Downregulation of the long non-coding RNA MEG3 promotes osteogenic differentiation of BMSCs and bone repairing by activating Wnt/β-catenin signaling pathway

Abstract Background: Previous studies have demonstrated long non-coding RNA maternally expressed gene 3 (MEG3) emerged as a key regulator in development and tumorigenesis. However, whether MEG3 participate in osteogenic differentiation and bone regeneration remains unclear. This study aims to investigate the function and mechanism of MEG3 in osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), and explores the use of MEG3 in skull defects bone repairing. Methods: Endogenous expression of MEG3 during BMSCs osteogenic differentiation were detected by qPCR. MEG3 was knockdown in BMSCs by lentivirus. The proliferation, osteogenic-related genes and proteins expression were assessed by the CCK-8, PCR, alizarin red and alkaline phosphatase staining in MEG3 knockdown BMSCs. Western blot was used to detected β-catenin expression in MEG3 knockdown BMSCs. DKK1 was used to block wnt/β-catenin pathway, the osteogenic-related genes and proteins expression were assessed by PCR, alizarin red and alkaline phosphatase staining in MEG3 knockdown BMSCs. MEG3 knockdown BMSCs scaffold with PHMG were implanted in a critical-sized skull defects of rat model, micro-CT, hematoxylin and eosin staining, and immunohistochemistry were performed to evaluate the bone repairing. Results: MEG3 was increased during osteogenic differentiation of BMSCs. Downregulation of MEG3 could promote osteogenic differentiation of BMSCs in vitro. Notably, a further mechanism study revealed MEG3 knockdown could activate Wnt/β-catenin signaling pathway in BMSCs. Wnt/β-catenin inhibition would impair MEG3-induced osteogenic differentiation of BMSCs. By using PHMG scaffold with MEG3 knockdown BMSCs, we found that downregulation of MEG3 in BMSCs could accelerated bone repairing in a critical-sized skull defects rat model. Conclusions: Our study reveals the important role of MEG3 during osteogenic differentiation and bone regeneration. Thus, MEG3 engineered BMSCs may be effective potential therapeutic targets for skull defects.