Myeloid differentiation and maturation of SCF+IL-3+IL-11 expanded AC133(+)/CD34(+) cells selected from high-risk breast cancer patients

The AC133 antigen is selectively expressed on subset of CD34(+) cells isola ted from leukapheresis products from high risk breast cancer patients recei ving chemotherapy plus G-CSF. MiniMACS AC133(+) isolated cells contained a mean of 85% (80-90) AC133(+) cells. Enriched AC133(+) cells coexpressed 80% CD34(+), 6.6% CD33(+) and 2% CD15(+). Separated AC133(+) cells contained 6 00 GRU-GM/10(4) cells and 70 BFU-E/10(4) cells. Flow-cytometric analysis in dicated that AC133(+) cells were isolated from cells population with low gr anularity (SS), while CD33(+) a CD15(+) cells had a high granularity. After a seven-day ex vivo expansion in the presence of SCF + IL-3 + IL-11 + the expansion of cells increased 19.4 times. The mean percentage of blasts decr eased from 100% at the start of culture to 81% on day 3 and 30% on day 7. P romyelocytes were slow to appear with 10% present on day 3, but thereafter increased to 33% on day 7. The appearance of myelocytes and metamyelocytes lagged 3 days behind promyelocytes and continued to increase during culture to become the predominant (30%) cell type on day 7, Very few neutrophils ( 2%) were observed in any of the cultures on day 7. Monocytes or macrophages were not detected on day 7. By day 7 megakaryocytes were present at low le vels (10%). The mean value of CFU-GM in the culture after day 7 of ex vivo expansion in the presence of SCF+IL-3+IL-11 had increased 45-fold, BFU-E 5- fold. After 7 days of expansion with IL-3+SCF+IL-11 cells expressed a mean of 12% CD34(+), 8% AC133(+), 59% CD33(+) and 30% CD15(+). The aim of this e xperiment was to determine whether ex vivo culture of peripheral blood AC13 3(+) cells could generate sufficient numbers of progenitors to potentially abrogate cytopenia after transplantation and passive purging of tumor cells .