CD34+ and CFU-GM doses don't predict platelet recovery in autologous blood stem cell transplantation

Purpose: Haematopoietic, especially platelet recovery is crucial in autologous stem cell rescue after high dose therapy (HDTR) in cancer. We were interested in the dose-effect-relationship between the haematopoietic progenitor cells (routinely quantified as CD34+ cells and CFU-GM) applied for transplantation and the duration of transfusion dependence (red cells and platelets). Methods: Haematopoietic progenitors in stem cell transplantais were determined by routine methods: CD34+ cells were quantified by flow cytometry, CFU-GM by cell culture in semi-solid medium containing methylcellulose. HDTR was performed in 21 patients of whom 7 received a tandem regimen. Results: After autologous stem cell reinfusion (n=28) of in the median 3.1 × 10E6 CD34+ cells/kg body weight (BW) (range: 2.0-7.9 × 10E6 CD34+ cells/kgBW) and 8.3 (3.5-19.1) × 10E5 CFU-GM/kg BW patients required 2 (0-8) red cell concentrates and 4 (1-10) platelet transfusions. Neutropenia (<500/×l) recovered within 9 (8-11) days after transplantation. Platelet dependence lasted 9.5 (5-15) days. The doses (CD34+ and CFU-GM, resp.) applied did neither correlate with the duration of neutropenia nor the interval of platelet dependence. In 4 patients the latter was beyond the upper quartile inspite of rapid recovery of granulocytopoiesis. Patients required substitution of red cells for 7.5 (0-18) days. Surprisingly, this Intervall was inversely correlated with the stem cell doses applied while the correlation was better with the amounts of CD34+ cells (r= - 0.703, p< 0.01) than those of CFU-GM (r= - 0.483, p= 0.01). These preliminary findings need to be confirmed in further studies. Conclusion: We like others did not find a correlation between platelet recovery and "stem cell dose" as assessed by CD34+ and CFU-GM. Additional parameters such as megacaryocyte progenitors are needed to ameliorate therapy safety and shorten hospitalization.