Engraftment Kinetics of Neutrophils and Platelets in Peripheral Blood Stem Cells Transplant Patients in a Quaternary Care Centre.

Background: This study aimed to evaluate the rate of neutrophil and platelet engraftment in pediatric hematopoietic stem cell transplant (HSCT) patients. Additionally, it sought to assess whether engraftment kinetics were influenced by CD34+ cell dose, CD3+ cell dose in T cell-replete transplants with post-transplant cyclophosphamide (PTCy), and the type of stem cell transplantation. Materials and Methods: The study included 60 pediatric patients undergoing hematopoietic stem cell transplantation between August 2023 and January 2024. Flow cytometry was used to quantify CD34+ cells. A peripheral smear and the haematology analyzer were used to measure the platelet count and neutrophils from day 1+ to day 28+. Results: Among 60 patients, 3 were autologous (5%), 15 were MRD (25%), 6 were MUD (10%), 30 were T-cell-repleted transplants with PTCy (50%), and 6 were TCRα/β-depleted transplants (10%). The neutrophil and platelet engraftment were correlated with demographic characteristics (e.g., age and gender) and clinical factors (e.g., transplant, diagnosis, and CD34+ cell dosage levels). In addition, CD3+ T cell dosages of ≥2×108 cells/kg or < 2×108 cells/kg were also correlated with engraftment kinetics. Both the type of peripheral blood stem cell transplant (PBSCT) and the CD3+ T cell dose showed a statistically significant association with neutrophil engraftment. Conclusion: This study showed a poor correlation between CD34+ cell dosage and engraftment. However, maximum engraftment occurred between day 10+ and day 14+ in fully matched transplants. T cell-repleted transplants with PTCy exhibited maximum engraftment between 15-18 days, and all TCR α/β depleted transplants engrafted between day 10+ and day 14+.