Peripheral blood progenitor cell collection in pediatric patients optimized by high pre-apheresis count of circulating CD34+ cells and high blood flow.

Collection of peripheral blood progenitor cells by leukapheresis is the preferred method to obtain grafts for autologous transplantation. Optimizing this procedure is important to warrant sufficient cell yield and reduce associated risks. To obtain sufficient to optimal yields of ≥ 2 to ≥ 5 × 10 CD34+ cells/kg body weight with a single leukapheresis procedure, success rates between 83 and 92% have been reported in children. In this retrospective study, we describe an improved protocol for autologous stem cell collection with an extraordinarily high success rate applied in 122 consecutive pediatric patients treated at the University Hospital Bern between 2004 and 2017. By comparing our data with previous studies, we identify two main optimizing factors: higher pre-apheresis CD34+ cell counts with a median of 130/µl and higher blood flow rates of 42-100 ml/min. Consequently, blood volumes processed were increased, duration of leukapheresis was shorter and CD34+ cell yields with a median of 19.0 × 10/kg body weight were higher than previously described. Safety in our study was comparable to previous studies. Based on our data, we present an innovative algorithm for determination of the necessary blood volume and time of pediatric leukapheresis procedure.