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Background: Surgery often leads to massive destruction of the skeleton. Cell-based bone reconstruction therapies promise new therapeutic opportunities for the repair of bone. Embryonic stem cells (ESCs) can be differentiated into osteogenic cells and are a potential cell source for bone tissue engineering. The purpose of this in vivo study was to investigate the bone formation in various constructs containing ESCs (with and without micromass technology) and insoluble collagenous bone matrix (ICBM)., Methods: Murine ESCs were cultured as monolayer cultures as well as micromasses and seeded on ICBM. These constructs were implanted in immunodeficient rats. After one week, one, two and three months CT-scans were performed to detect any calcifications and the rats were sacrificed., Results: The radiological examination shows a steep increase of the mineralized tissue in group 1 (ICBM+seeded ESC). This increase can be considered as statistical significant. In contrast, the volume of the mineralization in group 2 (ICBM+ESC-spheres) and group 3 (ESC-spheres) does not increase significantly during the study., Conclusion: ESCs in combination with ICBM do promote ectopic bone formation in vivo. Thus, this cell population as well as the biomaterial ICBM might be promising components for bone tissue engineering.

Background: Facial trauma or tumor surgery in the head and face area often lead to massive destruction of the facial skeleton. Cell-based bone reconstruction therapies promise to offer new therapeutic opportunities for the repair of bone damaged by disease or injury. Currently, embryonic stem cells (ESCs) are discussed to be a potential cell source for bone tissue engineering. The purpose of this study was to investigate various supplements in culture media with respect to the induction of osteogenic differentiation., Methods: Murine ESCs were cultured in the presence of LIF (leukemia inhibitory factor), DAG (dexamethasone, ascorbic acid and beta-glycerophosphate) or bone morphogenetic protein-2 (BMP-2). Microscopical analyses were performed using von Kossa staining, and expression of osteogenic marker genes was determined by real time PCR., Results: ESCs cultured with DAG showed by far the largest deposition of calcium phosphate-containing minerals. Starting at day 9 of culture, a strong increase in collagen I mRNA expression was detected in the DAG-treated cells. In BMP-2-treated ESCs the collagen I mRNA induction was less increased. Expression of osteocalcin, a highly specific marker for osteogentic differentiation, showed a double-peaked curve in DAG-treated cells. ESCs cultured in the presence of DAG showed a strong increase in osteocalcin mRNA at day 9 followed by a second peak starting at day 17., Conclusion: Supplementation of ESC cell cultures with DAG is effective in inducing osteogenic differentiation and appears to be more potent than stimulation with BMP-2 alone. Thus, DAG treatment can be recommended for generating ESC populations with osteogenic differentiation that are intended for use in bone tissue engineering.