Alkaline Phosphatase Secretion Research Articles

NIR-Responsive Deployable and Self-Fitting 4D-Printed Bone Tissue Scaffold.

The treatment of irregular-shaped and critical-sized bone defects poses a clinical challenge. Deployable, self-fitting tissue scaffolds that can be implanted by minimally invasive procedures are a promising solution. Toward this, we fabricated NIR-responsive and programmable polylactide-co-trimethylene carbonate (PLMC) scaffolds nanoengineered with polydopamine nanoparticles (PDA) by extrusion-based three-dimensional (3D) printing. The 3D-printed scaffolds demonstrated excellent (>99%), fast (under 30 s), and tunable shape recovery under NIR irradiation. PLMC-PDA composites demonstrated significantly higher osteogenic potential in vitro as revealed by the significantly enhanced alkaline phosphatase (ALP) secretion and mineral deposition in contrast to neat PLMC. Intraoperative deployability and in vivo bone regeneration ability of PLMC-PDA composites were demonstrated, using self-fitting scaffolds in critical-sized cranial bone defects in rabbits. The 3D-printed scaffolds were deformed into compact shapes that could self-fit into the defect shape intraoperatively under low power intensity (0.76 W cm-2) NIR. At 6 and 12 weeks postsurgical implantation, near-complete bone regeneration was observed in PLMC-PDA composites, unlike neat PLMC through microcomputed tomography (micro-CT) analysis. The potential clinical utility of the 3D-printed composites to secure complex defects was confirmed through self-fitting of the scaffolds into irregular defects in ex vivo models of rabbit tibia, mandible, and tooth models. Taken together, the composite scaffolds fabricated here offer an innovative strategy for minimally invasive deployment to fit irregular and complex tissue defects for bone tissue regeneration.

Impact of Strontium, Magnesium, and Zinc Ions on the In Vitro Osteogenesis of Maxillary Sinus Membrane Stem Cells.

Human Maxillary Sinus Membrane Stem Cells (hMSMSCs) contribute significantly to bone formation following maxillary sinus floor augmentation (MSFA). The biological behavior of mesenchymal stem cells is notably influenced by varying concentrations of magnesium (Mg2+), strontium (Sr2+), and zinc (Zn2+) ions; however, their specific effects on hMSMSCs have not been comprehensively studied. We isolated hMSMSCs and identified their mesenchymal stem cell characteristics by flow cytometry and multilineage differentiation experiments. Subsequently, the hMSMSCs were cultured in media containing different concentrations of these metal ions. The proliferation and viability of hMSMSCs were assessed using CCK-8 and Calcein AM/PI staining. After osteogenic induction, cells were evaluated for alkaline phosphatase (ALP) activity, ALP staining, and Alizarin Red staining. Additionally, qRT-PCR was used to detect differences in osteogenic gene expression, and immunofluorescence staining was used to observe variations in OCN protein levels. The results indicated that 1 mM Mg2+, 0.01 mM Sr2+, and 0.001 mM Zn2+ significantly improved the proliferation and activity of hMSMSCs. These concentrations also notably enhanced ALP secretion, increased bone-related gene expression, and augmented osteocalcin expression and formation of extracellular calcium nodules, thereby improving osteogenic differentiation. However, higher concentrations of Mg2+, Sr2+, and Zn2+ decreased cell viability and osteogenic differentiation. Mg2+, Sr2+, and Zn2+ promote osteogenic differentiation and proliferation of hMSMSCs in a concentration-dependent manner, indicating that the type and concentration of ions in the extracellular environment can significantly alter hMSMSCs behavior, which is a crucial consideration for material design in maxillary sinus elevation applications.

Characterization and engineering of the type 3 secretion system needle monomer from Salmonella through the construction and screening of a comprehensive mutagenesis library.

Protein production strategies in bacteria are often limited due to the need for cell lysis and complicated purification schemes. To avoid these challenges, researchers have developed bacterial strains capable of secreting heterologous protein products outside the cell, but secretion titers often remain too low for commercial applicability. Improved understanding of the link between secretion system structure and its secretory abilities can help overcome the barrier to engineering higher secretion titers. Here, we investigated this link with the PrgI protein, the monomer of the secretory channel of the type 3 secretion system (T3SS) of Salmonella enterica. Despite detailed knowledge of the PrgI needle's assembly and structure, little is known about how its structure influences its secretory capabilities. To study this, we recently constructed a comprehensive codon mutagenesis library of the PrgI protein utilizing a novel one-pot recombineering approach. We then screened this library for functional T3SS assembly and secretion titer by measuring the secretion of alkaline phosphatase using a high-throughput activity assay. This allowed us to construct a first-of-its-kind secretion fitness landscape to characterize the PrgI needle's mutability at each position as well as the mutations which lead to enhanced T3SS secretion. We discovered new design rules for building a functional T3SS as well as identified hypersecreting mutants. This work can be used to increase understanding of the T3SS's assembly and identify further targets for engineering. This work also provides a blueprint for future efforts to engineer other complex protein assemblies through the construction of fitness landscapes.IMPORTANCEProtein secretion offers a simplified alternative method for protein purification from bacterial hosts. However, the current state-of-the-art methods for protein secretion in bacteria are still hindered by low yields relative to traditional protein purification strategies. Engineers are now seeking strategies to enhance protein secretion titers from bacterial hosts, often through genetic manipulations. In this study, we demonstrate that protein engineering strategies focused on altering the secretion apparatus can be a fruitful avenue toward this goal. Specifically, this study focuses on how changes to the PrgI needle protein from the type 3 secretion system from Salmonella enterica can impact secretion titer. We demonstrate that this complex is amenable to comprehensive mutagenesis studies and that this can yield both PrgI variants with increased secretory capabilities and insight into the normal functioning of the type 3 secretion system.

Surface modification of titanium implants via PLLA/HA fibrous composite coating to improve piezoelectric properties

Titanium (Ti)-based implants are among the most advantageous biomaterials in both orthopedic and dental applications, owing to their excellent properties and biocompatibility. However, their bioinert surface poses challenges to osteointegrity, raising concerns about implant loosening. The present study examines the effect of surface modification of Ti by applying a bioactive piezoelectric fibrous coating comprised of electrospun poly(L-lactide) (PLLA) as a biodegradable piezopolymer and varying amounts of hydroxyapatite (HA) filler (5−20 wt%) as an osteoconductive piezoceramic. According to SEM micrographs, adding HA increased the fiber diameter, porosity, and pore size of the fibrous structure. Furthermore, peeling test of the fibrous coating demonstrated that applying a polydopamine (PDA) coating before electrospinning onto the Ti substrate effectively enhanced the adhesion strength of the coating. Additionally, the PLLA/HA composite coating exhibited increased piezoelectric properties, with piezoresponse rising from 2.41 ± 0.192 mV/N (5 wt% HA) to 5.42 ± 0.192 mV/N (20 wt% HA). Similarly, PLLA/HA coatings showed superior apatite-forming ability in simulated body fluid (SBF) at 7 and 28 days, with significantly higher calcium-phosphate deposition and a Ca/P ratio close to natural bone, surpassing the neat PLLA coating and bare Ti substrate. Finally, testing with MG-63 cell lines indicated that fibrous composite coatings enhance cell support, demonstrating optimal alkaline phosphatase (ALP) secretion levels and positive cell attachment. Consequently, the surface-modified Ti with fibrous PLLA/HA coating emerges as a promising strategy for the clinical treatment of bone defects.

NOD2 contributes to Parvimonas micra-induced bone resorption in diabetic rats with experimental periodontitis.

Type 2 diabetes mellitus (T2DM) may affect the oral microbial community, exacerbating periodontal inflammation; however, its pathogenic mechanisms remain unclear. As nucleotide-binding oligomerization domain 2 (NOD2) plays a crucial role in the activation during periodontitis (PD), it is hypothesized that changes in the oral microbial community due to diabetes enhance periodontal inflammation through the activation of NOD2. We collected subgingival plaque from 180 subjects who were categorized into two groups based on the presence or absence of T2DM. The composition of oral microbiota was detected by 16S rRNA high-throughput sequencing. In animal models of PD with or without T2DM, we assessed alveolar bone resorption by micro-computerized tomography and used immunohistochemistry to detect NOD2 expression in alveolar bone. Primary osteoblasts were cultured in osteogenic induction medium with high or normal glucose and treated with inactivated bacteria. After 24h of inactivated bacteria intervention, the osteogenic differentiation ability was detected by alkaline phosphatase (ALP) staining, and the expressions of NOD2 and interleukin-12 (IL-6) were detected by western blot. The relative abundance of Parvimonas and Filifactor in the T2DM group was increased compared to the group without T2DM. In animal models, alveolar bone mass was decreased in PD, particularly in T2DM with PD (DMPD) group, compared to controls. Immunohistochemistry revealed NOD2 in osteoblasts from the alveolar bone in both the PD group and DMPD group, especially in the DMPD group. In vitro, intervention with inactivated Parvimonas significantly reduced ALP secretion of primary osteoblasts in high glucose medium, accompanied by increased expression of NOD2 and IL-6. The results suggest that T2DM leading to PD may be associated with the activation of NOD2 by Parvimonas.

Enhanced osteogenic and ROS-scavenging MXene nanosheets incorporated gelatin-based nanocomposite hydrogels for critical-sized calvarial defect repair

The healing of critical-sized bone defects is a major challenge in the field of bone tissue engineering. Gelatin-related hydrogels have emerged as a potential solution due to their desirable properties. However, their limited osteogenic, mechanical, and reactive oxygen species (ROS)-scavenging capabilities have hindered their clinical application. To overcome this issue, we developed a biofunctional gelatin-Mxene nanocomposite hydrogel. Firstly, we prepared two-dimensional (2D) Ti3C2 MXene nanosheets using a layer delamination method. Secondly, these nanosheets were incorporated into a transglutaminase (TG) enzyme-containing gallic acid-imbedded gelatin (GGA) pre-gel solution to create an injectable GGA-MXene (GM) nanocomposite hydrogel. The GM hydrogels exhibited superior compressive strength (44–75.6 kPa) and modulus (24–44.5 kPa) compared to the GGA hydrogels. Additionally, the GM hydrogel demonstrated the ability to scavenge reactive oxygen species (OH- and DPPH radicals), protecting MC3T3-E1 cells from oxidative stress. GM hydrogels were non-toxic to MC3T3-E1 cells, increased alkaline phosphatase secretion, calcium nodule formation, and upregulated osteogenic gene expressions (ALP, OCN, and RUNX2). The GM400 hydrogel was implanted in critical-sized calvarial defects in rats. Remarkably, it exhibited significant potential for promoting new bone formation. These findings indicated that GM hydrogel could be a viable candidate for future clinical applications in the treatment of critical-sized bone defects.

Architecture of β-lactoglobulin coating modulates bioinspired alginate dialdehyde-gelatine/polydopamine scaffolds for subchondral bone regeneration

In this study, we developed polydopamine (PDA)-functionalized alginate dialdehyde-gelatine (ADA-GEL) scaffolds for subchondral bone regeneration. These polymeric scaffolds were then coated with β-Lactoglobulin (β-LG) at concentrations of 1 mg/ml and 2 mg/ml. Morphological analysis indicated a homogeneous coating of the β-LG layer on the surface of network-like scaffolds. The β-LG-coated scaffolds exhibited improved swelling capacity as a function of the β-LG concentration. Compared to ADA-GEL/PDA scaffolds, the β-LG-coated scaffolds demonstrated delayed degradation and enhanced biomineralization. Here, a lower concentration of β-LG showed long-lasting stability and superior biomimetic hydroxyapatite mineralization. According to the theoretical findings, the single-state, representing the low concentration of β-LG, exhibited a homogeneous distribution on the surface of the PDA, while the dimer-state (high concentration) displayed a high likelihood of uncontrolled interactions. β-LG-coated ADA-GEL/PDA scaffolds with a lower concentration of β-LG provided a biocompatible substrate that supported adhesion, proliferation, and alkaline phosphatase (ALP) secretion of sheep bone marrow mesenchymal stem cells, as well as increased expression of osteopontin (SPP1) and collagen type 1 (COL1A1) in human osteoblasts. These findings indicate the potential of protein-coated scaffolds for subchondral bone tissue regeneration. Statement of SignificanceThis study addresses a crucial aspect of osteochondral defect repair, emphasizing the pivotal role of subchondral bone regeneration. The development of polydopamine-functionalized alginate dialdehyde-gelatine (ADA-GEL) scaffolds, coated with β-Lactoglobulin (β-LG), represents a novel approach to potentially enhance subchondral bone repair. β-LG, a milk protein rich in essential amino acids and bioactive peptides, is investigated for its potential to promote subchondral bone regeneration. This research explores computationally and experimentally the influence of protein concentration on the ordered or irregular deposition, unravelling the interplay between coating structure, scaffold properties, and in-vitro performance. This work contributes to advancing ordered protein coating strategies for subchondral bone regeneration, providing a biocompatible solution with potential implications for supporting subsequent cartilage repair.

Tailored thymoquinone intercalated Layered Double Hydroxide (LDH) nanocomposites to accelerate mineralization for enhanced osteogenesis

The tunable nature of two-dimensional nanostructured Layered Double Hydroxides [LDH] and their effective intercalation ability with biomolecules make them inevitable functional hybrid materials for versatile biomedical applications. In an attempt to meet the limitations in existing bone reconstruction practice, the present work reports the synthesis of zinc and iron-based LDH [Zn-Fe LDH] and its subsequent intercalation with thymoquinone [TQ-Zn-Fe LDH] to augment osteoblastic differentiation and proliferation for accelerated bone mineralization. Structural studies depicted the polycrystalline and amorphous nature of ZnFe LDH and TQ-Zn-Fe LDH respectively. The biocompatible nature of LDHs was proven by negative cytotoxicity, cell adhesion, and proliferation assays studied in MG-63 cell lines. Gene expression studies of the nanocomposites showed a fold change of 5–10 in osteoblastic differentiation and proliferation. However, TQ-Zn-Fe LDH treated cells showed significantly higher protein translation levels of osteogenesis markers and elevated alkaline phosphatase secretion and calcium deposition on day 21, confirming their osteogenic efficiency. Thus, acquired results speculate the osteogenic potential of thymoquinone intercalated TQ-Zn-Fe-LDH to meet the limitations in bone reconstruction practice.

Strontium and copper co-doped nanohydroxyapatite for bone augmentation

Abstract Bone disorders and conditions have been increasing at an alarming rate all over the world, especially in niches where increased obesity and poor physical activity have been prevailing. Synthetic nanohydroxyapatite (HAp) is one of the remedies to reconstruct bone formation. Its rate of dissolution and compatibility is in the moderately acceptable range. The doping of HAp with bone-forming ions can make them highly biologically compatible materials. In the present work, we formulated HAp doped with essential micronutrients of strontium and copper. Nanoglobular Sr and Cu doped HAp (SC-HAp) with an average size of 30 nm was prepared. The SC-HAp was partially crystalline and amorphous, which could influence the dissolution rate of the material. The biomineralization ability of the SC-HAp seemed to be effective in apatite formation. The calcium, collagen and alkaline phosphatase secretion levels after the addition of SC-HAp on MG63 cells indicate the bone-forming capacity of the material. Further, the cell proliferation rate was enhanced compared to the control with SC-HAp.

In vitro and vivo biocompatibility and degradability of low-alloyed Mg-Zn-Ca-MgO composite as bone repair biomaterials

Abstract Magnesium alloys have gained attention as biodegradable bone repair biomaterials. Unlike non-biodegradable materials like titanium and tantalum, biodegradable implants offer advantages in promoting bone healing and minimizing chronic inflammatory reactions. However, the impact of the implant's degradation on the osteogenic environment remains a concern. The Mg-Zn-Ca-MgO composite, being biocompatible and containing osteogenic ions, is a promising candidate. This study assesses the degradability and in vitro/in vivo biocompatibility of two Mg-Zn-Ca-MgO composites with varying degradation rates. The Mg-1Zn-0.2Ca-1.0MgO composite was prepared, and leaching solutions were created following standard protocols. MC3T3-E1 cell cultures were conducted to assess cell toxicity, alkaline phosphatase (ALP) staining, cytoskeleton morphology, and osteogenic protein expression. In vivo biodegradation and bone regeneration capacity were evaluated in rat femoral condyles. Benefiting from the more protective corrosion product layer on the surface, the ultra-fine grained (UFG) composite showed better corrosion resistance and lower Mg2+ release than the coarse-grained (CG) composite. UFG material exhibited higher cell viability, cytoskeleton integrity, ALP secretion, and osteogenic protein expression. In vivo, UFG composites led to greater bone regeneration and exhibited excellent biocompatibility. The UFG Mg-Zn-Ca-MgO composite demonstrates enhanced biocompatibility, corrosion resistance, and bone regeneration potential. This study highlights the importance of controlling Mg ion release for optimal bone healing in biodegradable materials.

3D Niche-Inspired Scaffolds as a Stem Cell Delivery System for the Regeneration of the Osteochondral Interface.

The regeneration of the osteochondral unit represents a challenge due to the distinct cartilage and bone phases. Current strategies focus on the development of multiphasic scaffolds that recapitulate features of this complex unit and promote the differentiation of implanted bone-marrow derived stem cells (BMSCs). In doing so, challenges remain from the loss of stemness during in vitro expansion of the cells and the low control over stem cell activity at the interface with scaffolds in vitro and in vivo. Here, this work scaffolds inspired by the bone marrow niche that can recapitulate the natural healing process after injury. The construct comprises an internal depot of quiescent BMSCs, mimicking the bone marrow cavity, and an electrospun (ESP) capsule that "activates" the cells to migrate into an outer "differentiation-inducing" 3D printed unit functionalized with TGF-β and BMP-2 peptides. In vitro, niche-inspired scaffolds retained a depot of nonproliferative cells capable of migrating and proliferating through the ESP capsule. Invasion of the 3D printed cavity results in location-specific cell differentiation, mineralization, secretion of alkaline phosphatase (ALP) and glycosaminoglycans (GAGs), and genetic upregulation of collagen II and collagen I. In vivo, niche-inspired scaffolds are biocompatible, promoted tissue formation in rat subcutaneous models, and regeneration of the osteochondral unit in rabbit models.

FABRICATION OF A HIGH-THROUGHPUT 3D-PRINTED OSTEOGENIC CORAL-CONTAINING SCAFFOLD

In 2021 the bone grafting market was worth €2.72 billion globally. As allograft bone has a limited supply and risk of disease transmission, the demand for synthetic grafting substitutes (BGS) continues to grow while allograft bone grafts steadily decrease. Synthetic BGS are low in mechanical strength and bioactivity, inspiring the development of novel grafting materials, a traditionally laborious and expensive process. Here a novel BGS derived from sustainably grown coral was evaluated. Coral-derived scaffolds are a natural calcium carbonate bio-ceramic, which induces osteogenesis in bone marrow mesenchymal stem cells (MSCs), the cells responsible for maintaining bone homeostasis and orchestrating fracture repair. By 3D printing MSCs in coral-laden bioinks we utilise high throughput (HT) fabrication and evaluation of osteogenesis, overcoming the limitations of traditional screening methods.MSC and coral-laden GelXA (CELLINK) bioinks were 3D printed in square bottom 96 well plates using a CELLINK BIO X printer with pneumatic adapter Samples were non-destructively monitored during the culture period, evaluating both the sample and the culture media for metabolism (PrestoBlue), cytotoxicity (lactose dehydrogenase (LDH)) and osteogenic differentiation (alkaline phosphatase (ALP)). Endpoint, destructive assays used included qRT-PCR and SEM imaging.The inclusion of coral in the printed bioink was biocompatable with the MSCs, as reflected by maintained metabolism and low LDH release. The inclusion of coral induced osteogenic differentiation in the MSCs as seen by ALP secretion and increased RUNX2, collagen I and osteocalcin transcription.Sustainably grown coral was successfully incorporated into bioinks, reproducibly 3D printed, non-destructively monitored throughout culture and induced osteogenic differentiation in MSCs. This HT fabrication and monitoring workflow offers a faster, less labour-intensive system for the translation of bone substitute materials to clinic.Acknowledgements: This work was co-funded by Enterprise Ireland and Zoan Biomed through Innovation Partnership IP20221024.

An injectable magnesium-coordinated phosphate chitosan-based hydrogel loaded with vancomycin for antibacterial and osteogenesis in the treatment of osteomyelitis.

Microbial infections of bones, particularly after joint replacement surgery, are a common occurrence in clinical settings and often lead to osteomyelitis (OM). Unfortunately, current treatment approaches for OM are not satisfactory. To address this issue, this study focuses on the development and evaluation of an injectable magnesium oxide (MgO) nanoparticle (NP)-coordinated phosphocreatine-grafted chitosan hydrogel (CMPMg-VCM) loaded with varying amounts of vancomycin (VCM) for the treatment of OM. The results demonstrate that the loading of VCM does not affect the formation of the injectable hydrogel, and the MgO-incorporated hydrogel exhibits anti-swelling properties. The release of VCM from the hydrogel effectively kills S.aureus bacteria, with CMPMg-VCM (50) showing the highest antibacterial activity even after prolonged immersion in PBS solution for 12 days. Importantly, all the hydrogels are non-toxic to MC3T3-E1 cells and promote osteogenic differentiation through the early secretion of alkaline phosphatase and calcium nodule formation. Furthermore, in vivo experiments using a rat OM model reveal that the CMPMg-VCM hydrogel effectively kills and inhibits bacterial growth, while also protecting the infected bone from osteolysis. These beneficial properties are attributed to the burst release of VCM, which disrupts bacterial biofilm, as well as the release of Mg ions and hydroxyl by the degradation of MgO NPs, which inhibits bacterial growth and prevents osteolysis. Overall, the CMPMg-VCM hydrogel exhibits promising potential for the treatment of microbial bone infections.

Biomimetic thymoquinone incorporated nanofibrous matrix as periosteum substitute to promote bone healing

The resemblance of nanofibers to the extracellular matrix (ECM) makes it suitable for various tissue engineering application. In this study, electro-spun polycaprolactone (PCL)-gelatin nanofibers had been fabricated with the incorporation thymoquinone (TQ) biomolecule as a periosteum substitute to promote regeneration of bone. The fabricated nanofibrous matrix possess osteo-conductive and osteo-inductive property. It is biocompatible and also acts as an excellent drug delivery vehicle. The significant expression of the bone matrix proteins, alkaline phosphatase secretion and calcium deposition studied in the MG-63 osteoblast like cells seeded on the nanofibrous matrix proves that it makes a suitable periosteum-substitute by enhancing bone mineralization.

Coupling of cylindrospermopsin and pho-harboring Verrucomicrobia supports the formation of Raphidiopsis blooms in low-phosphorus waters

Cylindrospermopsin (CYN) can induce phytoplankton community to secrete alkaline phosphatase (ALP), which is one of the important strategies for the bloom-forming cyanobacterium Raphidiopsis to thrive in extremely low-phosphorus (P) waters. However, how bacterioplankton community, another major contributor to ALPs in waters, couples to Raphidiopsis through CYN, and the role of this coupling in supporting the dominance of Raphidiopsis in nature remain largely unknown. Here, we conducted microcosm experiments to address this knowledge gap, using a combination of differential filtration-based and metagenomics-based methods to identify the sources of ALPs. We found that, compared with algal-derived ALPs, bacteria-derived ALPs exhibited a more pronounced and sensitive response to CYN. This response to CYN was enhanced under low-P conditions. Interestingly, we found that Verrucomicrobia made the largest contribution to the total abundance of pho genes, which encode ALPs. Having high gene abundance of the CYN-sensing PI3K-AKT signaling pathway, Verrucomicrobia's proportion increased with higher concentrations of CYN under low-P conditions, thereby explaining the observed increase in pho gene abundance. Compared with other cyanobacterial genera, Raphidiopsis had a higher abundance of the pst gene. This suggests that Raphidiopsis exhibited a greater capacity to uptake the inorganic P generated by ALPs secreted by other organisms. Overall, our results reveal the mechanism of CYN-induced ALP secretion and its impact on planktonic P-cycling, and provide valuable insights into the role of CYN in supporting the formation of Raphidiopsis blooms.

Functionalization of poly (lactic-co-glycolic acid) nano‑calcium sulphate and fucoidan 3D scaffold using human bone marrow mesenchymal stromal cells for bone tissue engineering application

This study aimed to functionalize a novel porous PLGA (Poly lactic-co-glycolic acid) composite scaffold in combination with nano‑calcium sulphate (nCS) and/or fucoidan (FU) to induce osteogenic differentiation of human bone marrow stromal cells. The composite scaffolds (PLGA-nCS-FU, PLGA-nCS or PLGA-FU) were fabricated and subjected to characterization using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Energy Dispersive X-Ray (EDX). The biocompatibility and osteogenic induction potential of scaffolds on seeded human bone marrow derived mesenchymal stromal cells (hBMSCs) were studied using cell attachment and alamar blue cell viability and alkaline phosphatase (ALP), osteocalcin and osteogenic gene expression, respectively. The composition of different groups was reflected in FTIR, XRD and EDX. The SEM micrographs revealed a difference in the surface of the scaffold before and after FU addition. The confocal imaging and SEM micrographs confirmed the attachment of cells onto all three composite scaffolds. However, the AB assay indicated a significant increase (p < 0.05) in cell viability/proliferation seeded on PLGA-nCS-FU on day 21 and 28 as compared with other combinations. A 2-fold significant increase (p < 0.05) in ALP and OC secretion of seeded hBMSCs onto PLGA-nCS-FU was observed when compared with other combinations. A significant increase in RUNX2, OPN, COL-I and ALP genes were observed in the cells seeded on PLGA-nCS-FU on day 14 and 28 as compared with day 0. In conclusion, the incorporation of both Fucoidan and Nano‑calcium sulphate with PLGA showed a promising improvement in the osteogenic potential of hBMSCs. Therefore, PLGA-nCS-FU could be the ideal candidate for subsequent pre-clinical studies to develop a successful bone substitute to repair critical bone defects.

Effects of cerium-doped bioactive glass incorporation on an alginate/gelatin scaffold for bone tissue engineering: In vitro characterizations

Bioactive glasses (BGs) have been extensively employed in treating bone defects due to their capacity to bond and integrate with hard and soft tissues. To promote their characteristics, BGs are doped with therapeutic inorganic ions; Among these, Cerium (Ce) is of special attention because of its material and biological properties. This study aimed to investigate the effects of the addition of Ce to BG on the physicochemical and biological properties of the alginate/gelatin (Alg-Gel) scaffold compared with a similar scaffold that only contains BG45S5. The scaffolds were characterized for their biocompatibility using human bone marrow-derived mesenchymal stem cells (hBM-MSCs) by MTT analysis. The osteogenic differentiation of hBM-MSCs cultured on the scaffolds was assessed by evaluating the alkaline phosphatase (ALP) activity and the expression of osteogenic-related genes. Scanning electron microscopy of the prepared scaffolds showed an interconnected porous structure with an average diameter of 212–272 μm. The Young's modulus of the scaffolds significantly increased from 13 ± 0.82 MPa for Alg-Gel to 91 ± 1.76 MPa for Alg-Gel-BG/Ce. Ce doping improved the osteogenic differentiation of hBM-MSCs and ALP secretion compared to the other samples, even without adding an osteogenic differentiation medium. The obtained results demonstrated the biocompatibility and osteo-inductive potentials of the Alg-Gel-BG/Ce scaffold for bone tissue engineering.

Low-molecular-weight fucoidan ameliorates calcium-deficient-diet–induced bone loss and osteoarthritis via CaSR level regulation

Fucoidans—sulfated and fucosylated polysaccharides extracted from brown seaweed—reportedly accelerate bone growth and prevent osteoarthritis (OA) progression. In this study, we examined the effects of low-molecular-weight fucoidan (LMF) on the molecular mechanism of extracellular calcium concentration in vitro and in vivo. In MG63 cells, LMF significantly increased the activity of alkaline phosphatase (ALP) and expression of calcium-sensing receptor (CaSR), runt-related transcription factor 2 (Runx2), and osteoprotegerin (OPG) under low- and normal-[Ca+2]0 conditions, but only decreased the expression of receptor activator of the nuclear factor κB ligand (RANKL) under normal-[Ca+2]0 conditions. In the calcium-deficient diet model, LMF significantly increased body length, growth rate, bone-specific ALP secretion, trabecular number, and CaSR protein expression, without body weight changes. In the OA model, LMF significantly increased bone volume and CaSR protein expression and reduced joint inflammation. Overall, our results indicate that LMF reduced calcium-deficient-diet–induced bone loss and OA via CaSR level regulation.

Vanadium-Doped Mesoporous Bioactive Glass Promotes Osteogenic Differentiation of rBMSCs via the WNT/β-Catenin Signaling Pathway.

Pentavalent vanadium [V(V)] has been studied as bioactive ions to improve the bone defect repair; however, its osteogenic promotion mechanism is still not fully understood so far. In this study, a V-doped mesoporous bioactive glass (V-MBG) was prepared, and its effects on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and potential signaling pathways were investigated. The physicochemical characterization revealed that the incorporation of V slightly reduced the specific surface area and increased the mesoporous pore size, and the abundant mesopores of V-MBG were beneficial to the sustained dissolution of V(V) ions as well as calcium, silicon, and phosphorus ions. Cell proliferation results indicated that the high dilution ratio (>16) V-MBG extract markedly promoted the proliferation of rBMSCs compared with the control group and the same dilution ratio MBG extract. Compared with the same dilution ratio MBG extract, diluted V-MBG extracts markedly promoted the secretion of alkaline phosphatase (ALP) and osteocalcin (OCN) protein at day 7 but insignificantly stimulated the runt-related transcription factor 2 (RUNX2) and vascular endothelial growth factor (VEGF) protein synthesis. In depth, the diluted V-MBG extracts remarkably up-regulated the expression of WNT/β-catenin pathway direct target genes, including WNT3a, β-catenin, and AXIN2 genes in contrast to the same dilution ratio MBG extracts, suggesting that the released V(V) ions might promote osteogenic differentiation of rBMSCs via the WNT/β-catenin signaling pathway.

Evaluation of Osteogenic Potential of Fucoidan Containing Chitosan Hydrogel in the Treatment of Periodontal Intra-Bony Defects-A Randomized Clinical Trial.

Periodontal diseases significantly impact about half of the global population, and their treatment often encompasses relieving symptoms as well as regenerating the destroyed tissues. Revolutionary research in the management of periodontal disease includes biomaterials, a boon to re-generative dentistry owing to their excellent biological properties: non-toxicity, anti-inflammatory, biocompatibility, biodegradability, and adhesion. This study aimed to fabricate an injectable fucoidan containing chitosan hydrogel and prove its effectiveness in periodontal bone regeneration. The injectable hydrogel was prepared using the sol-gel method and was subjected to various physical, chemical, and biological characterizations to understand its efficacy in formation of new bone. The effectiveness of the developed hydrogel was assessed in periodontal bony defects to study the soft and hard tissue changes. A total of 40 periodontitis patients with bony defects were recruited and randomized into two groups to receive fucoidan-chitosan hydrogel and concentrated growth factor, respectively. Customized acrylic stents were used to guide the hydrogel placement into the defect site. Post-surgical changes in clinical parameters were assessed at 3, 6, and 9 months to appreciate the soft and hard tissue changes using repeated measures analysis of variance and Bonferroni's post hoc test. Significance was kept at 5%. The porosity, water uptake of the prepared hydrogel showed good efficacy, with particle size of the fucoidan containing chitosan hydrogel of 6.000 nm. The MG-63 osteoblasts cell line revealed biocompatibility, biodegradability and showed slow and sustained drug release, increased cell proliferation, and enhanced alkaline phosphatase secretion. Mineralization assay was greatest in the fucoidan containing chitosan hydrogel. Clinically, it exhibited significantly lower probing depth values and a higher mean improvement in clinical attachment level as compared to the concentrated growth factor (CGF) group at the end of 3 and 6 months (p < 0.05). The mean of the defect fills in the fucoidan containing chitosan group was 1.20 at the end of 9 months (p < 0.001) as compared with defect fills observed in the CGF group. The presence of fucoidan in the hydrogel significantly contributed to bone regeneration in humans, thus strengthening its potential in tissue engineering. Fucoidan-chitosan will be a promising biomaterial for bone tissue regeneration.