Marrowresiding

Marrowresiding is a term used in hematology and immunology to denote cells or cell populations that reside within the bone marrow rather than circulating in the bloodstream. It encompasses a range of hematopoietic and stromal cells that persist in the marrow microenvironment for extended periods. The term emphasizes residency in the marrow niche, a specialized microenvironment created by stromal cells, endothelial cells, osteoblasts, and extracellular matrix components that regulate cell fate and hematopoiesis.

Typical marrow-resident cells include hematopoietic stem and progenitor cells; mesenchymal stromal cells; marrow-resident macrophages; and certain tissue-resident lymphocytes, notably bone marrow resident memory T cells. These populations often form stable, spatially organized networks that support ongoing blood formation, immune surveillance, and bone remodeling.

Marrow residence has functional implications: it enables long-term maintenance of stem cell pools, rapid response to hematopoietic stress, and localized immune functions. Disturbances to marrow-residing populations can contribute to hematologic disorders or affect responses to therapies.

Researchers identify marrow-residing cells using lineage tracing, imaging (e.g., intravital microscopy), flow cytometry, and single-cell sequencing to distinguish resident from circulating cells.

See also: bone marrow, hematopoiesis, tissue-resident memory T cells, bone marrow niche.