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Background: Leukapheresis for peripheral blood stem cell collection is increasingly being carried out in pediatric cancer patients. Aim of this study was to report experience of the Padua Apheresis Unit on a series of children weighting < 15 kg who have undergone such an apheresis procedure., Methods: This retrospective study includes 15 pediatric patients affected with various malignancies (neuroblastoma: 7; acute myelogenous leukemia: 3; rhabdomyosarcoma: 2; PNET: 1; retinoblastoma: 1; Burkitt's lymphoma: 1) collecting peripheral blood stem cells by a Cobe Spectra blood cell separator. Main procedure parameters, including vascular access, leukapheresis duration, blood flow rate, processed blood volumes, side effects, mononuclear and CD34+ cell yields, have been registered., Results: Altogether 22 sessions have been carried out, by processing a mean of 2.8 blood volumes. No leukapheresis related complications have been recorded, such as hypotension, hypocalcemia and hypothermia. Noteworthy, in 4 procedures two or more peripheral venipunctures have been performed to ensure an adequate blood flow., Conclusions: Leukapheresis for peripheral blood stem cell collection can be safely and efficaciously carried out in pediatric patients, even weighing < 15 kg, on the condition that certain aspects of apheresis practice in children (vascular access, volume shifts, anticoagulation, side effects) are carefully considered.

Thirty-seven patients underwent peripheral blood stem cell (PBSC) collection from May 1994 to May 1997. Twenty-five were males and 12 were females, the median age at collection was 11.5 years (range 1-27.4) and the median weight was 38 kg (range 9-80). As mobilising chemotherapy, cyclophosphamide, etoposide, doxorubicin and cytosine arabinoside were the drugs most frequently used in association with G-CSF for a total of 47 courses. Sixty-one aphereses were performed with a median collection of CD34+ and CFU-GM cells/kg of 3.6 x 10(6) (range 0.6-31.8) and 24.4 x 10(4) (range 0.1-1260), respectively. Minimal residual disease (MRD) was found in five of the 30 investigated aphereses. Twenty-one of the 37 patients underwent high-dose chemotherapy with autologous stem cell rescue: in seven the stem cell source was peripheral blood and bone marrow. The median duration of hospitalization was 18 days for the PBSC group and 23 days for the PBSC/ABMT group. Overall survival was 78.7% at a median follow-up of 18 months (range 2-31) and the DFS was 52% without difference depending on stem cell source. Compared to a historical group of ABMT patients, the PBSC group showed a statistical advantage in terms of neutrophils and platelet engraftment, blood and platelet requirements, and length of hospitalization. PBSC collection is a feasible procedure also in the paediatric setting providing that vascular access is adequate. As already reported, PBSC transplant results in faster engraftment and shorter hospitalization that could allow a better utilization of health financial resources. The question whether the source of stem cells could influence transplant outcome would require a prospective randomised study.

Peripheral blood stem cells (PBSC) are now routinely collected for use as hematopoietic support after high-dose chemotherapy for various malignancies. Nevertheless, few data are still available on PBSC collection in pediatric patients, owing to technical problems associated with the leukapheresis procedure in children. This paper briefly summarizes current knowledge about some technical aspects of pediatric leukapheresis for PBSC collection, according to the review of the literature and our personal experience on 60 procedures performed in 36 children affected with various malignancies. Technical issues include venous access, risk of volume shift due to exceeding extracorporeal circulation, and anticoagulation, that can induce severe side-effects. Moreover, criteria for optimizing the PBSC harvesting procedure in children, in particular the correct timing of leukapheresis, are discussed.