Function Of Osteoblastic Cells Research Articles

The role of autophagy/lipophagy in the response of osteoblastic cells to hyperlipidemia (Review).

There has been interest in the connection between cardiovascular diseases and osteoporosis, both of which share hyperlipidemia as a common pathological basis. Osteoporosis is a progressive metabolic bone disease characterized by reduced bone mass, deteriorated bone microstructure, increased bone fragility and heightened risk of bone fractures. Dysfunction of osteoblastic cells, vital for bone formation, is induced by excessive internalization of lipids under hyperlipidemic conditions, forming the crux of hyperlipidemia-associated osteoporosis. Autophagy, a process fundamental to cell self-regulation, serves a critical role in osteoblastic cell function and bone formation. When activated by lipids, lipophagy inhibits osteoblastic cell differentiation in response to elevated lipid concentrations, resulting in reduced bone mass and osteoporosis. However, an in-depth understanding of the precise roles and mechanisms of lipophagy in the regulation of osteoblastic cell function is required. Study of the molecular mechanisms governing osteoblastic cell response to excessive lipids can result in a clearer understanding of osteoporosis; therefore, potential strategies for preventing hyperlipidemia-induced osteoporosis can be developed. The present review discusses recent progress in elucidating the molecular mechanisms of lipophagy in the regulation of osteoblastic cell function, offering insights into hyperlipidemia-induced osteoporosis.

Hydroxyapatite (HA) scaffold supplemented with VEGF and BMP-2 growth factors enhanced osteogenic proliferation and differentiation of MC3T3-E1 cells

Background: Engineered bone tissue, made up of hydroxyapatite (HA) scaffold is the current alternative in bone transplant. The scaffold needs to mimic the extracellular matrix (ECM) to support bone growth and repair. Vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2) are vital in producing a suitable ECM environment to promote bone regeneration. Objective: To elucidate the synergistic effect of VEGF and BMP-2 growth factors on MC3T3-E1 osteoblast cells. Method: MC3T3-E1 cells were cultured in vitro and seeded onto a HA scaffold supplied with VEGF and BMP-2 growth factors. The characterisation of its mineralisation was evaluated on Day three and Day seven using the Alizarin Red staining (ARS) technique. Result: Positive ARS staining was observed in the HA scaffold supplied with VEGF and BMP-2 growth factors in vitro, thus indicating that a high level of calcium was deposited. These results suggest that the combined use of VEGF and BMP-2 will increase cell proliferation and osteoblast differentiation in vitro. Conclusion: Therefore, the synergistic effects of VEGF and BMP-2-loaded HA scaffold confirm the process as a promising approach to enhance the osteogenic effect and support cellular functions of osteoblastic cells in bone tissue engineering applications.

Sema4D is diminished in leukocyte platelet-rich fibrin and impairs pre-osteoblastic MC3T3-E1 cells' functionality.

ObjectiveSemaphorin 4D (Sema4D) is a coupling factor expressed on osteoclasts that may hinder osteoblast differentiation. Since the leukocyte platelet-rich fibrin (L-PRF) membrane promotes growth factor concentration, this study aims to quantify the amount of Sema4D in L-PRF membranes, and analyze the impact of Sema4D on osteoblast cell function in vitro. DesignEnzyme-linked immunosorbent assay (ELISA) was used to quantify the levels of Sema4D in both L-PRF and whole blood (serum). To analyze the impairment of Sema4D on osteoblasts, MC3T3-E1 cells were induced to osteogenic differentiation and exposed to Sema4D ranging from 10 to 500 ng/ml concentrations. The following parameters were assayed: 1) cell viability by MTT assay after 24, 48, and 72 h; 2) matrix mineralization by Alizarin Red staining after 14 days, 3) Runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN), osteonectin (ONC), bone sialoprotein (BSP) and alkaline phosphatase (ALP) gene expression by qPCR. For all data, the significance level was set at 5%. ResultsThe amount of Sema4D in the whole blood (serum) was higher than in L-PRF. Osteoblasts exposed to Sema4D at all tested concentrations exhibited a decrease in matrix mineralization formation as well in RUNX-2, OCN, ONC, BSP, and ALP gene expression (p < 0.05). ConclusionThe presence of Sema4D, a molecule known for suppressing osteoblast activity, diminishes within L-PRF, enhancing its ability to facilitate bone regeneration.

Post-Transcriptional Regulatory Crosstalk between MicroRNAs and Canonical TGF-β/BMP Signalling Cascades on Osteoblast Lineage: A Comprehensive Review

MicroRNAs (miRNAs) are a family of small, single-stranded, and non-protein coding RNAs about 19 to 22 nucleotides in length, that have been reported to have important roles in the control of bone development. MiRNAs have a strong influence on osteoblast differentiation through stages of lineage commitment and maturation, as well as via controlling the activities of osteogenic signal transduction pathways. Generally, miRNAs may modulate cell stemness, proliferation, differentiation, and apoptosis by binding the 3'-untranslated regions (3'-UTRs) of the target genes, which then can subsequently undergo messenger RNA (mRNA) degradation or protein translational repression. MiRNAs manage the gene expression in osteogenic differentiation by regulating multiple signalling cascades and essential transcription factors, including the transforming growth factor-beta (TGF-β)/bone morphogenic protein (BMP), Wingless/Int-1(Wnt)/β-catenin, Notch, and Hedgehog signalling pathways; the Runt-related transcription factor 2 (RUNX2); and osterix (Osx). This shows that miRNAs are essential in regulating diverse osteoblast cell functions. TGF-βs and BMPs transduce signals and exert diverse functions in osteoblastogenesis, skeletal development and bone formation, bone homeostasis, and diseases. Herein, we highlighted the current state of in vitro and in vivo research describing miRNA regulation on the canonical TGF-β/BMP signalling, their effects on osteoblast linage, and understand their mechanism of action for the development of possible therapeutics. In this review, particular attention and comprehensive database searches are focused on related works published between the years 2000 to 2022, using the resources from PubMed, Google Scholar, Scopus, and Web of Science.

RGD peptide functionalized graphene oxide: a bioactive surface for cell-material interactions

Recently, functionalized graphene-based nanomaterials have gained tremendous attention in biomedical field owing to their biocompatibility, surface functionalizability and their unique mechanical, electronic, and optical properties. Herein, we report a facile one step modification of graphene oxide by RGD peptide, which is known to improve the tissue– material contact by highly specific binding to cellular membrane receptors known as integrins. A detailed structural and morphological characterization of the obtained RGD functionalized graphene oxide (GO-RGD) was performed. The synthesized bioactive composite was used to prepare RGD-GO films by a vacuum filtration method. Additionally, mouse osteoblastic cell (MC3T3-E1) functions including cell attachment, adhesion, proliferation, and differentiation were investigated on GO-RGD films. The results indicated that MC3T3-E1 cell functions were significantly enhanced on GO-RGD films comparing with GO films without functionalization. This study not only demonstrates a facile approach to functionalize graphene oxide with bioactive peptides, but also provides a potential biomaterial for bone repair by improving osteoblastic cell functions.

Functional regulation of osteoblastic MC3T3E-1 cells by hyperbaric oxygen treatment

ObjectivesThe purpose of the present study was to examine the influence of hyperbaric oxygen (HBO) on the function of osteoblastic MC3T3-E1 cells. DesignMurine MC3T3-E1 cells were exposed to HBO treatment (at 2.5 absolute atmospheric pressure with 100% oxygen, 90 min per day) for 28 days. Alkaline phosphatase (ALP) staining, activity, and calcium (Ca) content were measured. Gene expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), hypoxia-inducible factor-1α (HIF-1α), type 1 collagen (COL1), and osteocalcin (OCN) was assessed using real-time quantitative polymerase chain reaction after a single HBO exposure for 1.5, 6, and 12 h. Furthermore, adenosine triphosphate (ATP) levels were measured using a luminescent cell viability assay. ResultsALP activity and Ca content were higher in the HBO group compared to those in the control group. Gene expression of bFGF, COL1, and OCN was upregulated in the HBO group; however, that of VEGF and HIF-1α significantly decreased in the HBO group in comparison with that in the control group. ATP levels were significantly higher in the HBO group compared to those in the control group. ConclusionsThese findings suggest that HBO accelerates bone formation by increasing the ATP levels of osteoblasts, and bFGF can act as a substitute for VEGF in vascularization by HBO application.

Direct effects of octreotide on osteoblast cell proliferation and function.

Octreotide (OCT) is a first-generation somatostatin analog (SSA) used in the treatment of acromegaly and neuroendocrine tumors (NETs). In both diseases, OCT interacts with somatostatin receptors 2 and 5 (SSTR2 and SSTR5), inhibiting hormone hypersecretion and cell proliferation. Skeletal health is an important clinical concern inacromegaly and NETs, since acromegalic osteopathy and NET bone metastasis occur in a remarkable number of patients. While OCT's effect on NET and pituitarycells has been extensively investigated, its direct action on bone cells remains unknown. Here, we investigated OCT direct effects on cell proliferation, differentiation, mineralization, and chemoattractant capacity of murine primary osteoblasts and osteoblast cell line MC3T3-E1. OCT inhibited osteoblasts and MC3T3-E1 cell proliferation (-30 ± 16%, and -22 ± 4%, both p < 0.05vs control) and increased MC3T3-E1 cell apoptosis (+ 76 ± 32%, p < 0.05 vs control). The anti-proliferative action of OCT was mediated by SSTR2 and SSTR5 in MC3T3-E1, while its pro-apoptotic effect was abrogated in SSTR2-silenced cells. The analysis of genes related to the early and late phases of osteoblast differentiation showed that OCT did not affect Alp, Runx2, Bglap, Spp1, and Sost levels in MC3T3-E1 cells. Similarly, OCT did not affect ALP activity, mineralization, and osteoclastogenic induction. Finally, Vegfa expression decreased in OCT-treated MC3T3-E1 cells and OCT inhibited pancreatic NET cell migration toward the osteoblast-conditioned medium. This study provides the first evidence of the direct action of OCT on osteoblasts which may have clinically relevant implications for the management of skeletal health in subjects with acromegaly and metastatic NETs.

Modification of heat-induced whey protein isolate hydrogel with highly bioactive glass particles results in promising biomaterial for bone tissue engineering

This study deals with the design and comprehensive evaluation of novel hydrogels based on whey protein isolate (WPI) for tissue regeneration. So far, WPI has been considered mainly as a food industry by-product and there are very few reports on the application of WPI in tissue engineering (TE). In this work, WPI-based hydrogels were modified with bioactive glass (BG), which is commonly used as a bone substitute material. Ready-to-use, sterile hydrogels were produced by a simple technique, namely heat-induced gelation. Two different concentrations (10 and 20% w/w) of sol–gel-derived BG particles of two different sizes (2.5 and <45 µm) were compared. µCT analysis showed that hydrogels were highly porous with almost 100% pore interconnectivity. BG particles were generally homogenously distributed in the hydrogel matrix, affecting pore size, and reducing material porosity. Thermal analysis showed that the presence of BG particles in WPI matrix reduced water content in hydrogels and improved their thermal stability. BG particles decreased enzymatic degradation of the materials. The materials underwent mineralization in simulated biological fluids (PBS and SBF) and possessed high radical scavenging capacity. In vitro tests indicated that hydrogels were cytocompatible and supported MG-63 osteoblastic cell functions.

Bone metabolism and the development of denosumab: a narrative review

: The bone of human body provides many basic functions, including normal bone metabolism. Bone plays an important role in maintaining physiological homeostasis of the body. The balance between osteolysis and osteogenesis is important in bone metabolism. This process reflects the osteoblast and osteolytic cell function of coordination. RANKL/RANK/OPG pathway plays a central regulatory role in normal bone remodeling. RANKL/RANK/OPG regulates the axis of Bone, which is an important way to influence bone formation and dynamic equilibrium. In the process of tumor osteolytic bone metastasis and giant cell tumor (GCT) of bone, the expression of RANKL increases, which leads to excessive bone resorption. Denosumab can specifically block RANKL, thereby inhibiting the activity of osteoclasts and blocking the development of disease. Skeletal-related event (SRE) caused by bone metastases not only reduce patients’ physical function and quality of life, but also increase the risk of death. How to optimize the management of bone metastasis and relieve the pain caused by bone metastasis has become a hot spot in the field of cancer. Based on a series of clinical studies, Denosumab has been approved by the U. S. Food and Drug Administration for osteoporosis, solid tumor bone metastasis, GCT of bone, malignant tumor hypercalcemia and other fields. In China, Denosumab was indicated to treat GCT of bone, as well as SRE caused by solid tumor bone metastases and multiple myeloma.

Exosomes derived from macrophages upon Zn ion stimulation promote osteoblast and endothelial cell functions.

Osteogenesis and angiogenesis are both important for implant osseointegration, which can be tailored by immunomodulation of macrophages. Zn, a novel biodegradable material, can modulate macrophage functions in its ionic form. However, whether macrophage-derived exosomes, novel carriers of intracellular communication, participate in the process is still unclear. The present work shows that Zn ions in the concentration range of 0-100 μM have no significant influence on macrophage viability, proliferation, morphology, and secretion amount of exosomes, but generally downregulate the gene expression of both M1 and M2 markers. The exosomes can be ingested continuously by osteoblasts and endothelial cells. The osteoblasts show the highest alkaline phosphatase activity after ingesting the exosomes derived from macrophages upon 4 μM Zn ion stimulation. In contrast, the endothelial cells migrate the furthest distance after ingesting the exosomes upon 20 μM Zn ion stimulation. These results indicate that Zn ions may vary the composition of macrophage-derived exosomes, which in turn affects the osteogenesis and angiogenesis. These findings are meaningful for the surface design of immunomodulatory biomaterials from the perspective of macrophage-derived exosomes.

Nanograins on Ti-25Nb-3Mo-2Sn-3Zr alloy facilitate fabricating biological surface through dual-ion implantation to concurrently modulate the osteogenic functions of mesenchymal stem cells and kill bacteria

Surface mechanical attrition treatment (SMAT) method is an effective way to generate nanograined (NG) surface on Ti-25Nb-3Mo-2Sn-3Zr (wt.%) (named as TLM), a kind of β-type titanium alloy, and the achieved nanocrystalline surface was proved to promote positive functions of osteoblastic cells. In this work, to further endow the NG TLM alloy with both good osteogenic and antibacterial properties, magnesium (Mg), silver (Ag) ion or both were introduced onto the NG TLM surface by ion implantation process, as a comparison, the Mg and Ag ions were also co-implanted onto coarsegrained (CG) TLM surface. The obtained results show that subsequent ion implantation does not remarkably induce the surface roughness and topography alteration of the SMAT-treated layers, and it also has little impact on the microstructure of the SMAT-derived β-Ti nanograins. In addition, the implanted Mg and Ag ions are observed to exist as MgO and metallic Ag nanoparticles (NPs) embedding tightly in the β-Ti matrix with grain size of about 15 and 7 nm, respectively. Initial cell adhesion and functions (including proliferation, osteo-differentiation and extracellular matrix mineralization) of rabbit bone marrow mesenchymal stem cells (rBMMSCs) and the bacterial colonization of Staphylococcus aureus (S. aureus) on the different surfaces were investigated. The in-vitro experimental results reveal that the Mg and Ag single-ion implanted NG surface either significantly promotes the rBMMSCs response or inhibits the growth of S. aureus, whereas the Mg/Ag co-implanted NG surface could concurrently enhance the rBMMSCs functions as well as inhibit the bacterial growth compared to the NG surface, and this efficacy is more pronounced as compared to the Mg/Ag co-implantation in the CG surface. The SMAT-achieved nanograins in the TLM surface layer are identified to not only play a leading role in determining the fate of rBMMSCs but also facilitate fabricating dual-functional surface with both good osteogenic and antibacterial activities through co-implantation of Mg and Ag ions. Our investigation provides a new strategy to develop high-performance Ti-based implants for clinical application.

Phosvitin Derived Phospho-Peptides Show Better Osteogenic Potential than Intact Phosvitin in MC3T3-E1 Osteoblastic Cells.

Phosphorylated proteins from food sources have been investigated as regulators of bone formation with potential benefits in treating osteoporosis. Egg, a cheap and nutritious food, is also the source of various proteins and bioactive peptides with applications in human health. Egg yolk is rich in phosvitin, the most phosphorylated protein in nature. Phosvitin has been shown to improve bone health in experimental animals, although the molecular mechanisms and its specific effects on bone-forming osteoblastic cells are incompletely understood. Previous work in our group has identified pancreatin-generated phosvitin phospho-peptides (PPP) as a potential source for bioactive peptides. Given this background, we examined the roles of both phosvitin and PPP in the function of osteoblastic cells. Our results demonstrated their potential to improve bone health by promoting osteoblast differentiation and proliferation, suppressing osteoclast recruitment and the deposition of extracellular matrix, although PPP appeared to demonstrate superior osteogenic functions compared to phosvitin alone.

17β-Estradiol improves osteoblastic cell function through the Sirt1/NF-κB/MMP-8 pathway

Objective: This study aims to investigate the beneficial effects of 17β-estradiol supplementation on the function of osteoblastic cells through the Sirtuin-1/nuclear transcription factor-κB/matrix metalloproteinase-8 (Sirt1/NF-κB/MMP-8) pathway.Methods: Mouse primary osteoblasts were obtained from neonatal mouse calvaria, and the cells were treated with or without 17β-estradiol. We first detected the effect of 17β-estradiol on the function of osteoblastic cells. Then, the changes in estrogen receptor-α (ERα), Sirt1, NF-κB, and MMP-8 were determined after the osteoblasts were treated with 17β-estradiol. During supplementation with 17β-estradiol, knockdown of Sirt1 in osteoblasts was used to further measure the changes of NF-κB and MMP-8 and observe the cell function.Results: In primary osteoblastic cells, exposure to 17β-estradiol improved cell viability and increased the levels of bone formation biomarkers, including osteocalcin, osteoprotegerin (OPG), procollagen type 1 N-terminal propeptide (P1NP), and alkaline phosphatase (ALP). In addition, 17β-estradiol supplement activated ERα and Sirt1 expression and inhibited NF-κB and MMP-8 expression. Moreover, these effects induced by 17β-estradiol were reversed by knockdown of Sirt1 in mouse primary osteoblasts.Conclusion: 17β-Estradiol replacement therapy may treat postmenopausal osteoporosis by improving osteoblastic cell function via the Sirt1/NF-κB/MMP-8 pathway.

Hyperglycemia impairs osteoblast cell migration and chemotaxis due to a decrease in mitochondrial biogenesis.

Diabetes is associated with an increase in skeletal fragility and risk of fracture. However, the underlying mechanism for the same is not well understood. Specifically, the results from osteoblast cell culture studies are ambiguous due to contradicting reports. The use of supraphysiological concentrations in these studies, unachievable in vivo, might be the reason for the same. Therefore, here, we studied the effect of physiologically relevant levels of high glucose during diabetes (11.1mM) on MC3T3-E1 osteoblast cell functions. The results showed that high glucose exposure to osteoblast cells increases their differentiation and mineralization without any effect on the proliferation. However, high glucose decreases their migratory potential and chemotaxis with a decrease in the associated cell signaling. Notably, this decrease in cell migration in high glucose conditions was accompanied by aberrant localization of Dynamin 2 in osteoblast cells. Besides, high glucose also caused a shift in mitochondrial dynamics towards the appearance of more fused and lesser fragmented mitochondria, with a concomitant decrease in the expression of DRP1, suggesting decreased mitochondrial biogenesis. In conclusion, here we are reporting for the first time that hyperglycemia causes a reduction in osteoblast cell migration and chemotaxis. This decrease might lead to an inefficient movement of osteoblasts to the erosion site resulting in uneven mineralization and skeletal fragility found in type 2 diabetes patients, in spite of having normal bone mineral density (BMD).

Strontium- and Cobalt-Doped Multicomponent Mesoporous Bioactive Glasses (MBGs) for Potential Use in Bone Tissue Engineering Applications.

Mesoporous bioactive glasses (MBGs) offer suitable platforms for drug/ion delivery in tissue engineering strategies. The main goal of this study was to prepare strontium (Sr)- and cobalt (Co)-doped MBGs; strontium is currently used in the treatment of osteoporosis, and cobalt is known to exhibit pro-angiogenic effects. Sr- and Co-doped mesoporous glasses were synthesized for the first time in a multicomponent silicate system via the sol–gel method by using P123 as a structure-directing agent. The glassy state of the Sr- and Co-doped materials was confirmed by XRD before immersion in SBF, while an apatite-like layer was detected onto the surface of samples post-immersion. The textural characteristics of MBGs were confirmed by nitrogen adsorption/desorption measurements. In vitro experiments including MTT assay, Alizarin red staining, and cell attachment and migration showed the cytocompatibility of all the samples as well as their positive effects on osteoblast-like cell line MG-63. Early experiments with human umbilical vein endothelial cells also suggested the potential of these MBGs in the context of angiogenesis. In conclusion, the prepared materials were bioactive, showed the ability to improve osteoblast cell function in vitro and could be considered as valuable delivery vehicles for therapeutics, like Co2+ and Sr2+ ions.

G-CSF partially mediates bone loss induced by Staphylococcus aureus infection in mice.

Bone loss in Staphylococcus aureus (S. aureus) osteomyelitis poses a serious challenge to orthopedic treatment. The present study aimed to elucidate how S. aureus infection in bone might induce bone loss. The C57BL/6 mice were injected with S. aureus (106 CFU/ml, 100 μl) or with the same amount of vehicle (control) via the tail vein. Microcomputed tomography (microCT) analysis showed bone loss progressing from week 1 to week 5 after infection, accompanied by a decreased number of osteocalcin-positive stained osteoblasts and the suppressed mRNA expression of Runx2 and osteocalcin. Transcriptome profiles of GSE30119 were downloaded and analyzed to determine the differences in expression of inflammatory factors between patients with S. aureus infected osteomyelitis and healthy controls, the data showed significantly higher mRNA expression of granulocyte colony-stimulating factor (G-CSF) in the whole blood from patients with S. aureus infection. Enzyme-linked immunosorbent assay (ELISA) analysis confirmed an increased level of G-CSF in the bone marrow and serum from S. aureus infected mice, which might have been due to the increased amount of F4/80+ macrophages. Interestingly, G-CSF neutralizing antibody treatment significantly rescued the bone loss after S. aureus infection, as evidenced by its roles in improving BV/TV and preserving osteocalcin- and osterix-positive stained cells. Importantly, we found that G-CSF level was significantly up-regulated in the serum from osteomyelitis patients infected by S. aureus Together, S. aureus infection might suppress the function of osteoblastic cells and induce progressive bone loss by up-regulating the level G-CSF, suggesting a therapeutic potential for G-CSF neutralization in combating bone loss in S. aureus osteomyelitis.

Qualitative screening and determination of tryptamins by HPLC method

Surface mechanical attrition treatment (SMAT) method is an effective way to generate nanograined (NG) surface on Ti-25Nb-3Mo-2Sn-3Zr (wt.%) (named as TLM), a kind of β-type titanium alloy, and the achieved nanocrystalline surface was proved to promote positive functions of osteoblastic cells. In this work, to further endow the NG TLM alloy with both good osteogenic and antibacterial properties, magnesium (Mg), silver (Ag) ion or both were introduced onto the NG TLM surface by ion implantation process, as a comparison, the Mg and Ag ions were also co-implanted onto coarsegrained (CG) TLM surface. The obtained results show that subsequent ion implantation does not remarkably induce the surface roughness and topography alteration of the SMAT-treated layers, and it also has little impact on the microstructure of the SMAT-derived β-Ti nanograins. In addition, the implanted Mg and Ag ions are observed to exist as MgO and metallic Ag nanoparticles (NPs) embedding tightly in the β-Ti matrix with grain size of about 15 and 7 nm, respectively. Initial cell adhesion and functions (including proliferation, osteo-differentiation and extracellular matrix mineralization) of rabbit bone marrow mesenchymal stem cells (rBMMSCs) and the bacterial colonization of Staphylococcus aureus (S. aureus) on the different surfaces were investigated. The in-vitro experimental results reveal that the Mg and Ag single-ion implanted NG surface either significantly promotes the rBMMSCs response or inhibits the growth of S. aureus, whereas the Mg/Ag co-implanted NG surface could concurrently enhance the rBMMSCs functions as well as inhibit the bacterial growth compared to the NG surface, and this efficacy is more pronounced as compared to the Mg/Ag co-implantation in the CG surface. The SMAT-achieved nanograins in the TLM surface layer are identified to not only play a leading role in determining the fate of rBMMSCs but also facilitate fabricating dual-functional surface with both good osteogenic and antibacterial activities through co-implantation of Mg and Ag ions. Our investigation provides a new strategy to develop high-performance Ti-based implants for clinical application.

Nano-hydroxyapatite-alginate-gelatin microcapsule as a potential osteogenic building block for modular bone tissue engineering

To develop osteogenic building blocks for modular bone tissue engineering applications, influence of gelatin as cell adhesive molecule and nano-hydroxyapatite (nHA) as osteoconductive component was examined on alginate-based hydrogel properties and microencapsulated osteoblast-like cell behavior by using factorial experimental design technique. nHA and alginate showed a statistically significant impact on swelling reduction, and improvement of stability and mechanical strength of hydrogels, respectively. Gelatin influence, however, was in a reverse manner. nHA played imperative roles in promoting microencapsulated osteoblastic cell proliferation and function due to its bioactivity and mechanical strength improvement of hydrogels to the modulus range of mineralized bone tissue in vivo. The results and their statistical analysis also revealed the importance of interaction effect of gelatin and nHA. Proliferation and osteogenic function of the cells fluctuated with increasing gelatin concentration of microcapsules in the presence of nHA, demonstrating that hydrogel properties should be balanced to provide an efficient 3D osteoconductive microcapsule. Alginate (1%)-gelatin (2.5%)-nHA (0.5%) microcapsule with compressive modulus of 0.19 MPa ± 0.02, swelling ratio of 52% ± 8 (24 h) and degradation rate of 12% ± 4 (96 h) revealed a maximum performance for the cell proliferation and function, indicating a potential microcapsule composition to prepare building blocks for modular bone tissue engineering.

ClC-3 chloride channels are involved in estradiol regulation of bone formation by MC3T3-E1 osteoblasts.

Evidence has been reported by us and others supporting the important roles of chloride channels in a number of osteoblast cell functions. The ClC-3 chloride channel is activated by estradiol binding to estrogen receptor alpha on the cell membranes of osteoblasts. However, the functions of these chloride channels in estrogen regulation of osteoblast metabolism remain unclear. In the present study, the roles of chloride channels in estrogen regulation of osteoblasts were investigated in the osteoblastic cell line MC3T3-E1. Estrogen 17β-estradiol enhanced collagen I protein expression, alkaline phosphatase activity, and mineralization were inhibited, by chloride channel blockers. Estradiol promoted ClC-3 chloride channel protein expression. Silencing of ClC-3 chloride channel expression prevented the elevation of osteodifferentiation in osteoblasts, which were regulated by estrogen. These data suggest that estrogen can regulate bone formation by activating ClC-3 chloride channels and the activation of ClC-3 chloride channels can enhance the osteodifferentiation in osteoblasts.

Accelerated Bone Regeneration by Nitrogen-Doped Carbon Dots Functionalized with Hydroxyapatite Nanoparticles.

We investigated the osteogenic potential of nitrogen-doped carbon dots (NCDs) conjugated with hydroxyapatite (HA) nanoparticles on the MC3T3-E1 osteoblast cell functions and in a zebrafish (ZF) jawbone regeneration (JBR) model. The NCDs-HA nanoparticles were fabricated by a hydrothermal cum co-precipitation technique. The surface structures of NCDs-HA nanoparticles were characterized by X-ray diffraction; Fourier transform infrared (FTIR), UV-vis, and laser fluorescence spectroscopies; and scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS), and NMR analyses. The TEM data confirmed that the NCDs are well conjugated on the HA nanoparticle surfaces. The fluorescent spectroscopy results indicated that the NCDs-HA exhibited promising luminescent emission in vitro. Finally, we validated the chemical structure of NCDs-HA nanoparticles on the basis of FTIR, EDS, and 31P NMR analysis and observed that NCDs are bound with HA by electrostatic interaction and H-bonding. Cell proliferation assay, alkaline phosphatase, and Alizarin red staining were used to confirm the effect of NCDs-HA nanoparticles on MC3T3-E1 osteoblast proliferation, differentiation, and mineralization, respectively. Reverse transcriptase polymerase chain reaction was used to measure the expression of the osteogenic genes like runt-related transcription factor 2, alkaline phosphatase, and osteocalcin. ZF-JBR model was used to confirm the effect of NCDs-HA nanoparticles on bone regeneration. NCDs-HA nanoparticles demonstrated cell imaging ability, enhanced alkaline phosphatase activity, mineralization, and expression of the osteogenic genes in osteoblast cells, indicating possible theranostic function. Further, NCDs-HA nanoparticles significantly enhanced ZF bone regeneration and mineral density compared to HA nanoparticles, indicating a therapeutic potential of NCDs-HA nanoparticles in bone regeneration and fracture healing.