Stimulatory effects of the fast setting and suitable degrading Ca–Si–Mg cement on both cementogenesis and angiogenesis differentiation of human periodontal ligament cells

Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells

3D-printed scaffolds are suitable for patient-specific implant preparation for bone regeneration in large-scale critical bone defects. In addition, these scaffolds should have mechanical and biological properties similar to those of natural bone tissue. In this study, 3D-printed barium-doped calcium silicate (BaCS)/poly-ε-caprolactone (PCL) composite scaffolds were fabricated as an alternative strategy for bone tissue engineering to achieve appropriate physicochemical characteristics and stimulate osteogenesis. Scaffolds containing 10% Ba (Ba10) showed optimal mechanical properties, preventing premature scaffold degradation during immersion while enabling ion release in a sustained manner to achieve the desired therapeutic goals. In addition, Wharton's jelly mesenchymal stem cells (WJMSCs) were used to assess biocompatibility and osteogenic differentiation behaviour. WJMSCs were cultured on the scaffold and permeabilised via ICP to analyse the presence of Si and Ba ions in the medium and cell lysates, suggesting that the ions released by the scaffold could effectively enter the cells. The protein expression of CaSR, PI3K, Akt, and JNK confirmed that CaSR could activate cells cultured in Ba10, thereby affecting the subsequent PI3k/Akt and JNK pathways and further promoting osteogenic differentiation. The in vivo performance of the proposed scaffolds was assessed using micro-CT and histological slices, which revealed that the BaCS scaffolds could further enhance bone regeneration, compared with bare scaffolds. These results suggest the potential use of 3D-printed BaCS/PCL scaffolds as next-generation substitutes for bone regeneration.

Synergistic Effect of Static Magnetic Fields and 3D-Printed Iron-Oxide-Nanoparticle-Containing Calcium Silicate/Poly-ε-Caprolactone Scaffolds for Bone Tissue Engineering

In scaffold-regulated bone regeneration, most three-dimensional (3D)-printed scaffolds do not provide physical stimulation to stem cells. In this study, a magnetic scaffold was fabricated using fused deposition modeling with calcium silicate (CS), iron oxide nanoparticles (Fe₃O₄), and poly-ε-caprolactone (PCL) as the matrix for internal magnetic sources. A static magnetic field was used as an external magnetic source. It was observed that 5% Fe₃O₄ provided a favorable combination of compressive strength (9.6 ± 0.9 MPa) and degradation rate (21.6 ± 1.9% for four weeks). Furthermore, the Fe₃O₄-containing scaffold increased in vitro bioactivity and Wharton's jelly mesenchymal stem cells' (WJMSCs) adhesion. Moreover, it was shown that the Fe₃O₄-containing scaffold enhanced WJMSCs' proliferation, alkaline phosphatase activity, and the osteogenic-related proteins of the scaffold. Under the synergistic effect of the static magnetic field, the CS scaffold containing Fe₃O₄ can not only enhance cell activity but also stimulate the simultaneous secretion of collagen I and osteocalcin. Overall, our results demonstrated that Fe₃O₄-containing CS/PCL scaffolds could be fabricated three dimensionally and combined with a static magnetic field to affect cell behaviors, potentially increasing the likelihood of clinical applications for bone tissue engineering.

Combined Effects of Polydopamine-Assisted Copper Immobilization on 3D-Printed Porous Ti6Al4V Scaffold for Angiogenic and Osteogenic Bone Regeneration

Numerous studies have demonstrated that biological compounds and trace elements such as dopamine (DA) and copper ions (Cu) could be modified onto the surfaces of scaffolds using a one-step immersion process which is simple, inexpensive and, most importantly, non-cytotoxic. The development and emergence of 3D printing technologies such as selective laser melting (SLM) have also made it possible for us to fabricate bone scaffolds with precise structural designs using metallic compounds. In this study, we fabricated porous titanium scaffolds (Ti) using SLM and modified the surface of Ti with polydopamine (PDA) and Cu. There are currently no other reported studies with such a combination for osteogenic and angiogenic-related applications. Results showed that such modifications did not affect general appearances and microstructural characteristics of the porous Ti scaffolds. This one-step immersion modification allowed us to modify the surfaces of Ti with different concentrations of Cu ions, thus allowing us to fabricate individualized scaffolds for different clinical scenarios. The modification improved the hydrophilicity and surface roughness of the scaffolds, which in turn led to promote cell behaviors of Wharton’s jelly mesenchymal stem cells. Ti itself has high mechanical strength, therefore making it suitable for surgical handling and clinical applications. Furthermore, the scaffolds were able to release ions in a sustained manner which led to an upregulation of osteogenic-related proteins (bone alkaline phosphatase, bone sialoprotein and osteocalcin) and angiogenic-related proteins (vascular endothelial growth factor and angiopoietin-1). By combining additive manufacturing, Ti6Al4V scaffolds, surface modification and Cu ions, the novel hybrid 3D-printed porous scaffold could be fabricated with ease and specifically benefited future bone regeneration in the clinic.

The State of the Art and Prospects for Osteoimmunomodulatory Biomaterials

The critical role of the immune system in host defense against foreign bodies and pathogens has been long recognized. With the introduction of a new field of research called osteoimmunology, the crosstalk between the immune and bone-forming cells has been studied more thoroughly, leading to the conclusion that the two systems are intimately connected through various cytokines, signaling molecules, transcription factors and receptors. The host immune reaction triggered by biomaterial implantation determines the in vivo fate of the implant, either in new bone formation or in fibrous tissue encapsulation. The traditional biomaterial design consisted in fabricating inert biomaterials capable of stimulating osteogenesis; however, inconsistencies between the in vitro and in vivo results were reported. This led to a shift in the development of biomaterials towards implants with osteoimmunomodulatory properties. By endowing the orthopedic biomaterials with favorable osteoimmunomodulatory properties, a desired immune response can be triggered in order to obtain a proper bone regeneration process. In this context, various approaches, such as the modification of chemical/structural characteristics or the incorporation of bioactive molecules, have been employed in order to modulate the crosstalk with the immune cells. The current review provides an overview of recent developments in such applied strategies.

Bioactive Herbal Extracts of Traditional Chinese Medicine Applied with the Biomaterials: For the Current Applications and Advances in the Musculoskeletal System

Traditional Chinese medicine (TCM) has demonstrated superior therapeutic effect for musculoskeletal diseases for thousands of years. Recently, the herbal extracts of TCM have received rapid advances in musculoskeletal tissue engineering (MTE). A literature review collecting both English and Chinese references on bioactive herbal extracts of TCM in biomaterial-based approaches was performed. This review provides an up-to-date overview of application of TCMs in the field of MTE, involving regulation of multiple signaling pathways in osteogenesis, angiogenesis, anti-inflammation, and chondrogenesis. Meanwhile, we highlight the potential advantages of TCM, opening the possibility of its extensive application in MTE. Overall, the superiority of traditional Chinese medicine turns it into an attractive candidate for coupling with advanced additive manufacturing technology.

Constructing a Sr2+-Substituted Surface Hydroxyapatite Hexagon-Like Microarray on 3D-Plotted Hydroxyapatite Scaffold to Regulate Osteogenic Differentiation

Surface topography and chemical characteristics can regulate stem cell proliferation and differentiation, and decrease the bone-healing time. However, the synergetic function of the surface structure and chemical cues in bone-regeneration repair was rarely studied. Herein, a strontium ion (Sr2+)-substituted surface hydroxyapatite (HA) hexagon-like microarray was successfully constructed on 3D-plotted HA porous scaffold through hydrothermal reaction to generate topography and chemical dual cues. The crystal phase of the Sr2+-substituted surface microarray was HA, while the lattice constant of the Sr2+-substituted microarray increased with increasing Sr2+-substituted amount. Sr2+-substituted microarray could achieve the sustainable release of Sr2+, which could effectively promote osteogenic differentiation of human adipose-derived stem cells (ADSCs) even without osteogenic-induced media. Osteogenic characteristics were optimally enhanced using the higher Sr2+-substituted surface microarray (8Sr-HA). Sr2+-substituted microarray on the scaffold surface could future improve the osteogenic performance of HA porous scaffold. These results indicated that the Sr2+-substituted HA surface hexagon-like microarray on 3D-plotted HA scaffolds had promising biological performance for bone-regeneration repair scaffold.

Bioinspired Fabrication of Calcium-Doped TiP Coating with Nanofibrous Microstructure to Accelerate Osseointegration

Bioinspired by the morphology of osteoclast-resorbed bone surfaces, we prepared a calcium-doped titanium phosphate (Ca-TiP) coating, which consists of a nanofibrous network, on titanium (Ti) substrate via a simple two-step hydrothermal method, trying to mimic natural bone compositionally and microstructurally. The in vitro studies show that the Ca-TiP coating with synergistic features of nanofibrous biomimetic topography and surface chemistry could elicit intensively osteogenic behavior and responses including enhanced cell adhesion, spreading, and proliferation as well as alkaline phosphatase (ALP) activity and up-regulated expression of bone-related genes, which inevitably benefit the formation of new bone and the quality of osseointegration. When the two control groups are compared in vivo, the significantly improved new bone formation in the early stage and the much stronger interfacial bonding with the surrounding bone for Ca-TiP coating suggest that Ca-TiP coating modified Ti implants hold great potential for orthopedic and dental applications.

Effect of Bone Morphogenic Protein-2-Loaded Mesoporous Strontium Substitution Calcium Silicate/Recycled Fish Gelatin 3D Cell-Laden Scaffold for Bone Tissue Engineering

Bone has a complex hierarchical structure with the capability of self-regeneration. In the case of critical-sized defects, the regeneration capabilities of normal bones are severely impaired, thus causing non-union healing of bones. Therefore, bone tissue engineering has since emerged to solve problems relating to critical-sized bone defects. Amongst the many biomaterials available on the market, calcium silicate-based (CS) cements have garnered huge interest due to their versatility and good bioactivity. In the recent decade, scientists have attempted to modify or functionalize CS cement in order to enhance the bioactivity of CS. Reports have been made that the addition of mesoporous nanoparticles onto scaffolds could enhance the bone regenerative capabilities of scaffolds. For this study, the main objective was to reuse gelatin from fish wastes and use it to combine with bone morphogenetic protein (BMP)-2 and Sr-doped CS scaffolds to create a novel BMP-2-loaded, hydrogel-based mesoporous SrCS scaffold (FGSrB) and to evaluate for its composition and mechanical strength. From this study, it was shown that such a novel scaffold could be fabricated without affecting the structural properties of FGSr. In addition, it was proven that FGSrB could be used for drug delivery to allow stable localized drug release. Such modifications were found to enhance cellular proliferation, thus leading to enhanced secretion of alkaline phosphatase and calcium. The above results showed that such a modification could be used as a potential alternative for future bone tissue engineering research.

Macro-Microporous Surface with Sulfonic Acid Groups and Micro-Nano Structures of PEEK/Nano Magnesium Silicate Composite Exhibiting Antibacterial Activity and Inducing Cell Responses

Purpose

To improve the surface bio-properties of polyetheretherketone (PEEK)/nano magnesium silicate (n-MS) composite (PC).

Materials and Methods

The surface of PC was firstly treated by particle impact (PCP) and subsequently modified by concentrated sulfuric acid (PCPS).

Results

PCPS surface exhibited not only macropores with sizes of about 150 μm (fabricated by particle impact) but also micropores with sizes of about 2 μm (created by sulfonation of PEEK) on the macroporous walls, and sulfonic acid (-SO₃H) groups were introduced on PCPS surface. In addition, many n-MS nanoparticles were exposed on the microporous walls, which formed micro-nano structures. Moreover, the surface roughness and hydrophilicity of PCPS were obviously enhanced as compared with PC and PCP. Moreover, the apatite mineralization of PCPS in simulated body fluid (SBF) was obviously improved as compared with PC. Furthermore, compared with PC and PCP, PCPS exhibited antibacterial performances due to the presence of -SO₃H groups. In addition, the responses (eg, adhesion and proliferation as well as differentiation) of bone marrow mesenchymal stem cell of rat to PCPS were significantly promoted as compared with PC and PCP.

Conclusion

PCPS with macro-microporous surface containing -SO₃H groups and micro-nano structures exhibited antibacterial activity and induced cell responses, which might possess large potential for bone substitute and repair.

The Calcium Channel Affect Osteogenic Differentiation of Mesenchymal Stem Cells on Strontium-Substituted Calcium Silicate/Poly-ε-Caprolactone Scaffold

There had been a paradigm shift in tissue engineering studies over the past decades. Of which, part of the hype in such studies was based on exploring for novel biomaterials to enhance regeneration. Strontium ions have been reported by others to have a unique effect on osteogenesis. Both in vitro and in vivo studies had demonstrated that strontium ions were able to promote osteoblast growth, and yet at the same time, inhibit the formation of osteoclasts. Strontium is thus considered an important biomaterial in the field of bone tissue engineering. In this study, we developed a Strontium-calcium silicate scaffold using 3D printing technology and evaluated for its cellular proliferation capabilities by assessing for protein quantification and mineralization of Wharton’s Jelly mesenchymal stem cells. In addition, verapamil (an L-type of calcium channel blocker, CCB) was used to determine the mechanism of action of strontium ions. The results found that the relative cell proliferation rate on the scaffold was increased between 20% to 60% within 7 days of culture, while the CCB group only had up to approximately 10% proliferation as compared with the control specimen. Besides, the CCB group had downregulation and down expressions of all downstream cell signaling proteins (ERK and P38) and osteogenic-related protein (Col I, OPN, and OC). Furthermore, CCB was found to have 3–4 times lesser calcium deposition and quantification after 7 and 14 days of culture. These results effectively show that the 3D printed strontium-contained scaffold could effectively stimulate stem cells to undergo bone differentiation via activation of L-type calcium channels. Such results showed that strontium-calcium silicate scaffolds have high development potential for bone tissue engineering.

Application of piezoelectric cells printing on three-dimensional porous bioceramic scaffold for bone regeneration

In recent years, the additive manufacture was popularly used in tissue engineering, as the various technologies for this field of research can be used. The most common method is extrusion, which is commonly used in many bioprinting applications, such as skin. In this study, we combined the two printing techniques; first, we use the extrusion technology to form the ceramic scaffold. Then, the stem cells were printed directly on the surface of the ceramic scaffold through a piezoelectric nozzle. We also evaluated the effects of polydopamine (PDA)-coated ceramic scaffolds for cell attachment after printing on the surface of the scaffold. In addition, we used fluorescein isothiocyanate to simulate the cell adhered on the scaffold surface after ejected by a piezoelectric nozzle. Finally, the attachment, growth, and differentiation behaviors of stem cell after printing on calcium silicate/polycaprolactone (CS/PCL) and PDACS/PCL surfaces were also evaluated. The PDACS/PCL scaffold is more hydrophilic than the original CS/PCL scaffold that provided for better cellular adhesion and proliferation. Moreover, the cell printing technology using the piezoelectric nozzle, the different cells can be accurately printed on the surface of the scaffold that provided and analyzed more information of the interaction between different cells on the material. We believe that this method may serve as a useful and effective approach for the regeneration of defective complex hard tissues in deep bone structures.

The synergistic effects of graphene-contained 3D-printed calcium silicate/poly-ε-caprolactone scaffolds promote FGFR-induced osteogenic/angiogenic differentiation of mesenchymal stem cells

Graphene-contained calcium silicate (CS)/polycaprolactone (PCL) scaffold (GCP) provides an alternative solution that can bring several bone formation properties, such as osteoinductive. This study finds out the optimal percentage of graphene additive to calcium silicate and polycaprolactone mixture for excellent in vitro and in vivo bone-regeneration ability, in addition, this scaffold could fabricate by 3D printing technology and demonstrates distinct mechanical, degradation, and biological behavior. With controlled structure and porosity by 3D printing, osteogenesis and proliferation capabilities of Wharton's Jelly derived mesenchymal stem cells (WJMSCs) were significantly enhanced when cultured on 3D printed GCP scaffolds. In this study, it was also discovered that fibroblast growth factor receptor (FGFR) plays an active role in modulating differentiation behavior of WJMSCs cultured on GCP scaffolds. The validation has been proved by analyzed the decreased cell proliferation, osteogenic-related protein (ALP and OC), and angiogenic-related protein (VEGF and vWF) with FGFR knockdown on all experimental groups. Moreover, this study infers that the GCP scaffold could induce the effects of proliferation, differentiation and related protein expression on WJMSCs through FGFR pathway. In summary, this research indicated the 3D-printed GCP scaffolds own the dual bioactivities to reach the osteogenesis and vascularization for bone regeneration.

Substitutions of strontium in bioactive calcium silicate bone cements stimulate osteogenic differentiation in human mesenchymal stem cells

Calcium silicate cements have been considered as alternative bone substitutes owing to its extraordinary bioactivity and osteogenicity. Unfortunately, the major disadvantage of the cements was the slow degradation rate which may limit the efficiency of bone regeneration. In this study, we proposed a facile method to synthesize degradable calcium silicate cements by incorporating strontium into the cements through solid-state sintering. The effects of Sr incorporation on physicochemical and biological properties of the cements were evaluated. Although, our findings revealed that the incorporation of strontium retarded the hardening reaction of the cements, the setting time of different cements (11-19 min) were in the acceptable range for clinical use. The presence of Sr in the CS cements would hampered the precipitation of calcium phosphate products on the surface after immersion in SBF, however, a layer of precipitated calcium phosphate products can be formed on the surface of the Sr-CS cement within 1 day immersion in SBF. More importantly, the degradation rate of the cements increased with increasing content of strontium, consequentially raised the levels of released strontium and silicon ions. The elevated dissolving products may contribute to the enhancement of the cytocompatibility, alkaline phosphatase activity, osteocalcin secretion, and mineralization of human Wharton's jelly mesenchymal stem cells. Together, it is concluded that the strontium-incorporated calcium silicate cement might be a promising bone substitute that could accelerate the regeneration of irregularly shaped bone defects.

Enhanced Capability of Bone Morphogenetic Protein 2-loaded Mesoporous Calcium Silicate Scaffolds to Induce Odontogenic Differentiation of Human Dental Pulp Cells

INTRODUCTION

Calcium silicate bioceramics have been broadly used as reparative or grafting materials with good bioactivity and biocompatibility in dental application. It has been shown that applying a mesoporous process to calcium silicate gives it great potential as a controlled drug delivery system.

METHODS

The aim of this study was to investigate a novel osteoinductive scaffold by loading bone morphogenetic protein 2 (BMP-2) to mesoporous calcium silicate (MesoCS) and fabricating it as 3-dimensional scaffolds using fused deposition modeling combined with polycaprolactone.

RESULTS

The MesoCS/BMP-2 scaffold showed similar patterns to that of a calcium silicate scaffold in releasing calcium and silicon ions in a simulated body fluid (SBF) immersion test for 7 days, but BMP-2 continued releasing from the MesoCS/BMP-2 scaffold significantly more than the CS scaffold from 48 hours to 7 days. Adhesion and proliferation of human dental pulp cells cultured on a MesoCS/BMP-2 scaffold were also more significant than scaffolds without BMP-2 or mesoporous as well as the results of the test on alkaline phosphatase activity.

CONCLUSIONS

The results support that the novel 3-dimensional-printed MesoCS scaffold performed well as BMP-2 delivery system and would be an ideal odontoinductive biomaterial in regenerative endodontics.

3D-Printed Bioactive Calcium Silicate/Poly-ε-Caprolactone Bioscaffolds Modified with Biomimetic Extracellular Matrices for Bone Regeneration

Currently, clinically available orthopedic implants are extremely biocompatible but they lack specific biological characteristics that allow for further interaction with surrounding tissues. The extracellular matrix (ECM)-coated scaffolds have received considerable interest for bone regeneration due to their ability in upregulating regenerative cellular behaviors. This study delves into the designing and fabrication of three-dimensional (3D)-printed scaffolds that were made out of calcium silicate (CS), polycaprolactone (PCL), and decellularized ECM (dECM) from MG63 cells, generating a promising bone tissue engineering strategy that revolves around the concept of enhancing osteogenesis by creating an osteoinductive microenvironment with osteogenesis-promoting dECM. We cultured MG63 on scaffolds to obtain a dECM-coated CS/PCL scaffold and further studied the biological performance of the dECM hybrid scaffolds. The results indicated that the dECM-coated CS/PCL scaffolds exhibited excellent biocompatibility and effectively enhanced cellular adhesion, proliferation, and differentiation of human Wharton's Jelly mesenchymal stem cells by increasing the expression of osteogenic-related genes. They also presented anti-inflammatory characteristics by showing a decrease in the expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1 (IL-1). Histological analysis of in vivo experiments presented excellent bone regenerative capabilities of the dECM-coated scaffold. Overall, our work presented a promising technique for producing bioscaffolds that can augment bone tissue regeneration in numerous aspects.

Improved Bioactivity of 3D Printed Porous Titanium Alloy Scaffold with Chitosan/Magnesium-Calcium Silicate Composite for Orthopaedic Applications

Recently, cases of bone defects have been increasing incrementally. Thus, repair or replacement of bone defects is gradually becoming a huge problem for orthopaedic surgeons. Three-dimensional (3D) scaffolds have since emerged as a potential candidate for bone replacement, of which titanium (Ti) alloys are one of the most promising candidates among the metal alloys due to their low cytotoxicity and mechanical properties. However, bioactivity remains a problem for metal alloys, which can be enhanced using simple immersion techniques to coat bioactive compounds onto the surface of Ti⁻6Al⁻4V scaffolds. In our study, we fabricated magnesium-calcium silicate (Mg⁻CS) and chitosan (CH) compounds onto Ti⁻6Al⁻4V scaffolds. Characterization of these surface-modified scaffolds involved an assessment of physicochemical properties as well as mechanical testing. Adhesion, proliferation, and growth of human Wharton's Jelly mesenchymal stem cells (WJMSCs) were assessed in vitro. In addition, the cell attachment morphology was examined using scanning electron microscopy to assess adhesion qualities. Osteogenic and mineralization assays were conducted to assess osteogenic expression. In conclusion, the Mg⁻CS/CH coated Ti⁻6Al⁻4V scaffolds were able to exhibit and retain pore sizes and their original morphologies and architectures, which significantly affected subsequent hard tissue regeneration. In addition, the surface was shown to be hydrophilic after modification and showed mechanical strength comparable to natural bone. Not only were our modified scaffolds able to match the mechanical properties of natural bone, it was also found that such modifications enhanced cellular behavior such as adhesion, proliferation, and differentiation, which led to enhanced osteogenesis and mineralization downstream. In vivo results indicated that Mg⁻CS/CH coated Ti⁻6Al⁻4V enhances the bone regeneration and ingrowth at the critical size bone defects of rabbits. These results indicated that the proposed Mg⁻CS/CH coated Ti⁻6Al⁻4V scaffolds exhibited a favorable, inducive micro-environment that could serve as a promising modification for future bone tissue engineering scaffolds.

Mineral Trioxide Aggregate Mixed with 5-Aminolevulinic Acid for the Photodynamic Antimicrobial Strategy in Hard Tissue Regeneration

Aminolevulinic acid (ALA) based photodynamic antimicrobial strategy can provide good antimicrobial effects and be used for medical applications. The aim of this study was to apply this strategy to Mineral Trioxide Aggregate (MTA), which is commonly used as a filling material for root endings and by doing so, to increase the bactericidal capability of MTA, as well as to investigate its characterization, cytocompatibility, and odontogenic differentiation potential. MTA is known to be a derivative of calcium silicate (CS). In this study, MTA specimens with or without ALA and light treatment were prepared. Diametral tensile strength values (DTS), setting durations, X-ray diffraction (XRD) spectra, apatite-mineralization, and antimicrobial abilities of the MTA, were also analyzed. Human dental pulp cells (hDPCs) can proliferate into the newly formed matrix and differentiate into odontoblasts to reinforce and strengthen the root. Levels of hDPCs proliferation and its odontogenic capabilities when cultured on MTA with ALA and light treatment, and the percentages of cells existing in the various cell cycle stages, were further evaluated in this study. The results indicated that MTA added ALA with light treatment had greater antibacterial ability and cytocompatibility, compared to MTA alone. A higher percentage S phase of the cells cultured on MTA added ALA with light treatment was observed. Furthermore, hDPCs cultured on MTA added ALA with light treatment had the highest expression levels of the odontoblastic differentiation markers. ALA has great antimicrobial efficiency and is a potential material for future medical applications. ALA-based photodynamic antibacterial strategy applied in the MTA has great antibacterial ability, cytocompatibility, and odontoblastic differentiation potential, and can facilitate the development of root canal treatment.

Surface Modification of Calcium Silicate via Mussel-Inspired Polydopamine and Effective Adsorption of Extracellular Matrix to Promote Osteogenesis Differentiation for Bone Tissue Engineering

Calcium silicate-based cement has garnered huge interest in recent years, due to its versatility and potential in mass fabrication of a variety of bioceramics. For this study, the main objective was to fabricate functionalized calcium silicate (CS) powder integrated with a simple bio-inspired surface modification using polydopamine (PDA), to regulate cellular behaviors such as cellular adhesion, and subsequently cell differentiation and proliferation. For this study, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques were used to analyze the chemical compositions and observe the surface characteristics of our PDA coated CS cements. Such modifications were found to enhance Wharton Jelly's mesenchymal stem cells (WJMSC) in various ways. Firstly, PDA-coated CS cements were found to significantly enhance cell adhesion with higher expressions of cell adhesion markers, such as focal adhesion kinase and integrins. This was further supported by morphology analysis of the cells. This enhanced cell adhesion, in turn, led to significantly higher secretion of extracellular matrix (ECM) proteins, such as collagen I and fibronectin, which directly promoted cell attachments and proliferation. In our osteogenesis assays, it was found that secretion and expression of osteogenesis related genes and proteins were significantly higher and were dependent on the PDA content. Therefore, these results demonstrated that such simple bio-inspired modification techniques of synthetic degradable CS cements can be applied as a future modification, to modify and convert inert surfaces of synthetic bone grafts to enhance and modulate the cell behaviors of WJMSCs. This in turn can be used as a potential alternative for further bioengineering research.

Effects of bone morphogenic protein-2 loaded on the 3D-printed MesoCS scaffolds

BACKGROUND/PURPOSE

The mesoporous calcium silicate (MesoCS) 3D-printed scaffold show excellent bioactivity and can enhance the bone-like apatite formation. The purpose of this study aims to consider the effects of the different loading methods on the novel grafting materials which composed of bone morphogenetic protein-2 (BMP-2) loaded MesoCS scaffold by employing 3D-printing technique.

METHODS

The MesoCS scaffold were fabricated by fused deposition modeling. In this study, there are two methods of loading BMP-2: (1) the pre-loading (PL) method by mixing MesoCS and BMP-2 as a raw material for a 3D-printer, and (2) the direct-loading (DL) method by soaking the 3D-printed MesoCS scaffold in a BMP-2 solution. The characteristics of MesoCS scaffold were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their physical properties, biocompatibility, and osteogenic-related ability were also evaluated.

RESULTS

The 3D MesoCS/PCL scaffolds showed excellent biocompatibility and physical properties. After soaking in simulated body fluid, the bone-like apatite layer of the PL and DL groups could be formed. In addition, the DL group released fifty percent more than the PL group at the end of the first day and PL showed a sustained release profile after 2 weeks.

CONCLUSION

The 3D MesoCS/PCL porous scaffolds were successfully fabricated via a 3D printing system and were tested in vitro and were found to show good cellular activity for cell behavior although the PL method was not favorable for clinical application in relation with the preservation of BMP-2. With regards to different growth factor loading methods, this study demonstrated that PL of BMP-2 into MesoCS prior to printing will result in a more sustained drug release pattern as compared to traditional methods of scaffolds directly immersed with BMP-2.

Osteogenic and angiogenic potentials of the cell-laden hydrogel/mussel-inspired calcium silicate complex hierarchical porous scaffold fabricated by 3D bioprinting

3D printing has been popularly used in the bone tissue engineering, as many of the biomaterials for this field of study can be prepared for and produced from this additive manufacturing technique. In this study, we strategized a solvent-free processing to fabricate the polydopamine-modified calcium silicate (PDACS)/poly-caprolactone (PCL) scaffold with Wharton's jelly mesenchymal stem cells (WJMSCs) incorporated with human umbilical vein endothelial cells (HUVEC)-laden hydrogel. The PDACS/PCL/hydrogel 3D scaffold yielded a Young's modulus of the 3D scaffolds as high as 75 MPa. In addition, the vascular morphogenesis and cellular behaviors regulated by our hybrid scaffolds were also intricately evaluated. Furthermore, the HUVEC in the bioink exhibited higher levels of angiogenic biomarkers and showed potential for the formation of complex vascular networks. Higher levels of bone formation proteins were also observed in our composites. Such a hybrid of synthetic materials with cell constituents not only enhances osteogenesis but also stimulates vessel network development in angiogenesis, presenting the fact that 3D printing can be further applied in improving bone tissue regeneration in numerous aspects. We believe that this method may serve as a useful and effective approach for the regeneration of defective complex hard tissues in deep bone structures.

Bioactive calcium silicate/poly-ε-caprolactone composite scaffolds 3D printed under mild conditions for bone tissue engineering

The present study provides a solvent-free processing method for establishing the ideal porous 3-dimension (3D) scaffold filled with different ratios of calcium silicate-based (CS) powder and polycaprolactone (PCL) for 3D bone substitute application. Characterization of hybrid scaffolds developed underwent assessments for physicochemical properties and biodegradation. Adhesion and growth of human Wharton's Jelly mesenchymal stem cells (WJMSCs) on the CS/PCL blended scaffold were investigated in vitro. Cell attachment and morphology were examined by scanning electron microscope (SEM) and confocal microscope observations. Colorimetric assay was tested for assessing cell metabolic activity. In addition, RT-qPCR was also performed for the osteogenic-related and angiogenesis-related gene expression. As a result, the hydrophilicity of the scaffolds was further significantly improved after we additive CS into PCL, as well as the compressive strength up to 5.8 MPa. SEM showed that a great amount of precipitated bone-like apatite formed on the scaffold surface after immersed in the simulated body fluid. The 3D-printed scaffolds were found to enhance cell adhesion, proliferation and differentiation. Additionally, results of osteogenesis and angiogenesis proteins were expressed obviously greater in the response of WJMSCs. These results indicate the CS/PCL composite exhibited a favorable bioactivity and osteoconductive properties that could be served as a promising biomaterial for bone tissue engineering scaffolds.

The effects of Biodentine/polycaprolactone three-dimensional-scaffold with odontogenesis properties on human dental pulp cells

AIM

To determine the feasibility of using three-dimensional printed Biodentine/polycaprolactone composite scaffolds for orthopaedic and dental applications. The physicochemical properties and the odontogenic differentiation of human dental pulp cells (hDPCs) were investigated.

METHODOLOGY

Biodentine was well-suspended in ethanol and dropped slowly into molten polycaprolactone with vigorous stirring. The Biodentine/polycaprolactone composite scaffolds were then fabricated into controlled macropore sizes and structures using an extrusion-based three-dimensional (3D) printer. The mechanical properties, bioactivity, and the proliferation and odontogenic differentiation of human dental pulp cells (hDPCs) cultured on the scaffolds were evaluated.

RESULTS

Biodentine/polycaprolactone scaffolds had uniform macropores 550 μm in size with established interconnections and a compressive strength of 6.5 MPa. In addition, the composite scaffolds exhibited a good apatite-forming ability and were capable of supporting the proliferation and differentiation of hDPCs.

CONCLUSION

The composite scaffolds fabricated by an extrusion-based 3D printing technique had similar characteristics to Biodentine cement, including bioactivity and the ability to promote the differentiation of hDPCs. These results indicate that the composite scaffold would be a candidate for dental and bone regeneration.

Hydroxyapatite Nanowire@Magnesium Silicate Core-Shell Hierarchical Nanocomposite: Synthesis and Application in Bone Regeneration

Multifunctional biomaterials that simultaneously combine high biocompatibility, biodegradability, and bioactivity are promising for applications in various biomedical fields such as bone defect repair and drug delivery. Herein, the synthesis of hydroxyapatite nanowire@magnesium silicate nanosheets (HANW@MS) core-shell porous hierarchical nanocomposites (nanobrushes) is reported. The morphology of the magnesium silicate (MS) shell can be controlled by simply varying the solvothermal temperature and the amount of Mg²⁺ ions. Compared with hydroxyapatite nanowires (HANWs), the HANW@MS core-shell porous hierarchical nanobrushes exhibit remarkably increased specific surface area and pore volume, endowing the HANW@MS core-shell porous hierarchical nanobrushes with high-performance drug loading and sustained release. Moreover, the porous scaffold of HANW@MS/chitosan (HANW@MS/CS) is prepared by incorporating the HANW@MS core-shell porous hierarchical nanobrushes into the chitosan (CS) matrix. The HANW@MS/CS porous scaffold not only promotes the attachment and growth of rat bone marrow derived mesenchymal stem cells (rBMSCs), but also induces the expression of osteogenic differentiation related genes and the vascular endothelial growth factor (VEGF) gene of rBMSCs. Furthermore, the HANW@MS/CS porous scaffold can obviously stimulate in vivo bone regeneration, owing to its high bioactive performance on the osteogenic differentiation of rBMSCs and in vivo angiogenesis. Since Ca, Mg, Si, and P elements are essential in human bone tissue, HANW@MS core-shell porous hierarchical nanobrushes with multifunctional properties are expected to be promising for various biomedical applications such as bone defect repair and drug delivery.

Calcium Silicate/Chitosan-Coated Electrospun Poly (Lactic Acid) Fibers for Bone Tissue Engineering

Electrospinning technology allows fabrication of nano- or microfibrous fibers with inorganic and organic matrix and it is widely applied in bone tissue engineering as it allows precise control over the shapes and structures of the fibers. Natural bone has an ordered composition of organic fibers with dispersion of inorganic apatite among them. In this study, poly (lactic acid) (PLA) mats were fabricated with electrospinning and coated with chitosan (CH)/calcium silicate (CS) mixer. The microstructure, chemical component, and contact angle of CS/CH-PLA composites were analyzed by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. In vitro, various CS/CH-coated PLA mats increased the formation of hydroxyapatite on the specimens' surface when soaked in cell cultured medium. During culture, several biological characteristics of the human mesenchymal stem cells (hMSCs) cultured on CS/CH-PLA groups were promoted as compared to those on pure PLA mat. Increased secretion levels of Collagen I and fibronectin were observed in calcium silicate-powder content. Furthermore, with comparison to PLA mats without CS/CH, CS10 and CS15 mats markedly enhanced the proliferation of hMSCs and their osteogenesis properties, which was characterized by osteogenic-related gene expression. These results clearly demonstrated that the biodegradable and electroactive CS/CH-PLA composite mats are an ideal and suitable candidate for bone tissue engineering.

The Horizon of Materiobiology: A Perspective on Material-Guided Cell Behaviors and Tissue Engineering

Although the biological functions of cell and tissue can be regulated by biochemical factors (e.g., growth factors, hormones), the biophysical effects of materials on the regulation of biological activity are receiving more attention. In this Review, we systematically summarize the recent progress on how biomaterials with controllable properties (e.g., compositional/degradable dynamics, mechanical properties, 2D topography, and 3D geometry) can regulate cell behaviors (e.g., cell adhesion, spreading, proliferation, cell alignment, and the differentiation or self-maintenance of stem cells) and tissue/organ functions. How the biophysical features of materials influence tissue/organ regeneration have been elucidated. Current challenges and a perspective on the development of novel materials that can modulate specific biological functions are discussed. The interdependent relationship between biomaterials and biology leads us to propose the concept of "materiobiology", which is a scientific discipline that studies the biological effects of the properties of biomaterials on biological functions at cell, tissue, organ, and the whole organism levels. This Review highlights that it is more important to develop ECM-mimicking biomaterials having a self-regenerative capacity to stimulate tissue regeneration, instead of attempting to recreate the complexity of living tissues or tissue constructs ex vivo. The principles of materiobiology may benefit the development of novel biomaterials providing combinative bioactive cues to activate the migration of stem cells from endogenous reservoirs (i.e., cell niches), stimulate robust and scalable self-healing mechanisms, and unlock the body's innate powers of regeneration.

Laser Sintered Magnesium-Calcium Silicate/Poly-ε-Caprolactone Scaffold for Bone Tissue Engineering

In this study, we manufacture and analyze bioactive magnesium-calcium silicate/poly-ε-caprolactone (Mg-CS/PCL) 3D scaffolds for bone tissue engineering. Mg-CS powder was incorporated into PCL, and we fabricated the 3D scaffolds using laser sintering technology. These scaffolds had high porosity and interconnected-design macropores and structures. As compared to pure PCL scaffolds without an Mg-CS powder, the hydrophilic properties and degradation rate are also improved. For scaffolds with more than 20% Mg-CS content, the specimens become completely covered by a dense bone-like apatite layer after soaking in simulated body fluid for 1 day. In vitro analyses were directed using human mesenchymal stem cells (hMSCs) on all scaffolds that were shown to be biocompatible and supported cell adhesion and proliferation. Increased focal adhesion kinase and promoted cell adhesion behavior were observed after an increase in Mg-CS content. In addition, the results indicate that the Mg-CS quantity in the composite is higher than 10%, and the quantity of cells and osteogenesis-related protein of hMSCs is stimulated by the Si ions released from the Mg-CS/PCL scaffolds when compared to PCL scaffolds. Our results proved that 3D Mg-CS/PCL scaffolds with such a specific ionic release and good degradability possessed the ability to promote osteogenetic differentiation of hMSCs, indicating that they might be promising biomaterials with potential for next-generation bone tissue engineering scaffolds.

Fabrication and characterization of polycaprolactone and tricalcium phosphate composites for tissue engineering applications

Background/purpose

β-Tricalcium phosphate (β-TCP) is an osteoconductive material which has been used for clinical purposes for several years, as is polycaprolactone (PCL), which has already been approved for a number of medical and drug delivery devices. In this study we have incorporated various concentrations of β-TCP into PCL with the aim of developing an injectable, mechanically strong, and biodegradable material which can be used for medical purposes without organic solvents.

Materials and methods

This study assesses the physical and chemical properties of this material, evaluates the in vitro bioactivity of the PCL/β-TCP composites, and analyzes cell proliferation and osteogenic differentiation when using human bone marrow mesenchymal stem cells (hBMSCs).

Results

The results show that weight losses of approximately 5.3%, 12.1%, 18.6%, and 25.2%, were observed for the TCP0, TCP10, TCP30, and TCP50 composites after immersion in simulated body fluid for 12 weeks, respectively, indicating significant differences (P < 0.05). In addition, PCL/β-TCP composites tend to have lower contact angles (47 ± 1.5° and 58 ± 1.7° for TCP50 and TCP30, respectively) than pure PCL (85 ± 1.3°), which are generally more hydrophilic. After 7 days, a significant (22% and 34%, respectively) increase (P < 0.05) in alkaline phosphatase level was measured for TCP30 and TCP50 in comparison with the pure PCL.

Conclusion

PCL/TCP is biocompatible with hBMSCs. It not only promotes proliferation of hBMSCs but also helps to differentiate reparative hard tissue. We suggest 50% (weight) PCL-containing β-TCP biocomposites as the best choice for hard tissue repair applications.

Hinokitiol-Loaded Mesoporous Calcium Silicate Nanoparticles Induce Apoptotic Cell Death through Regulation of the Function of MDR1 in Lung Adenocarcinoma Cells

Hinokitiol is a tropolone-related compound found in heartwood cupressaceous plants. Hinokitiol slows the growth of a variety of cancers through inhibition of cell proliferation. The low water solubility of hinokitiol leads to less bioavailability. This has been highlighted as a major limiting factor. In this study, mesoporous calcium silicate (MCS) nanoparticles, both pure and hinokitiol-loaded, were synthesized and their effects on A549 cells were analyzed. The results indicate that Hino-MCS nanoparticles induce apoptosis in higher concentration loads (>12.5 μg/mL) for A549 cells. Hino-MCS nanoparticles suppress gene and protein expression levels of multiple drug resistance protein 1 (MDR1). In addition, both the activity and the expression levels of caspase-3/-9 were measured in Hino-MCS nanoparticle-treated A549 cells. The Hino-MCS nanoparticles-triggered apoptosis was blocked by inhibitors of pan-caspase, caspase-3/-9, and antioxidant agents (N-acetylcysteine; NAC). The Hino-MCS nanoparticles enhance reactive oxygen species production and the protein expression levels of caspase-3/-9. Our data suggest that Hino-MCS nanoparticles trigger an intrinsic apoptotic pathway through regulating the function of MDR1 and the production of reactive oxygen species in A549 cells. Therefore, we believe that Hino-MCS nanoparticles may be efficacious in the treatment of drug-resistant human lung cancer in the future.

Enhanced adhesion and differentiation of human mesenchymal stem cell inside apatite-mineralized/poly(dopamine)-coated poly(ε-caprolactone) scaffolds by stereolithography

The purpose of this study is to develop PCL scaffolds using stereolithography technology and induced modifications using a poly dopamine (PDA)-coated/HA precipitate to stimulate human mesenchymal stem cells (hMSCs).

Preparation of the fast setting and degrading Ca-Si-Mg cement with both odontogenesis and angiogenesis differentiation of human periodontal ligament cells

Develop a fast setting and controllable degrading magnesium-calcium silicate cement (Mg-CS) by sol-gel, and establish a mechanism using Mg ions to stimulate human periodontal ligament cells (hPDLs) are two purposes of this study. We have used the diametral tensile strength measurement to obtain the mechanical strength and stability of Mg-CS cement; in addition, the cement degradation properties is realized by measuring the releasing amount of Si and Mg ions in the simulated body fluid. The other cell characteristics of hPDLs, such as proliferation, differentiation and mineralization were examined while hPDLs were cultured on specimen surfaces. This study found out the degradation rate of Mg-CS cements depends on the Mg content in CS. Regarding in vitro bioactivity; the CS cements were covered with abundant clusters of apatite spherulites after immersion of 24h, while less apatite spherulites were formatted on the Mg-rich cement surfaces. In addition, the authors also explored the effects of Mg ions on the odontogenesis and angiogenesis differentiation of hPDLs in comparison with CS cement. The proliferation, alkaline phosphatase, odontogenesis-related genes (DSPP and DMP-1), and angiogenesis-related protein (vWF and ang-1) secretion of hPDLs were significantly stimulated when the Mg content of the specimen was increased. The results in this study suggest that Mg-CS materials with this modified composition could stimulate hPDLs behavior and can be good bioceramics for bone substitutes and hard tissue regeneration applications as they stimulate odontogenesis/angiogenesis.