Human bone marrow contains at least two distinct types of stem cells in terms of sensitivity to radiation. Hematopoietic Stem Cells (HSCs) are extremely sensitive to radiation, whereas Mesenchymal Stem Cells (MSCs) are highly resistant to radiationinduced damage. Exposure of bone marrow to radiation leads to the rapid depletion of radio-sensitive HSCs and their progenitors, and hematopoietic failure presenting with pancytopenia. Bone marrow transplantation is a useful clinical treatment for this hematopoietic failure. Engrafted donor HSCs may home to the most appropriate sites, created by depletion of the host HSCs and their progenitors, and then reconstruct hematopoiesis. Host MSCs that survive radiation exposure support the regeneration of the donor hematopoietic system, although the underlying mechanism is unclear. MSCs are considered key components of the HSC niche, a specialized microenvironment that regulates the maintenance of HSCs and the production and maturation of hematopoietic progenitors. Because MSCs are also present as minor components in transplanted bone marrow cells, donor MSCs are likely to meet and interact with the host MSCs in the patientâs bone marrow.
Katsushi Tajima, Clinical Impact of Radiation-Resistant Mesenchymal Stem Cells in Bone Marrow Deduced from Preclinical Studies
Last date updated on July, 2014