Isolating endosteal mesenchymal progenitors from rodent long bones.

Bone marrow mesenchymal stem cells (MSCs) are promising therapeutic tools for tissue repair and the treatment of a number of human diseases. As a result, there is substantial interest in characterizing and expanding these cells to uncover their therapeutic potential. For preclinical studies, mesenchymal progenitors, containing both MSCs and their proliferative progeny, are commonly isolated from the central region of rodent long bones. However, challenges exist in expanding these central mesenchymal progenitors in culture. We have recently identified another population of progenitors within rodent long bones that resides close to the bone surface, which we termed endosteal mesenchymal progenitors. These cells are more metabolically active and more responsive to external stimuli compared to central mesenchymal progenitors and therefore, they represent a biologically important target for MSC research. This chapter describes in detail a unique enzymatic digestion approach to isolate and culture endosteal mesenchymal progenitors as well as their central counterparts from rodent long bones.