Mechanical stretch-induced osteogenic differentiation of human jaw bone marrow mesenchymal stem cells (hJBMMSCs) via inhibition of the NF-κB pathway

Abstract

Severe malocclusion can contribute to several serious dental and physical conditions, such as digestive difficulties, periodontal disease, and severe tooth decay. Orthodontic treatment is mainly used to treat malocclusion. Forces in orthodontic tooth results in bone resorption on the pressure side and bone deposition on the tension side. Osteoblasts have been considered as the key component in bone regeneration on the tension side. However, the underlying mechanisms remain unclear. In this study, we focus on how mechanical stretch regulates the osteogenesis during orthodontic treatment. Human jaw bone marrow mesenchymal stem cells (hJBMMSCs) were isolated from healthy adult donors and cultured in regular medium (control) or osteogenic medium (OS). Under OS culture, hJBMMSCs presented osteogenic differentiation potentials, as evidenced by increased mineralization, enhanced calcium deposition, and upregulated expression of osteogenesis markers (ALP, osterix, and Runx). What’s more, the OS-induced osteogenesis of hJBMMSCs is associated with the dephosphorylation of IKK, activation of IKBα, and phosphorylation/nucleic accumulation of P65, which all indicated the inhibition of NF-κB activity. Overexpressing P65 in hJBMMSCs, which could constantly activate NF-κB, prevented the osteogenic differentiation in the OS. After that, we applied the Flexcell tension system, which could cause mechanical stretch on cultured hJBMMSCs to mimic the tension forces during tooth movement. Mechanical stretch resulted in 3.5−fold increase of ALP activity and 2.4–fold increase of calcium deposition after 7 days and 21 days treatment, respectively. The expression levels of ALP, Run×2, and Osterix were also significantly upregulated. In the meantime, applying mechanical stretch on OS-cultured hJBMMSCs also dramatically promoted the OS-induced osteogenesis. Both OS and mechanical stretch downregulated NF-κB activity. By overexpressing P65 in hJBMMSCs, neither OS nor mechanical stretch could induce their osteogenesis. These results indicated that, like OS induction, mechanical stretch-facilitated osteogenesis of hJBMMSCs by inhibiting NF-κB in the noninflammatory environments.

Kartogenin preconditioning commits mesenchymal stem cells to a precartilaginous stage with enhanced chondrogenic potential by modulating JNK and β‐catenin–related pathways

“…The CBFα subunits are encoded by the RUNXs, which contain 3 members: RUNX1, ‐X2, and ‐X3 (29, 30). RUNX1 is responsible for early MSC commitment toward the chondrogenic lineage, whereas RUNX2 mediates the initial steps of terminal chondrocyte maturation, hypertrophy, and mineralization (31–33). Therefore, the particular levels of phospho‐JNK/ β‐catenin might also mediate the prochondrogenic and antiossific effects of KGN preconditioning by interfering with the balance of RUNX1/2.…”

The interactions between mTOR and NF‐κB: A novel mechanism mediating mechanical stretch‐stimulated osteoblast differentiation

“…Second, it has been shown that the NF‐κB signaling acts as a negative regulator of osteoblast differentiation and bone formation (Kim et al, 2017; Li et al, 2015; Mishra et al, 2020; Novack, 2011). Chen, Liu et al (2018) found that mechanical stretch induced osteogenic differentiation of human bone marrow mesenchymal stem cells via inhibition of NF‐κB signaling. We herein clarified the role of NF‐κB signaling in stretch‐induced osteogenic differentiation in osteoblasts.…”

“…NF‐κB is found to be a negative regulator of osteoblastic differentiation and bone formation (Chang et al, 2009; Krum et al, 2010; Novack, 2011). It has been shown that mechanical stretch promotes osteogenic differentiation in bone marrow mesenchymal stem cells and osteoblasts by inhibiting the NF‐κB activity (Chen, Liu, et al, 2018; Xu et al, 2020). However, the role of either mTOR or NF‐κB in the regulation of stretch‐induced osteogenic differentiation in osteoblasts remains not fully understood.…”

Parthenolide Has Negative Effects on In Vitro Enhanced Osteogenic Phenotypes by Inflammatory Cytokine TNF-α via Inhibiting JNK Signaling

“…NF-κB is a major transcription factor that regulates the expression of inflammatory mediators and cytokines, and its activation plays a critical role in the initiation and development of inflammatory bone disease, suggesting that the inhibition of NF-κB signaling could represent a promising therapeutic target for the inhibition of osteolysis. Although the effects of NF-κB activation on osteoblast differentiation and bone formation under in vitro culture conditions remain under debate, in general, NF-κB activation has been implicated in the stimulation of osteoclast differentiation and the inhibition of osteogenic differentiation in MSCs [23][24][25][26]. Chang et al [27] reported that the time-and stage-specific inactivation of NF-κB signaling in differentiated osteoblasts significantly increased trabecular bone mass and bone mineral density, without affecting osteoclast activities in young mice, and rescued bone loss in an ovariectomized adult mouse model.…”