New Proposed Guidelines for Early Identification of Successful Myeloid and Erythroid Engraftment in Hematopoietic Stem Cell Transplantation

Background: After hematopoietic stem cell transplantation (HSCT), early detection of engraftment would be of critical value for clinicians. The aim of this study was to identify faster parameters for engraftment. Methods: We evaluated blood cell parameters including complete blood count (CBC), differential counts, and various reticulocyte parameters in 115 patients who received HSCT (allogeneic, n = 93; autologous, n = 22) in the purpose of identifying possible improved laboratory guidelines for engraftment prediction. Results and Conclusion: Days to white blood cell (WBC) count over 100 cells/μl with more than two-fold increase from nadir after transplantation (proposed new WBC guideline) preceded absolute neutrophil count (ANC) >500 cells/μl by 1.7 days. Among erythroid parameters, the earliest marker for erythroid engraftment was high light scattering reticulocytes (HLR) >0.1 (proposed new red blood cell guideline), which preceded reticulocyte counts (RET) >1% and immature reticulocyte fraction >0.5 by 3.9 and 1.6 days, respectively. Among the clinical parameters compared, those with statistically significant influence on myeloid engraftment were donor type (P = 0.009) and conditioning intensity (P = 0.009). As for erythroid recovery, ABO incompatibility was the only significant factor. In conclusion, the new guidelines may ensure engraftment several days earlier than the conventional parameters, which may help clinicians for decision-making on rescue therapy earlier.