patients whose median post-pheresis platelet count was 6.0 x 10(9)/l (3.0-9.01). It is concluded that collection of PBSC in young children is feasible and safe and can be performed through a cuffed CVL at the time of WBC recovery post mobilization with chemotherapy and G-CSF. Cytopheresis can be effectively performed when the peripheral WBC count approaches 1.0 x 10(9)/l. Following stem cell infusion, engraftment was prompt and durable.