Mobilization and engraftment of peripheral blood stem cells in healthy related donors >55 years old.

Background Aims: The increasing scarcity of young related donors has led to the use of older donors for related allogeneic hematopoietic stem cell transplantation (HSCT). This study analyzed the influence of age on the results of mobilization of peripheral blood stem cells (PBSCs) in healthy donors as well as on the engraftment and outcome of HSCT.

Methods: A retrospective analysis from a single center was performed comparing the results of PBSC mobilization from related healthy donors according to their age.

Results: The study included 133 consecutive related donors. The median age was 50 years (range, 4-77 years); 70 (53%) donors were males, and 44 (33%) were >55 years old. All donors were mobilized with granulocyte colony-stimulating factor for 5 days. The peak CD34(+) cell count in peripheral blood was higher in younger than in older donors (median, 90.5 CD34(+) cells/μL [range, 18-240 CD34(+) cells/μL] versus 72 CD34(+) cells/μL [range, 20-172.5 CD34(+) cells/μL], P = 0.008). The volume processed was lower in younger than in older donors (16,131 mL [range, 4424-36,906 mL] versus 18,653 mL [range, 10,003-26,261 mL], P = 0.002) with similar CD34(+) cells collected (579.3 × 10(6) cells [range, 135.14 × 10(6)-1557.24 × 10(6) cells] versus 513.69 × 10(6) cells [range, 149.81 × 10(6)-1290 × 10(6) cells], P = 0.844). There were no differences in time to recovery of neutrophils and platelets or in the incidences of acute and chronic graft-versus-host disease, overall survival, non-relapse mortality and relapse incidence.

Conclusions: Donors >55 years old mobilized fewer CD34(+) cells and required a greater volume to collect a similar number of CD34(+) cells. The outcome of HSCT was not influenced by donor age. Donor age should not be a limitation for related allogeneic HSCT.