Recipient hematopoietic system and bone marrow niche (BM niche)

The recipient hematopoietic system and bone marrow niche represent the complex physiological environment responsible for the production and maintenance of blood cells. This system consists of hematopoietic stem cells (HSCs) and their supporting microenvironment, which includes mesenchymal stromal cells, endothelial cells, and osteoblasts that provide critical regulatory signals (Source: NIH, National Cancer Institute). In the context of hematopoietic stem cell transplantation (HSCT) and gene therapy, this system is the primary site for therapeutic intervention, where conditioning regimens are used to deplete the recipient's own stem cells and immune system to allow for the engraftment of donor or gene-modified cells (Source: StatPearls, Hematopoietic Stem Cell Transplantation). The bone marrow niche provides the necessary signals for stem cell self-renewal and differentiation, and its clearance is essential for successful transplantation. Targeting this system involves balancing the need for effective niche clearance with the risks of systemic toxicity and long-term complications like graft-versus-host disease or organ failure. Modern approaches aim to move from non-specific chemotherapy and radiation toward targeted monoclonal antibodies and small molecules that specifically clear the niche with reduced off-target effects (Source: PubMed, PMID: 32814554).

Other names

Bone marrow microenvironmentHematopoietic nicheRecipient marrowHematopoietic stem cell niche

Conditioning of the recipient hematopoietic system involves the depletion of endogenous hematopoietic stem cells and immune cells through DNA alkylation, antimetabolite-induced apoptosis, or targeted antibody-mediated clearance to facilitate the engraftment of transplanted cells (Source: StatPearls, Hematopoietic Stem Cell Transplantation; PubMed PMID: 31515458).