Stromal cells.

Stromal cells, or mesenchymal stem cells, are adherent clonogenic cells that can form colonies. They are mainly isolated from bone marrow but can also be found in umbilical cord blood, adipose tissues and amniotic fluids. These stem cells are easy to culture in vitro, and can differentiate into osteoblasts, chondrocytes, or adipocytes when stimulated appropriately. When seeded on a natural (titanium, ceramics, collagen fibers, silk, etc.) or synthetic (PLLA, PLGA, etc.) biomaterial scaffold, they adhere and differentiate to form a new tissue. Many studies have also explored stromal cell differentiation in bioreactors to form a 3-dimensional culture. This review focuses on the biomaterials used for tissue engineering with stromal cells.