Dentin Matrix Protein 1 on Titanium Surface Facilitates Osteogenic Differentiation of Stem Cells

Injectable MXene/Ag-HA composite hydrogel for enhanced alveolar bone healing and mechanistic study

Introduction

Alveolar bone defects pose significant challenges in dentistry. Due to the complexity of alveolar bone anatomy and insufficient repair mechanisms, large bone defects are difficult for the body to heal naturally. Clinical treatment typically involves the use of bone substitute materials. However, current substitutes often suffer from limitations such as insufficient osteoinductivity, rapid degradation, inflammatory responses, and poor mechanical properties. Additionally, the irregular morphology of alveolar bone defects complicates the application of solid bone substitutes, potentially leading to secondary damage at the repair site.

Methods

To address these challenges, this study introduces an innovative approach by integrating MXene nanomaterials into Ag-HA/GelMA hydrogels to create an injectable MXene/Ag-HA composite hydrogel. MXene nanomaterials are renowned for their excellent biocompatibility, antibacterial properties, and mechanical strength.

Results

The results indicate that the MXene/Ag-HA composite hydrogel exhibits satisfactory mechanical and biological properties. Specifically, it demonstrates excellent antibacterial, antioxidant, and osteogenic activities. Gene expression analysis further reveals that the MXene composite hydrogel promotes osteogenesis by regulating the expression of Dmp1 and Dusp1.

Discussion

The findings of this study suggest that the MXene/Ag-HA composite hydrogel is a promising candidate for alveolar bone repair and regeneration. The integration of MXene nanomaterials into the hydrogel enhances its mechanical and biological properties, making it well-suited for the treatment of irregular alveolar bone defects. Furthermore, the study underscores the vast potential of MXene nanomaterials in the biomedical field, hinting at potential applications beyond alveolar bone repair.

Advancing bone regeneration: Unveiling the potential of 3D cell models in the evaluation of bone regenerative materials

Bone, a rigid yet regenerative tissue, has garnered extensive attention for its impressive healing abilities. Despite advancements in understanding bone repair and creating treatments for bone injuries, handling nonunions and large defects remains a major challenge in orthopedics. The rise of bone regenerative materials is transforming the approach to bone repair, offering innovative solutions for nonunions and significant defects, and thus reshaping orthopedic care. Evaluating these materials effectively is key to advancing bone tissue regeneration, especially in difficult healing scenarios, making it a critical research area. Traditional evaluation methods, including two-dimensional cell models and animal models, have limitations in predicting accurately. This has led to exploring alternative methods, like 3D cell models, which provide fresh perspectives for assessing bone materials' regenerative potential. This paper discusses various techniques for constructing 3D cell models, their pros and cons, and crucial factors to consider when using these models to evaluate bone regenerative materials. We also highlight the significance of 3D cell models in the in vitro assessments of these materials, discuss their current drawbacks and limitations, and suggest future research directions. STATEMENT OF SIGNIFICANCE: This work addresses the challenge of evaluating bone regenerative materials (BRMs) crucial for bone tissue engineering. It explores the emerging role of 3D cell models as superior alternatives to traditional methods for assessing these materials. By dissecting the construction, key factors of evaluating, advantages, limitations, and practical considerations of 3D cell models, the paper elucidates their significance in overcoming current evaluation method shortcomings. It highlights how these models offer a more physiologically relevant and ethically preferable platform for the precise assessment of BRMs. This contribution is particularly significant for "Acta Biomaterialia" readership, as it not only synthesizes current knowledge but also propels the discourse forward in the search for advanced solutions in bone tissue engineering and regeneration.

Lin28 affects the proliferation and osteogenic differentiation of human dental pulp stem cells by directly inhibiting let-7b maturation

OBJECTIVE

Activation of Lin28 gene under certain conditions promotes tissue damage repair. However, it remains unknown whether conditional expression of Lin28 facilitates the recovery of damaged pulp tissue. In the study, we focus on exploring the effects and possible regulatory mechanisms of Lin28 on the proliferation and differentiation of human dental pulp stem cells (hDPSCs).

MATERIALS AND METHODS

We adopted techniques such as the ethynyl-2'-deoxyuridine (EdU) incorporation assay, RNA-protein immunoprecipitation (RIP) analysis, and luciferase assays to study the regulation of hDPSCs by Lin28. Furthermore, gain-of-function and loss-of-function analyses were also used in explored factors regulating hDPSCs activation.

RESULTS

The results show that Lin28 inhibited osteogenic differentiation by directly targets pre-let-7b. Through bioinformatics sequencing and dual luciferase experiments we learned that let-7b directly targets the IGF2BP2 3'UTR. Silencing of IGF2BP2 showed a similar biological effect as overexpression of let-7b. Overexpression of IGF2BP2 counteracted the differentiation-promoting effects produced by let-7b overexpression.

DISCUSSION/CONCLUSIONS

In conclusion, the RNA-binding protein Lin28 regulates osteogenic differentiation of hDPSCs by inhibiting let-7 miRNA maturation. And mature let-7b directly regulated the expression of IGF2BP2 by targeting the 3'UTR region of IGF2BP2 mRNA thus further inhibiting the differentiation of hDPSCs.

Injectable CNPs/DMP1-loaded self-assembly hydrogel regulating inflammation of dental pulp stem cells for dentin regeneration

Vital pulp preservation, which is a clinical challenge of aseptic or iatrogenic accidental exposure of the pulp, in cases direct pulp capping is the main technology. Human dental pulp stem cells (hDPSCs) play a critical role in pulp tissue repair, but their differentiative ability could be inhibited by the potential infection and inflammatory response of the exposed pulp. Therefore, inflammatory regulation and differentiated promotion of hDPSCs are both essential for preserving living pulp teeth. In this study, we constructed a functional dental pulp-capping hydrogel by loading cerium oxide nanoparticles (CNPs) and dentin matrix protein-1 (DMP1) into an injectable Fmoc-triphenylalanine hydrogel (Fmoc-phe3 hydrogel) as CNPs/DMP1/Hydrogel for in situ drugs delivery. With a view to long-term storage and release of CNPs (anti-inflammatory and antioxidant) to regulate the local inflammatory environment and DMP1 to promote the regeneration of dentin. Results of CCK-8, LDH release, hemolysis, and Live/Dead assessment of cells demonstrated the good biocompatibility of CNPs/DMP1/Hydrogel. The levels of alkaline phosphatase activity, quantification of the mineralized nodules, expressions of osteogenic genes and proteins demonstrated CNPs/DMP1/Hydrogel could protect the activity of hDPSCs' osteogenic/dentinogenic differentiation by reducing the inflammation response via releasing CNPs. The therapy effects were further confirmed in rat models, CNPs/DMP1/Hydrogel reduced the necrosis rate of damaged pulp and promoted injured pulp repair and reparative dentin formation with preserved vital pulps. In summary, the CNPs/DMP1/Hydrogel composite is an up-and-coming pulp-capping material candidate to induce reparative dentin formation, as well as provide a theoretical and experimental basis for developing pulp-capping materials.

The role of EMILIN-1 in the osteo/odontogenic differentiation of dental pulp stem cells

BACKGROUND

Human dental pulp stem cells (hDPSCs) may be the best choice for self-repair and regeneration of teeth and maxillofacial bone tissue due to their homogeneous tissue origin, high proliferation and differentiation rates, and no obvious ethical restrictions. Recently, several studies have shown that extracellular matrix (ECM) proteins can effectively regulate the proliferation and differentiation fate of mesenchymal stem cells (MSCs). However, the role of elastin microfibril interface-located protein-1 (EMILIN-1), a new ECM glycoprotein, in osteo/odontogenic differentiation of hDPSCs has not been reported. The aim of this study was to explore the effect of EMILIN-1 during osteo/odontogenic differentiation of hDPSCs.

METHODS

hDPSCs were cultured in osteo/odontogenic induction medium. qPCR and Western blot analysis were performed to detect osteo/odonto-specific genes/proteins expression as well as the expression of EMILIN-1. After knockdown of Emilin-1 in hDPSCs with small interfering RNA and exogenous addition of recombinant human EMILIN-1 protein (rhEMILIN-1), Cell Counting Kit-8 assay, alkaline phosphatase staining, alizarin red S staining, qPCR and Western blot were performed to examine the effect of EMILIN-1 on proliferation and osteo/odontogenic differentiation of hDPSCs.

RESULTS

During the osteo/odontogenic induction of hDPSCs, the expression of osteo/odonto-specific genes/proteins increased, as did EMILIN-1 protein levels. More notably, knockdown of Emilin-1 decreased hDPSCs proliferation and osteo/odontogenic differentiation, whereas exogenous addition of rhEMILIN-1 increased them.

CONCLUSIONS

These findings suggested that EMILIN-1 is essential for the osteo/odontogenic differentiation of hDPSCs, which may provide new insights for teeth and bone tissue regeneration.

Intermittent compressive force regulates dentin matrix protein 1 expression in human periodontal ligament stem cells

Background/purpose

Mechanical force differentially regulates periodontal ligament functions depending on types, magnitudes, and duration of stimulation. Intermittent compressive force (ICF) promotes an in vitro mineralization in human periodontal ligament cells. The present study investigated the effect of ICF on dentin matrix protein-1 (DMP1) expression in human periodontal ligament stem cells (hPDLSCs).

Materials and methods

Cells were treated with ICF in a serum-free culture medium for 24 h The mRNA and protein expression were examined using real-time polymerase chain reaction, immunofluorescence staining and Western blot analysis, respectively.

Results

The exposure to ICF in a serum-free condition significantly induced DMP1 expression in both mRNA and protein levels. The effect of ICF-induced DMP1 expression was inhibited by pretreatment with cycloheximide, indicating the requirement of the intermediated molecule(s). Pretreatment with transforming growth factor β (TGF-β) receptor inhibitor (SB431542) or neutralized antibody against TGF-β1 prior to ICF application abolished the effect of ICF-induced DMP1 expression. Further, recombinant TGF-β1 treatment stimulated DMP1 expression.

Conclusion

The present study illustrated that ICF induces DMP1 expression in hPDLSCs via the regulation of TGF-β signaling pathway.