Yong-Mook Choi

Myeloid differentiation of human cord blood CD34+ cells during ex vivo expansion using thrombopoietin, flt3‐ligand and/or granulocyte‐colony stimulating factor

We investigated the phenotypic changes of human umbilical cord blood (CB) CD34+ cells during ex vivo expansion using thrombopoietin (TPO), flt3‐ligand (FL), and/or granulocyte‐colony stimulating factor (G‐CSF). During ex vivo expansion of CD34+ cells isolated from human CB for up to 5 weeks, surface expression of molecules on the cultured cells including CD64 (FcγRI), CD32 (FcγRII), CD16 (FcγRIII), CD11b (MAC‐1) and CD18 (β2‐integrin) was analysed by flow cytometry along with simultaneous measurement of apoptosis by 7‐aminoactinomycin D staining method. CD64, CD32 and/or CD18 expressing cells appeared in the cultures both with and without the addition of G‐CSF until the tenth day. However, without G‐CSF, CD16+ fractions did not appear and CD11b+ fractions were not maintained. With G‐CSF, the CD16+ or CD11b+ fractions appeared only from the second week. These results suggest that G‐CSF is necessary for the late stage of myeloid maturation during which CD16 and CD11b are expressed.

Efficacy of tandem high-dose chemotherapy and autologous stem cell rescue in patients over 1 year of age with stage 4 neuroblastoma: the Korean Society of Pediatric Hematology-Oncology experience over 6 years (2000-2005).

The efficacy of tandem high-dose chemotherapy and autologous stem cell rescue (HDCT/ASCR) was investigated in patients with high-risk neuroblastoma. Patients over 1 yr of age who were newly diagnosed with stage 4 neuroblastoma from January 2000 to December 2005 were enrolled in The Korean Society of Pediatric Hematology-Oncology registry. All patients who were assigned to receive HDCT/ASCR at diagnosis were retrospectively analyzed to investigate the efficacy of single or tandem HDCT/ASCR. Seventy and 71 patients were assigned to receive single or tandem HDCT/ASCR at diagnosis. Fifty-seven and 59 patients in the single or tandem HDCT group underwent single or tandem HDCT/ASCR as scheduled. Twenty-four and 38 patients in the single or tandem HDCT group remained event free with a median follow-up of 56 (24-88) months. When the survival rate was analyzed according to intent-to-treat at diagnosis, the probability of the 5-yr event-free survival±95% confidence intervals was higher in the tandem HDCT group than in the single HDCT group (51.2±12.4% vs. 31.3±11.5%, P=0.030). The results of the present study demonstrate that the tandem HDCT/ASCR strategy is significantly better than the single HDCT/ASCR strategy for improved survival in the treatment of high-risk neuroblastoma patients.