**2.2 Bone marrow-derived stromal cells**

Friedenstein and colleagues reported first on the isolation of bone marrowderived stem cells from BM stroma and incubated it in plastic culture dishes and identified mesenchymal stem cells as colony-forming unit fibroblasts (CFU-Fs) [4]. The BM stroma is made up of a network of fibroblast-like cells and includes a subpopulation of multipotent cells which are able to generate the mesenchyme, known as the mass of tissue, that develops mainly from the mesoderm of the embryo subpopulation. The cells are referred to as mesenchymal stem cells (MSCs) [5]. The *Friedenstein* culture method revealed that MSCs are capable of differentiating into several connective tissue cell types [6], described first by Pittenger and associates [7].
