Accelerated telomere shortening following allogeneic transplantation is independent of the cell source and occurs within the first year post transplant

Telomere shortening has been documented in the blood cells of recipients of allogeneic bone marrow transplants compared with their donors. Allogeneic peripheral blood progenitor cells (PBPCs) have been increasingly used as an alternative to bone marrow. Their advantages include earlier engraftment a nd immune reconstitution following transplantation. We have measured telome re length of neutrophils and T cells in fully engrafted recipients of allog eneic bone marrow (n = 19) and allogeneic PBPC (n=17) and also measured seq uential telomere length in four patients after transplantation. Overall, si gnificant telomere shortening occurred in recipients in neutrophils (0.3 kb , P<0.001) and T cells (0.2 kb, P = 0.045), The data demonstrate that first , the degree of shortening was the same for BM and PBPC transplants and was not related to the time taken to engraft neutrophils and platelets and sec ond, telomere shortening occurs in the first year post transplant without f urther shortening during the period of observation. These data suggest that the superiority of engraftment seen in PBPC transplants is independent of telomere shortening and other mechanisms such as homing or seeding may be m ore important.