Induction of Osteoblasts by Direct Reprogramming of Mouse Fibroblasts.

In the tissue culture dish, osteoblast cells can be derived from mesenchymal stem cells (MSCs) and pluripotent stem cells (PSCs) including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). However, differentiation of osteoblasts from PSCs is time-consuming and low yield. In contrast, we identified four osteogenic transcription factors, Runx2, Osx, Dlx5, and ATF4, that rapidly and efficiently reprogram mouse fibroblasts derived from 2.3 kb type I collagen promoter-driven green fluorescent protein (Col2.3GFP) transgenic mice into induced osteoblast cells (iOBs). iOBs exhibit osteoblast morphology, form mineralized nodules, and express Col2.3GFP and gene markers of osteoblast differentiation. Our method provides a robust system to rapidly generate appropriate and abundant osteoblast cells for osteogenesis and bone regeneration study.