Allogeneic hematopoietic stem cell transplantation is a curative treatment for severe aplastic anemia, but selecting the best donor remains a critical and sometimes difficult decision for clinicians. Traditionally, fully matched sibling donors have been preferred whenever available. However, new evidence suggests that this long-standing principle may need to be reconsidered.
In a large multicenter retrospective study, researchers analyzed outcomes from 795 patients with severe aplastic anemia who underwent allogeneic stem cell transplantation between 2012 and 2020 at 11 transplant centers in China. Patients received grafts either from matched sibling donors or from haploidentical (partially matched family) donors, reflecting real-world clinical practice.
The study found that donor age was a decisive factor influencing long-term outcomes. Donors aged 50 years or older were associated with significantly worse overall survival, failure-free survival, and graft-versus-host disease–free survival, regardless of donor type. In contrast, patients who received transplants from younger donors experienced consistently better outcomes.
Notably, when donor age and donor type were analyzed together, younger haploidentical donors performed as well as—or even better than—older matched sibling donors. This finding indicates that biological donor characteristics, such as stem cell fitness and immune reconstitution capacity, may play a more important role than genetic matching alone in severe aplastic anemia.
“Our results suggest that donor age should be a key consideration in donor selection for severe aplastic anemia,” said Prof. Xiaojun Huang, from Peking University People’s Hospital. “With modern haploidentical transplantation strategies, a younger partially matched donor may be a preferable option compared with an older fully matched sibling donor.”
The findings are particularly relevant in regions where matched sibling donors are scarce and haploidentical transplantation has become increasingly common. Severe aplastic anemia is a non-malignant disease, and long-term quality of life—free from graft failure or severe graft-versus-host disease—is a major clinical goal.
According to the authors, these results support a shift toward a more individualized donor selection strategy that prioritizes donor age alongside, rather than secondary to, genetic compatibility. Further prospective studies and immunological analyses are needed to better understand the biological mechanisms underlying these observations.
Science Bulletin
Observational study