An article from the Examiner looks at progress towards tissue engineered bone grafts based on the use of scaffolding materials, stem cells and knowledge of the chemical cues that prompt differentiation. "Under the microscope, the scaffold looks like a jungle gym made up of a bunch of little glass balls fused together. Each of the balls is composed of a polymer that harmlessly degrades in the body. To the polymer scaffold, he adds adult stem cells that have been isolated from a patient's fat tissue ... There they come under the influence of a [bone morphogenetic protein, or BMP] that has been also added to the scaffold ... One of the functions of BMPs is to transform adult stem cells in the bone marrow into bone-forming cells, or osteoblasts."
Link: http://www.dcexaminer.com/articles/2005/04/14/features/science/98science13bones.txt