Bone morphogenetic protein-5, a key molecule that mediates differentiation in MC3T3E1 osteoblast cell line

Osteoimmune-modulating and BMP-2-eluting anodised 3D printed titanium for accelerated bone regeneration

3D printing of titanium (Ti) metal has potential to transform the field of personalised orthopaedics and dental implants. However, the impacts of controlled surface topographical features of 3D printed Ti implants on their interactions with the cellular microenvironment and incorporation of biological growth factors, which are critical in guiding the integration of implants with bone, are not well studied. In the present study, we explore the role of surface topological features of 3D printed Ti implants using an anodised titania nanotube (TiNT) surface layer in guiding their immune cell interaction and ability to deliver bioactive form of growth factors. TiNT layers with precisely controlled pore diameter (between 21and 130 nm) were anodically grown on 3D printed Ti surfaces to impart a nano-micro rough topology. Immune biomarker profiles at gene and protein levels show that anodised 3D Ti surfaces with smaller pores resulted in classical activation of macrophages (M1-like), while larger pores (i.e., >100 nm) promoted alternate activation of macrophages (M2-like). The in vitro bone mineralisation studies using the conditioned media from the immunomodulatory studies elucidate a clear impact of pore diameter on bone mineralisation. The tubular structure of TiNTs was utilised as a container to incorporate recombinant human bone morphogenetic protein-2 (BMP-2) in the presence of various sugar and polymeric cryoprotectants. Sucrose offered the most sustainable release of preserved BMP-2 from TiNTs. Downstream effects of released BMP-2 on macrophages as well as bone mineralisation were assessed showing bioactivity retention of the released rhBMP-2. Overall, the TiNT surface topography in combination with controlled, sustained, and local release of bioactive growth factors can potentially enhance the osseointegration outcomes of custom 3D printed Ti implants in the clinic.

Resveratrol Synergistically Promotes BMP9-Induced Osteogenic Differentiation of Mesenchymal Stem Cells

Background. Mesenchymal stem cells (MSCs) differentiate into osteocytes, adipocytes, and chondrocytes. Resveratrol and bone morphogenetic protein 9 (BMP9) are known osteogenic induction factors of MSCs, but the effect of both resveratrol and BMP9 on osteogenesis is unknown. Herein, we explored whether resveratrol cooperates with BMP9 to improve osteogenic induction. Methods. The osteogenic induction of resveratrol and BMP9 on C3H10T1/2 cells was evaluated by detecting the staining and activity of the early osteogenic marker alkaline phosphatase (ALP). In addition, the late osteogenic effect was measured by the mRNA and protein levels of osteogenic markers, such as osteopontin (OPN) and osteocalcin (OCN). To assess the bone formation function of resveratrol plus BMP9 in vivo, we transplanted BMP9-infected C3H10T1/2 cells into nude mice followed by intragastric injection of resveratrol. Western blot (WB) analysis was utilized to elucidate the mechanism of resveratrol plus BMP9. Results. Resveratrol not only enhanced osteogenic induction alone but also improved BMP9-induced ALP at 3, 5, and 7 d postinduction. Both the early osteogenic markers (ALP, Runx2, and SP7) and the late osteogenic markers (OPN and OCN) were significantly increased when resveratrol was combined with BMP9. The fetal limb explant culture further verified these results. The in vivo bone formation experiment, which involved transplanting BMP9-overexpressing C3H10T1/2 cells into nude mice, also confirmed that resveratrol synergistically enhanced the BMP9-induced bone formation function. Resveratrol phosphorylated adenosine monophosphate- (AMP-) activated protein kinase (AMPK) and stimulated autophagy, but these effects were abolished by inhibiting AMPK and Beclin1 using an inhibitor or siRNA. Conclusions. Resveratrol combined with BMP9 significantly improves the osteogenic induction of C3H10T1/2 cells by activating AMPK and autophagy.

Upregulated bone morphogenetic protein 5 enhances proliferation and epithelial-mesenchymal transition process in benign prostatic hyperplasia via BMP/Smad signaling pathway

BACKGROUND

Benign prostatic hyperplasia (BPH) is one of the most common illnesses in aging men. Recent studies found that bone morphogenetic protein 5 (BMP5) is upregulated in BPH tissues, however, the role of BMP5 in the development of BPH has not been examined. The current study aims to elucidate the potential roles of BMP5 and related signaling pathways in BPH.

METHODS

Human prostate cell lines (BPH-1, WPMY-1) and human/rat hyperplastic prostate tissues were utilized. Western blot, quantitative real-time polymerase chain reaction, immunofluorescent staining, and immunohistochemical staining were performed. BMP5-silenced and -overexpressed cell models were generated and then cell cycle progression, apoptosis, and proliferation were determined. The epithelial-mesenchymal transition (EMT) was also quantitated. And rescue experiments by BMP/Smad signaling pathway agonist or antagonist were accomplished. Moreover, BPH-related tissue microarray analysis was performed and associations between clinical parameters and expression of BMP5 were analyzed.

RESULTS

Our study demonstrated that BMP5 was upregulated in human and rat hyperplastic tissues and localized both in the epithelial and stromal compartments of the prostate tissues. E-cadherin was downregulated in hyperplastic tissues, while N-cadherin and vimentin were upregulated. Overexpression of BMP5 enhanced cell proliferation and the EMT process via phosphorylation of Smad1/5/8, while knockdown of BMP5 induced cell cycle arrest at G0/G1 phase and blocked the EMT process. Moreover, a BMP/Smad signaling pathway agonist and antagonist reversed the effects of BMP5 silencing and overexpression, respectively. In addition, BMP5 expression positively correlated with prostate volume and total prostate-specific antigen.

CONCLUSION

Our novel data suggest that BMP5 modulated cell proliferation and the EMT process through the BMP/Smad signaling pathway which could contribute to the development of BPH. However, further studies are required to determine the exact mechanism. Our study also indicated that BMP/Smad signaling may be rediscovered as a promising new therapeutic target for the treatment of BPH.

Novel dental implant modifications with two-staged double benefits for preventing infection and promoting osseointegration in vivo and in vitro

Peri-implantitis are a major problem causing implant failure these days. Accordingly, anti-infection during the early stage and subsequent promotion of osseointegration are two main key factors to solve this issue. Micro-arc oxidation (MAO) treatment is a way to form an oxidation film on the surface of metallic materials. The method shows good osteogenic properties but weak antibacterial effect. Therefore, we developed combined strategies to combat severe peri-implantitis, which included the use of a novel compound, PD, comprising dendrimers poly(amidoamine) (PAMAM) loading dimethylaminododecyl methacrylate (DMADDM) as well as MAO treatment. Here, we explored the chemical properties of the novel compound PD, and proved that this compound was successfully synthesized, with the loading efficiency and encapsulation efficiency of 23.91% and 31.42%, respectively. We further report the two-stage double benefits capability of PD + MAO: (1) in the first stage, PD + MAO could decrease the adherence and development of biofilms by releasing DMADDM in the highly infected first stage after implant surgery both in vitro and in vivo; (2) in the second stage, PD + MAO indicated mighty anti-infection and osteoconductive characteristics in a rat model of peri-implantitis in vivo. This study first reports the two-staged, double benefits of PD + MAO, and demonstrates its potential in clinical applications for inhibiting peri-implantitis, especially in patients with severe infection risk.

Influence of the TGF-β Superfamily on Osteoclasts/Osteoblasts Balance in Physiological and Pathological Bone Conditions

The balance between bone forming cells (osteoblasts/osteocytes) and bone resorbing cells (osteoclasts) plays a crucial role in tissue homeostasis and bone repair. Several hormones, cytokines, and growth factors-in particular the members of the TGF-β superfamily such as the bone morphogenetic proteins-not only regulate the proliferation, differentiation, and functioning of these cells, but also coordinate the communication between them to ensure an appropriate response. Therefore, this review focuses on TGF-β superfamily and its influence on bone formation and repair, through the regulation of osteoclastogenesis, osteogenic differentiation of stem cells, and osteoblasts/osteoclasts balance. After introducing the main types of bone cells, their differentiation and cooperation during bone remodeling and fracture healing processes are discussed. Then, the TGF-β superfamily, its signaling via canonical and non-canonical pathways, as well as its regulation by Wnt/Notch or microRNAs are described and discussed. Its important role in bone homeostasis, repair, or disease is also highlighted. Finally, the clinical therapeutic uses of members of the TGF-β superfamily and their associated complications are debated.

The osteogenesis performance of titanium modified via plasma-enhanced chemical vapor deposition: in vitro and in vivo studies

Titanium (Ti) and its alloys are widely used in dental implants due to their favorable mechanical properties and biocompatibility. Surface characteristics, including physical and chemical properties, are crucial factors to enhance the osteogenesis performance of Ti. The aim of this study is to evaluate amino group surface modification to facilitate the osteogenic potential and bone repair of dental implants both in vitro and in vivo. Herein, amino group-modified Ti surfaces were constructed via the plasma-enhanced chemical vapor deposition (PECVD) technique with an allylamine monomer. The adhesion, proliferation, alkaline phosphate activity and osteogenesis-related genetic expression of MG-63 cells on the surfaces were performed in vitro and presented a significant increase in amino group-modified Ti compared with that in Ti. The in vivo study in miniature pigs was evaluated through micro-computed tomography analysis and histological evaluation, which exhibited enhanced new bone formation in amino group-modified Ti compared with that in Ti after implantation for 4, 8 and 12 weeks. Consequently, amino group surface modification with the PECVD technique may provide a promising modification method to enhance the osteogenesis performance of Ti implants.

Enhanced bioactivity and osteogenic property of carbon fiber reinforced polyetheretherketone composites modified with amino groups

Polyetheretherketone (PEEK) is considered as a potential dental and orthopedic implant material owing to its favorable thermal and chemical stability, biocompatibility and mechanical properties. However, the inherent bio-inert and inferior osseointegration of PEEK have hampered its clinical application. In addition, carbon fiber is widely used as a filler to reinforce polymers for sturdy composites owing to its high strength, modulus, etc. In the study, carbon fiber reinforced PEEK (CPEEK) composites were fabricated and modified with amino groups by plasma-enhanced chemical vapor deposition surface modification technique. The surface characterization of composites was evaluated by FE-SEM, EDS, AFM, Water contact angle, XPS and FTIR, which revealed that amino groups were successfully incorporated on the modified CPEEK surface and significantly increased the hydrophilicity. In vitro study, cell adhesion, proliferation, ALP activity, ECM mineralization, real-time PCR analysis, and ELISA analysis showed the adhesion, proliferation and osteogenic differentiation of MG-63 cells on the amino group-modified CPEEK surface were higher than the CPEEK, equal to or better than pure titanium. Hence, the results indicated that the amino group-modified CPEEK possessed enhanced bioactivity and osteogenic property, which may be a potential candidate material for dental implants.

Surface Immobilization of TiO2 Nanotubes with Bone Morphogenetic Protein-2 Synergistically Enhances Initial Preosteoblast Adhesion and Osseointegration

Although titanium (Ti) alloys have been widely used as implant materials, the bioinertness of pristine Ti impairs their bioactivity and early osseointegration. In the present work, we prepared TiO₂ nanotubes (TNT) layer on the titanium (Ti) surface by anodic oxidation. The anodized surface was functionalized with human bone morphogenetic protein-2 coating to form the hBMP-2/TNT surface. The release behavior of hBMP-2 on the hBMP-2/TNT surface displayed a controlled and sustained pattern, compared to that on the hBMP-2/Ti surface, which showed a rapid release. In vitro cellular activity tests demonstrated that both TNT and hBMP-2/Ti surfaces, particularly the hBMP-2/TNT surface, enhanced adhesion, proliferation, and differentiation of osteoblast cells. Increased cell adhesion, improved cytoskeleton organization, and immunofluorescence staining of vinculin were observed on the modified surfaces. The TNT, hBMP-2/Ti, and hBMP-2/TNT surfaces, especially the hBMP-2/TNT surface, further displayed an upregulated gene expression of adhesion and osteogenic markers vinculin, collagen type 1, osteopontin, and osteocalcin, compared to the pristine Ti surface. In vivo experiments using a rat model demonstrated that the TNT and hBMP-2/Ti surfaces, in particular the hBMP-2/TNT surface, improved osseointegration and showed a superior bone bonding ability compared to Ti. Our study revealed a synergistic role played by TiO₂ nanotubes nanotopography and hBMP-2 in promoting initial osteoblast adhesion, proliferation, differentiation, and osseointegration, thus suggesting a promising method for better modifying the implant surface.

Improved osteoblast adhesion and osseointegration on TiO2 nanotubes surface with hydroxyapatite coating

To improve initial osteoblast adhesion and subsequent osseointegration, TiO₂ nanotubes layer was constructed on the titanium (Ti) surface by anodic oxidation (AO), with an additional hydroxyapatite (HA) coating to form the AO/HA surface. Tests on in vitro cellular activity displayed that the AO surface, especially the AO/HA surface, promoted initial adhesion, proliferation and differentiation of osteoblast cells. The modified AO and AO/HA surfaces further presented an up-regulated gene expression of osteogenic and adhesion markers collagen type 1 (COL), osteopontin (OPN), osteocalcin (OCN) and vinculin. In addition, in vivo experiments with a rat model demonstrated that the AO surface, particularly the AO/HA surface, achieved earlier osseointegration and a superior bone bonding ability compared with Ti. Our study shed light on a synergistic role played by nanotopography and HA in promoting osteoblast adhesion, proliferation, differentiation and osseointegration, thus suggesting a promising method for better modifying the implant surface.

The Effect of β-Aminopropionitrile on Skeletal Micromorphology and Osteogenesis

Collagen cross-linking, as a form of collagen post-translational modification, plays a crucial role in maintaining bone mechanical properties as well as in regulating cell biological functions. Shifts in cross-links profile are found apparently correlated to kinds of skeletal pathology and diseases, whereas little is known about the relationship between collagen cross-links and osteogenesis. Here, we hypothesized that the inhibition of collagen cross-links could impair skeletal microstructure and inhibit osteogenesis. A mouse model of collagen cross-linking defects has been established using subcutaneous injection of 350 mg/kg β-aminopropionitrile (BAPN) daily for 4 weeks, and same dose of phosphate buffered saline (PBS) served as control group. The analysis of bone microstructural parameters revealed a significant decrease of bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), and increase of bone surface ratio (BS/BV), structure model index (SMI) as well as trabecular separation (Tb.Sp) in the experimental group (p < 0.05), whereas there was no difference observed in bone mineral density (BMD). Histological staining displayed that the BAPN treatment caused thinner trabeculae and decrease of collagen content in proximal tibiae. The analysis of osteogenesis PCR (Polymerase Chain Reaction) array reflected that BAPN remarkably influenced the expression of Alpl, Bglap, Bgn, Bmp5, Col10a1, Col1a1, Col1a2, Col5a1, Itga2b, and Serpinh1. The results of immunohistochemistry displayed a significant reduction in the mean optical densities of OCN and COL1 at the presence of BAPN. The overall results of this study suggested that BAPN alters bone microstructure and hinders the expression of osteogenic genes without affecting mineralization processes, indicating the influences of collagen cross-links on osteogenesis may be a potential pathological mechanism in skeletal diseases.

Enhancement of osteogenesis of rabbit bone marrow derived mesenchymal stem cells by transfection of human BMP-2 and EGFP recombinant adenovirus via Wnt signaling pathway

Bone marrow mesenchymal stem cells (BMSCs) are considered the most important seed cells in bone tissue engineering. The present study aimed to investigate the potential of rabbit BMSCs in osteogenesis after the transfection of human BMP-2 and EGFP recombinant adenovirus. Rabbit BMSCs were isolated and the surface stem cell makers, including CD29, CD44 and CD45 were detected by flow cytometry. The expression of BMP-2 mRNA and protein in BMSCs were detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. After an induction with osteogenic medium, the alkaline phosphatase (ALK) activity at 7 days, the type I collagen at 14 days, and the calcium nodules at 21 days were performed using an ALK activity kit, immunohistochemical staining and alizarin red S staining, respectively. The expression levels of proteins related to the Wnt signaling pathway were detected by western blot analysis. The positive rates of CD29, CD44 and CD45 were 62.92±1.99, 93.55±0.99 and 0.21±0.12%. The expression of BMP-2 mRNA and protein was significantly upregulated in Ad-BMP-2/EGFP transfected BMSCs. Furthermore, Ad-BMP-2/EGFP induced ALP activity, promoted the production of type I collagen and calcium nodule formation in rabbit BMSCs. The levels of β-catenin, cyclin D1, Runx2 and c-myc were upregulated in Ad-hBMP-2/EGFP transfected BMSCs, while the level of GSK3β was significantly decreased. Results also indicated that the overexpression of BMP-2 by Ad-hBMP-2/EGFP enhanced the osteogenic differentiation ability of cultured rabbit BMSCs via stimulating the Wnt signaling pathway with the accumulation of β-catenin and suppression of GSK3β. The Ad-hBMP-2/EGFP transfected rabbit BMSCs are expected to be a good seed cell in bone tissue engineering.