Application of Adipose Tissue Stem Cells in Regenerative Dentistry: A Systematic Review

[Hmga2 knockdown enhances osteogenic differentiation of adipose-derived mesenchymal stem cells and accelerates bone defect healing in mice]

OBJECTIVE

To investigate the role of high-mobility group AT-hook 2 (HMGA2) in osteogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) and the effect of Hmga2 knockdown for promoting bone defect repair.

METHODS

Bioinformatics studies using the GEO database and Rstudio software identified HMGA2 as a key factor in adipogenic-osteogenic differentiation balance of ADSCs. The protein-protein interaction network of HMGA2 in osteogenic differentiation was mapped using String and visualized with Cytoscape to predict the downstream targets of HMGA2. Primary mouse ADSCs (mADSCs) were transfected with Hmga2 siRNA, and the changes in osteogenic differentiation of the cells were evaluated using alkaline phosphatase staining and Alizarin red S staining. The expressions of osteogenic markers Runt-related transcription factor 2 (RUNX2), osteopontin (OPN), and osteocalcein (OCN) in the transfected cells were detected using RT-qPCR and Western blotting. In a mouse model of critical-sized calvarial defects, mADSCs with Hmga2-knockdown were transplanted into the defect, and bone repair was evaluated 6 weeks later using micro-CT scanning and histological staining.

RESULTS

GEO database analysis showed that HMGA2 expression was upregulated during adipogenic differentiation of ADSCs. Protein-protein interaction network analysis suggested that the potential HMGA2 targets in osteogenic differentiation of ADSCs included SMAD7, CDH1, CDH2, SNAI1, SMAD9, IGF2BP3, and ALDH1A1. In mADSCs, Hmga2 knockdown significantly upregulated the expressions of RUNX2, OPN, and OCN and increased cellular alkaline phosphatase activity and calcium deposition. In a critical-sized calvarial defect model, transplantation of mADSCs with Hmga2 knockdown significantly promoted new bone formation.

CONCLUSION

HMGA2 is a crucial regulator of osteogenic differentiation in ADSCs, and Hmga2 knockdown significantly promotes osteogenic differentiation of ADSCs and accelerates ADSCs-mediated bone defect repair in mice.

Stem cells in regenerative dentistry: Current understanding and future directions

BACKGROUND

Regenerative dentistry aims to enhance the structure and function of oral tissues and organs. Modern tissue engineering harnesses cell and gene-based therapies to advance traditional treatment approaches. Studies have demonstrated the potential of mesenchymal stem cells (MSCs) in regenerative dentistry, with some progressing to clinical trials. This review comprehensively examines animal studies that have utilized MSCs for various therapeutic applications. Additionally, it seeks to bridge the gap between related findings and the practical implementation of MSC therapies, offering insights into the challenges and translational aspects involved in transitioning from preclinical research to clinical applications.

HIGHLIGHTS

To achieve this objective, we have focused on the protocols and achievements related to pulp-dentin, alveolar bone, and periodontal regeneration using dental-derived MSCs in both animal and clinical studies. Various types of MSCs, including dental-derived cells, bone-marrow stem cells, and umbilical cord stem cells, have been employed in root canals, periodontal defects, socket preservation, and sinus lift procedures. Results of such include significant hard tissue reconstruction, functional pulp regeneration, root elongation, periodontal ligament formation, and cementum deposition. However, cell-based treatments for tooth and periodontium regeneration are still in early stages. The increasing demand for stem cell therapies in personalized medicine underscores the need for scientists and responsible organizations to develop standardized treatment protocols that adhere to good manufacturing practices, ensuring high reproducibility, safety, and cost-efficiency.

CONCLUSION

Cell therapy in regenerative dentistry represents a growing industry with substantial benefits and unique challenges as it strives to establish sustainable, long-term, and effective oral tissue regeneration solutions.

Enhanced remineralisation ability and antibacterial properties of sol-gel glass ionomer cement modified by fluoride containing strontium-based bioactive glass or strontium-containing fluorapatite

OBJECTIVES

This study aimed to compare two types of bioactive additives which were strontium-containing fluorinated bioactive glass (SrBGF) or strontium-containing fluorapatite (SrFA) added to sol-gel derived glass ionomer cement (SGIC). The objective was to develop antibacterial and mineralisation properties, using bioactive additives, to minimize the occurrence of caries lesions in caries disease.

METHODS

Synthesized SrBGF and SrFA nanoparticles were added to SGIC at 1 wt% concentration to improve antibacterial properties against S. mutans, promote remineralisation, and hASCs and hDPSCs viability. Surface roughness and ion-releasing behavior were also evaluated to clarify the effect on the materials. Antibacterial activity was measured via agar disc diffusion and bacterial adhesion. Remineralisation ability was assessed by applying the material to demineralised teeth and subjecting them to a 14-day pH cycle, followed by microCT and SEM-EDS analysis.

RESULTS

The addition of SrFA into SGIC significantly improved its antibacterial property. SGIC modified with either SrBGF or SrFA additives could similarly induce apatite crystal precipitation onto demineralised dentin and increase dentin density, indicating its ability to remineralise dentin. Moreover, this study also showed that SGIC modified with SrBGF or SrFA additives had promising results on the in vitro cytotoxicity of hASC and hDPSC.

SIGNIFICANT

SrFA has superior antibacterial property as compared to SrBGF while demonstrating equal remineralisation ability. Furthermore, the modified SGIC showed promising results in reducing the cytotoxicity of hASCs and hDPSCs, indicating its potential for managing caries.

Fundamentals and Translational Applications of Stem Cells and Biomaterials in Dental, Oral and Craniofacial Regenerative Medicine

Regenerative dental medicine continuously expands to improve treatments for prevalent clinical problems in dental and oral medicine. Stem cell based translational opportunities include regenerative therapies for tooth restoration, root canal therapy, and inflammatory processes (e.g., periodontitis). The potential of regenerative approaches relies on the biological properties of dental stem cells. These and other multipotent somatic mesenchymal stem cell (MSC) types can in principle be applied as either autologous or allogeneic sources in dental procedures. Dental stem cells have distinct developmental origins and biological markers that determine their translational utility. Dental regenerative medicine is supported by mechanistic knowledge of the molecular pathways that regulate dental stem cell growth and differentiation. Cell fate determination and lineage progression of dental stem cells is regulated by multiple cell signaling pathways (e.g., WNTs, BMPs) and epigenetic mechanisms, including DNA modifications, histone modifications, and non-coding RNAs (e.g., miRNAs and lncRNAs). This review also considers a broad range of novel approaches in which stem cells are applied in combination with biopolymers, ceramics, and composite materials, as well as small molecules (agonistic or anti-agonistic ligands) and natural compounds. Materials that mimic the microenvironment of the stem cell niche are also presented. Promising concepts in bone and dental tissue engineering continue to drive innovation in dental and non-dental restorative procedures.

lncRNA-KCNQ1OT1: A Potential Target in Exosomes Derived from Adipose-Derived Stem Cells for the Treatment of Osteoporosis

BACKGROUND

Osteoporosis is a worldwide medical and socioeconomic burden characterized by systemic impairment of bone strength and microstructure. Exosomes derived from adipose-derived stem cells (ADSCs-Exos) have been confirmed to play effective roles in the repair of various tissues and organs. This study was aimed at investigating the role of ADSCs-Exos and a novel long noncoding RNA KCNQ1OT1 played in osteoporosis as well as the underlying mechanism.

METHODS

Primary osteoblasts were treated with different doses of tumor necrosis factor-α (TNF-α) (0, 1, 2.5, 5, and 10 ng/ml) and then cocultured with ADSCs-Exos or exosome-derived from lnc-KCNQ1OT1-modified ADSCs (KCNQ1OT1-Exos). The expression of miRNA-141-5p (miR-141-5p) and lnc-KCNQ1OT1 was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of cleaved-caspase-3, caspase-3, and Bax was determined by Western blot. Cell viability and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) and flow cytometry analysis, respectively. The binding sites between KCNQ1OT1 and miR-141-5p were validated by dual-luciferase reporter assay.

RESULTS

TNF-α dose-dependently increased miR-141-5p expression, inhibited viability, and promoted apoptosis of osteoblasts. However, miR-141-5p silencing or cocultured with ADSCs-Exos attenuated these effects. In addition, KCNQ1OT1-Exos could more significantly attenuate the induced cytotoxicity and apoptosis compared to ADSCs-Exos. Moreover, miR-141-5p was confirmed as the target of KCNQ1OT1 by luciferase reporter assay.

CONCLUSIONS

ADSCs-Exos can attenuate cytotoxicity and apoptosis of TNF-α-induced primary osteoblasts. KCNQ1OT1-Exos have a more significant inhibitory effect compared to ADSCs-Exos by the function of sponging miR-141-5p, suggesting that KCNQ1OT1-Exos can be promising agents in osteoporosis treatment.