Enhanced differentiation of dental pulp cells cultured on microtubular polymer scaffolds in vitro

Glycogen synthase kinase 3 inhibition enhances mineral nodule formation by cementoblasts in vitro

This study aimed to investigate whether GSK-3 inhibition (CHIR99021) effectively promoted mineralization by cementoblasts (OCCM-30). OCCM-30 cells were used and treated with different concentrations of CHIR99021 (2.5, 5, and 10 mM). Experiments included proliferation and viability, cellular metabolic activity, gene expression, and mineral nodule formation by Xylene Orange at the experimental time points. In general, CHIR99021 did not significantly affect OCCM-30 viability and cell metabolism (MTT assay) (p > 0.05), but increased OCCM-30 proliferation at 2.5 mM on days 2 and 4 (p < 0.05). Data analysis further showed that inhibition of GSK-3 resulted in increased transcript levels of Axin2 in OCCM-30 cells starting as early as 4 h, and regulated the expression of key bone markers including alkaline phosphatase (Alp), runt-related transcription factor 2 (Runx-2), osteocalcin (Ocn), and osterix (Osx). In addition, CHIR99021 led to an enhanced mineral nodule formation in vitro under both osteogenic and non-osteogenic conditions as early as 5 days after treatment. Altogether, the results of the current study suggest that inhibition of GSK-3 has the potential to promote cementoblast differentiation leading to increased mineral deposition in vitro.

The potential of eggshell hydroxyapatite, collagen, and EGCG (HAp-Col-EGCG) scaffold as a pulp regeneration material

Background

Hydrogel scaffold is a biomaterial that can facilitate cells in forming a tissue structure. It can promote cell adhesion, migration, and proliferation. Further research to find a new scaffold from natural resources is challenging, so this study aimed to characterize a hydrogel composite scaffold, which has the potential to be used as a regenerative material.

Methods

The formulation of HAp-Col-EGCG was mixed with different ratios of 1%, 2%, and 4% hydroxyapatite. We analyzed its injectability, pH, and gelation time. Scanning electron microscopy (SEM), energy X-ray Spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR) were used to evaluate the surface morphologies, element composition, and chemical properties of HAp-Col-EGCG.

Results

The results showed that the injectability test was almost 90 % in all groups. There was no significant difference in the median value of the pH at 0, 20, and 60 min in all groups, but there was a significant difference at 40 min. The average gelation times in all groups were not significant. SEM-EDX showed a microporous scaffold, with the HAp particles well distributed in the collagen pores at a ratio of 1.9, 2.29, and 1.89 Ca/P. The FTIR results showed intermolecular bonds in the HAp-Col-EGCG scaffold. The X-ray diffraction analysis showed that collagen and EGCG did not affect the crystal structure and size of HAp. Cytotoxicity test showed more dental pulp cell viability at the 4 % HAp concentration at 514.35 ± 15.45.

Conclusion

This study indicates that hydrogel scaffold from eggshell hydroxyapatite, collagen, and EGCG has a high potential for pulp regenerative therapy.

Synthetic materials in craniofacial regenerative medicine: A comprehensive overview

The state-of-the-art approach to regenerating different tissues and organs is tissue engineering which includes the three parts of stem cells (SCs), scaffolds, and growth factors. Cellular behaviors such as propagation, differentiation, and assembling the extracellular matrix (ECM) are influenced by the cell's microenvironment. Imitating the cell's natural environment, such as scaffolds, is vital to create appropriate tissue. Craniofacial tissue engineering refers to regenerating tissues found in the brain and the face parts such as bone, muscle, and artery. More biocompatible and biodegradable scaffolds are more commensurate with tissue remodeling and more appropriate for cell culture, signaling, and adhesion. Synthetic materials play significant roles and have become more prevalent in medical applications. They have also been used in different forms for producing a microenvironment as ECM for cells. Synthetic scaffolds may be comprised of polymers, bioceramics, or hybrids of natural/synthetic materials. Synthetic scaffolds have produced ECM-like materials that can properly mimic and regulate the tissue microenvironment's physical, mechanical, chemical, and biological properties, manage adherence of biomolecules and adjust the material's degradability. The present review article is focused on synthetic materials used in craniofacial tissue engineering in recent decades.

Advances in Scaffolds Used for Pulp-Dentine Complex Tissue Engineering - A Narrative Review

Pulp necrosis in immature teeth disrupts root development and predisposes roots to fracture as a consequence of their thin walls and open apices. Regenerative endodontics is a developing treatment modality whereby necrotic pulps are replaced with newly formed healthy tissue inside the root canal. Many clinical studies have demonstrated the potential of this strategy to stimulate root maturation and apical root-end closure. However, clinical outcomes are patient-dependent and unpredictable. The development of predictable clinical protocols is achieved through the interplay of the three classical elements of tissue engineering, namely, stem cells, signaling molecules, and scaffolds. Scaffolds provide structural support for cells to adhere and proliferate and also regulate cell differentiation and metabolism. Hence, designing and fabricating an appropriate scaffold is a crucial step in tissue engineering. In this review, four main classes of scaffolds used to engineer pulp-dentine complexes, including bioceramic-based scaffolds, synthetic polymer-based scaffolds, natural polymer-based scaffolds, and composite scaffolds, are covered. Additionally, recent advances in the design, fabrication, and application of such scaffolds are analysed along with their advantages and limitations. Finally, the importance of vascular network establishment in the success of pulp-dentine complex regeneration and strategies used to create scaffolds to address this challenge are discussed.

Challenges of Engineering Biomimetic Dental and Paradental Tissues

BACKGROUND

Loss of the dental and paradental tissues resulting from trauma, caries or from systemic diseases considered as one of the most significant and frequent clinical problem to the healthcare professionals. Great attempts have been implemented to recreate functionally, healthy dental and paradental tissues in order to substitute dead and diseased tissues resulting from secondary trauma of car accidents, congenital malformations of cleft lip and palate or due to acquired diseases such as cancer and periodontal involvements.

METHOD

An extensive literature search has been done on PubMed database from 2010 to 2019 about the challenges of engineering a biomimetic tooth (BioTooth) regarding basic biology of the tooth and its supporting structures, strategies, and different techniques of obtaining biological substitutes for dental tissue engineering.

RESULTS

It has been found that great challenges need to be considered before engineering biomimetic individual parts of the tooth such as enamel, dentin-pulp complex and periodontium. In addition, two approaches have been adopted to engineer a BioTooth. The first one was to engineer a BioTooth as an individual unit and the other was to engineer a BioTooth with its supporting structures.

CONCLUSION

Engineering of BioTooth with its supporting structures thought to be in the future will replace the traditional and conventional treatment modalities in the field of dentistry. To accomplish this goal, different cell lines and growth factors with a variety of scaffolds at the nano-scale level are now in use. Recent researches in this area of interest are dedicated for this objective, both in vivo and in vitro. Despite progress in this field, there are still many challenges ahead and need to be overcome, many of which related to the basic tooth biology and its supporting structures and some others related to the sophisticated techniques isolating cells, fabricating the needed scaffolds and obtaining the signaling molecules.

[Effects of scaffold microstructure and mechanical properties on regeneration of tubular dentin]

Tubular dentin is of great significance in the process of tooth tissue and tooth regeneration, because it is not only the structural feature of primary dentin, but also can affect the tooth sensory function, affect the differentiation of dental pulp cells and provide strong mechanical support for teeth. Scaffold is one of the three elements of tissue engineering dentin regeneration. Most experiments on dentin regeneration involve the study of the microstructure and mechanical properties of the scaffold. The microstructure and mechanical characteristics of scaffold materials have important effects on the differentiation and adhesion of odontoblast, it can directly affect the tissue structure of regenerated dentin.