The transcription factor Ets2 and its transcriptional targets osteopontin (OPN) and osteocalcin (OC) are expressed in tissue-engineered bone constructs in vitro. Up to now little is known about the role of Ets2 in tissue-engineering applications. This study was intended to investigate the hypothesis that protein expression of Ets2 is correlated with the expression of bone-specific proteinsin tissue-engineeredbone constructs. Cell-seeded three-dimensional bone constructs manufactured with osteoblastic cells and poly(lactic-co-glycolic acid) polymer fleeces over a period of 21 days were analyzed by SDS-PAGE and Western blotting. The protein expression of OPN, OC, osteonectin and collagen type I was analyzed. Cellularity, alkaline phosphatase-specific activity and histology confirmed the osteoblastic phenotype of the constructs. Correlations between Ets2 expression and OPN and Ets2 and collagen type I expression could be detected during the phase of late osteoblastic differentiation between days 9 and 21. The correlation between OC and collagen type I was significant in this late stage of osteoblastic differentiation. These results suggest that there is a strong interplay of Ets2 with bone-specific proteins in cell-seeded three-dimensional bone constructs. This study is a crucial step to elucidate the complex interplay of bone-related proteins in the application of bone tissue engineering.
(c) 2007 S. Karger AG, Basel.