Stem cells as bone marrow residents

In addition to being a source of hematopoietic and mesenchymal stromal cells, bone marrow is known to be the source of stem cell populations, which express pluripotent markers and are capable of differentiating into cells of three germinative layers (ectoderm, mesoderm, and endoderm). Recently, a new population of so-called “very small embryonic like cells” (VSELs) has been identified in the bone marrow in addition to well-known pluripotential cells, such as MIAMI, MSC, and MAPS. The presence of stem cells with a wide spectrum of differentiation capacities in the bone marrow allows an alternative interpretation of the phenomenon of plasticity and the possibility of their switch from a canonical to a nontrivial path of differentiation. The phenotypic features of VSELs, their differentiation capacities, ontogenetic origin, and relationships with other types of stem cells are studied. The role of bone marrow stem cells and induced pluripotential stem cells in regeneration processes and their possible therapeutic application are discussed.