Morinda Officinalis-derived extracellular vesicle-like particles: Anti-osteoporosis effect by regulating MAPK signaling pathway

BACKGROUND

Postmenopausal osteoporosis (PMOP) is a systemic bone disease characterized by low bone mass and microstructural damage. Morinda Officinalis (MO) contains various components with anti-PMOP activities. Morinda Officinalis-derived extracellular vesicle-like particles (MOEVLPs) are new active components isolated from MO, and no relevant studies have investigated their anti-osteoporosis effect and mechanism.

PURPOSE

To investigate the alleviating effect of MOEVLPs on PMOP and the underlying mechanism.

METHODS

Differential centrifugation and ultracentrifugation were used to isolate MOEVLPs from MO. Transmission electron microscopy (TEM), flow nano analyzer, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), agarose gel electrophoresis, and thin-layer chromatography were employed to characterize MOEVLPs. PMOP mouse models were utilized to examine the anti-PMOP effect of MOEVLPs. H&E and immunohistochemical staining were used for drug safety and osteogenic effect assessment. Mouse embryo osteoblast precursor cells (MC3T3-E1) were used in vitro experiments. CCK-8 kit, alizarin red staining, proteomic, bioinformatic analyses, and western blot were used to explore the mechanism of MOEVLPs.

RESULTS

In this study, MOEVLPs from MO were successfully isolated and characterized. Animal experiments demonstrated that MOEVLPs exhibited specific femur targeting, were non-toxic to the heart, liver, spleen, lung, kidney, and aorta, and possessed anti-PMOP properties. The ability of MOEVLPs to strengthen bone formation was better than that of alendronate. In vitro experiments, results revealed that MOEVLPs did not significantly enhance osteogenic differentiation in MC3T3-E1 cells. Instead, MOEVLPs promoted the proliferation of MC3T3-E1 cells. Proteomic and bioinformatic analyses suggested that the proliferative effect of MOEVLPs was closely associated with the mitogen-activated protein kinase (MAPK) signaling pathway, particularly the altered expression of cAMP response element-binding protein (CREB) and ribosomal S6 kinase 1 (RSK1). Western blot results further confirmed these findings.

CONCLUSION

Our studies successfully isolated high-quality MOEVLPs and demonstrated that MOEVLPs can alleviate PMOP by promoting osteoblast proliferation through the MAPK pathway. MOEVLPs have the potential to become a novel and natural anti-PMOP drug.

Long non-coding RNA MIAT serves as a biomarker of fragility fracture and promotes fracture healing

BACKGROUND

Fragility fracture is common in the elderly. Osteoblast differentiation is essential for bone healing and regeneration. Expression pattern of long non-coding RNA MIAT during fracture healing was examined, and its role in osteoblast differentiation was investigated.

METHODS

90 women with simple osteoporosis and 90 women with fragility fractures were included. Another 90 age-matched women were set as the control group. mRNA levels were tested using RT-qPCR. Cell viability was detected via CCK-8, and osteoblastic biomarkers, including ALP, OCN, Collagen I, and RUNX2 were tested via ELISA. The downstream miRNAs and genes targeted by MIAT were predicted by bioinformatics analysis, whose functions and pathways were annotated via GO and KEGG analysis.

RESULTS

Serum MIAT was upregulated in osteoporosis women with high accuracy of diagnostic efficacy. Serum MIAT was even elevated in the fragility fracture group, but decreased in a time manner after operation. MIAT knockdown promoted osteogenic proliferation and differentiation of MC3T3-E1, but the influences were reversed by miR-181a-5p inhibitor. A total of 137 overlapping target genes of miR-181a-5p were predicted based on the miRDB, TargetScan and microT datasets, which were mainly enriched for terms related to signaling pathways regulating pluripotency of stem cells, cellular senescence, and osteoclast differentiation.

CONCLUSIONS

LncRNA MIAT serves as a promising biomarker for osteoporosis, and promotes osteogenic differentiation via targeting miR-181a-5p.

Identification of the murine osteoblastic cell MC3T3-E1 as a permissive cell line in response to lumpy skin disease virus

Lumpy skin disease virus (LSDV) is a rapidly emerging pathogen in China. Screening suitable cells for LSDV replication is vital for future research on pathogenic mechanisms and vaccine development. Previous comparative studies have identified that the rodent-derived BHK21 is a highly susceptible cell model to LSDV infection. Using western blot, indirect immune-fluorescence assay, flow cytometry, and transmission electron microscopy methods, this study is the first to identify the murine osteoblastic cell line MC3T3-E1 as a novel permissive cell model for LSDV infection. The establishment of MC3T3-E1 as a suitable infectious cell model enhances our understanding of the species range and cell types of the permissive cells and nonpermissive that support LSDV replication. It is helpful to accelerate future research on the pathogenesis, clinical application, and vaccine development of LSDV.

17β-Estradiol (E2) Activates Matrix Mineralization through Genomic/Nongenomic Pathways in MC3T3-E1 Cells

Estrogen plays an important role in osteoporosis prevention. We herein report the possible novel signaling pathway of 17β-estradiol (E2) in the matrix mineralization of MC3T3-E1, an osteoblast-like cell line. In the culture media-containing stripped serum, in which small lipophilic molecules such as steroid hormones including E2 were depleted, matrix mineralization was significantly reduced. However, the E2 treatment induced this. The E2 effects were suppressed by ICI182,780, the estrogen receptor (ER)α, and the ERβ antagonist, as well as their mRNA knockdown, whereas Raloxifene, an inhibitor of estrogen-induced transcription, and G15, a G-protein-coupled estrogen receptor (GPER) 1 inhibitor, had little or no effect. Furthermore, the E2-activated matrix mineralization was disrupted by PMA, a PKC activator, and SB202190, a p38 MAPK inhibitor, but not by wortmannin, a PI3K inhibitor. Matrix mineralization was also induced by the culture media from the E2-stimulated cell culture. This effect was hindered by PMA or heat treatment, but not by SB202190. These results indicate that E2 activates the p38 MAPK pathway via ERs independently from actions in the nucleus. Such activation may cause the secretion of certain signaling molecule(s), which inhibit the PKC pathway. Our study provides a novel pathway of E2 action that could be a therapeutic target to activate matrix mineralization under various diseases, including osteoporosis.

In vitro cytotoxicity of magnetic-fluorescent bioactive glasses on SaOS-2, MC3T3-E1, BJ fibroblast cells, their hemolytic activity, and sorafenib release behavior

In the study, the fabrication of superparamagnetic-fluorescent bioactive glasses in the form of the particle, nanofiber, and 3D scaffolds was performed by including maghemite (γ-Fe2O3) nanoparticles and photoluminescent rare earth element ions (Eu3+, Gd3+, and Yb3+) using sol-gel, electrospinning, and robocasting techniques, respectively. The in vitro cytotoxicity of the magnetic-fluorescent bioactive glasses on osteosarcoma SaOS-2, pre-osteoblast MC3T3-E1, and BJ fibroblast cells, as well as their hemolytic activity and sorafenib tosylate loading and release behavior, were investigated. The cytotoxicity of the bioactive glass samples was tested using the MTT assay. Additionally, the alkaline phosphatase activity of the studied glasses was examined as a function of time. The mineralization behavior of the pre-osteoblast cell-seeded glass samples was analyzed using Alizarin red S staining. Results revealed that the in vitro cytotoxicity of the studied bioactive glasses in the form of particles and nanofibers depended on the sample concentration, whereas in the case of the 3D scaffolds, no cytotoxic response was observed on the osteosarcoma, pre-osteoblast, and fibroblast cells. Similarly, particle and nanofiber-based glass samples induced dose-dependent hemolysis on red blood cells. Drug loading rates were much lower for the 3D scaffolds compared to the particle and nanofiber-based samples. Drug release rates ranged from 25 % to 90 %, depending on the bioactive glass morphology and the pH of the release medium. It was concluded that the studied bioactive glasses have the potential to be used in tissue engineering applications and cancer therapy.

Doxorubicin loaded octacalcium phosphate particles as controlled release drug delivery systems: Physico-chemical characterization, in vitro drug release and evaluation of cell death pathway

Mastering new and efficient ways to obtain successful drug delivery systems (DDS) with controlled release became a paramount quest in the scientific community. Increase of malignant bone tumors and the necessity to optimize an approach of localized drug delivery require research to be even more intensified. Octacalcium phosphate (OCP), with a number of advantages over current counterparts is extensively used in bone engineering. The aim of the present research was to synthesize bioactive and biocompatible doxorubicin (DOX) containing OCP particles. DOX-OCP was successfully obtained in situ in an exhaustive range of added drug (1-20 wt%, theoretical loading). Based on XRD, above 10 wt% of DOX, OCP formation was inhibited and the obtained product was low crystalline α-TCP. In-vitro drug release was performed in pH 7.4 and 6.0. In both pH environments DOX had a continuous release over six weeks. However, the initial drug burst for pH 7.4, in the first 24 h, ranged from 15.9 ± 1.3 % to 33.5 ± 12 % and for pH 6.0 23.7 ± 1.5 % to 36.2 ± 12 %.The DOX-OCP exhibited an inhibitory effect on viability of osteosarcoma cell lines MG63, U2OS and HOS. In contrast, MC3T3-E1 cells (IC50 > 0.062 µM) displayed increased viability and proliferation from 3rd to 7th day. Testing of the DDS on ferroptotic markers (CHAC1, ACSL4 and PTGS2) showed that OCP-DOX does not induce ferroptotic cell death. Moreover, the evaluation of protein levels of cleaved PARP, by western blotting analysis, corroborated that apoptosis is the main pathway of programmed cell death in osteosarcoma cells induced by DOX-OCP.

Molecular mechanism of resveratrol promoting differentiation of preosteoblastic MC3T3-E1 cells based on network pharmacology and experimental validation

The purpose of this study was to investigate the mechanism by which resveratrol (Res) inhibits apoptosis and promotes proliferation and differentiation of pre-osteoblastic MC3T3-E1 cells, laying the groundwork for the treatment of osteoporosis (OP). The TCMSP database was used to find the gene targets for Res. The GeneCards database acquire the gene targets for OP. After discovering the potential target genes, GO, KEGG, and Reactome enrichment analysis were conducted. Verifying the major proteins involved in apoptosis can bind to Res using molecular docking. CCK8 measured the proliferative activity of mouse pre-osteoblasts in every group following Res intervention. Alkaline phosphatase staining (ALP) and alizarin red staining to measure the ability of osteogenic differentiation. RT-qPCR to determine the expression levels of Runx2 and OPG genes for osteogenic differentiation ability of cells. Western blot to measure the degree of apoptosis-related protein activity in each group following Res intervention. The biological processes investigated for GO of Res therapeutic OP involved in cytokine-mediated signaling pathway, negative regulation of apoptotic process, Aging, extrinsic apoptotic signaling pathway in absence of ligand, according to potential therapeutic target enrichment study. Apoptosis, FoxO signaling pathway, and TNF signaling pathway are the primary KEGG signaling pathways. Recactome pathways are primarily engaged in Programmed Cell Death, Apoptosis, Intrinsic Apoptotic Pathway, and Caspase activation via extrinsic apoptotic signaling pathways. This research established a new approach for Res treatment of OP by demonstrating how Res controls the apoptosis-related proteins TNF, IL6, and CASP3 to suppress osteoblast death and increase osteoclastogenesis.

MicroRNA-877-5p promotes osteoblast differentiation by targeting EIF4G2 expression

Stimulating bone formation potentially suggests therapeutics for orthopedic diseases including osteoporosis and osteoarthritis. Osteoblasts are key to bone remodeling because they act as the only bone-forming cells. miR-877-5p has a chondrocyte-improving function in osteoarthritis, but its effect on osteoblast differentiation is unknown. Here, miR-877-5p-mediated osteoblast differentiation was studied. Real-time reverse transcriptase-polymerase chain reaction was performed to measure miR-877-5p expression during the osteogenic differentiation of MC3T3-E1 cells. Osteoblast markers, including alkaline phosphatase (ALP), collagen type I a1 chain, and osteopontin, were measured and detected by alizarin red staining and ALP staining. Potential targets of miR-877-5p were predicted from three different algorithms: starBase ( http://starbase.sysu.edu.cn/ ), PITA ( http://genie.weizmann.ac.il/pubs/mir07/mir07_data.html ), and miRanda ( http://www.microrna.org/microrna/home.do ). It was further verified by dual luciferase reporter gene assay. The experimental results found that miR-877-5p was upregulated during the osteogenic differentiation of MC3T3-E1 cells. Overexpression of miR-877-5p promoted osteogenic differentiation, which was characterized by increased cell mineralization, ALP activity, and osteogenesis-related gene expression. Knockdown of miR-877-5p produced the opposite result. Dual luciferase reporter gene assay showed that miR-877-5p directly targeted eukaryotic translation initiation factor 4γ2 (EIF4G2). Overexpression of EIF4G2 inhibited osteogenic differentiation and reversed the promoting effect of overexpression of miR-135-5p on osteogenic differentiation. These results indicate that miR-877-5p might have a therapeutic application related to its promotion of bone formation through targeting EIF4G2.

Liraglutide attenuates palmitate-induced apoptosis via PKA/β-catenin/Bcl-2/Bax pathway in MC3T3-E1 cells

Liraglutide (LRG), one agonist of glucagon-like peptide-1 receptor (GLP1R), has multiple lipid-lowering effects in type 2 diabetes mellitus, however, studies on the role of LRG in saturated fatty acid-induced bone loss are limited. Therefore, our aim was to investigate whether LRG reduces palmitate (PA)-induced apoptosis and whether the mechanism involves PKA/β-catenin/Bcl-2/Bax in osteoblastic MC3T3-E1 cells. MC3T3-E1 cells were treated with different concentrations of PA, LRG, or pretreated with Exendin 9-39 and H89, cell viability, intracellular reactive oxygen species (ROS), cAMP levels, apoptosis and the expression of protein kinase A (PKA) and phosphorylation of PKA (p-PKA), β-catenin and phosphorylation of β-catenin (Ser675)(p-β-catenin), GLP1R, cleaved-capase 3, Bcl2-Associated X Protein (Bax) and B-cell lymphoma-2 (Bcl-2) along with expression of Osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) were evaluated. PA treatment inhibited cell proliferation and cAMP levels, elevated intracellular ROS levels and promoted apoptosis, increased protein expressions of RANKL, Bax and cleaved-caspase3, meanwhile decreased protein expression of OPG and Bcl-2 in a dose-dependent manner. LRG inverted PA-induced apoptosis, increased cAMP levels, promoted expression of p-PKA, p-β-catenin (Ser675) and reversed these gene expressions via increasing GLP1R expression. Pretreatment of the cells with Exendin 9-39 and H89 partially eradicated the protective effect of LRG on PA-induced apoptosis and gene expressions. Therefore, these findings indicated that LRG attenuates PA-induced apoptosis possibly by GLP1R-mediated PKA/β-catenin/Bcl-2/Bax pathway in MC3T3-E1 cells. Our results point to LRG as a new strategy to attenuate bone loss associated with high fat diet beyond its lipid-lowering actions. LRG inhibits PA-mediated apoptosis via GLP1R-mediated PKA/β-catenin/Bcl-2/ Bax pathway, while possibly enhances PA-inhibited differentiation by regulating the expression of OPG and RANKL.

Thermoresponsive Alginate-Graft-pNIPAM/Methyl Cellulose 3D-Printed Scaffolds Promote Osteogenesis In Vitro

In this work, a sodium alginate-based copolymer grafted by thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) chains was used as gelator (Alg-g-PNIPAM) in combination with methylcellulose (MC). It was found that the mechanical properties of the resulting gel could be enhanced by the addition of MC and calcium ions (Ca2+). The proposed network is formed via a dual crosslinking mechanism including ionic interactions among Ca2+ and carboxyl groups and secondary hydrophobic associations of PNIPAM chains. MC was found to further reinforce the dynamic moduli of the resulting gels (i.e., a storage modulus of ca. 1500 Pa at physiological body and post-printing temperature), rendering them suitable for 3D printing in biomedical applications. The polymer networks were stable and retained their printed fidelity with minimum erosion as low as 6% for up to seven days. Furthermore, adhered pre-osteoblastic cells on Alg-g-PNIPAM/MC printed scaffolds presented 80% viability compared to tissue culture polystyrene control, and more importantly, they promoted the osteogenic potential, as indicated by the increased alkaline phosphatase activity, calcium, and collagen production relative to the Alg-g-PNIPAM control scaffolds. Specifically, ALP activity and collagen secreted by cells were significantly enhanced in Alg-g-PNIPAM/MC scaffolds compared to the Alg-g-PNIPAM counterparts, demonstrating their potential in bone tissue engineering.

GPER1 contributes to T3-induced osteogenesis by mediating glycolysis in osteoblast precursors

Triiodothyronine (T3) is critical to osteogenesis, which is the key factor in bone growth. Our transcriptomic and metabolomic analysis results indicated that T3 leads to enhanced expression of G protein-coupled estrogen receptor 1 (GPER1) as well as increases in glycolysis metabolite levels. Accordingly, our study aimed to explore the role of GPER1-mediated glycolysis in T3-regulated osteogenesis. The MC3T3-E1 cell line was used as an osteoblast precursor model. After treatment with T3, a GPER1-specific antagonist (G15) and inhibitor of glycolysis (3PO) were used to explore the roles of GPER1 and glycolysis in T3-regulated osteogenesis, as measured by ALP activity, Alizarin red staining intensity and osteogenic molecule expression. Our results showed that T3 promoted osteogenesis-related activity, which was reversed by treatment with G15. In addition, T3 enhanced the glycolytic potential and production of lactic acid (LD) in MC3T3-E1 cells, and treatment with G15 restored the aforementioned effects of T3. Ultimately, the pharmacological inhibition of glycolysis with 3PO blocked the ability of T3 to enhance osteogenic activities. In conclusion, GPER1 mediates glycolysis in osteoblast precursors, which is critical for T3-promoted osteogenesis.

Methoxyflavones isolated from the whole plant of Scutellaria rubropunctata Hayata var. rubropunctata promote osteoblast differentiation in MC3T3-E1 cells

In this study, we isolated two new methoxyflavones (1 and 2) and eight known methoxyflavones (3-10) from the whole plant of Scutellaria rubropunctata Hayata var. rubropunctata (SR). Based on spectroscopic analyses, the methoxyflavones were identified as 5,8,2',6'-tetramethoxy-6,7-methylenedioxyflavone (1) and 5,2',6'-trimethoxy-6,7-methylenedioxyflavone (2). We reported SR might have effects on promoting osteoblast differentiation and stimulating estrogen receptor (ER) in the previous study. Then, the effects of 1-10 on pre-osteoblast MC3T3-E1 cells were investigated, and 1, 2, and 9 were observed to promote alkaline phosphatase activity. To evaluate their effect on osteogenesis-related genes, we performed gene expression analysis using quantitative real-time PCR after treatment of MC3T3-E1 cells with these compounds. Although 2 was only effective at lower concentrations, 1 and 9 upregulated the mRNA levels of Runx2, Osterix, Osteopontin, Osteocalcin, Smad1, and Smad4. These results indicate that 1 and 9 may induce osteoblast differentiation by activating Runx2 via the BMP/Smad pathway and may play a central role in the promotion of osteoblast differentiation by SR. The ER agonist activity of 1-10 were tested using a luciferase reporter assay in HEK293 cells. However, none of the compounds exhibited remarkable activity. Thus, SR may contain other compounds that contribute to its ER agonist activity.

Extract of Artemisia dracunculus L. Modulates Osteoblast Proliferation and Mineralization

Thiazolidinediones (TZD) significantly improve insulin sensitivity via action on adipocytes. Unfortunately, TZDs also degrade bone by inhibiting osteoblasts. An extract of Artemisia dracunculus L., termed PMI5011, improves blood glucose and insulin sensitivity via skeletal muscle, rather than fat, and may therefore spare bone. Here, we examine the effects of PMI5011 and an identified active compound within PMI5011 (2',4'-dihydroxy-4-methoxydihydrochalcone, DMC-2) on pre-osteoblasts. We hypothesized that PMI5011 and DMC-2 will not inhibit osteogenesis. To test our hypothesis, MC3T3-E1 cells were induced in osteogenic media with and without PMI5011 or DMC-2. Cell lysates were probed for osteogenic gene expression and protein content and were stained for osteogenic endpoints. Neither compound had an effect on early stain outcomes for alkaline phosphatase or collagen. Contrary to our hypothesis, PMI5011 at 30 µg/mL significantly increases osteogenic gene expression as early as day 1. Further, osteogenic proteins and cell culture mineralization trend higher for PMI5011-treated wells. Treatment with DMC-2 at 1 µg/mL similarly increased osteogenic gene expression and significantly increased mineralization, although protein content did not trend higher. Our data suggest that PMI5011 and DMC-2 have the potential to promote bone health via improved osteoblast maturation and activity.

Intervention Effects of Deer-Tendon Collagen Hydrolysates on Osteoporosis In Vitro and In Vivo

Deer tendon, a deer processing byproduct, is an excellent protein source for the preparation of peptides for improving osteoporosis by its high protein content and high nutritional value. The optimal process of collagen acid extraction was implemented and the results showed that the acid concentration was 7%, the material-liquid ratio was 1:25, and the soaking time was 48 h. DTCHs could promote MC3T3-E1 cell proliferation and increase alkaline phosphatase activities in vitro. In addition, compared with the model group, the DTCHs treatment groups with an oral dosage of 350, 750, and 1500 mg/kg rat/day could significantly improve the shape, weight, bone mechanics, and alkaline phosphatase activities of tail-suspended mice. Bone microstructure and mineralization also recovered significantly in vivo. This result is expected to provide the structural and biological information for DTCHs-based functional foods.

Persicae Semen Promotes Bone Union in Rat Fractures by Stimulating Osteoblastogenesis through BMP-2 and Wnt Signaling

Fractures cause extreme pain to patients and impair movement, thereby significantly reducing their quality of life. However, in fracture patients, movement of the fracture site is restricted through application of a cast, and they are reliant on conservative treatment through calcium intake. Persicae semen (PS) is the dried mature seeds of Prunus persica (L.) Batsch, and in this study the effects of PS on osteoblast differentiation and bone union promotion were investigated. The osteoblast-differentiation-promoting effect of PS was investigated through alizarin red S and Von Kossa staining, and the regulatory role of PS on BMP-2 (Bmp2) and Wnt (Wnt10b) signaling, representing a key mechanism, was demonstrated at the protein and mRNA levels. In addition, the bone-union-promoting effect of PS was investigated in rats with fractured femurs. The results of the cell experiments showed that PS promotes mineralization and upregulates RUNX2 through BMP-2 and Wnt signaling. PS induced the expression of various osteoblast genes, including Alpl, Bglap, and Ibsp. The results of animal experiments show that the PS group had improved bone union and upregulated expression of osteogenic genes. Overall, the results of this study suggest that PS can promote fracture recovery by upregulating osteoblast differentiation and bone formation, and thus can be considered a new therapeutic alternative for fracture patients.

Resveratrol induces proliferation and differentiation of mouse pre-osteoblast MC3T3-E1 by promoting autophagy

BACKGROUND

In mouse, it was discovered that resveratrol (Res) enhanced osteoporosis (OP) by boosting osteogenesis. Besides, Res can also have an impact on MC3T3-E1 cells, which are crucial for the control of osteogenesis and thus increase osteogenesis. Although some articles have discovered that Res enhanced autophagy to promote the value-added differentiation of MC3T3, it is unclear exactly how this affects the process of osteogenesis in mouse. Therefore, we will show that Res encourages MC3T3-E1 proliferation and differentiation in mouse pre-osteoblasts and further investigate the autophagy-related mechanism for this impact.

METHODS

(1) MC3T3-E1 cells were separated into blank control group and various concentrations (0.01, 0.1, 1, 10, 100µmol/L) of group in order to determine the ideal Res concentration. In the Res group, Cell Counting Kit-8 (CCK-8) was used to measure the proliferation activity of pre-osteoblasts in mice in each group after resveratrol intervention. Alkaline Phosphatase (ALP) and alizarin red staining were used to gauge the degree of osteogenic differentiation, and RT-qPCR was used to measure the expression levels of Runx2 and OCN in the osteogenic differentiation ability of the cells. (2) In the experiment, four groups were set up: the control group, 3MA group, Res group, and Res + 3MA group. To examine cell mineralization, ALP and alizarin red staining were utilized. RT-qPCR and Western blot detection of cell autophagy activity levels and osteogenic differentiation capacity in each group following intervention.

RESULTS

(1) Resveratrol might increase the number of mice pre-osteoblast, with the impact being most pronounced at 10µmol/L (P < 0.05). The nodules developed substantially more often than in the blank control group, and Runx2 and OCN expressions significantly increased (P < 0.05). (2) In contrast to the Res group, after 3MA purine blocked autophagy, the Res + 3MA group's alkaline phosphatase staining and the development of mineralized nodules were reduced. Runx2, OCN, LC3II / LC3I expression decreased, p62 expression increased (P < 0.05).

CONCLUSION

The present study partially or indirectly demonstrated that Res may, through increased autophagy, induce osteogenic differentiation of MC3T3-E1 cells.

DMP1 and IFITM5 Regulate Osteogenic Differentiation of MC3T3-E1 on PEO-Treated Ti-6Al-4V-Ca2+/Pi surface

Despite numerous studies on various surface modifications on titanium and its alloys, it remains unclear what kind of titanium-based surface modifications are capable of controlling cell activity. This study aimed to understand the mechanism at the cellular and molecular levels and investigate the in vitro response of osteoblastic MC3T3-E1 cultured on the Ti-6Al-4V surface modified by plasma electrolytic oxidation (PEO) treatment. A Ti-6Al-4V surface was prepared by PEO at 180, 280, and 380 V for 3 or 10 min in an electrolyte containing Ca²⁺/P_i ions. Our results showed that PEO-treated Ti-6Al-4V-Ca²⁺/P_i surfaces enhanced the cell attachment and differentiation of MC3T3-E1 compared to the untreated Ti-6Al-4V control but did not affect cytotoxicity as shown by cell proliferation and cell death. Interestingly, on the Ti-6Al-4V-Ca²⁺/P_i surface treated by PEO at 280 V for 3 or 10 min, MC3T3-E1 showed a higher initial adhesion and mineralization. In addition, the alkaline phosphatase (ALP) activity significantly increased in MC3T3-E1 on the PEO-treated Ti-6Al-4V-Ca²⁺/P_i (280 V for 3 or 10 min). In RNA-seq analysis, the expression of dentin matrix protein 1 (DMP1), sortilin 1 (Sort1), signal-induced proliferation-associated 1 like 2 (SIPA1L2), and interferon-induced transmembrane protein 5 (IFITM5) was induced during the osteogenic differentiation of MC3T3-E1 on the PEO-treated Ti-6Al-4V-Ca²⁺/P_i. DMP1 and IFITM5 silencing decreased the expression of bone differentiation-related mRNAs and proteins and ALP activity in MC3T3-E1. These results suggest that the PEO-treated Ti-6Al-4V-Ca²⁺/P_i surface induces osteoblast differentiation by regulating the expression of DMP1 and IFITM5. Therefore, surface microstructure modification through PEO coatings with Ca²⁺/P_i ions could be used as a valuable method to improve biocompatibility properties of titanium alloys.

MiR-181a-5p promotes osteogenesis by targeting BMP3

High-throughput microRNA (miRNA) sequencing of osteoporosis was analyzed from the Gene Expression Omnibus (GEO) database to investigate specific microRNAs that control osteogenesis. MiR-181a-5p was differentially expressed among healthy subjects and those with osteoporosis. Inhibitors and mimics were transfected into cells to modulate miR-181a-5p levels to examine the role in MC3T3-E1 functions. Alkaline phosphatase (ALP) staining and Alizarin Red S (ARS) staining were used for morphological detection, and proteins of ALP and Runt-related transcription factor 2 (RUNX2), as osteogenesis markers, were detected. During the osteogenic differentiation of MC3T3-E1, the transcription level of miR-181a-5p was significantly increased. The inhibition of miR-181a-5p suppressed MC3T3-E1 osteogenic differentiation, whereas its overexpression functioned oppositely. Consistently, the miR-181a-5p antagomir aggravated osteoporosis in old mice. Additionally, we predicted potential target genes via TargetScan and miRDB and identified bone morphogenetic protein 3 (BMP3) as the target gene. Moreover, the reduced expression of miR-181a-5p was validated in our hospitalized osteoporotic patients. These findings have substantial implications for the strategies targeting miR-181a-5p to prevent osteoporosis and potential related fractures.

SOX2 suppresses osteoblast differentiation of MC3T3-E1 cells through activating the transcription of LGR4

Osteogenic differentiation is a crucial process of new bone formation. This study aimed to explore the roles and mechanism of SRY-Box Transcription Factor 2 (SOX2) on proliferation and osteogenic differentiation of MC3T3-E1 cells. Bone morphogenetic protein 2 (BMP2) was used to induce the osteogenic differentiation of MC3T3-E1 cells. The expression of SOX2 was determined by quantitative real-time PCR (RT-PCR) at different time points after induction. The SOX2 overexpression plasmids were constructed and transfected into MC3T3-E1 cells. Osteogenic differentiation was evaluated by Alizarin Red S staining and alkaline phosphatase (ALP) assay. The expressions of osteogenic differentiation markers including runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (OCN) were detected by western blot assay. Luciferase reporter and CHIP assays were used to confirm that SOX2 regulated the transcriptional activation of leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4). We found that SOX2 was down-regulated upon BMP2-induced osteogenic differentiation in MC3T3-E1 cells. Overexpression of SOX2 effectively inhibited osteogenic differentiation with decreased ALP activity, calcification, and osteogenic differentiation markers' expression including Runx2, OPN, and OCN. LGR4 was identified as a target of SOX2, and the inhibitory effect of SOX2 on osteogenic differentiation was reversed by knockdown of LGR4. The present study confirmed that SOX2 suppressed osteogenic differentiation of MC3T3-E1 cells through targeting LGR4, which possesses a therapeutic strategy for bone formation and generation.

N-acetyl Cysteine Inhibits Cell Proliferation and Differentiation of LPSInduced MC3T3-E1 Cells Via Regulating Inflammatory Cytokines

BACKGROUND

Peri-implantitis is one of the most common complications in oral implantation and could lead to the loss of the function of bone tissues around implants.

METHODS

This study used lipopolysaccharide (LPS) as a stimulant for MC3T3-E1 cells and N-acetyl cysteine (NAC) as an inhibitor to inhibit the effect of LPS to investigate the effect of NAC on the expression of bone formation related factors and inflammatory-related factors of osteoblasts under the action of LPS.

RESULTS

In this study, we found that the cell proliferation and cell differentiation were significantly promoted when NAC concentrations were between 0 ~ 0.5 mM, but were inhibited when the concentration exceeded 0.5 mM. LPS had a slightly promoting effect on the cell proliferation before 20 μg/mL but inhibited the cell proliferation after 20 μg/mL. LPS reduced protein and gene expressions of Runx2, ALP and BGP and increased protein and gene expressions of NF-κB and TNF-α. NAC reversibly regulated the LPS's regulation on the expression of MC3T3-E1 cell cytokine gene and protein.

CONCLUSION

The optimal NAC concentration for treating MC3T3-E1 cells is 0.5 mM, and the optimal LPS concentration for stimulating MC3T3-E1 cells is 20 μg/mL. NAC plays an active role in regulating the differentiation of MC3T3-E1 cells, and can inhibit LPS to regulate the differentiation of MC3T3-E1 cells. NAC promotes the expression of an osteogenic factor of MC3T3-E1cells and inhibits the expression of inflammatory cytokines.

Human Recombinant Lactoferrin Promotes Differentiation and Calcification on MC3T3-E1 Cells

Lactoferrin (LF), known to be present in mammalian milk, has been reported to promote the proliferation of osteoblasts and suppress bone resorption by affecting osteoclasts. However, the mechanisms underlying the effects of human sources LF on osteoblast differentiation have not yet been elucidated, and almost studies have used LF from bovine sources. The presented study aimed to characterize the molecular mechanisms of bovine lactoferrin (IF-I) and human recombinant lactoferrin (LF-II) on MC3T3-E1 pre-osteoblast cells. MC3T3-E1 cells were treated with LF, ascorbic acid, and β-glycerophosphate (β-GP). Cell proliferation was analyzed using the MTT assay. Alkaline phosphatase activation and osteopontin expression levels were evaluated via cell staining and immunocytochemistry. The differentiation markers were examined using quantitative real-time PCR. The cell viability assay showed the treatment of 100 μg/mL LF significantly increased; however, it was suppressed by the simultaneous treatment of ascorbic acid and β-GP. Alizarin red staining showed that the 100 μg/mL treatment of LF enhanced calcification. Quantitative real-time PCR showed a significant increase in osterix expression. The results suggest that treatment with both LFs enhanced MC3T3-E1 cell differentiation and promoted calcification. The mechanisms of calcification suggest that LFs are affected by an increase in osterix and osteocalcin mRNA levels.

Dibutyl phthalate causes MC3T3-E1 cell damage by increasing ROS to promote the PINK1/Parkin-mediated mitophagy

Dibutyl phthalate (DBP) is a plasticizer widely used in daily production, which causes serious environmental pollution, and damage to brain, liver, kidney, and lung by producing excessive reactive oxygen species (ROS) after entering the body. DBP can also cause skeletal dysplasia, but it is unclear whether ROS is involved. In addition, overproduction of ROS can activate mitophagy, which is an important mechanism for regulating mitochondrial quality and cell homeostasis. In order to investigate whether DBP can damage MC3T3-E1 cells (osteoblast cell line) and whether ROS and mitophagy are involved, DBP toxicity experiment, Parkin gene silencing experiment, and N-acetylcysteine (NAC) intervention experiment were performed on MC3T3-E1 cells in turn. First, we found that DBP caused MC3T3-E1 cell viability decline and osteogenic dysfunction, accompanied by the overproduction of ROS and the activation of mitophagy. Then, we found that silencing Parkin expression alleviated DBP-induced apoptosis and osteogenic dysfunction of MC3T3-E1 cells. In addition, NAC treatment inhibited the PINK1/Parkin-mediated mitophagy and alleviated the apoptosis and osteogenic dysfunction of MC3T3-E1 cells caused by DBP. Our research results showed that DBP could cause MC3T3-E1 cell damage by increasing ROS to promote the PINK1/Parkin-mediated mitophagy.

MiR-20a: a mechanosensitive microRNA that regulates fluid shear stress-mediated osteogenic differentiation via the BMP2 signaling pathway by targeting BAMBI and SMAD6

Background

MicroRNAs (miRNAs) are crucial regulators of diverse biological and pathological processes. This study aimed to investigate the role of microRNA 20a (miR-20a) in fluid shear stress (FSS)-mediated osteogenic differentiation.

Methods

In the present study, we subjected osteoblast MC3T3-E1 cells or mouse bone marrow stromal cells (BMSCs) to single bout short duration FSS (12 dyn/cm² for 1 hour) using a parallel plate flow system. The expression of miR-20a was quantified by miRNA array profiling and real-time quantitative polymerase chain reaction (qRT-PCR) during FSS-mediated osteogenic differentiation. The expression of osteogenic differentiation markers such as Runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), and SP7 transcription factor (SP7) was detected. Bioinformatics analysis and a luciferase assay were performed to confirm the potential targets of miR-20a.

Results

Osteoblast-expressed miR-20a is sensitive to the mechanical environments of FSS, which are differentially up-regulated during steady FSS-mediated osteogenic differentiation. MiR-20a enhances FSS-induced osteoblast differentiation by activating the bone morphogenetic protein 2 (BMP2) signaling pathway. Both BMP and activin membrane-bound inhibitor (BAMBI) and mothers against decapentaplegic family member 6 (SMAD6) are targets of miR-20a that negatively regulate the BMP2 signaling pathway.

Conclusions

MiR-20a is a novel mechanosensitive miRNA that can enhance osteoblast differentiation in FSS mechanical environments, implying that this miRNA might be a target for bone tissue engineering and orthodontic bone remodeling for regenerative medicine applications.

Comparison between hydroxyapatite and polycaprolactone in inducing osteogenic differentiation and augmenting maxillary bone regeneration in rats

Background

The selection of appropriate scaffold plays an important role in ensuring the success of bone regeneration. The use of scaffolds with different materials and their effect on the osteogenic performance of cells is not well studied and this can affect the selection of suitable scaffolds for transplantation. Hence, this study aimed to investigate the comparative ability of two different synthetic scaffolds, mainly hydroxyapatite (HA) and polycaprolactone (PCL) scaffolds in promoting in vitro and in vivo bone regeneration.

Method

In vitro cell viability, morphology, and alkaline phosphatase (ALP) activity of MC3T3-E1 cells on HA and PCL scaffolds were determined in comparison to the accepted model outlined for two-dimensional systems. An in vivo study involving the transplantation of MC3T3-E1 cells with scaffolds into an artificial bone defect of 4 mm length and 1.5 mm depth in the rat's left maxilla was conducted. Three-dimensional analysis using micro-computed tomography (micro-CT), hematoxylin and eosin (H&E), and immunohistochemistry analyses evaluation were performed after six weeks of transplantation.

Results

MC3T3-E1 cells on the HA scaffold showed the highest cell viability. The cell viability on both scaffolds decreased after 14 days of culture, which reflects the dominant occurrence of osteoblast differentiation. An early sign of osteoblast differentiation can be detected on the PCL scaffold. However, cells on the HA scaffold showed more prominent results with intense mineralized nodules and significantly (p < 0.05) high levels of ALP activity with prolonged osteoblast induction. Micro-CT and H&E analyses confirmed the in vitro results with bone formation were significantly (p < 0.05) greater in HA scaffold and was supported by IHC analysis which confirmed stronger expression of osteogenic markers ALP and osteocalcin.

Conclusion

Different scaffold materials of HA and PCL might have influenced the bone regeneration ability of MC3T3-E1. Regardless, in vitro and in vivo bone regeneration was better in the HA scaffold which indicates its great potential for application in bone regeneration.

Strontium based Astragalus polysaccharides promote osteoblasts differentiation and mineralization

Bone formation and repair represent a clinical challenge. In this work, we designed and synthesized strontium Astragalus polysaccharide (APS-Sr), a novel polysaccharide compound that should have therapeutic effects on both anti-inflammation and promoting bone formation. Using material characterization techniques, including SEM, FITR, XRD, etc., we verified the successful synthesis of this compound. Moreover, we examined the potential of this compound for promoting bone repair and inhibiting inflammatory response by cell proliferation assay, ALP and Alizarin Red staining experiments and RT-qPCR. The biological experiment results showed that APS-Sr can effectively inhibit inflammatory factors, promote osteogenic differentiation and up-regulate the bone growth factors. It is therefore believed that APS-Sr should be a promising polysaccharide compound in bone-related biomedical applications.