[CD34-positive cell selection using an Isolex 300 system in patients with solid tumors and its application for...

Using an Isolex 300 immunomagnetic cell separator, we carried out CD34+ cell selection in samples from 4 patients with solid tumors: 2 patients with relapsed breast cancer, 1 post-operative patient with advanced breast cancer, and 1 post-operative patient with advanced ovarian cancer. Peripheral blood stem cells were mobilized by G-CSF and high-dose chemotherapy (CAF or VIC-E regimen). The mean recovery rate for CD34+ cells was 62.0% and the mean purity was 89.5%. However, the mean recovery for colony-forming cells (CFC) was only 10.9%, suggesting that recovered CD34+ cells may be damaged during the separation of immunomagnetic beads by releasing peptide or by 4 cycles of cytocentrifugation (at 800 G for 10 min). Approximately 30% of the CFC, consisting largely of BFU-E, had been recovered in the CD34- cell fraction. Recently, it has been reported that primitive long-term hematopoietic repopulating cells may express weakly or not at all for CD34 antigen. This suggests that careful follow-up monitoring is necessary for long-term hematopoietic reconstitution after CD34+ cell transplantation.