Evaluation of Transplanted Stem Cell Dynamic Variables in the Bone Marrow of Children with Malignancies

Objective: According to risk classifications, the transplant of healthy hematopoietic stem cells in the bone marrow is a priority treatment option for hematopoietic diseases. The effectiveness of hematopoietic stem cell transplantation after bone marrow transplantation is largely dependent on the capacity of the bone marrow microenvironment to accept transplanted cells. Detailed analysis of hematopoietic stem cell kinetics after transplantation is very important, as initial transplantation of hematopoietic stem cells affects prognosis. In this study, hematopoietic stem and progenitor cell percentage values were evaluated together with other transplantation-related parameters to determine the capacity of stem cell dynamic variables in the bone marrow. Methods: Dynamic variables in hematopoietic stem cell fate in bone marrow transplantation include many parameters; hematopoietic stem cell transplantation rates in the apheresis product of 13 patients and cell counts per kilogram and engraftment times, CD34+ cell rates, CD34+ cell counts per kilogram, chimerism rates, Graft-versus-Host Disease grades, white blood cell counts, and post-transplant relapse status. In the apheresis products collected from the patients before transplantation, hematopoietic stem and progenitor cells were identified by the immunophenotypic barcode "CD34+, CD38-, CD45RA-, CD90+, CD49f+", and data analysis was performed with the BD FACSDivaTM software by studying on the BD FACSCanto II flow cytometer device. Results: According to the results of the pearson correlation analysis (non-parametric correlations), a strong positive and significant relationship was found between the number of hematopoietic stem cell transplantation per kg and the percentage of hematopoietic stem cell transplantation of the patients (r=.733, p<.05). According to the results of the analysis, there was a moderately significant and positive relationship (r=.631, p<.05) between the percentage of hematopoietic stem cell transplantation and platelet engraftment time, while there was a strong inverse relationship between erythrocyte engraftment time (r=-.730, p<.01). A strong positive and significant relationship was found between the number of Hematopoietic stem cell transplantation cells per kilogram infused into the patients and the platelet engraftment times (r=.780, p<.05). Conclusion: This study confirms that a mean cell dose of hematopoietic stem and progenitor cells ≥ 2.57 x 106/kg infused provides rapid short- and long-term platelet engraftment in pediatric patients undergoing autologous and allogeneic transplantation. This study is important in terms of revealing the possible relationship between pulling forward the platelet engraftment time and the number and percentage of Hematopoietic stem and progenitor cells in our transplanted patients. It is also important that a statistically significant inverse relationship was determined between HSPC values and mean erythrocyte engraftment times.