Peptide decorated demineralized dentin matrix with enhanced bioactivity, osteogenic differentiation via carboxymethyl chitosan

In Vivo Evaluation of Regenerative Osteogenic Potential Using a Human Demineralized Dentin Matrix for Dental Application

BACKGROUND

The use of a demineralized dentin matrix (DDM) has garnered substantial importance in dentistry. This study was carried out to evaluate the osteoinductive performance of DDM in comparison to nano-hydroxyapatite (n-HA) on calvarial critical-sized bone defect.

METHODS

Two critical-sized defects (CSDs) were bilaterally trephined in the calvarium of sixteen healthy white rabbits. The rabbits were categorized into four groups: in group 1, the defect was left empty; in group 2, defects were filled with sodium alginate (SA) hydrogel as a sole material; in group 3, defects were treated with nano-hydroxyapatite hydrogel (NHH); in group 4, defects were treated using demineralized dentin matrix hydrogel (DDMH). Histological and immunohistochemical analyses were carried out to evaluate the total areas of newly formed bone.

RESULTS

The DDMH group showed that new woven bone tissue progressively bridged the defect area while there was no bone in the control group. Collagen expression was significantly different in the DDMH- and NHH-treated groups compared to in the SA group at 4 and 8 weeks (p < 0.01). OCN expression was significantly higher in the DDMH group in comparison to in the NHH or SA groups at 8 weeks (p < 0.01).

CONCLUSIONS

The DDMH group exhibited significantly higher levels of new bone formation compared to the NHH group at both 4 and 8 weeks post-surgically.

Define of Optimal Addition Period of Osteogenic Peptide to Accelerate the Osteogenic Differentiation of Human Pluripotent Stem Cells

BACKGROUND

The addition of growth factiors is commonly applied to improve the osteogenic differentiation of stem cells. However, for human pluripotent stem cells (hPSCs), their complex differentiation processes result in the unknown effect at different stages. In this study, we focused on the widely used bone forming peptide-1 (BFP-1) and investigated the effect and mechanisms of its addition on the osteogenic induction of hPSCs as a function of the supplementation period.

METHODS

Monolayer-cultured hPSCs were cultured in osteogenic induction medium for 28 days, and the effect of BFP-1 peptide addition at varying weeks was examined. After differentiation for varying days (0, 7, 14, 21 and 28), the differentiation efficiency was determined by RT-PCR, flow cytometry, immunofluorescence, and alizarin red staining assays. Moreover, the expression of marker genes related to germ layers and epithelial-mesenchymal transition (EMT) was investigated at day 7.

RESULTS

Peptide treatment during the first week promoted the generation of mesoderm cells and mesenchymal-like cells from hiPSCs. Then, the upregulated expression of osteogenesis marker genes/proteins was detected in both hESCs and hiPSCs during subsequent inductions with BFP-1 peptide treatment. Fortunately, further experimental design confirmed that treating the BFP-1 peptide during 7-21 days showed even better performance for hESCs but was ineffective for hiPSCs.

CONCLUSION

The differentiation efficiency of cells could be improved by determining the optimal treatment period. Our study has great value in maximizing the differentiation of hPSCs by adding osteogenesis peptides based on the revealed mechanisms and promoting the application of hPSCs in bone tissue regeneration.

A bi-layered asymmetric membrane loaded with demineralized dentin matrix for guided bone regeneration

OBJECTIVES

Guided bone regeneration (GBR) is a well-established method for repairing hard tissue deficiency in reconstructive dentistry. The aim of this study was to investigate the barrier function, osteogenic activity and immunomodulatory ability of a novel bi-layered asymmetric membrane loaded with demineralized dentin matrix (DDM).

METHODS

DDM particles were harvested from healthy, caries-free permanent teeth. Electrospinning technique was utilized to prepare bi-layered DDM-loaded poly(lactic-co-glycolic acid) (PLGA)/poly(lactic acid) (PLA) membranes (abbreviated as DPP bilayer membranes). We analyzed the membranes' surface properties, cytocompatibility and barrier function, and evaluated their osteogenic activity in vitro. In addition, its effects on the osteogenic immune microenvironment were also investigated.

RESULTS

Synthetic DPP bilayer membranes presented suitable surface characteristics and satisfactory cytocompatibility. Transwell assays showed significant fewer migrated cells by the DPP bilayer membranes compared with blank control, with or without in vitro degradation (all P < 0.001). In vitro experiments indicated that our product elevated messenger ribonucleic acid (mRNA) expression levels of osteogenic genes alkaline phosphatase (ALP), osteopontin (OPN), osteocalcin (OCN) and runt-related transcription factor 2 (Runx2). Among all groups, 20% DPP bilayer membrane displayed highest ALP activity (P < 0.001). Furthermore, DPP bilayer membranes enhanced the mRNA expression of M2 macrophage markers and increased the proportion of CD206+ M2 macrophages by 100% (20% DPP: P < 0.001; 30% DPP: P < 0.001; 40% DPP: P < 0.05), thus exerting an inflammation suppressive effect.

CONCLUSIONS

DPP bilayer membranes exhibited notable biological safety and osteogenic activity in vitro, and have potential as a prospective candidate for GBR approach in the future.

Evaluation of osteogenic potential of demineralized dentin matrix hydrogel for bone formation

OBJECTIVES

Dentin, the bulk material of the tooth, resemble the bone's chemical composition and is considered a valuable bone substitute. In the current study, we assessed the cytotoxicity and osteogenic potential of demineralized dentin matrix (DDM) in comparison to HA nanoparticles (n-HA) on bone marrow mesenchymal stem cells (BMMSCs) using a hydrogel formulation.

MATERIALS AND METHODS

Human extracted teeth were minced into particles and treated via chemical demineralization using ethylene diamine tetra-acetic acid solution (EDTA) to produce DDM particles. DDM and n-HA particles were added to the sodium alginate then, the combination was dripped into a 5% (w/v) calcium chloride solution to obtain DDM hydrogel (DDMH) or nano-hydroxyapatite hydrogel (NHH). The particles were evaluated by dynamic light scattering (DLS) and the hydrogels were evaluated via scanning electron microscope (SEM). BMMSCs were treated with different hydrogel concentrations (25%, 50%, 75% and neat/100%) and cell viability was evaluated using MTT assay after 72 h of culture. Collagen-I (COL-I) gene expression was studied with real-time quantitative polymerase chain reaction (RT-qPCR) after 3 weeks of culture and alkaline phosphatase (ALP) activity was assessed using enzyme-linked immune sorbent assay (ELISA) over 7th, 10th, 14th and 21st days of culture. BMMSCs seeded in a complete culture medium were used as controls. One-way ANOVA was utilized to measure the significant differences in the tested groups.

RESULTS

DLS measurements revealed that DDM and n-HA particles had negative values of zeta potential. SEM micrographs showed a porous microstructure of the tested hydrogels. The viability results revealed that 100% concentrations of either DDMH or NHH were cytotoxic to BMMSCs after 72 h of culture. However, the cytotoxicity of 25% and 50% concentrations of DDMH were not statistically significant compared to the control group. RT-qPCR showed that COL-I gene expression was significantly upregulated in BMMSCs cultured with 50% DDMH compared to all other treated or control groups (P < 0.01). ELISA analysis revealed that ALP level was significantly increased in the groups treated with 50% DDMH compared to 50% NHH after 21 days in culture (P < 0.001).

CONCLUSION

The injectable hydrogel containing demineralized dentin matrix was successfully formulated. DDMH has a porous structure and has been shown to provide a supporting matrix for the viability and differentiation of BMMSCs. A 50% concentration of DDMH was revealed to be not cytotoxic to BMMSCs and may have a great potential to promote bone formation ability.

Mineralization promotion and protection effect of carboxymethyl chitosan biomodification in biomimetic mineralization

Biomimetic mineralization emphasizes reversing the process of dental caries through bio-inspired strategies, in which mineralization promotion and collagen protection are equally important. In this study, carboxymethyl chitosan (CMC) was deemed as an analog of glycosaminoglycan for biomimetic modification of collagen, both of the mineralization facilitation and collagen protection effect were evaluated. Experiments were carried out simultaneously on two-dimensional monolayer reconstituted collagen model, three-dimensional reconstituted collagen model and demineralized dentin model. In three models, CMC was successfully cross-linked onto collagen utilizing biocompatible 1-Ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxy sulfosuccinimide sodium salt to achieve biomodification. Results showed that CMC biomodification increased collagen's hydrophilicity, calcium absorption capacity and thermal degradation resistance. In demineralized dentin model, the activity of endogenous matrix metalloproteinases was significantly inhibited by CMC biomodification. Furthermore, CMC biomodification significantly improved cross-linking and intrafibrillar mineralization of collagen, especially in the two-dimensional monolayer reconstituted collagen model. This study provided a biomimetic mineralization strategy with comprehensive consideration of collagen protection, and enriched the application of chitosan-based materials in dentistry.

Spatiotemporal Regulation of the Bone Immune Microenvironment via Dam-Like Biphasic Bionic Periosteum for Bone Regeneration

The bone immune microenvironment (BIM) regulates bone regeneration and affects the prognosis of fractures. However, there is currently no effective strategy that can precisely modulate macrophage polarization to improve BIM for bone regeneration. Herein, a hybridized biphasic bionic periosteum, inspired by the BIM and functional structure of the natural periosteum, is presented. The gel phase is composed of genipin-crosslinked carboxymethyl chitosan and collagen self-assembled hybrid hydrogels, which act as the "dam" to intercept IL-4 released during the initial burst from the bionic periosteum fiber phase, thus maintaining the moderate inflammatory response of M1 macrophages for mesenchymal stem cell recruitment and vascular sprouting at the acute fracture. With the degradation of the gel phase, released IL-4 cooperates with collagen to promote the polarization towards M2 macrophages, which reconfigure the local microenvironment by secreting PDGF-BB and BMP-2 to improve vascular maturation and osteogenesis twofold. In rat cranial defect models, the controlled regulation of the BIM is validated with the temporal transition of the inflammatory/anti-inflammatory process to achieve faster and better bone defect repair. This strategy provides a drug delivery system that constructs a coordinated BIM, so as to break through the predicament of the contradiction between immune response and bone tissue regeneration.

Treated Dentin Matrix in Tissue Regeneration: Recent Advances

Tissue engineering is a new therapeutic strategy used to repair serious damage caused by trauma, a tumor or other major diseases, either for vital organs or tissues sited in the oral cavity. Scaffold materials are an indispensable part of this. As an extracellular-matrix-based bio-material, treated dentin matrixes have become promising tissue engineering scaffolds due to their unique natural structure, astonishing biological induction activity and benign bio-compatibility. Furthermore, it is important to note that besides its high bio-activity, a treated dentin matrix can also serve as a carrier and release controller for drug molecules and bio-active agents to contribute to tissue regeneration and immunomodulation processes. This paper describes the research advances of treated dentin matrixes in tissue regeneration from the aspects of its vital properties, biologically inductive abilities and application explorations. Furthermore, we present the concerning challenges of signaling mechanisms, source extension, individualized 3D printing and drug delivery system construction during our investigation into the treated dentin matrix. This paper is expected to provide a reference for further research on treated dentin matrixes in tissue regeneration and better promote the development of relevant disease treatment approaches.

Demineralized Dentin Matrix for Dental and Alveolar Bone Tissues Regeneration: An Innovative Scope Review

Background:

Dentin is a permeable tubular composite and complex structure, and in weight, it is composed of 20% organic matrix, 10% water, and 70% hydroxyapatite crystalline matrix. Demineralization of dentin with gradient concentrations of ethylene diamine tetraacetic acid, 0.6 N hydrochloric acid, or 2% nitric acid removes a major part of the crystalline apatite and maintains a majority of collagen type I and non-collagenous proteins, which creates an osteoinductive scaffold containing numerous matrix elements and growth factors. Therefore, demineralized dentin should be considered as an excellent naturally-derived bioactive material to enhance dental and alveolar bone tissues regeneration.

Method:

The PubMed and Midline databases were searched in October 2021 for the relevant articles on treated dentin matrix (TDM)/demineralized dentin matrix (DDM) and their potential roles in tissue regeneration.

Results:

Several studies with different study designs evaluating the effect of TDM/DDM on dental and bone tissues regeneration were found. TDM/DDM was obtained from human or animal sources and processed in different forms (particles, liquid extract, hydrogel, and paste) and different shapes (sheets, slices, disc-shaped, root-shaped, and barrier membranes), with variable sizes measured in micrometers or millimeters, demineralized with different protocols regarding the concentration of demineralizing agents and exposure time, and then sterilized and preserved with different techniques. In the act of biomimetic acellular material, TDM/DDM was used for the regeneration of the dentin-pulp complex through direct pulp capping technique, and it was found to possess the ability to activate the odontogenic differentiation of stem cells resident in the pulp tissues and induce reparative dentin formation. TDM/DDM was also considered for alveolar ridge and maxillary sinus floor augmentations, socket preservation, furcation perforation repair, guided bone, and bioroot regenerations as well as bone and cartilage healing.

Conclusion:

To our knowledge, there are no standard procedures to adopt a specific form for a specific purpose; therefore, future studies are required to come up with a well-characterized TDM/DDM for each specific application. Likely as decellularized dermal matrix and prospectively, if the TDM/DDM is supplied in proper consistency, forms, and in different sizes with good biological properties, it can be used efficiently instead of some widely-used regenerative biomaterials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13770-022-00438-4.

Selected Spectroscopic Techniques for Surface Analysis of Dental Materials: A Narrative Review

The presented work focuses on the application of spectroscopic methods, such as Infrared Spectroscopy (IR), Fourier Transform Infrared Spectroscopy (FT-IR), Raman spectroscopy, Ultraviolet and Visible Spectroscopy (UV-Vis), X-ray spectroscopy, and Mass Spectrometry (MS), which are widely employed in the investigation of the surface properties of dental materials. Examples of the research of materials used as tooth fillings, surface preparation in dental prosthetics, cavity preparation methods and fractographic studies of dental implants are also presented. The cited studies show that the above techniques can be valuable tools as they are expanding the research capabilities of materials used in dentistry.