Non-multipotent stroma inhibit the proliferation and differentiation of mesenchymal stromal cells in vitro

Background aims. The ability to expand and maintain bone marrow (BM)-derived mesenchymal stem cells (MSC) in vitro is an important aspect of their therapeutic potential. Despite this, the exact composition of stromal cell types within these cultures and the potential effects of non-stem cells on the maintenance of MSC are poorly understood. Methods. C57BL/6J BM stroma was investigated as a model to determine the relationship between MSC and non-multipotent cells in vitro. Whole BM and single-cell derived cultures were characterized using flow cytometry and cell sorting combined with multipotent differentiation. Proliferation of individual stromal populations was evaluated using BrdU. Results. At a single-cell level, MSC were distinguished from committed progenitors, and cells lacking differentiation ability, by the expression of CD105 (CD105