Duration to Engraftment Requires Significantly Much More Time in Myelodysplastic Syndrome (MDS) Patients as Compared to Acute Myeloid Leukemia (AML) Patients Following Allogeneic Stem Cell Transplantation.

Normal hematopoiesis is characterized by the balanced interplay between hematopoietic stem cells and the cells and molecules that forms part of the microenvironment in which blood cell production takes place. Myelodysplastic syndrome (MDS) marrow stroma cells are known to fail in supporting the growing of normal stem cells. We therefore retrospectively analyzed the duration to engraftment of absolute neutrophil count (ANC) ≥0.5 x 10⁹/L and ≥1.0 x 10⁹/L and the time interval to platelet recovery of ≥20 and ≥50 x 10⁹/L in 42 MDS patients as compared to 42 patients suffering from primary acute myeloid leukemia (AML), following allogeneic stem cell transplantation (SCT). Significant shorter time to engraftment was documented in AML as compared to MDS patients in all 4 parameters. These results hold true even if we sub-grouped the patients according to gender, age, with the age of 50 years old being the cutoff between young and elderly patients, or when the donor was related to the patient. Moreover, sub-grouping the patients from each diagnosis according to the conditioning regimens that were given prior to transplantation revealed the same significant better results for the AML patients when received a non-myeloablative regimen. To the best of our knowledge, this is the first time that such a comparison is being made. We suggest that duration to engraftment in MDS patients takes significantly longer time and this may influence and worsen their course of transplantation in terms of morbidity as well as mortality.