Skeletogenesis: In Vitro Analysis of Bone Cell Differentiation

A common goal of cell biologists is the establishment of in vitro model systems that faithfully recapitulate a particular biological process that occurs in vivo. Currently, numerous methodologies exist for in vitro analysis of osteoblastic cells, however, many of these methods depend on the use of fetal tissue, osteosarcoma, or immortalized cell lines. Although all of these model systems have generated a great deal of knowledge on the phenotypic character of osteoblastic cells as they undergo the maturational process that ultimately leads to the formation of a mineralized matrix, a great deal of variability has been noted in the literature from one culture method to another. This variability can arise from differences in the animal species and the developmental age of the starting material used for the establishment of such cultures, the amount of soft tissue associated with the starting material, and alterations in patterns of phenotypic expression owing to tumorogenic or immortalization processes (1 ).