IN-VITRO DIFFERENTIATION OF CHICK-EMBRYO BONE-MARROW STROMAL CELLS INTO CARTILAGINOUS AND BONE-LIKE TISSUES

Bone marrow stromal cells, progenitor cells involved in repair of bone and cartilage, can potentially provide a source for autologous skelet al tissue engineering. We investigated which factors were required to induce in vitro differentiation of avian bone marrow stromal cells int o three-dimensional cartilaginous and bone-like tissues. Bone marrow s tromal cells from embryonic chicks were expanded in monolayers, seeded onto biodegradable polyglycolic acid scaffolds, and cultured for 4 we eks in orbitally mixed Petri dishes. Cell-polymer constructs developed an organized extracellular matrix containing glycosaminoglycans and c ollagen, whereas control bone marrow stromal cell pellet cultures were smaller and consisted predominantly of fibrous tissue. Bone marrow st romal cells expanded with fibroblast growth factor-2 and seeded onto p olymer scaffolds formed highly homogeneous three-dimensional tissues t hat contained cartilage-specific molecular markers and had biochemical compositions comparable with avian epiphyseal cartilage. When cell-po lymer constructs were cultured in the presence of beta-glycerophosphat e and dexamethasone, the extracellular matrix mineralized and bone-spe cific proteins were expressed. Our work shows that cell expansion in t he presence of fibroblast growth factor-2 and cultivation on a three-d imensional polymer scaffold allows differentiation of chick bone marro w stromal cells into three-dimensional cartilaginous tissues. In the i n vitro system studied, the same population could be selectively induc ed to regenerate either cartilaginous or bone-like tissue.