Summary:Peripheral blood stem cell (PBSC) harvesting in the smallest children (weight Ͻ10 kg) using separators is complicated by specific problems. The volume of the separation set exceeds 25% of the total blood volume and the vascular access is generally not sufficient. Therefore, a simple manual technique for PBSC harvesting was developed. Three children (6-9 kg), with newly diagnosed tumours were scheduled to be treated with three to six sequential courses of high-dose chemotherapy, each followed by PBSC support. PBSC harvests were started after mobilization using cyclophosphamide and G-CSF when the peripheral blood CD34 ؉ cell count exceeded 50/ l. About 50 ml of blood was drawn from a venous catheter, injected into a transfer bag containing ACD-A, and centrifuged. The buffy coat obtained was pooled in a collection bag, remaining plasma and erythrocytes were immediately reinfused and a subsequent cycle started. From three to 13 cycles were performed in 1-3 days and 18.0-32.2 ؋ 10 6 CD34 ؉ cells/kg were collected. We did not detect any bacterial contamination or any notable complications. Fifteen PBSC reinfusions have been performed to date, each with rapid engraftment taking between 7 and 13 days. Patients are in very good PR (18 months from diagnosis) or in CR (6 and 8 months). We can conclude that this procedure is feasible and safe. Bone Marrow Transplantation (2002) 29, 57-61. DOI: 10.1038/sj/bmt/1703334 Keywords: PBSC; children; harvest; mobilization Infants with high-risk malignancies such as primitive neuroectodermal tumour (PNET) and metastatic sarcomas are difficult to cure with conventional therapy without profound sequelae, and a different approach is warranted. The aim of new protocols is to use several cycles of a regimen containing a small number of agents with known activity at maximum tolerated doses. The use of PBSC rescue after each high-dose chemotherapy appears to be the most favourable way to avoid delays between courses and to minimize risks from prolonged neutropenia and thrombocytopenia. PBSC have some advantages compared to bone marrow, including minor invasivity, 1 and more rapid reconstitution of both haematopoiesis and immune function. 2 However, limited data are available on PBSC collection in the smallest pediatric patients weighing less than 10 kg. 3-6 PBSC collections using automated or semi-automated devices (eg COBE Spectra) in these patients are much more complicated and risky than in older children or adults. Small children are very sensitive to hypocalcaemia. The volume of the disposable apheretic set is more than 25% of the total blood volume (TBV), and flow capacity of the most frequently used permanent tunnelled central venous catheter (CVC) is usually not sufficient for leukapheresis.In our department, PBSCs have been collected from 40 children since 1998 and a total of more than 1100 aphereses have been performed since 1995. In spite of our previous experience in older children 7 and considering the increased risk of leukapheresis in the smallest children, we have de...

Peripheral blood stem cell (PBSC) harvesting in the smallest children (weight <10 kg) using separators is complicated by specific problems. The volume of the separation set exceeds 25% of the total blood volume and the vascular access is generally not sufficient. Therefore, a simple manual technique for PBSC harvesting was developed. Three children (6-9 kg), with newly diagnosed tumours were scheduled to be treated with three to six sequential courses of high-dose chemotherapy, each followed by PBSC support. PBSC harvests were started after mobilization using cyclophosphamide and G-CSF when the peripheral blood CD34+ cell count exceeded 50/microl. About 50 ml of blood was drawn from a venous catheter, injected into a transfer bag containing ACD-A, and centrifuged. The buffy coat obtained was pooled in a collection bag, remaining plasma and erythrocytes were immediately reinfused and a subsequent cycle started. From three to 13 cycles were performed in 1-3 days and 18.0-32.2 x 10(6) CD34+cells/kg were collected. We did not detect any bacterial contamination or any notable complications. Fifteen PBSC reinfusions have been performed to date, each with rapid engraftment taking between 7 and 13 days. Patients are in very good PR (18 months from diagnosis) or in CR (6 and 8 months). We can conclude that this procedure is feasible and safe.

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