Feasibility of a PB CD34⁺ cell transplantation procedure using standard leukapheresis products in very small children

Abstract

To evaluate the feasibility and efficacy of CD34⁺ cell immunoselection from routine peripheral blood stem cell (PBSC) harvests in very small children a prospective study was performed in 15 children with advanced neuroblastoma weighing 20 kg or less. Products of two consecutive leukaphereses carried out on a COBE Spectra separator after G-CSF alone mobilization were pooled for immunoselection on Ceprate column. The median number of CD34⁺ cells and total CFU-GM collected were respectively 5.9 × 10⁶/kg (range 2.3–23.4) and 126.9 × 10⁴/kg (range 52.9–559.9). After separation the median number of CD34⁺ cells in the adsorbed fraction was 2.6 × 10⁶/kg (range 1–9.8) with a median purity of 54% (range 21–82) and a median of 95.7-fold (range 35–250) enrichment. Thirteen patients underwent autografts with CD34⁺ PBSCs after a busulfan 600 mg/m² + melphalan 180 mg/m² preparative regimen. The median number of days to achieve an absolute granulocyte count of 0.5 × 10⁹/l and a platelet count of 20 × 10⁹/l were respectively, 12 (range 10–24) and 35 (range 25–43). The median number of platelet transfusions was nine (range 2–15). We conclude that safe and effective immunoselection and transplantation of CD34⁺ PBSC can be accomplished in children with low body mass.