Gene expression associated with morphological changes in osteoblasts.

In the field of bone-tissue engineering, bone morphogenetic protein (BMP)-2 plays a central role because of its potent bone-induction ability. However, the widespread use of BMP-2 is prevented by its dose-dependent inflammation-related side effects. One reason why optimising BMP-induced bone formation is challenging is that this induction process in vivo remains poorly elucidated. Here, RNA-sequencing was performed to identify changes in gene expression in OBs. Out of 23,284 genes, 182 genes showed an adjusted fold-change of >2.0 and an FPKM >0.1 from Day 10 to Day 14. Among the 182 genes, 32 genes associated with ‘organisation of cytoskeleton’ were upregulated on Day 14. We examined the differences in gene expression in osteoblasts between Day 10 and Day 14, a period during which active morphological change and mineralisation were observed. Fluorescence-activated cell sorting was used to isolate ECFP+ osteoblasts in the lesions where ectopic bone formation was occurring, and transcriptome profiling through RNA-sequencing was performed to identify changes in gene expression in osteoblasts.