Protection of the receptor binding domain (RBD) dimer against SARS-CoV-2 and its variants.

IMPORTANCE: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants achieved immune escape and became less virulent and easily transmissible through rapid mutation in the spike protein, thus the efficacy of vaccines on the market or in development continues to be challenged. Updating the vaccine, exploring compromise vaccination strategies, and evaluating the efficacy of candidate vaccines for the emerging variants in a timely manner are important to combat complex and volatile SARS-CoV-2. This study reports that vaccines prepared from the dimeric receptor-binding domain (RBD) recombinant protein, which can be quickly produced using a mature and stable process platform, had both good immunogenicity and protection in vivo and could completely protect rodents from lethal challenge by SARS-CoV-2 and its variants, including the emerging Omicron XBB.1.16, highlighting the value of dimeric recombinant vaccines in the post-COVID-19 era.

Effect of Microplastic Types on the In Vivo Bioavailability of Polychlorinated Biphenyls.

As MPs are released into the soil, various equilibrium statuses are expected. MPs could play roles as a "source," a "cleaner," or a "sink" of HOCs. Three types of MPs (LDPE, PLA, and PS) were selected to study their effect on polychlorinated biphenyl (PCBs) relative bioavailability (RBA) measured by a mouse model. As a "source" of HOCs, exposure to MP-sorbed PCBs resulted in their accumulation in adipose tissue with PCB RBA as 101 ± 6.73% for LDPE, 76.2 ± 19.2% for PLA, and 9.22 ± 2.02% for PS. The addition of 10% MPs in PCB-contaminated soil led to a significant (p < 0.05) reduction in PCB RBA (52.2 ± 16.7%, 49.3 ± 4.85%, and 47.1 ± 5.99% for LDPE, PLA, and PS) compared to control (75.0 ± 4.26%), implying MPs acted as "cleaner" by adsorbing PCBs from the digestive system and reducing PCB accumulation. MPs acted as a "sink" for PCBs in contaminated soil after aging, but the sink effect varied among MP types with more pronounced effect for LDPE than PLA and PS. Therefore, the role played by MPs in bioavailability of HOCs closely depended on the MP types as well as the equilibrium status among MPs, soil, and HOCs.

Matrigel Scaffolding Enhances BMP9-induced Bone Formation in Dental Follicle Stem/Precursor Cells.

Bone tissue engineering requires a combination of cells, efficient biochemical and physicochemical factors, and biocompatible scaffolds. In this study, we evaluated the potential use of injectable Matrigel as a scaffold for the delivery of rat dental follicle stem/precursor cells (rDFSCs) transduced by bone morphogenetic protein (BMP) 9 to enhance osteogenic differentiation in vitro and promote ectopic bone formation in vivo. Recombinant adenovirus was used to overexpress BMP9 in rDFSCs. Alkaline phosphatase activity was measured using a histochemical staining assay and a chemiluminescence assay kit. Quantitative real-time polymerase chain reaction was used to determine mRNA expression levels of bone-related genes including distal-less homeobox 5 (DLX5), osteopontin (OPN), osterix (Osx), and runt-related transcription factor 2 (Runx2). Matrix mineralization was examined by Alizarin Red S staining. rDFSCs proliferation was analyzed using the Cell Counting Kit-8 assay. Subcutaneous implantation of rDFSCs-containing Matrigel scaffolds was used, and micro-computed tomography analysis, histological evaluation, and trichrome staining of implants extracted at 6 weeks were performed. We found that BMP9 enhanced alkaline phosphatase activity and mineralization in rDFSCs. The expression of bone-related genes (DLX5, OPN, Osx, and Runx2) was also increased as a result of BMP9 stimulation. Micro-computed tomography analysis and histological evaluation revealed that the bone masses retrieved from BMP9-overexpressing rDFSCs were significantly more pronounced in those with than in those without Matrigel. Our results suggest that BMP9 effectively promote osteogenic differentiation of rDFSCs, and Matrigel facilitate BMP9-induced osteogenesis of rDFSCs in vivo.

Bone Regeneration of Canine Peri-implant Defects Using Cell Sheets of Adipose-Derived Mesenchymal Stem Cells and Platelet-Rich Fibrin Membranes.

PURPOSE: Insufficient bone volume compromises the success rate and osseointegration of immediate implantation. The objective of the present study was to engineer bone tissue by using adipose-derived stem cell (ASC) sheets and autologous platelet-rich fibrin (PRF) to enhance new bone formation and osseointegration around dental implants. MATERIAL AND METHODS: The proliferation and osteogenic potential of ASCs treated with autologous PRF were evaluated with CCK-8 assays, alkaline phosphatase staining, and real-time quantitative polymerase chain reaction. A 3-wall bone defect around each immediate implant was generated in the mandible and randomly treated with ASC sheets plus PRF (group A), ASC sheets only (group B), PRF only (group C), or no treatment (group D). Micro-computed tomography, biomechanical tests, fluorescent bone labeling, and histologic assessments were performed to evaluate bone regeneration capacity. RESULTS: The proliferation and osteogenic potential of canine ASCs were markedly enhanced by PRF. Group A exhibited considerably more new bone formation and re-osseointegration (41.17 ± 1.44 and 55.06 ± 0.06%, respectively) than did the other 3 groups. Fluorescent labeling showed that the most rapid bone remodeling activity occurred in group A (P < .05). CONCLUSION: These results suggest that sheets of ASC combined with autologous PRF could be a promising tissue-engineering strategy for bone formation in immediate implantation.

iTRAQ-Based Proteomic Analysis Exploring the Influence of Hypoxia on the Proteome of Dental Pulp Stem Cells under 3D Culture.

Hypoxic preconditioning is commonly applied to enhance mesenchymal stem cells (MSCs) therapeutic effect before transplantation. Elucidating the effect of hypoxic preconditioning would be beneficial for improved application. However, the influence of hypoxia on dental tissue derived MSCs cultured in 3D was unknown. Thus, the present study is to investigate gene expression and proteome of dental pulp stem cells (DPSCs) after hypoxic preconditioning. DPSCs were isolated, cultured in a 3D system under the normoxic and hypoxic conditions. The gene expression was examined with reverse transcription polymerase chain reaction, and the proteome was analyzed using iTRAQ-based mass spectrometry. The expressions of HIF-1α, VEGFA, KDR at mRNA level was upregulated while BMP-2 was downregulated. Two thousand one hundred and fifteen proteins were identified and 57 proteins exhibited significant differences after hypoxic preconditioning (30 up-regulated, 27 down-regulated). Bioinformatic analysis revealed the majority of up-regulated proteins are involved in cellular process, angiogenesis, protein binding and transport, regulation of response to stimulus, metabolic processes, and immune response. Increased IL-6 and decreased TGF-1ß protein expression under hypoxic condition were verified by ELISA. Hypoxic preconditioning partly affected the gene and protein expression in DPSCs under 3D culture and may enhance the efficacy of MSCs transplantation.

Pro-Inflammatory Cytokine TNF-α Attenuates BMP9-Induced Osteo/ Odontoblastic Differentiation of the Stem Cells of Dental Apical Papilla (SCAPs).

BACKGROUND/AIMS: Periapical periodontitis is a common oral disease caused by bacterial invasion of the tooth pulp, which usually leads to local release of pro-inflammatory cytokines and osteolytic lesion. This study is intended to examine the effect of TNF-α on BMP9-induced osteogenic differentiation of the stem cells of dental apical papilla (SCAPs). METHODS: Rat model of periapical periodontitis was established. TNF-α expression was assessed. Osteogenic markers and ectopic bone formation in iSCAPs were analyzed upon BMP9 and TNF-α treatment. RESULTS: Periapical periodontitis was successfully established in rat immature permanent teeth with periapical lesions, in which TNF-α was shown to release during the inflammatory phase. BMP9-induced alkaline phosphatase activity, the expression of osteocalcin and osteopontin, and matrix mineralization in iSCAPs were inhibited by TNF-α in a dose-dependent fashion, although increased AdBMP9 partially overcame TNF-α inhibition. Furthermore, high concentration of TNF-α effectively inhibited BMP9-induced ectopic bone formation in vivo. CONCLUSION: TNF-α plays an important role in periapical bone defect during the inflammatory phase and inhibits BMP9-induced osteoblastic differentiation of iSCAPs, which can be partially reversed by high levels of BMP9. Therefore, BMP9 may be further explored as a potent osteogenic factor to improve osteo/odontogenic differentiation in tooth regeneration in chronic inflammation conditions.

Heteroatom-engineered multicolor lignin carbon dots enabling bimodal fluorescent off-on detection of metal-ions and glutathione.

Carbon dots (CDs) have emerged as a promising subclass of optical nanomaterials with versatile functions in multimodal biosensing. Howbeit the rapid, reliable and reproducible fabrication of multicolor CDs from renewable lignin with unique groups (e.g., -OCH3, -OH and -COOH) and alterable moieties (e.g., ß-O-4, phenylpropanoid structure) remains challenging due to difficult-to-control molecular behavior. Herein we proposed a scalable acid-reagent strategy to engineer a family of heteroatom-doped multicolor lignin carbon dots (LCDs) that are functioned as the bimodal fluorescent off-on sensing of metal-ions and glutathione (GSH). Benefiting from the modifiable photophysical structure via heteroatom-doping (N, S, W, P and B), the multicolor LCDs (blue, green and yellow) with a controllable size distribution of 2.06-2.22 nm deliver the sensing competences to fluorometric probing the distinctive metal-ion systems (Fe3+, Al3+ and Cu2+) under a broad response interval (0-500 µM) with excellent sensitivity and limit of detection (LOD, 0.45-3.90 µM). Meanwhile, we found that the addition of GSH can efficiently restore the fluorescence of LCDs by forming a stable Fe3+-GSH complex with a LOD of 0.97 µM. This work not only sheds light on evolving lignin macromolecular interactions with tunable luminescent properties, but also provides a facile approach to synthesize multicolor CDs with advanced functionalities.

Computer-aided discovery of a novel thermophilic laccase for low-density polyethylene degradation.

Polyethylene (PE) and industrial dyes are recalcitrant pollutants calling for the development of sustainable solutions for their degradation. Laccases have been explored for removal of contaminants and pollutants, including dye decolorization and plastic degradation. Here, a novel thermophilic laccase from PE-degrading Lysinibaccillus fusiformis (LfLAC3) was identified through a computer-aided and activity-based screening. Biochemical studies of LfLAC3 indicated its high robustness and catalytic promiscuity. Dye decolorization experiments showed that LfLAC3 was able to degrade all the tested dyes with decolorization percentage from 39% to 70% without the use of a mediator. LfLAC3 was also demonstrated to degrade low-density polyethylene (LDPE) films after eight weeks of incubation with either crude cell lysate or purified enzyme. The formation of a variety of functional groups was detected using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Damage on the surfaces of PE films was observed via scanning electron microscopy (SEM). The potential catalytic mechanism of LfLAC3 was disclosed by structure and substrate-binding modes analysis. These findings demonstrated that LfLAC3 is a promiscuous enzyme that has promising potential for dye decolorization and PE degradation.

Comparison of the biomechanical differences in the occlusal movement of wild-type and BMP9 knockout mice with apical periodontitis.

Apical periodontitis is a common clinical disease caused by bacteria; bacterial metabolites can cause an imbalance in bone homeostasis, bone mass reduction, and tooth loss. Bone resorption in apical periodontitis causes a concentration of stress in the tooth and periodontal tissues during occlusion, which aggravates the disease. Emerging evidence indicates that bone morphogenetic protein 9 (BMP9), also known as growth differentiation factor 2(Gdf2), may play an important role in tooth and dentoalveolar development. Herein, we investigated the role of BMP9 in the development of apical periodontitis and its effects on the biomechanics of dentoalveolar bone. Apical periodontitis models were established in five BMP9 knockout (KO) mice and five C57BL/6 WT (wild-type) mice. At baseline and 14, 28, and 42 days after modeling, in vivo micro-computed tomography analysis and three-dimensional (3D) reconstruction were performed to evaluate the apical lesion in each mouse, and confirm that the animal models were successfully established. Finite element analysis (FEA) was performed to study the stress and strain at the alveolar fossa of each mouse under the same vertical and lateral stress. FEA revealed that the stress and strain at the alveolar fossa of each mouse gradually concentrated on the tooth cervix. The stress and strain at the tooth cervix gradually increased with time but were decreased at day 42. Under the same lingual loading, the maximum differences of the stress and strain at the tooth root in KO mice were greater than those in WT mice. Thus, these findings demonstrate that BMP9 could affect the biomechanical response of the alveolar fossa at the tooth root in mice with apical periodontitis. Moreover, the effects of BMP9 on the biomechanical response of the alveolar bone may be site-dependent. Overall, this work contributes to an improved understanding of the pathogenesis of apical periodontitis and may inform the development of new treatment strategies for apical periodontitis.

Electrosprayed minocycline hydrochloride-loaded microsphere/SAIB hybrid depot for periodontitis treatment.

Minocycline hydrochloride (MINO) has been one of the most frequently used antibiotics in the treatment of periodontitis due to its antibacterial activity and osteogenesis effects; however, high levels of MINO administered during the treatment halt the formation of new bone. Therefore, the purpose of the present study was to prepare a MINO-microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot to reduce the burst release of MINO and ensure antibacterial and osteogenesis effects of MINO in the treatment of periodontitis. Uniform microspheres, approximately 5 µm size, with a slightly rough surface and different MINO loading (10, 12, and 14%) were prepared, and the microspheres were added into SAIB, after which the burst release significantly decreased from 66.18 to 2.92%, from 71.82 to 3.82%, and from 73.35 to 4.45%, respectively, and the release from all the MINO-microspheres/SAIB hybrid depots lasted for 77 days. In addition, cytotoxicity test showed that the MINO-microsphere with 12% drug loading promoted the proliferation of osteoblasts the most and was subsequently used in vivo experiments. Moreover, in the model of ligatured-induced periodontitis in SD rats, the MINO-microsphere/SAIB hybrid depot not only significantly increased the alveolar bone height and bone volume but also reduced the inflammation of the periodontal tissue. Additionally, it also inhibited the expression of the receptor activator of nuclear factor-kappa B ligand (RANKL) and promoted the expression of osteoprotegerin (OPG).. These results indicated that the MINO-microsphere/SAIB hybrid depot might be promising in the treatment of periodontitis.

Special AT-rich sequence-binding protein 2 (Satb2) synergizes with Bmp9 and is essential for osteo/odontogenic differentiation of mouse incisor mesenchymal stem cells.

OBJECTIVES: Mouse incisor mesenchymal stem cells (MSCs) have self-renewal ability and osteo/odontogenic differentiation potential. However, the mechanism controlling the continuous self-renewal and osteo/odontogenic differentiation of mouse incisor MSCs remains unclear. Special AT-rich sequence-binding protein 2 (SATB2) positively regulates craniofacial patterning, bone development and regeneration, whereas SATB2 deletion or mutation leads to craniomaxillofacial dysplasia and delayed tooth and root development, similar to bone morphogenetic protein (BMP) loss-of-function phenotypes. However, the detailed mechanism underlying the SATB2 role in odontogenic MSCs is poorly understood. The aim of this study was to investigate whether SATB2 can regulate self-renewal and osteo/odontogenic differentiation of odontogenic MSCs. MATERIALS AND METHODS: Satb2 expression was detected in the rapidly renewing mouse incisor mesenchyme by immunofluorescence staining, quantitative RT-PCR and Western blot analysis. Ad-Satb2 and Ad-siSatb2 were constructed to evaluate the effect of Satb2 on odontogenic MSCs self-renewal and osteo/odontogenic differentiation properties and the potential role of Satb2 with the osteogenic factor bone morphogenetic protein 9 (Bmp9) in vitro and in vivo. RESULTS: Satb2 was found to be expressed in mesenchymal cells and pre-odontoblasts/odontoblasts. We further discovered that Satb2 effectively enhances mouse incisor MSCs self-renewal. Satb2 acted synergistically with the potent osteogenic factor Bmp9 in inducing osteo/odontogenic differentiation of mouse incisor MSCs in vitro and in vivo. CONCLUSIONS: Satb2 promotes self-renewal and osteo/odontogenic differentiation of mouse incisor MSCs. Thus, Satb2 can cooperate with Bmp9 as a new efficacious bio-factor for osteogenic regeneration and tooth engineering.

Role of Special AT-Rich Sequence-Binding Protein 2 in the Osteogenesis of Human Dental Mesenchymal Stem Cells.

Dental mesenchymal stem cells (MSCs) are recognized as a critical factor in repair of defective craniofacial bone owing to the multiple differentiation potential, the ability to regenerate distinct tissues, and the advantage that they can be easily obtained by relatively noninvasive procedures. Special AT-rich sequence-binding protein 2 (SATB2) is a nuclear matrix protein, involved in chromatin remodeling and transcriptional regulation, and has been reported to be as a positive regulator of osteoblast differentiation, bone formation, and bone regeneration in MSCs. In this study, we systematically investigated the capability of SATB2 to promote the osteogenic differentiation of periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs), and stem cells from human exfoliated deciduous teeth (SHED). RNA-seq analysis and quantitative real-time PCR (RT-PCR) revealed that genes regulating osteogenic differentiation were differentially expressed among three cell types and SATB2 was found to be expressed at a relatively high level. When the three cell types overexpressed SATB2 with AdSATB2 infection, alkaline phosphatase (ALP) staining, ALP activity, Alizarin Red S staining, and quantification tended to increase with an increasing infection rate. It showed opposite results after infection with AdsiSATB2. RNA-seq analysis indicated that the expression of downstream osteogenic genes was affected by AdSATB2 infection and quantitative RT-PCR confirmed that nine osteogenic genes (Spp1, Sema7a, Atf4, Ibsp, Col1a1, Sp7, Igfbp3, Dlx3, and Alpl) were upregulated, to various extents, following SATB2 overexpression. In addition, quantitative PCR results indicated that SATB2 affected the expression of MSC markers. These results suggested an important role of SATB2 in the osteogenesis of PDLSCs, DPSCs, and SHED. Further research is warranted to investigate SATB2-mediated regulation of osteogenic differentiation and to evaluate the therapeutic use of SATB2 for the regeneration of defective craniofacial bone tissue.

Dentinogenesis and Tooth-Alveolar Bone Complex Defects in BMP9/GDF2 Knockout Mice.

Tooth development is regulated by sequential and reciprocal epithelium-mesenchymal interactions and their related molecular signaling pathways, such as bone morphogenetic proteins (BMPs). Among the 14 types of BMPs, BMP9 (also known as growth differentiation factor 2) is one of the most potent BMPs to induce osteogenic differentiation of mesenchymal stem cells. The purpose of this study was to examine potential roles of BMP9 signaling in tooth development. First, we detected the expression pattern of BMP9 in tooth germ during postnatal tooth development, and we found that BMP9 was widely expressed in odontoblasts, ameloblasts, dental pulp cells, and osteoblasts in alveolar bones. Then, we established a BMP9-KO mouse model. Gross morphological examination revealed that the tooth cusps of BMP9-KO mice were significantly abraded with shorter roots. Micro-computed tomography and three-dimensional reconstruction analysis indicated that the first molars of the BMP9-KO mice exhibited a reduced thickness dentin, enlarged pulp canals, and shortened roots, resembling the phenotypes of the common hereditary dental disease dentinogenesis imperfecta. Further, the alveolar bone of the BMP9-KO mutants was found to be shorter and had a decreased mineral density and trabecular thickness and bone volume fraction compared with that of the wild-type control. Mechanistically, we demonstrated that both dentin sialophosphoprotein and dentin matrix protein 1 were induced in dental stem cells by BMP9, whereas their expression was reduced when BMP9 was silenced. Further studies are required to determine whether loss of or decreased BMP9 expression is clinically associated with dentinogenesis imperfecta. Collectively, our results strongly suggest that BMP9 may play an important role in regulating dentinogenesis and tooth development. Further research is recommended into the therapeutic uses of BMP9 to regenerate traumatized and diseased tissues and for the bioengineering of replacement teeth.

Dental pulp stem cells express tendon markers under mechanical loading and are a potential cell source for tissue engineering of tendon-like tissue.

Postnatal mesenchymal stem cells have the capacity to differentiate into multiple cell lineages. This study explored the possibility of dental pulp stem cells (DPSCs) for potential application in tendon tissue engineering. The expression of tendon-related markers such as scleraxis, tenascin-C, tenomodulin, eye absent homologue 2, collagens I and VI was detected in dental pulp tissue. Interestingly, under mechanical stimulation, these tendon-related markers were significantly enhanced when DPSCs were seeded in aligned polyglycolic acid (PGA) fibre scaffolds. Furthermore, mature tendon-like tissue was formed after transplantation of DPSC-PGA constructs under mechanical loading conditions in a mouse model. This study demonstrates that DPSCs could be a potential stem cell source for tissue engineering of tendon-like tissue.

Synergism of cellulase, xylanase, and pectinase on hydrolyzing sugarcane bagasse resulting from different pretreatment technologies.

Sugarcane bagasse (SCB) resulting from different pretreatments was hydrolyzed by enzyme cocktails based on replacement of cellulase (Celluclast 1.5 L:Novozym 188=1FPU:4pNPGU) by xylanase or pectinase at different proportions. Lignin content of NaOH pretreated SCB and hemicellulose content of H2SO4 pretreated SCB were the lowest. NaOH pretreatment showed the best for monosaccharide production among the four pretreatments. Synergism was apparently observed between cellulase and xylanase for monosaccharide production from steam exploded SCB (SESB), NaOH, and H2O2 pretreated SCB. No synergism was observed between cellulase and pectinase for producing glucose. Additionally, no synergism was present when H2SO4 pretreated SCB was used. Replacement of 20% of the cellulase by xylanase enhanced the glucose yield by 6.6%, 8.8%, and 9.5% from SESB, NaOH, and H2O2 pretreated SCB, respectively. Degree of synergism between cellulase and xylanase had positive relationship with xylan content and was affected by hydrolysis time.

One-pot simultaneous saccharification and fermentation: a preliminary study of a novel configuration for cellulosic ethanol production.

Combination of size reduction and mild alkali pretreatment may be a feasible way to produce bioethanol without rinsing and detoxifying the solid substrate. Based on that, a fermentation configuration named one-pot SSF in which pretreatment and fermentation steps were integrated was developed. Additionally, the effect of laccase on fermentation performance was investigated. Delignification was the major effect of the alkali pretreatment at 121°C for 60min. The highest glucose and xylose yield, which obtained from the smallest particle at a substrate loading of 2%, was 6.75 and 2.71g/L, respectively. Laccase improved the fermentation efficiency by 6.8% for one-pot SSF and 5.7% for SSF. Bioethanol from one-pot SSF with laccase supplementation reached 67.56% of the theoretical maximum, whereas that from SSF with laccase supplementation reached 57.27%. One-pot SSF might be a promising configuration to produce bioethanol because of 100% solid recovery, and rinsing water and detoxification elimination.

Solvent extraction of antioxidants from steam exploded sugarcane bagasse and enzymatic convertibility of the solid fraction.

Solvent extraction of steam exploded lignocellulosic biomass may be a potential way to obtain antioxidative extracts and to enhance the enzymatic convertibility of the solid residue. Boiling solvent extraction (BSE) showed higher solid and phenolic yields than room temperature extraction. Solubilities of phenolics and sugars were higher in anhydrous ethanol (AE) and deionized water (DW) than in ethyl acetate under each individual extraction condition. The antioxidant activities of the AE and DW extract obtained under BSE were better than those of 10mM vitamin C. Conversion of the solid fractions into reducing sugar using Celluclast 1.5L and Novozym 188 after AE and DW extraction was 95.13% and 92.97%, respectively, higher than that obtained with SESB (88.95%).