15-PGDH inhibition enhances hematopoietic regeneration during aging.

Hematopoietic aging is characterized by diminished stem cell regenerative capacity and an increased risk of hematologic dysfunction. We previously identified that the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH) regulates hematopoietic stem cell activity. Here, we expand on this work and demonstrate that in aged mice, (1) 15-PGDH expression and activity remain conserved in the bone marrow and spleen, suggesting it remains a viable therapeutic target in aging, (2) prolonged PGDH inhibition (PGDHi) significantly increases the frequency and number of phenotypic hematopoietic stem and progenitor cells across multiple compartments, with transcriptional changes indicative of enhanced function, (3) PGDHi-treated bone marrow enhances short-term hematopoietic recovery following transplantation, leading to improved peripheral blood output and accelerated multilineage reconstitution, and (4) PGDHi confers a competitive advantage in primary hematopoietic transplantation while mitigating age-associated myeloid bias in secondary transplants. Notably, these effects occur without perturbing steady-state blood production, suggesting that PGDHi enhances hematopoiesis under regenerative conditions while maintaining homeostasis. Our work identifies PGDHi as a translatable intervention to rejuvenate aged HSCs and mitigate hematopoietic decline.