Influence of the Bone Marrow Microenvironment on Hematopoietic Stem Cell Behavior Post-Allogeneic Transplantation: Development of Clonal Hematopoiesis and Telomere Dynamics.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potential cure for myelodysplastic neoplasms (MDSs) and other hematologic malignancies. This study investigates post-transplantation genetic evolution and telomere dynamics in hematopoietic cells, with a focus on clonal hematopoiesis (CH). We conducted a longitudinal analysis of 21 MDS patients who underwent allo-HSCT between September 2009 and February 2015. Genetic profiles of hematopoietic cells from both recipients and donors were compared at equivalent pre- and post-transplantation time points. Targeted sequencing identified CH-associated mutations, and real-time quantitative PCR measured telomere length. Furthermore, we compared CH incidence between recipients and age-matched controls from the GENIE cohort from routine health checkups. Post-allo-HSCT, 38% of recipients developed somatic mutations not detected before transplantation, indicating de novo CH originating from donor cells. Compared to age-matched healthy controls, recipients showed a significantly higher incidence of CH, suggesting increased susceptibility to genetic changes post-transplant. Telomere length analysis also revealed accelerated shortening in transplanted cells, highlighting the heightened stress and proliferation demands in the new microenvironment. Our findings reveal a notable incidence of donor-derived CH in allo-HSCT recipients, alongside significant telomere attrition. This suggests the potential influence of the marrow microenvironment on genetic and molecular changes in hematopoietic cells.