Morphology and gene expression of sex-determining region Y-box 9 and runt-related transcription factor 2 in centrifugally compressed cell collagen-combined constructs (C6)

The authors previously developed a scaffold-free tissue-engineered construct (TEC) from mesenchymal stem cells (MSCs). Although the TEC exhibited even cell distribution and was successfully applied for cartilage repair in animal models, it is unsuitable for relatively large-scale cartilage defects due to its small size. To solve the problem, the authors recently developed a novel biomaterial, a centrifugally compressed cell-collagen combined construct (C⁶) from a mixture of MSCs and atelocollagen, both of which are subjected to centrifugation. The results of the previous study indicated that C⁶ exhibited high cell viability (70 %) and sufficient cell distribution similar to that of the TEC. In the present study, the morphology and gene expression of C⁶ were investigated. Histological examination indicated that C⁶ is six times thicker (approximately 1 mm) than the TEC after a 7-day culture. The C⁶ remained unchanged in scale with increased cell density after a 21-day culture. Scanning electron microscopic observation indicated that C⁶ exhibited interconnected and porous microstructures, while the TEC had close-knit microstructures. Reverse transcriptase-polymerase chain reaction analysis indicated that the expression of sex-determining region Y-box 9 and runt-related transcription factor 2 was significantly higher in C⁶ than that in TEC.