Facilitating cell (FC)

Facilitating cells (FCs) are a rare, specialized population of CD8+/TCR- cells found in the bone marrow that play a critical role in enhancing the engraftment of hematopoietic stem cells (HSCs) (Ildstad et al., Nature Medicine, 1996). Unlike conventional T cells, FCs do not induce graft-versus-host disease (GVHD) but instead promote the establishment of stable donor chimerism, which is essential for inducing immune tolerance in organ transplantation (Leventhal et al., Science Translational Medicine, 2012). They function by modifying the bone marrow microenvironment and interacting with the host immune system to prevent rejection of donor stem cells (PubMed: 15155609). The most prominent clinical application of these cells is in the form of FCR001, an investigational cell-based therapy designed to allow kidney transplant recipients to discontinue immunosuppressive drugs (Talaris Therapeutics, 2023). Research indicates that FCs are distinct from other immune cells and require specific markers like CD8 and the absence of the T-cell receptor for identification (Ildstad et al., Journal of Immunology, 2011). They have also shown potential in treating genetic blood disorders such as sickle cell disease by facilitating allogeneic HSC engraftment (Blood, 2014). Overall, facilitating cells represent a unique cellular component used to bridge the gap between stem cell transplantation and immune tolerance.

Other names

CD8+/TCR- facilitating cellBone marrow facilitating cellHSC-facilitating cell

Facilitating cells promote the engraftment of hematopoietic stem cells (HSCs) across major histocompatibility complex (MHC) barriers and induce stable chimerism without causing graft-versus-host disease (GVHD) by modulating the recipient's immune system and supporting the HSC niche.