MicroRNA-146a-loaded magnesium silicate nanospheres promote bone regeneration in an inflammatory microenvironment

Reconstruction of irregular oral-maxillofacial bone defects with an inflammatory microenvironment remains a challenge,as chronic local inflammation can largely impair bone healing.Here,we used magnesium silicate nanospheres(MSNs)to load microRNA-146a-5p(miR-146a)to fabricate a nanobiomaterial,MSN+miR-146a,which showed synergistic promoting effects on the osteogenic differentiation of human dental pulp stem cells(hDPSCs).In addition,miR-146a exhibited an anti-inflammatory effect on mouse bone marrow-derived macrophages(BMMs)under lipopolysaccharide(LPS)stimulation by inhibiting the NF-κB pathway via targeting tumor necrosis factor receptor-associated factor 6(TRAF6),and MSNs could simultaneously promote M2 polarization of BMMs.MiR-146a was also found to inhibit osteoclast formation.Finally,the dual osteogenic-promoting and immunoregulatory effects of MSN+miR-146a were further validated in a stimulated infected mouse mandibular bone defect model via delivery by a photocuring hydrogel.Collectively,the MSN+miR-146a complex revealed good potential in treating inflammatory irregular oralmaxillofacial bone defects.

Benidipine-loaded nanoflower-likemagnesium silicate improves bone regeneration

Regeneration and reconstruction of bone tissue is always a challenge for clinicians due to the uncertainty of bone repair materials in terms of long-term and efficient effects on osteoblasts.Here,we propose a novel strategy combining benidipine,an antihypertensive drug and nanoparticles to synergistically promote the healing of bone defects.Loose and porous benidipine-loaded magnesium silicate nanoparticles were prepared and validated for their biosafety.The nanoparticles were efficiently taken up by preosteoblasts and uniformly distributed around the nucleus.After internalization into cells,the nanosystem is degraded by lysosomes,and the effect of promoting osteogenic differentiation is reflected by the continuous release of benidipine,silicon and magnesium ions.Our results clearly evaluated that the nanoflower-like magnesium silicate delivering benidipine tends to be more appropriate for the bone regeneration in preosteoblasts,indicating that it might be a potential approach in guiding bone repair in clinical applications.

miR-21 promotes the differentiation of hair folliclederived neural crest stem cells into Schwann cells

Hair follicle-derived neural crest stem cells can be induced to differentiate into Schwann cells in vivo and in vitro. However, the underlying regulatory mechanism during cell differentiation remains poorly understood. This study isolated neural crest stem cells from human hair folli-cles and induced them to differentiate into Schwann cells. Quantitative RT-PCR showed that microRNA （miR）-21 expression was gradually increased during the differentiation of neural crest stem cells into Schwann cells. After transfection with the miR-21 agonist （agomir-21）, the differentiation capacity of neural crest stem cells was enhanced. By contrast, after transfection with the miR-21 antagonist （antagomir-21）, the differentiation capacity was attenuated. Further study results showed that SOX-2 was an effective target of miR-21. Without compromising SOX2 mRNA expression, miR-21 can down-regulate SOX protein expression by binding to the 3′-UTR of miR-21 mRNA. Knocking out the SOX2 gene from the neural crest stem cells significantly reversed the antagomir-21 inhibition of neural crest stem cells differentiating into Schwann cells. The results suggest that miR-21 expression was increased during the differentiation of neural crest stem cells into Schwann cells and miR-21 promoted the differentiation through down-regu-lating SOX protein expression by binding to the 3′-UTR of SOX2 mRNA.

Osteogenic effects of antihypertensive drug benidipine on mouse MC3T3-E1 cells in vitro

Hypertension is a prevalent systemic disease in the elderly,who can suffer from several pathological skeletal conditions simultaneously,including osteoporosis.Benidipine(BD),which is widely used to treat hypertension,has been proved to have a beneficial effect on bone metabolism.In order to confirm the osteogenic effects of BD,we investigated its osteogenic function using mouse MC3T3-E1 preosteoblast cells in vitro.The proliferative ability of MC3T3-E1 cells was significantly associated with the concentration of BD,as measured by methylthiazolyldiphenyl-tetrazolium bromide(MTT)assay and cell cycle assay.With BD treatment,the osteogenic differentiation and maturation of MC3T3-E1 cells were increased,as established by the alkaline phosphatase(ALP)activity test,matrix mineralized nodules formation,osteogenic genetic test,and protein expression analyses.Moreover,our data showed that the BMP2/Smad pathway could be the partial mechanism for the promotion of osteogenesis by BD,while BD might suppress the possible function of osteoclasts through the OPG/RANKL/RANK(receptor activator of nuclear factor-κB(NF-κB))pathway.The hypothesis that BD bears a considerable potential in further research on its dual therapeutic effect on hypertensive patients with poor skeletal conditions was proved within the limitations of the present study.