Haematopoietic stem cell number is not solely defined by niche availability.

ABSTRACT: Haematopoietic stem cells (HSCs) reside in specialized microenvironments, referred to as niches, and the classical model suggests that HSC numbers are predominantly determined by the niche size^1-5. However, the vast excess of niche cells relative to HSCs challenges this perspective. To rigorously define the role of niche size in regulating HSC numbers, we developed a femur-transplantation system, enabling us to increase available HSC niches. Notably, the addition of niches did not alter the total HSC numbers in the body, suggesting the presence of a systemic mechanism that limits HSC numbers. Additionally, HSC numbers in transplanted wild-type femurs did not exceed physiological levels when HSCs were mobilized from defective endogenous niches to the periphery, indicating that HS

SUBMITTER: Takeishi S 

PROVIDER: S-EPMC12527909 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature