Role of Hedgehog-Gli1 signaling in the enhanced proliferation and differentiation of MG63 cells enabled by hierarchical micro-/nanotextured topography

Porous metal materials for applications in orthopedic field: A review on mechanisms in bone healing

Background

Porous metal materials have been widely studied for applications in orthopedic field, owing to their excellent features and properties in bone healing. Porous metal materials with different compositions, manufacturing methods, and porosities have been developed. Whereas, the systematic mechanisms on how porous metal materials promote bone healing still remain unclear.

Methods

This review is concerned on the porous metal materials from three aspects with accounts of specific mechanisms, inflammatory regulation, angiogenesis and osteogenesis. We place great emphasis on different cells regulated by porous metal materials, including mesenchymal stem cells (MSCs), macrophages, endothelial cells (ECs), etc.

Result

The design of porous metal materials is diversified, with its varying pore sizes, porosity material types, modification methods and coatings help researchers create the most experimentally suitable and clinically effective scaffolds. Related signal pathways presented from different functions showed that porous metal materials could change the behavior of cells and the amount of cytokines, achieving good influence on osteogenesis.

Conclusion

This article summarizes the current progress achieved in the mechanism of porous metal materials promoting bone healing. By modulating the cellular behavior and physiological status of a spectrum of cellular constituents, such as macrophages, osteoblasts, and osteoclasts, porous metal materials are capable of activating different pathways and releasing regulatory factors, thus exerting pivotal influence on improving the bone healing effect.

The translational potential of this article

Porous metal materials play a vital role in the treatment of bone defects. Unfortunately, although an increasing number of studies have been concentrated on the effect of porous metal materials on osteogenesis-related cells, the comprehensive regulation of porous metal materials on the host cell functions during bone regeneration and the related intrinsic mechanisms remain unclear. This review summarizes different design methods for porous metal materials to fabricate the most suitable scaffolds for bone remodeling, and systematically reviews the corresponding mechanisms on inflammation, angiogenesis and osteogenesis of porous metal materials. This review can provide more theoretical framework and innovative optimization for the application of porous metal materials in orthopedics, dentistry, and other areas, thereby advancing their clinical utility and efficacy.

TiO2 nanotube topography enhances osteogenesis through filamentous actin and XB130-protein-mediated mechanotransduction

TiO2 nanotube topography, as nanomechanical stimulation, can significantly promote osteogenesis and improve the osteointegration on the interface of implants and bone tissue. However, the underlying mechanism has not been fully elucidated. XB130 is a member of the actin filament-associated protein family and is involved in the regulation of cytoskeleton and tyrosine kinase-mediated signalling as an adaptor protein. Whether XB130 is involved in TiO2 nanotubes-induced osteogenic differentiation and how it functions in mechano-biochemical signalling transduction remain to be elucidated. In this study, the role of XB130 on TiO2 nanotube-induced osteogenesis and mechanotransduction was systematically investigated. TiO2 nanotube topography was fabricated via anodic oxidation and characterized. The osteogenic effect was significantly accelerated by the TiO2 nanotube surface in vitro and vivo. XB130 was significantly upregulated during this process. Moreover, XB130 overexpression significantly promoted osteogenic differentiation, whereas its knockdown inhibited it. Filamentous actin depolymerization could change the expression and distribution of XB130, thus affecting osteogenic differentiation. Mechanistically, XB130 could interact with Src and result in the activation of the downstream PI3K/Akt/GSK-3β/β-catenin pathway, which accounts for the regulation of osteogenesis. This study for the first time showed that the enhanced osteogenic effect of TiO2 nanotubes could be partly due to the filamentous actin and XB130 mediated mechano-biochemical signalling transduction, which might provide a reference for guiding the design and modification of prostheses to promote bone regeneration and osseointegration. STATEMENT OF SIGNIFICANCE: TiO2 nanotubes topography can regulate cytoskeletal rearrangement and thus promote osteogenic differentiation of BMSCs. However, how filamentous actin converts mechanical stimulus into biochemical activity remains unclear. XB130 is a member of actin filament-associated protein family and involves in the regulation of tyrosine kinase-mediated signalling. Therefore, we hypothesised that XB130 might bridge the mechano-biochemical signalling transduction during TiO2 nanotubes-induced osteogenic differentiation. For the first time, this study shows that TiO2 nanotubes enhance osteogenesis through filamentous actin and XB130 mediated mechanotransduction, which provides new theoretical basis for guiding the design and modification of prostheses to promote bone regeneration and osseointegration.

Towards modular engineering of cell signalling: Topographically-textured microparticles induce osteogenesis via activation of canonical hedgehog signalling

Polymer microparticles possess great potential as functional building blocks for advanced bottom-up engineering of complex tissues. Tailoring the three-dimensional architectural features of culture substrates has been shown to induce osteogenesis in mesenchymal stem cells in vitro, but the molecular mechanisms underpinning this remain unclear. This study proposes a mechanism linking the activation of Hedgehog signalling to the osteoinductive effect of surface-engineered, topographically-textured polymeric microparticles. In this study, mesenchymal progenitor C3H10T1/2 cells were cultured on smooth and dimpled poly(D,l-lactide) microparticles to assess differences in viability, cellular morphology, proliferation, and expression of a range of Hedgehog signalling components and osteogenesis-related genes. Dimpled microparticles induced osteogenesis and activated the Hedgehog signalling pathway relative to smooth microparticles and 2D-cultured controls without the addition of exogenous biochemical factors. We observed upregulation of the osteogenesis markers Runt-related transcription factor2 (Runx2) and bone gamma-carboxyglutamate protein 2 (Bglap2), as well as the Hedgehog signalling components, glioma associated oncogene homolog 1 (Gli1), Patched1 (Ptch1), and Smoothened (Smo). Treatment with the Smo antagonist KAAD-cyclopamine confirmed the involvement of Smo in Gli1 target gene activation, with a significant reduction in the expression of Gli1, Runx2 and Bglap2 (p ≤ 0.001) following KAAD-cyclopamine treatment. Overall, our study demonstrates the role of the topographical microenvironment in the modulation of Hedgehog signalling, highlighting the potential for tailoring substrate topographical design to offer cell-instructive 3D microenvironments. Topographically-textured microparticles allow the modulation of Hedgehog signalling in vitro without adding exogenous biochemical agonists, thereby eliminating potential confounding artefacts in high-throughput drug screening applications.

Comparisons of gene expression between peripheral blood mononuclear cells and bone tissue in osteoporosis

Osteoporosis (OP) is one of the major public health problems in the world. However, the biomarkers between the peripheral blood mononuclear cells (PBMs) and bone tissue for prognosis of OP have not been well characterized. This study aimed to explore the similarities and differences of the gene expression profiles between the PBMs and bone tissue and identify potential genes, transcription factors (TFs) and hub proteins involved in OP. The patients were enrolled as an experimental group, and healthy subjects served as normal controls. Human whole-genome expression chips were used to analyze gene expression profiles from PBMs and bone tissue. And the differentially expressed genes (DEGs) were subsequently studied using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis. The above DEGs were constructed into protein-protein interaction network. Finally, TF-DEGs regulation networks were constructed. Microarray analysis revealed that 226 DEGs were identified between OP and normal controls in the PBMs, while 2295 DEGs were identified in the bone tissue. And 13 common DEGs were obtained by comparing the 2 tissues. The Gene Ontology analysis indicated that DEGs in the PBMs were more involved in immune response, while DEGs in bone were more involved in renal response and urea transmembrane transport. And the Kyoto Encyclopedia of Genes and Genomes analysis indicated almost all of the pathways in the PBMs were overlapped with those in the bone tissue. Furthermore, protein-protein interaction network presented 6 hub proteins: PI3K1, APP, GNB5, FPR2, GNG13, and PLCG1. APP has been found to be associated with OP. Finally, 5 key TFs were identified by TF-DEGs regulation networks analysis (CREB1, RUNX1, STAT3, CREBBP, and GLI1) and were supposed to be associated with OP. This study enhanced our understanding of the pathogenesis of OP. PI3K1, GNB5, FPR2, GNG13, and PLCG1 might be the potential targets of OP.

Role and Mechanism of a Micro-/Nano-Structured Porous Zirconia Surface in Regulating the Biological Behavior of Bone Marrow Mesenchymal Stem Cells

Zirconia as a promising dental implant material has attracted much attention in recent years. Improving the bone binding ability of zirconia is critical for clinical applications. Here, we established a distinct micro-/nano-structured porous zirconia through dry-pressing with addition of pore-forming agents followed by hydrofluoric acid etching (POROHF). Porous zirconia without hydrofluoric acid treatment (PORO), sandblasting plus acid-etching zirconia, and sintering zirconia surface were applied as controls. After human bone marrow mesenchymal stem cells (hBMSCs) were seeded on these four groups of zirconia specimens, we observed the highest cell affinity and extension on POROHF. In addition, the POROHF surface displayed an improved osteogenic phenotype in contrast to the other groups. Moreover, the POROHF surface facilitated angiogenesis of hBMSCs, as confirmed by optimal stimulation of vascular endothelial growth factor B and angiopoietin 1 (ANGPT1) expression. Most importantly, the POROHF group demonstrated the most obvious bone matrix development in vivo. To investigate further the underlying mechanism, RNA sequencing was employed and critical target genes modulated by POROHF were identified. Taken together, this study established an innovative micro-/nano-structured porous zirconia surface that significantly promoted osteogenesis and investigated the potential underlying mechanism. Our present work will improve the osseointegration of zirconia implants and help further clinical applications.

Effects of Allogeneic Bone Substitute Configurations on Cell Adhesion Process In Vitro

OBJECTIVE

To explore the potential effect of three allogenic bone substitute configurations on the viability, adhesion, and spreading of osteoblasts in vitro.

METHODS

Freeze-dried cortical bone were ground and fractions were divided into three groups with different sizes and shapes, defined as bone fiber (0.1 mm × 0.1 mm × 3 mm), bone powder (0.45-0.9 mm), and bone granule group (3-6 mm). MC3T3-E1 cells were divided and co-cultured within groups to induce cell adhesion. The configuration of allogenic bone was captured by scanning electron microscopy and confocal laser scanning microscopy, and substrate roughness values were quantified. Cell adhesion rate was assessed using the hemocyte counting method, cell viability was determined by CCK-8 assay and live/dead staining, and cell morphology was visualized by Phalloidin and DAPI, and the mRNA expression of adhesion-related gene (vinculin) of different substitutes were determined with quantitative real-time polymerase chain reaction.

RESULTS

The roughness values of bone fiber, bone powder, and bone granule group were 1.878 μm (1.578-2.415 μm), 5.066 μm (3.891-6.162 μm), and 0.860 μm (0.801-1.452 μm), respectively (bone powder group compared with bone granule group, H = 18.015, P < 0.001). Similar OD values of all groups in CCK-8 assay indicated good biocompatibility of these substitutes (bone fiber, 0.201 ± 0.004; bone powder, 0.206 ± 0.008; bone granule group, 0.197 ± 0.006; and the control group, 0.202 ± 0.016, F = 0.7152, P > 0.05). In addition, representative cell adhesion rates at 24 h showed significantly lower cell adhesion rate in bone fiber group (20.3 ± 1.6%) compared to bone powder (29.3 ± 4.4%) and bone granule group (27.3 ± 3.2%) (F = 10.51，P = 0.009 and P = 0.034, respectively), but there was no significant difference between the latter two groups (P > 0.05). Interestingly, the expression of vinculin mRNA steadily decreased in a time-dependent manner. The vinculin expression reached its peak at 6 h in each group, and the vinculin levels in bone fiber, bone powder, and bone granule group were 2.119 ± 0.052, 3.842 ± 0.108, and 3.585 ± 0.068 times higher than those in the control group, respectively (F = 733.643, all P < 0.001). Meanwhile, there was a significant difference in the expression of target gene between bone powder and bone granule group (P = 0.006).

CONCLUSION

All allogenic bone substitutes presented an excellent cell viability. Moreover, bone powder and bone granule group were more likely to promote cell adhesion and spreading compared to bone fiber group.

Effects of Modulation of the Hedgehog and Notch Signaling Pathways on Osteoblast Differentiation Induced by Titanium with Nanotopography

BACKGROUND

The events of bone formation and osteoblast/titanium (Ti) interactions may be affected by Hedgehog and Notch signalling pathways. Herein, we investigated the effects of modulation of these signalling pathways on osteoblast differentiation caused by the nanostructured Ti (Ti-Nano) generated by H₂SO₄/H₂O₂.

METHODS

Osteoblasts from newborn rat calvariae were cultured on Ti-Control and Ti-Nano in the presence of the Hedgehog agonist purmorphamine or antagonist cyclopamine and of the Notch antagonist N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) or agonist bexarotene. Osteoblast differentiation was evaluated by alkaline phosphatase activity and mineralization, and the expression of Hedgehog and Notch receptors was also evaluated.

RESULTS

In general, purmorphamine and DAPT increased while cyclopamine and bexarotene decreased osteoblast differentiation and regulated the receptor expression on both Ti surfaces, with more prominent effects on Ti-Nano. The purmorphamine and DAPT combination exhibited synergistic effects on osteoblast differentiation that was more intense on Ti-Nano.

CONCLUSION

Our results indicated that the Hedgehog and Notch signalling pathways drive osteoblast/Ti interactions more intensely on nanotopography. We also demonstrated that combining Hedgehog activation with Notch inhibition exhibits synergistic effects on osteoblast differentiation, especially on Ti-Nano. The uncovering of these cellular mechanisms contributes to create strategies to control the process of osseointegration based on the development of nanostructured surfaces.

From mesenchymal niches to engineered in vitro model systems: Exploring and exploiting biomechanical regulation of vertebrate hedgehog signalling

Tissue patterning is the result of complex interactions between transcriptional programs and various mechanical cues that modulate cell behaviour and drive morphogenesis. Vertebrate Hedgehog signalling plays key roles in embryogenesis and adult tissue homeostasis, and is central to skeletal development and the osteogenic differentiation of mesenchymal stem cells. The expression of several components of the Hedgehog signalling pathway have been reported to be mechanically regulated in mesodermal tissue patterning and osteogenic differentiation in response to external stimulation. Since a number of bone developmental defects and skeletal diseases, such as osteoporosis, are directly linked to aberrant Hedgehog signalling, a better knowledge of the regulation of Hedgehog signalling in the mechanosensitive bone marrow-residing mesenchymal stromal cells will present novel avenues for modelling these diseases and uncover novel opportunities for extracellular matrix-targeted therapies. In this review, we present a brief overview of the key molecular players involved in Hedgehog signalling and the basic concepts of mechanobiology, with a focus on bone development and regeneration. We also highlight the correlation between the activation of the Hedgehog signalling pathway in response to mechanical cues and osteogenesis in bone marrow-derived mesenchymal stromal cells. Finally, we propose different tissue engineering strategies to apply the expanding knowledge of 3D material-cell interactions in the modulation of Hedgehog signalling in vitro for fundamental and translational research applications.

Biomaterial Design Inspired by Regenerative Research Organisms

The efficacy of implanted biomaterials is largely dependent on the response of the host's immune and stromal cells. Severe foreign body response (FBR) can impede the integration of the implant into the host tissue and compromise the intended mechanical and biochemical function. Many features of FBR, including late-stage fibrotic encapsulation of implants, parallel the formation of fibrotic scar tissue after tissue injury. Regenerative organisms like zebrafish and salamanders can avoid fibrosis after injury entirely, but FBR in these research organisms is rarely investigated because their immune competence is much lower than humans. The recent characterization of a regenerative mammal, the spiny mouse (Acomys), has inspired us to take a closer look at cellular regulation in regenerative organisms across the animal kingdom for insights into avoiding FBR in humans. Here, we highlight how major features of regeneration, such as blastema formation, macrophage polarization, and matrix composition, can be modulated across a range of regenerative research organisms to elucidate common features that may be harnessed to minimize FBR. Leveraging a deeper understanding of regenerative biology for biomaterial design may help to reduce FBR and improve device integration and performance.

Effectiveness and Mechanisms of Low-Intensity Pulsed Ultrasound on Osseointegration of Dental Implants and Biological Functions of Bone Marrow Mesenchymal Stem Cells

Dental implant restoration is the preferred choice for patients with dentition defects or edentulous patients, and obtaining stable osseointegration is the determining factor for successful implant healing. The risk of implant failure during the healing stage is still an urgent problem in clinical practice due to differences in bone quality at different implant sites and the impact of some systemic diseases on bone tissue metabolism. Low-intensity pulsed ultrasound (LIPUS) is a noninvasive physical intervention method widely recognized in the treatment of bone fracture and joint damage repair. Moreover, many studies indicated that LIPUS could effectively promote the osseointegration of dental implants and improve the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). This review is aimed at investigating the research progress on the use of LIPUS in dental implant medicine from three aspects: (1) discuss the promoting effects of LIPUS on osseointegration and peri-implant bone regeneration, (2) summarize the effects and associated mechanisms of LIPUS on the biological functions of BMSCs, and (3) introduce the application and prospects of LIPUS in the clinical work of dental implantation. Although many challenges need to be overcome in the future, LIPUS is bound to be an efficient and convenient therapeutic method to improve the dental implantation success rate and expand clinical implant indications.

GSK-3β suppression upregulates Gli1 to alleviate osteogenesis inhibition in titanium nanoparticle-induced osteolysis

Wear particle-induced periprosthetic osteolysis (PPO) have become a major reason of joint arthroplasty failure and secondary surgery following joint arthroplasty and thus pose a severe threat to global public health. Therefore, determining how to effectively suppress particle-induced PPO has become an urgent problem. The pathological mechanism involved in the PPO signaling cascade is still unclear. Recently, the interaction between osteogenic inhibition and wear particles at the implant biological interface, which has received increasing attention, has been revealed as an important factor in pathological process. Additionally, Hedgehog (Hh)-Gli1 is a crucial signaling cascade which was regulated by multiple factors in numerous physiological and pathological process. It was revealed to exert a crucial part during embryonic bone development and metabolism. However, whether Hh-Gli1 is involved in wear particle-induced osteogenic inhibition in PPO remains unknown. Our present study explored the mechanism by which the Hh-Gli1 signaling cascade regulates titanium (Ti) nanoparticle-induced osteolysis. We found that Hh-Gli1 signaling was dramatically downregulated upon Ti particle treatment. Mechanistically, glycogen synthesis kinase 3β (GSK-3β) activation was significantly increased in Ti particle-induced osteogenic inhibition via changes in GSK-3β phosphorylation level and was found to participate in the posttranslational modification and degradation of the key transcription factor Gli1, thus decreasing the accumulation of Gli1 and its translocation from the cytoplasm to the nucleus. Collectively, these findings suggest that the Hh-Gli1 signaling cascade utilizes a GSK3β-mediated mechanism and may serve as a rational new therapeutic target against nanoparticle-induced PPO.

Research progress on the hedgehog signalling pathway in regulating bone formation and homeostasis

Bone formation is a complex regeneration process that was regulated by many signalling pathways, such as Wnt, Notch, BMP and Hedgehog (Hh). All of these signalling have been demonstrated to participate in the bone repair process. In particular, one promising signalling pathway involved in bone formation and homeostasis is the Hh pathway. According to present knowledge, Hh signalling plays a vital role in the development of various tissues and organs in the embryo. In adults, the dysregulation of Hh signalling has been verified to be involved in bone‐related diseases in terms of osteoarthritis, osteoporosis and bone fracture; and during the repair processes, Hh signalling could be reactivated and further modulate bone formation. In this chapter, we summarize our current understanding on the function of Hh signalling in bone formation and homeostasis. Additionally, the current therapeutic strategies targeting this cascade to coordinate and mediate the osteogenesis process have been reviewed.

Biocompatibility pathways and mechanisms for bioactive materials: The bioactivity zone

This essay analyzes the scientific evidence that forms the basis of bioactive materials, covering the fundamental understanding of bioactivity phenomena and correlation with the mechanisms of biocompatibility of biomaterials. This is a detailed assessment of performance in areas such as bone-induction, cell adhesion, immunomodulation, thrombogenicity and antimicrobial behavior. Bioactivity is the modulation of biological activity by characteristics of the interfacial region that incorporates the material surface and the immediate local host tissue. Although the term ‘bioactive material’ is widely used and has a well understood general meaning, it would be useful now to concentrate on this interfacial region, considered as ‘the bioactivity zone’. Bioactivity phenomena are either due to topographical/micromechanical characteristics, or to biologically active species that are presented in the bioactivity zone. Examples of topographical/micromechanical effects are the modulation of the osteoblast – osteoclast balance, nanotopographical regulation of cell adhesion, and bactericidal nanostructures. Regulation of bioactivity by biologically active species include their influence, especially of metal ions, on signaling pathways in bone formation, the role of cell adhesion molecules and bioactive peptides in cell attachment, macrophage polarization by immunoregulatory molecules and antimicrobial peptides. While much experimental data exists to demonstrate the potential of such phenomena, there are considerable barriers to their effective clinical translation. This essay shows that there is solid scientific evidence of the existence of bioactivity mechanisms that are associated with some types of biomaterials, especially when the material is modified in a manner designed to specifically induce that activity.

Beta1-integrin/Hedgehog-Gli1 signaling pathway fuels the diameter-dependent osteoblast differentiation on different TiO2 nanotubes: The optimal-diameter nanotubes for osteoblast differentiation

Micro/nanotextured topographies (MNTs) can modulate cell-biomaterial interactions mostly by their controllable geometrics. Among them, TiO₂ nanotubes, regarded as having a highly controllable nanoscale geometry, have been extensively investigated and applied and significantly affect diameter-dependent cell biological behaviors. In this study, we used five typical MNTs decorated with TiO₂ nanotubes with diameters of 30, 50, 70, 100 and 120 nm to explore the optimal nanotube diameter for improving the biofunctional properties and to more deeply understand the underlying mechanisms by which these MNTs affect osteogenic differentiation by revealing the effect of beta1-integrin/Hedgehog-Gli1 signaling on this process. The MNTs affected MG63 osteoblast-like cell spreading, osteogenic gene expression (BMP-2, Runx2 and ALP), mineralization and ALP activity in a diameter-dependent pattern, and the optimal TiO₂ nanotube diameter of 70 nm provided the best microenvironment for osteogenic differentiation as well as beta1-integrin/Hedgehog-Gli1 signaling activation. This enhanced osteogenic differentiation by the optimal-diameter TiO₂ nanotubes of 70 nm was attenuated via suppression of the beta1-integrin/ Hedgehog-Gli1 signaling, which indicated a significant role of this pathway in mediating the diameter-dependent osteogenic differentiation promotional effect of MNTs with different TiO₂ nanotube diameters. These results might provide deeper insights into the signal transduction mechanisms by which different nanoscale geometries influence cellular functions for biomaterial modification and biofunctionalization.

USP7 regulates the proliferation and differentiation of ATDC5 cells through the Sox9-PTHrP-PTH1R axis

This study aimed to examine the effect of ubiquitin-specific peptidase 7 (USP7) on the proliferation and differentiation of ATDC5 cells and explore the underlying mechanisms. PCR, western blot, and immunofluorescence staining were used to observe the expression of USP7 after chondrogenic induction. The expressions of markers of chondrogenic and hypertrophic differentiation, and parathyroid hormone-related protein (PTHrP)/parathyroid hormone 1 receptor (PTH1R) signalling, were assessed by PCR, western blot, and histological staining under USP7 knockdown or its inhibitor. Cell proliferation was assessed by the CCK-8 assay and crystal violet staining. An in vivo experiment was performed to verify the functions of USP7 through histological and immunohistochemistry staining. Cyclopamine and abaloparatide were used to verify the signalling pathway. The interactions between USP7 and both PTHrP and sex-determining region Y-box 9 (Sox9) were tested by co-immunoprecipitation. The relationship between Sox9 and PTHrP was tested by chromatin immunoprecipitation and siRNA. USP7 knockdown or its inhibitor suppressed cell proliferation and chondrogenic differentiation but improved hypertrophic differentiation. The in vivo study obtained the same results. USP7 knockdown or its inhibitor inhibited PTHrP/PTH1R signalling to exert its function. Supplementation with cyclopamine suppressed PTHrP/PTH1R signalling and inhibited ATDC5 cell proliferation and differentiation. Supplementation with abaloparatide activated PTH1R to upregulate proliferation and chondrogenic differentiation but downregulated hypertrophic differentiation. Furthermore, USP7 interacted with Sox9 and Sox9 bound to PTTHrP to promote its expression. In conclusion, USP7 modulates the proliferation and differentiation of ATDC5 cells via the Sox9-PTHrP-PTH1R axis.

Plant virus-based materials for biomedical applications: Trends and prospects

Nanomaterials composed of plant viral components are finding their way into medical technology and health care, as they offer singular properties. Precisely shaped, tailored virus nanoparticles (VNPs) with multivalent protein surfaces are efficiently loaded with functional compounds such as contrast agents and drugs, and serve as carrier templates and targeting vehicles displaying e.g. peptides and synthetic molecules. Multiple modifications enable uses including vaccination, biosensing, tissue engineering, intravital delivery and theranostics. Novel concepts exploit self-organization capacities of viral building blocks into hierarchical 2D and 3D structures, and their conversion into biocompatible, biodegradable units. High yields of VNPs and proteins can be harvested from plants after a few days so that various products have reached or are close to commercialization. The article delineates potentials and limitations of biomedical plant VNP uses, integrating perspectives of chemistry, biomaterials sciences, molecular plant virology and process engineering.

[Recent research progress of bioactivity mechanism and application of bone repair materials]

Large bone defect repair is a difficult problem to be solved urgently in orthopaedic field, and the application of bone repair materials is a feasible method to solve this problem. Therefore, bone repair materials have been continuously developed, and have evolved from autogenous bone grafts, allograft bone grafts, and inert materials to highly active and multifunctional bone tissue engineering scaffold materials. In this paper, the related mechanism of bone repair materials, the application of bone repair materials, and the exploration of new bone repair materials are introduced to present the research status and advance of the bone repair materials, and the development direction is also prospected.

Low-intensity pulsed ultrasound promotes spinal fusion and enhances migration and proliferation of MG63s through sonic hedgehog signaling pathway

Low-intensity pulsed ultrasound (LIPUS) has been found to accelerate the healing process of spinal fusion via a process closely related to osteoblast differentiation and migration. Sonic hedgehog (Shh) signaling plays an important role in development and homeostasis, including a critical function in bone formation. However, its role in spinal fusion during LIPUS treatment is still unknown. This study showed that LIPUS treatment after spinal fusion surgery increased bone formation. The increased bone mass under LIPUS treatment appeared to result from the increased migration and proliferation of osteoblasts, resulting from upregulation of the Shh signaling pathway. In contrast, inhibition of Shh reduced the migratory and proliferative ability of osteoblast-like MG63 cells and blocked the efficacy of LIPUS treatment.

In vitro and in vivo protein release and anti-ischemia/reperfusion injury properties of bone morphogenetic protein-2-loaded glycyrrhetinic acid-poly(ethylene glycol)-b-poly(l-lysine) nanoparticles

Here, we describe a bone morphogenetic protein-2 (BMP-2) nanocarrier based on glycyrrhetinic acid (GA)-poly(ethylene glycol) (PEG)-b-poly(l-lysine) (PLL). A protein nanocarrier was synthesized, characterized and evaluated as a BMP-2 delivery system. The designed nanocarrier was synthesized based on the ring-opening polymerization of amino acid N-carboxyanhydride. The final product was measured with ¹H nuclear magnetic resonance. GA-PEG-b-PLL nanocarrier could combine with BMP-2 through electrostatic interaction to form polyion complex (PIC) micelles. BMP-2 could be rapidly and efficiently encapsulated through the GA-PEG-b-PLL nanocarrier under physiological conditions, exhibiting efficient encapsulation and sustained release. In addition, the GA-PEG-b-PLL-mediated BMP-2 delivery system could target the liver against hepatic diseases as it has GA-binding receptors. The anti-hepatic ischemia/reperfusion injury (anti-HI/RI) effect of BMP-2/GA-PEG-b-PLL PIC micelles was investigated in rats using free BMP-2 and BMP-2/PEG-b-PLL PIC micelles as controls, and the results showed that BMP-2/GA-PEG-b-PLL PIC micelles indicated significantly enhanced anti-HI/RI property compared to BMP-2 and BMP-2/PEG-b-PLL. All results suggested that GA-PEG-b-PLL could be used as a potential BMP-2 nanocarrier.