Clinical scale isolation of highly purified peripheral CD34+progenitors for autologous and allogeneic transplantation in children.

We present our experience with three clinical scale isolation methods for positive selection of CD34+ progenitors from peripheral blood for autologous and allogeneic transplantation in children. A combination of the CellPro device and the Magnetic Activated Cell Sorting system (MACS), as well as two different combinations of MACS systems were used (VarioMACS-SuperMACS and SuperMACS-SuperMACS). With the CellPro-MACS combination (16 separations), a median purity of 96.2% and a median recovery of 42% CD34+ cells could be achieved, whereas the two step MACS systems (55 and 29 separations) showed a median purity of 97.6% and 98.0% and a median recovery of 96.5% and 97%, respectively. Depletion of T cells was profound (4-5 log). A total of 34 patients in the autologous and 18 patients in the allogeneic setting have been transplanted with highly enriched CD34+ cells, obtained by these methods. Only one patient failed to engraft, all other patients showed a rapid and sustained hematological engraftment with the longest follow-up of 3 years. In summary, especially the two step MACS systems have proven to be appropriate tools for enrichment of CD34+ cells, yielding both high purity and good recovery, and can thus be used for tumor cell purging in the autologous setting and for effective T cell depletion in the allogeneic setting.