摘要
Mesenchymal stem cells （MSCs） are found in multiple organs in the fetus, cord blood and adult tissues . However, in adults, the bone marrow is the major source of these stem cells. MSCs surround the blood vessels of bone marrow and are also in contact with the trabeculae . The immunology of MSCs is relevant to medicine. In bone marrow, MSCs could be considered ‘gate-keeper＇ cells. This designation is mostly due to its location in the abluminal surface of the main sinus, which forms the interface between the periphery and marrow cavity . Cells or organisms entering or exiting the marrow need to by-pass MSCs. The immune properties of MSCs suggest that these stem cells are not bystander cells, but perhaps, they are actively involved in homeostasis of bone marrow.
