The use of human dental pulp stem cells for in vivo bone tissue engineering: A systematic review

Graphene Oxide Quantum Dots-Preactivated Dental Pulp Stem Cells/GelMA Facilitates Mitophagy-Regulated Bone Regeneration

Background

In bone tissue engineering (BTE), cell-laden scaffolds offer a promising strategy for repairing bone defects, particularly when host cell regeneration is insufficient due to age or disease. Exogenous stem cell-based BTE requires bioactive factors to activate these cells. Graphene oxide quantum dots (GOQDs), zero-dimensional derivatives of graphene oxide, have emerged as potential osteogenic nanomedicines. However, constructing biological scaffolds with GOQDs and elucidating their biological mechanisms remain critical challenges.

Methods

We utilized GOQDs with a particle size of 10 nm, characterized by a surface rich in C-O-H and C-O-C functional groups. We developed a gelatin methacryloyl (GelMA) hydrogel incorporated with GOQDs-treated dental pulp stem cells (DPSCs). These constructs were transplanted into rat calvarial bone defects to estimate the effectiveness of GOQDs-induced DPSCs in repairing bone defects while also investigating the molecular mechanism underlying GOQDs-induced osteogenesis in DPSCs.

Results

GOQDs at 5 μg/mL significantly enhanced the osteogenic differentiation of DPSCs without toxicity. The GOQDs-induced DPSCs showed active osteogenic potential in three-dimensional cell culture system. In vivo, transplantation of GOQDs-preactivated DPSCs/GelMA composite effectively facilitated calvarial bone regeneration. Mechanistically, GOQDs stimulated mitophagy flux through the phosphatase-and-tensin homolog-induced putative kinase 1 (PINK1)/Parkin E3 ubiquitin ligase (PRKN) pathway. Notably, inhibiting mitophagy with cyclosporin A prevented the osteogenic activity of GOQDs.

Conclusion

This research presents a well-designed bionic GOQDs/DPSCs/GelMA composite scaffold and demonstrated its ability to promote bone regeneration by enhancing mitophagy. These findings highlight the significant potential of this composite for application in BTE and underscore the crucial role of mitophagy in promoting the osteogenic differentiation of GOQDs-induced stem cells.

Isolation, identification and osteogenic capability analysis of mesenchymal stem cells derived from different layers of human maxillary sinus membrane

AIM

To discover the populations of mesenchymal stem cells (MSCs) derived from different layers of human maxillary sinus membrane (hMSM) and evaluate their osteogenic capability.

MATERIALS AND METHODS

hMSM was isolated into a monolayer using the combined method of physical separation and enzymatic digestion. The localization of MSCs in hMSM was performed by immunohistological staining and other techniques. Lamina propria layer-derived MSCs (LMSCs) and periosteum layer-derived MSCs (PMSCs) from hMSM were expanded using the explant cell culture method and identified by multilineage differentiation assays, colony formation assay, flow cytometry and so on. The biological characteristics of LMSCs and PMSCs were compared using RNA sequencing, reverse transcription and quantitative polymerase chain reaction, immunofluorescence staining, transwell assay, western blotting and so forth.

RESULTS

LMSCs and PMSCs from hMSMs were both CD73-, CD90- and CD105-positive, and CD34-, CD45- and HLA-DR-negative. LMSCs and PMSCs were identified as CD171+/CD90+ and CD171-/CD90+, respectively. LMSCs displayed stronger proliferation capability than PMSCs, and PMSCs presented stronger osteogenic differentiation capability than LMSCs. Moreover, PMSCs could recruit and promote osteogenic differentiation of LMSCs.

CONCLUSIONS

This study identified and isolated two different types of MSCs from hMSMs. Both MSCs served as good potential candidates for bone regeneration.

Bone Regeneration with Mesenchymal Stem Cells in Scaffolds: Systematic Review of Human Clinical Trials

The aim of the study is to determine the effectiveness of stem cells in scaffolds in the treatment of bone deficits, in regard of bone regeneration, safety, rehabilitation and quality of life in humans. The systematic review was conducted in accordance with PRISMA 2020. A systematic search was conducted in three search engines and two registries lastly in 29-9-2022.for studies of the last 15 years. The risk of bias was assessed with RoB-2, ROBINS- I and NIH Quality of Before-After (Pre-Post) Studies with no Control group. The certainty of the results was assessed with the GRADE assessment tool. Due to heterogeneity, the results were reported in tables, graphs and narratively. The study protocol was published in PROSPERO with registration number CRD42022359049. Of the 10,091 studies retrieved, 14 were meeting the inclusion criteria, and were qualitatively analyzed. 138 patients were treated with mesenchymal stem cells in scaffolds, showing bone healing in all cases, and even with better results than the standard care. The adverse events were mild in most cases and in accordance with the surgery received. When assessed, there was a rehabilitation of the deficit and a gain in quality of life was detected. Although the heterogeneity between the studies and the small number of patients, the administration of mesenchymal stem cells in scaffolds seems safe and effective in the regeneration of bone defects. These results pave the way for the conduction of more clinical trials, with greater number of participants, with more standardized procedures.

Pioneering a paradigm shift in tissue engineering and regeneration with polysaccharides and proteins-based scaffolds: A comprehensive review

In the realm of modern medicine, tissue engineering and regeneration stands as a beacon of hope, offering the promise of restoring form and function to damaged or diseased organs and tissues. Central to this revolutionary field are biological macromolecules-nature's own blueprints for regeneration. The growing interest in bio-derived macromolecules and their composites is driven by their environmentally friendly qualities, renewable nature, minimal carbon footprint, and widespread availability in our ecosystem. Capitalizing on these unique attributes, specific composites can be tailored and enhanced for potential utilization in the realm of tissue engineering (TE). This review predominantly concentrates on the present research trends involving TE scaffolds constructed from polysaccharides, proteins and glycosaminoglycans. It provides an overview of the prerequisites, production methods, and TE applications associated with a range of biological macromolecules. Furthermore, it tackles the challenges and opportunities arising from the adoption of these biomaterials in the field of TE. This review also presents a novel perspective on the development of functional biomaterials with broad applicability across various biomedical applications.

[Advances in Molecular Regulatory Mechanisms of Jaw Repair and Reconstruction]

Jawbone injuries resulting from trauma, diseases, and surgical resections are commonly seen in clinical practice, necessitating precise and effective strategies for repair and reconstruction to restore both function and aesthetics. The precise and effective repair and the reconstruction of jawbone injuries pose a significant challenge in the field of oral and maxillofacial surgery, owing to the unique biomechanical characteristics and physiological functions of the jawbone. The natural repair process following jawbone injuries involves stages such as hematoma formation, inflammatory response, ossification, and bone remodeling. Bone morphogenetic proteins (BMPs), transforming growth factor beta (TGF-β), vascular endothelial growth factor (VEGF), and other growth factors play crucial roles in promoting jawbone regeneration. Cytokines such as interleukins and tumor necrosis factor play dual roles in regulating inflammatory response and bone repair. In recent years, significant progress in molecular biology research has been made in the field of jawbone repair and reconstruction. Tissue engineering technologies, including stem cell therapy, bioactive scaffolds, and growth factor delivery systems, have found important applications in jawbone repair. However, the intricate molecular regulatory mechanisms involved in the complex jawbone repair and reconstruction methods are not fully understood and still require further research. Future research directions will be focused on the precise control of these molecular processes and the development of more efficient combination therapeutic strategies to promote the effective and functional reconstruction of the jawbone. This review aims to examine the latest findings on the molecular regulatory mechanisms of the repair and reconstruction of jawbone injuries and the therapeutic strategies. The conclusions drawn in this article provide a molecular-level understanding of the repair of jawbone injuries and highlight potential directions for future research.

Comparison of Periodontal Ligament Stem Cells with Mesenchymal Stem Cells from Other Sources: A Scoping Systematic Review of In vitro and In vivo Studies

OBJECTIVE

The application of stem cells in regenerative medicine depends on their biological properties. This scoping review aimed to compare the features of periodontal ligament stem cells (PDLSSCs) with stem cells derived from other sources.

DESIGN

An electronic search in PubMed/Medline, Embase, Scopus, Google Scholar and Science Direct was conducted to identify in vitro and in vivo studies limited to English language.

RESULTS

Overall, 65 articles were included. Most comparisons were made between bone marrow stem cells (BMSCs) and PDLSCs. BMSCs were found to have lower proliferation and higher osteogenesis potential in vitro and in vivo than PDLSCs; on the contrary, dental follicle stem cells and umbilical cord mesenchymal stem cells (UCMSCs) had a higher proliferative ability and lower osteogenesis than PDLSCs. Moreover, UCMSCs exhibited a higher apoptotic rate, hTERT expression, and relative telomerase length. The immunomodulatory function of adipose-derived stem cells and BMSCs was comparable to PDLSCs. Gingival mesenchymal stem cells showed less sensitivity to long-term culture. Both pure and mixed gingival cells had lower osteogenic ability compared to PDLSCs. Comparison of dental pulp stem cells (DPSCs) with PDLSCs regarding proliferation rate, osteo/adipogenesis, and immunomodulatory properties was contradictory; however, in vivo bone formation of DPSCs seemed to be lower than PDLSCs.

CONCLUSION

In light of the performed comparative studies, PDLSCs showed comparable results to stem cells derived from other sources; however, further in vivo studies are needed to determine the actual pros and cons of stem cells in comparison to each other.

Dental Pulp Stem Cells for Bone Tissue Engineering: A Literature Review

Bone tissue engineering (BTE) is a promising approach for repairing and regenerating damaged bone tissue, using stem cells and scaffold structures. Among various stem cell sources, dental pulp stem cells (DPSCs) have emerged as a potential candidate due to their multipotential capabilities, ability to undergo osteogenic differentiation, low immunogenicity, and ease of isolation. This article reviews the biological characteristics of DPSCs, their potential for BTE, and the underlying transcription factors and signaling pathways involved in osteogenic differentiation; it also highlights the application of DPSCs in inducing scaffold tissues for bone regeneration and summarizes animal and clinical studies conducted in this field. This review demonstrates the potential of DPSC-based BTE for effective bone repair and regeneration, with implications for clinical translation.

Enhancement of mesenchymal stem cells' chondrogenic potential by type II collagen-based bioscaffolds

BACKGROUND

Osteoarthritis (OA) is a common degenerative chronic disease accounting for physical pain, tissue stiffness and mobility restriction. Current therapeutic approaches fail to prevent the progression of the disease considering the limited knowledge on OA pathobiology. During OA progression, the extracellular matrix (ECM) of the cartilage is aberrantly remodeled by chondrocytes. Chondrocytes, being the main cell population of the cartilage, participate in cartilage regeneration process. To this end, modern tissue engineering strategies involve the recruitment of mesenchymal stem cells (MSCs) due to their regenerative capacity as to promote chondrocyte self-regeneration.

METHODS AND RESULTS

In the present study, we evaluated the role of type II collagen, as the main matrix macromolecule in the cartilage matrix, to promote chondrogenic differentiation in two MSC in vitro culture systems. The chondrogenic differentiation of human Wharton's jelly- and dental pulp-derived MSCs was investigated over a 24-day culture period on type II collagen coating to improve the binding affinity of MSCs. Functional assays, demonstrated that type II collagen promoted chondrogenic differentiation in both MSCs tested, which was confirmed through gene and protein analysis of major chondrogenic markers.

CONCLUSIONS

Our data support that type II collagen contributes as a natural bioscaffold enhancing chondrogenesis in both MSC models, thus enhancing the commitment of MSC-based therapeutic approaches in regenerative medicine to target OA and bring therapy closer to the clinical use.

PSAT1 positively regulates the osteogenic lineage differentiation of periodontal ligament stem cells through the ATF4/PSAT1/Akt/GSK3β/β-catenin axis

BACKGROUND

Periodontal ligament stem cells (PDLSCs) are important seed cells for tissue engineering to realize the regeneration of alveolar bone. Understanding the gene regulatory mechanisms of osteogenic lineage differentiation in PDLSCs will facilitate PDLSC-based bone regeneration. However, these regulatory molecular signals have not been clarified.

METHODS

To screen potential regulators of osteogenic differentiation, the gene expression profiles of undifferentiated and osteodifferentiated PDLSCs were compared by microarray and bioinformatics methods, and PSAT1 was speculated to be involved in the gene regulation network of osteogenesis in PDLSCs. Lentiviral vectors were used to overexpress or knock down PSAT1 in PDLSCs, and then the proliferation activity, migration ability, and osteogenic differentiation ability of PDLSCs in vitro were analysed. A rat mandibular defect model was built to analyse the regulatory effects of PSAT1 on PDLSC-mediated bone regeneration in vivo. The regulation of PSAT1 on the Akt/GSK3β/β-catenin signalling axis was analysed using the Akt phosphorylation inhibitor Ly294002 or agonist SC79. The potential sites on the promoter of PSAT1 that could bind to the transcription factor ATF4 were predicted and verified.

RESULTS

The microarray assay showed that the expression levels of 499 genes in PDLSCs were altered significantly after osteogenic induction. Among these genes, the transcription level of PSAT1 in osteodifferentiated PDLSCs was much lower than that in undifferentiated PDLSCs. Overexpressing PSAT1 not only enhanced the proliferation and osteogenic differentiation abilities of PDLSCs in vitro, but also promoted PDLSC-based alveolar bone regeneration in vivo, while knocking down PSAT1 had the opposite effects in PDLSCs. Mechanistic experiments suggested that PSAT1 regulated the osteogenic lineage fate of PDLSCs through the Akt/GSK3β/β-catenin signalling axis. PSAT1 expression in PDLSCs during osteogenic differentiation was controlled by transcription factor ATF4, which is realized by the combination of ATF4 and the PSAT1 promoter.

CONCLUSION

PSAT1 is a potential important regulator of the osteogenic lineage differentiation of PDLSCs through the ATF4/PSAT1/Akt/GSK3β/β-catenin signalling pathway. PSAT1 could be a candidate gene modification target for enhancing PDLSCs-based bone regeneration.

Application of Biocompatible Scaffolds in Stem-Cell-Based Dental Tissue Engineering

Tissue engineering as an important field in regenerative medicine is a promising therapeutic approach to replace or regenerate injured tissues. It consists of three vital steps including the selection of suitable cells, formation of 3d scaffolds, and adding growth factors. Mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs) are mentioned as two main sources for this approach that have been used for the treatment of various types of disorders. However, the main focus of literature in the field of dental tissue engineering is on utilizing MSCs. On the other hand, biocompatible scaffolds play a notable role in this regenerative process which is mentioned to be harmless with acceptable osteoinductivity. Their ability in inhibiting inflammatory responses also makes them powerful tools. Indeed, stem cell functions should be supported by biomaterials acting as scaffolds incorporated with biological signals. Naturally derived polymeric scaffolds and synthetically engineered polymeric/ceramic scaffolds are two main types of scaffolds regarding their materials that are defined further in this review. Various strategies of tissue bioengineering can affect the regeneration of dentin-pulp complex, periodontium regeneration, and whole teeth bioengineering. In this regard, in vivo/ex vivo experimental models have been developed recently in order to perform preclinical studies of dental tissue engineering which make it more transferable to be used for clinic uses. This review summarizes dental tissue engineering through its different components. Also, strategies of tissue bioengineering and experimental models are introduced in order to provide a perspective of the potential roles of dental tissue engineering to be used for clinical aims.

Bioprinting and biomaterials for dental alveolar tissue regeneration

Three dimensional (3D) bioprinting is a powerful tool, that was recently applied to tissue engineering. This technique allows the precise deposition of cells encapsulated in supportive bioinks to fabricate complex scaffolds, which are used to repair targeted tissues. Here, we review the recent developments in the application of 3D bioprinting to dental tissue engineering. These tissues, including teeth, periodontal ligament, alveolar bones, and dental pulp, present cell types and mechanical properties with great heterogeneity, which is challenging to reproduce in vitro. After highlighting the different bioprinting methods used in regenerative dentistry, we reviewed the great variety of bioink formulations and their effects on cells, which have been established to support the development of these tissues. We discussed the different advances achieved in the fabrication of each dental tissue to provide an overview of the current state of the methods. We conclude with the remaining challenges and future needs.

Dental pulp stem cells for reconstructing bone defects: A systematic review and meta-analysis

BACKGROUND

Bone reconstruction with appropriate quality and quantity for dental implant replacement in the alveolar ridge is a challenge in dentistry. As dental pulp stem cells (DPSCs) could be a new perspective in bone regeneration in the future, this study investigated the bone regeneration process by DPSCs.

METHODS

Electronic searches for articles in the PubMed, EMBASE, and Scopus databases were completed until 21 April 2022. The most important inclusion criteria for selecting in vivo studies reporting quantitative data based on new bone volume and new bone area. The quality assessment was performed based on Cochrane's checklist.

RESULTS

After the title, abstract, and full-text screening of 762 studies, 23 studies were included. A meta-analysis of 70 studies that reported bone regeneration based on new bone area showed a statistically significant favorable influence on bone tissue regeneration compared to the control groups (P<0.00001, standardized mean difference [SMD]=2.40, 95% CI: 1.55‒3.26; I2=83%). Also, the meta-analysis of 14 studies that reported new bone regeneration based on bone volume showed a statistically significant favorable influence on bone tissue regeneration compared to the control groups (P=0.0003, SMD=1.85, 95% CI: 0.85‒2.85; I2=84%).

CONCLUSION

This systematic review indicated that DPSCs in tissue regeneration therapy significantly affected bone tissue complex regeneration. However, more and less diverse preclinical studies will enable more powerful meta-analyses in the future.

Tissue Engineering with Stem Cell from Human Exfoliated Deciduous Teeth (SHED) and Collagen Matrix, Regulated by Growth Factor in Regenerating the Dental Pulp

Maintaining dental pulp vitality and preventing tooth loss are two challenges in endodontic treatment. A tooth lacking a viable pulp loses its defense mechanism and regenerative ability, making it more vulnerable to severe damage and eventually necessitating extraction. The tissue engineering approach has drawn attention as an alternative therapy as it can regenerate dentin-pulp complex structures and functions. Stem cells or progenitor cells, extracellular matrix, and signaling molecules are triad components of this approach. Stem cells from human exfoliated deciduous teeth (SHED) are a promising, noninvasive source of stem cells for tissue regeneration. Not only can SHEDs regenerate dentin-pulp tissues (comprised of fibroblasts, odontoblasts, endothelial cells, and nerve cells), but SHEDs also possess immunomodulatory and immunosuppressive properties. The collagen matrix is a material of choice to provide structural and microenvironmental support for SHED-to-dentin pulp tissue differentiation. Growth factors regulate cell proliferation, migration, and differentiation into specific phenotypes via signal-transduction pathways. This review provides current concepts and applications of the tissue engineering approach, especially SHEDs, in endodontic treatment.

Osteogenic enhancement of modular ceramic nanocomposites impregnated with human dental pulp stem cells: an approach for bone repair and regenerative medicine

Background/aim

Human dental pulp-derived mesenchymal stem cells (hDP-MSCs) are a promising source of progenitor cells for bone tissue engineering. Nanocomposites made of calcium phosphate especially hydroxyapatite (HA) offer an impressive solution for orthopedic and dental implants. The combination of hDP-MSCs and ceramic nanocomposites has a promising therapeutic potential in regenerative medicine. Despite the calcium phosphate hydroxyapatite (HA)-based nanocomposites offer a good solution for orthopedic and dental implants, the heavy load-bearing clinical applications require higher mechanical strength, which is not of the HA’ properties that have low mechanical strength. Herein, the outcomes of using fabricated ceramic nanocomposites of hydroxyapatite/titania/calcium silicate mixed at different ratios (C1, C2, and C3) and impregnated with hDP-MSCs both in in vitro cultures and rabbit model of induced tibial bone defect were investigated. Our aim is to find out a new approach that would largely enhance the osteogenic differentiation of hDP-MSCs and has a therapeutic potential in bone regeneration.

Subjects and methods

Human DP-MSCs were isolated from the dental pulp of the third molar and cultured in vitro. Alizarin Red staining was performed at different time points to assess the osteogenic differentiation. Flow cytometer was used to quantify the expression of hDP-MSCs unique surface markers. Rabbits were used as animal models to evaluate the therapeutic potential of osteogenically differentiated hDP-MSCs impregnated with ceramic nanocomposites of hydroxyapatite/tatiana/calcium silicate (C1, C2, and C3). Histopathological examination and scanning electron microscopy (SEM) were performed to evaluate bone healing potential in the rabbit induced tibial defects three weeks post-transplantation.

Results

The hDP-MSCs showed high proliferative and osteogenic potential in vitro culture. Their osteogenic differentiation was accelerated by the ceramic nanocomposites’ scaffold and revealed bone defect’s healing in transplanted rabbit groups compared to control groups. Histopathological and SEM analysis of the transplanted hDP-MSCs/ceramic nanocomposites showed the formation of new bone filling in the defect area 3 weeks post-implantation. Accelerate osseointegration and enhancement of the bone-bonding ability of the prepared nanocomposites were also confirmed by SEM.

Conclusions

The results strongly suggested that ceramic nanocomposites of hydroxyapatite/ titania /calcium silicate (C1, C2, and C3) associated with hDP-MSCs have a therapeutic potential in bone healing in a rabbit model. Hence, the combined osteogenic system presented here is recommended for application in bone tissue engineering and regenerative medicine.

Criteria, Challenges, and Opportunities for Acellularized Allogeneic/Xenogeneic Bone Grafts in Bone Repairing

As bone grafts become more commonly needed by patients and as donors become scarcer, acellularized bone grafts (ABGs) are becoming more popular for restorative purposes. While autogeneic grafts are reliable as a gold standard, allogeneic and xenogeneic ABGs have been shown to be of particular interest due to the limited availability of autogeneic resources and reduced patient well-being in long-term surgeries. Because of the complete similarity of their structures with native bone, excellent mechanical properties, high biocompatibility, and similarities of biological behaviors (osteoinductive and osteoconductive) with local bones, successful outcomes of allogeneic and xenogeneic ABGs in both in vitro and in vivo research have raised hopes of repairing patients' bone injuries in clinical applications. However, clinical trials have been delayed due to a lack of standardized protocols pertaining to acellularization, cell seeding, maintenance, and diversity of ABG evaluation criteria. This study sought to uncover these factors by exploring the bone structures, ossification properties of ABGs, sources, benefits, and challenges of acellularization approaches (physical, chemical, and enzymatic), cell loading, and type of cells used and effects of each of the above items on the regenerative technologies. To gain a perspective on the repair and commercialization of products before implementing new research activities, this study describes the differences between ABGs created by various techniques and methods applied to them. With a comprehensive understanding of ABG behavior, future research focused on treating bone defects could provide a better way to combine the treatment approaches needed to treat bone defects.

A Novel Cell Delivery System Exploiting Synergy between Fresh Titanium and Fibronectin

Delivering and retaining cells in areas of interest is an ongoing challenge in tissue engineering. Here we introduce a novel approach to fabricate osteoblast-loaded titanium suitable for cell delivery for bone integration, regeneration, and engineering. We hypothesized that titanium age influences the efficiency of protein adsorption and cell loading onto titanium surfaces. Fresh (newly machined) and 1-month-old (aged) commercial grade 4 titanium disks were prepared. Fresh titanium surfaces were hydrophilic, whereas aged surfaces were hydrophobic. Twice the amount of type 1 collagen and fibronectin adsorbed to fresh titanium surfaces than aged titanium surfaces after a short incubation period of three hours, and 2.5-times more fibronectin than collagen adsorbed regardless of titanium age. Rat bone marrow-derived osteoblasts were incubated on protein-adsorbed titanium surfaces for three hours, and osteoblast loading was most efficient on fresh titanium adsorbed with fibronectin. The number of osteoblasts loaded using this synergy between fresh titanium and fibronectin was nine times greater than that on aged titanium with no protein adsorption. The loaded cells were confirmed to be firmly attached and functional. The number of loaded cells was strongly correlated with the amount of protein adsorbed regardless of the protein type, with fibronectin simply more efficiently adsorbed on titanium surfaces than collagen. The role of surface hydrophilicity of fresh titanium surfaces in increasing protein adsorption or cell loading was unclear. The hydrophilicity of protein-adsorbed titanium increased with the amount of protein but was not the primary determinant of cell loading. In conclusion, the osteoblast loading efficiency was dependent on the age of the titanium and the amount of protein adsorption. In addition, the efficiency of protein adsorption was specific to the protein, with fibronectin being much more efficient than collagen. This is a novel strategy to effectively deliver osteoblasts ex vivo and in vivo using titanium as a vehicle.

Stem cells and common biomaterials in dentistry: a review study

Stem cells exist as normal cells in embryonic and adult tissues. In recent years, scientists have spared efforts to determine the role of stem cells in treating many diseases. Stem cells can self-regenerate and transform into some somatic cells. They would also have a special position in the future in various clinical fields, drug discovery, and other scientific research. Accordingly, the detection of safe and low-cost methods to obtain such cells is one of the main objectives of research. Jaw, face, and mouth tissues are the rich sources of stem cells, which more accessible than other stem cells, so stem cell and tissue engineering treatments in dentistry have received much clinical attention in recent years. This review study examines three essential elements of tissue engineering in dentistry and clinical practice, including stem cells derived from the intra- and extra-oral sources, growth factors, and scaffolds.

Transplantation of SDF-1α-loaded liver extracellular matrix repopulated with autologous cells attenuated liver fibrosis in a rat model

Cell-based therapy and tissue engineering are promising substitutes for liver transplantation to cure end-stage liver disorders. However, the limited sources for healthy and functional cells and poor engraftment rate are main challenges to the cell-based therapy approach. On the other hand, feasibility of production and size of bioengineered tissues are primary bottlenecks in tissue engineering. Here, we induce regeneration in a rat fibrotic liver model by transplanting a natural bioengineered scaffold with a native microenvironment repopulated with autologous stem/progenitor cells. In the main experimental group, a 1 mm³ stromal derived factor-1α (SDF-1α; S) loaded scaffold from decellularized liver extracellular matrix (LEM) was transplanted (Tx) into a fibrotic liver and the endogenous stem/progenitor cells were mobilized via granulocyte colony stimulating factor (G-CSF; G) therapy. Four weeks after transplantation, changes in liver fibrosis and necrosis, efficacy of cell engraftment and differentiation, vasculogenesis, and liver function recovery were assessed in this (LEM-TxSG) group and compared to the other groups. We found significant reduction in liver fibrosis stage in the LEM-TxSG, LEM-TxS and LEM-TxG groups compared to the control (fibrotic) group. Liver necrosis grade, and alanine transaminase (ALT) and aspartate transaminase (AST) levels dramatically reduced in all experimental groups compared to the control group. However, the number of engrafted cells into the transplanted scaffold and ratio of albumin (Alb) positive cells per total incorporated cells were considerably higher in the LEM-TxSG group compared to the LEM-Tx, LEM-TxS and LEM-TxG groups. Serum Alb levels increased in the LEM-Tx, LEM-TxS, and LEM-TxG groups, and was highest in the LEM-TxSG group, which was significantly more than the fibrotic group. Small vessel formation in the LEM-TxSG group was significantly higher than the LEM-Tx and LEM-TxS groups. Totally, these findings support application of the in vivo tissue engineering approach as a possible novel therapeutic strategy for liver fibrosis.

Comparative proteomics analysis of human stem cells from dental gingival and periodontal ligament

Dental stem cells isolated from oral tissues have been shown to provide with high proliferation ability and multilineage differentiation potential. Gingival mesenchymal stem cells (GMSCs) and periodontal ligament stem cells (PDLSCs), kinds of dental stem cells, can be used as substitutes for tissue repair materials because of their similar regenerative functions. In this study, we aim to explore the similarities and differences between the protein profiles of GMSCs and PDLSCs through quantitative proteomics. A total of 2821 proteins were identified and retrieved, of which 271 were up-regulated and 57 were down-regulated in GMSCs compared to PDLSCs. GO analysis demonstrated that the 328 differentially abundant proteins (DAPs) were involved in the regulation of gene expression, metabolism and signal transduction in biological process, mainly distributed in organelles related to vesicle transport, and involved in the molecular function of binding protein. And KEGG analysis showed that the DAPs were committed to regulating the synthesis of proteasome and spliceosome. RT-qPCR results showed that ARPC1B, PDAP1 and SEC61B can be used as special markers to distinguish GMSCs from PDLSCs. This research contributes to explaining the molecular mechanism and promoting the clinical application of tissue regeneration of GMSCs and PDLSCs. This article is protected by copyright. All rights reserved.

Potential role of dental pulp stem cells conditioned medium for odontoblastic differentiation

Background

Functional bioengineered tooth regeneration using autologous or allogeneic alternative differentiated cells sources are thought to have a great potential in replacing conventional dentures. This study investigated the potential of dental pulp stem cells (DPSCs) conditioned medium for odontoblastic differentiation of Wharton’s jelly mesenchymal stem cells (WJMSCs). The DPSCs derived from healthy adult permanent first molars were cultured at high confluence prior to conditioned medium collection. The WJMSCs were cultured in six different treatments, with varying ratios of culture media to DPSCs-conditioned medium. MTT assay was used to measure the rate of proliferation of WJMSCs, while immunocytochemistry staining was utilised to detect the expression of dental matrix protein 1 (DMP-1). The deposited calcium was detected and analysed via Alizarin-Red Staining (ARS).

Results

It was found that the proliferation of WJMSCs cultured under the mixture of complete medium and DPSCs conditioned medium showed significantly lower than the control; presumably the cells started to exit proliferative state prior differentiation. In 14 days of induction, the cells in all treatments showed osteoblastic-like morphology, calcium compound deposits were observed at day 7, 10 and 14 of differentiation suggested that DPSCs conditioned medium could lead to osteoblastic/odontoblastic differentiation. However, the DMP-1 protein can be seen only expressed minimally at day 14 of conditioned medium induction.

Conclusions

In conclusion, DPSCs conditioned medium appeared as a potential odontoblastic induction approach for WJMSCs. To further investigate the stimulatory effects by DPSCs conditioned medium, specific signalling pathway need to be elucidated to enhance the differentiation efficiency.

Composite alginate-gelatin hydrogels incorporating PRGF enhance human dental pulp cell adhesion, chemotaxis and proliferation

The increasing prevalence of tissue injuries is fueling the development of autologous biological treatments for regenerative medicine. Here, we investigated the potential of three different bioinks based on the combination of gelatin and alginate (GA), enriched in either hydroxyapatite (GAHA) or hydroxyapatite and PRGF (GAHAP), as a favorable microenvironment for human dental pulp stem cells (DPSCs). Swelling behaviour, in vitro degradation and mechanical properties of the matrices were evaluated. Morphological and elemental analysis of the scaffolds were also performed along with cytocompatibility studies. The in vitro cell response to the different scaffolds was also assessed. Results showed that all scaffolds presented high swelling capacity, and those that contained HA showed higher Young's modulus. GAHAP had the lowest degradation rate and the highest values of cytocompatibility. Cell adhesion and chemotaxis were significantly increased when PRGF was incorporated to the matrices. GAHA and GAHAP compositions promoted the highest proliferative rate as well as significantly stimulated osteogenic differentiation. In conclusion, the enrichment with PRGF improves the regenerative properties of the composites favouring the development of personalized constructs.

Clinical Application of Stem Cell Therapy in Reconstructing Maxillary Cleft Alveolar Bone Defects: A Systematic Review of Randomized Clinical Trials

An alveolar cleft is the most common congenital bone defect. This systematic review aimed to investigate the use of stem cells for alveolar cleft repair and summarize the outcomes of clinical research studies. The electronic databases PubMed, Scopus, Web of Sciences, and Google Scholar were utilized to search the literature for relevant studies after administering specific inclusion and exclusion criteria. The search included articles that were published from 2011 to 2021 and specific keywords were used in the databases. The search was completed by two independent reviewers following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.Only four studies satisfied both the inclusion and exclusion criteria and were included in this systematic review. These studies investigated different aspects of bone reconstruction in the maxillary alveolar bone by stem cells, including cell types, clinical applications, biomaterial scaffolds, and follow-up period. The accumulated evidence in this systematic review is limited and insufficient to support the role of stem cell use in bone regeneration of maxillary alveolar bone defects. The outcome of using stem cells was studied only in 57 subjects from the four included studies. Although the noninvasive methods of isolating stem cells make them attractive resources for bone regeneration, more research is required in order to standardize and investigate stem cell therapy. This should be done beforehand in adults in less invasive procedures such as bone defect repair in dentistry prior to considering this type of therapy in this vulnerable patient population.

Mesenchymal Stem Cells Based Treatment in Dental Medicine: A Narrative Review

Application of mesenchymal stem cells (MSC) in regenerative therapeutic procedures is becoming an increasingly important topic in medicine. Since the first isolation of dental tissue-derived MSC, there has been an intense investigation on the characteristics and potentials of these cells in regenerative dentistry. Their multidifferentiation potential, self-renewal capacity, and easy accessibility give them a key role in stem cell-based therapy. So far, several different dental stem cell types have been discovered and their potential usage is found in most of the major dental medicine branches. These cells are also researched in multiple fields of medicine for the treatment of degenerative and inflammatory diseases. In this review, we summarized dental MSC sources and analyzed their treatment modalities with particular emphasis on temporomandibular joint osteoarthritis (TMJ OA).

Application of dental pulp stem cells in oral maxillofacial tissue engineering

In the maxillofacial area, soft and hard tissue abnormalities are caused by trauma, tumors, infection, and other causes that expose the maxillofacial region to the surface of the human body. Patients' normal physiological function and appearance are interfered with, and their mental health is adversely impacted, reducing their overall life quality. The pursuit of appropriate medical treatments to correct these abnormalities is thus vital. Autologous stem cell regeneration technology mainly focused on tissues has lately emerged as a significant problem in the medical community. Because of the capacity of dental pulp stem cells (DPSCs) to self-renew, the use of DPSCs from the human pulp tissues of deciduous teeth or permanent teeth has gained popularity among scientists as a stem cell-based therapy option. Aside from that, they are simple to extract and have minimal immunogenicity. As a result, bone tissue engineering may be a critical component in treating maxillofacial and periodontal bone abnormalities. DPSCs activity in maxillofacial and periodontal tissue-engineered bone tissue was investigated in this research.

Mapping the Secretome of Dental Pulp Stem Cells Under Variable Microenvironmental Conditions

There is substantial evidence supporting the anti-inflammatory and regenerative potential of dental pulp stem cells (DPSCs) through direct cell transplantation or paracrine action. However, DPSC secretome profile remains inadequately studied. This study provides proteomic profiling of the human DPSC secretome by comparatively analysising cell lysates and respective culture supernatants (i.e. conditioned media-CM) under variable oxygen tension conditions (normoxia-20% O₂/CM_Norm vs. hypoxia 2% O₂/CM_Hyp) and/or stimulation with Tumor Necrosis Factor alpha (TNF-α). DPSC-CM samples and respective crude lysates (DPSC-CL) were collected and subjected to SDS-PAGE, followed by LC-MS/MS analysis. The identified proteins were analyzed by Gene Ontology, Reactome, and String databases. The anti-inflammatory properties of DPSC-CMs were validated via an in vitro RAW_246.7 murine macrophages model through evaluation of the expression of pro-and anti-inflammatory markers by real-time PCR. Results showed a total of 2413 proteins identified in CM_Norm, 2479 in CM_Norm+TNF-α, 1642 in CM_Hyp, and 2002 in CM_Hyp + TNF-α samples. CM_Norm contained 122 proteins statistically significantly upregulated compared to the CM_Hyp and involved in pathways related to "ECM organization", "cellular response to hypoxia", and "IL signaling". Functional network analysis showed that TGFβ1, TIMP1 and TIMP2 were key nodes among proteins significantly upregulated in the CM_Norm compared to the CM_Hyp, interacting with more than 10 proteins, each. DPSC-CM application in the in vitro RAW_246.7 model decreased the expression of pro-inflammatory markers (MMP-3, MMP-9, MMP-13, MCP-1), while increasing anti-inflammatory markers (IL-10). Overall, DPSC-CM collected under normoxic conditions is enriched with anti-inflammatory, tissue repair and regenerative factors, which prompts further investigation on its therapeutic applications.

Effect of Inducible BMP-7 Expression on the Osteogenic Differentiation of Human Dental Pulp Stem Cells

BMP-7 has shown inductive potential for in vitro osteogenic differentiation of mesenchymal stem cells, which are an ideal resource for regenerative medicine. Externally applied, recombinant BMP-7 was able to induce the osteogenic differentiation of DPSCs but based on our previous results with BMP-2, we aimed to study the effect of the tetracyclin-inducible BMP-7 expression on these cells. DPSC, mock, and DPSC-BMP-7 cell lines were cultured in the presence or absence of doxycycline, then alkaline phosphatase (ALP) activity, mineralization, and mRNA levels of different osteogenic marker genes were measured. In the DPSC-BMP-7 cell line, the level of BMP-7 mRNA significantly increased in the media supplemented with doxycycline, however, the expression of Runx2 and noggin genes was upregulated only after 21 days of incubation in the osteogenic medium with doxycycline. Moreover, while the examination of ALP activity showed reduced activity in the control medium containing doxycycline, the accumulation of minerals remained unchanged in the cultures. We have found that the induced BMP-7 expression failed to induce osteogenic differentiation of DPSCs. We propose three different mechanisms that may worth investigating for the engineering of expression systems that can be used for the induction of differentiation of mesenchymal stem cells.

Magnesium Ammonium Phosphate Composite Cell-Laden Hydrogel Promotes Osteogenesis and Angiogenesis In Vitro

Injectable hydrogels provide an effective strategy for minimally invasive treatment on irregular bony defects in the maxillofacial region. To improve the osteoinduction of gelatin methacrylate (GelMA), we fabricated a three-dimensional (3D) culture system based on the incorporation of magnesium ammonium phosphate hexahydrate (struvite) into GelMA. The optimal concentration of struvite was investigated using the struvite extracts, and 500 μg mL^-1 was found to be the most suitable concentration for the osteogenesis of dental pulp stem cells (DPSCs) and angiogenesis of human umbilical vein endothelial cells (HUVECs). We prepared the GelMA composite (MgP) with 500 μg mL^-1 struvite. Struvite did not affect the cross-linking of GelMA and released Mg²⁺ during degradation. The cell delivery system using MgP improved the laden-cell viability, upregulated the expression of osteogenic and angiogenic-differentiation-related genes, and promoted cell migration. Overall, the modifications made to the GelMA in this study improved osteoinduction and demonstrated great potential for application in vascularized bone tissue regeneration.

Effects of pre-mixed hydraulic calcium silicate putties on osteogenic differentiation of human dental pulp stem cells in vitro

OBJECTIVES

An experimental tricalcium silicate and dicalcium silicate-containing endodontic putty has been designed to overcome the issue of reduced shelf life after exposure to atmospheric moisture during repeated opening of the container for clinical retrieval. The present study examined the effects of this experimental hydraulic putty on the mineralogenic characteristics of osteogenic lineage-committed human dental pulp stem cells (hDPSCs), by comparing the cellular responses with a commercially available putty (EndoSequence BC RRM Putty).

METHODS

The osteogenic potential of hDPSCs that had been exposed to the putties was examined using quantitative reverse-transcription polymerase chain reaction for osteogenic gene expressions and western blot for osteogenic protein expressions. Alkaline phosphatase activity assay and alizarin red S staining were performed to detect changes in production of the intracellular enzyme and extracellular matrix mineralization respectively.

RESULTS

Osteogenic differentiation of the hDPSCs was significantly enhanced after exposure to the pre-mixed hydraulic putties, with no significant difference between these two examined putties.

CONCLUSIONS

The experimental hydraulic tricalcium silicate putty enhances osteogenic differentiation of hDPSCs to the same extent as a commercially available tricalcium silicate putty.

CLINICAL SIGNIFICANCE

The experimental hydraulic putty appears to be an alternative to the commercial putty when used for applications involving the regeneration of bone in endodontics. Animal models are required for validating its potential in enhancing osteogenesis in vivo.

Ckip-1 regulates C3H10T1/2 mesenchymal cell proliferation and osteogenic differentiation via Lrp5

Casein kinase-2 interaction protein-1 (Ckip-1) is a negative regulator of bone formation. The identification of novel Ckip-1-related targets and their associated signaling pathways that regulate mesenchymal stem cell (MSC) osteogenic differentiation is required. The present study aimed to evaluate the effects of Ckip-1 knockdown on C3H10T1/2 MSC proliferation and osteogenic differentiation, and to explore the role of the canonical Wnt-signaling receptor Lrp5. Ckip-1-knockdown (shCkip-1), Ckip-1-overexpression (Ckip-1) and their corresponding control [shCtrl and empty vector (EV), respectively] cell groups were used in the present study. Immunofluorescence localization of Ckip-1 was observed. The expression of the key molecules of the canonical Wnt signaling pathway was examined in C3H10T1/2 cells following osteogenic induction. Moreover, the effects of Lrp5 knockdown in the presence or absence of Ckip-1 knockdown were examined on C3H10T1/2 cell proliferation and osteogenic differentiation. The results indicated an increase in cell proliferation and osteogenic differentiation in the shCkip-1 group compared with the shCtrl group. The expression levels of LDL receptor related protein 5 (Lrp5), lymphoid enhancer binding factor 1 (Lef1) and transcription factor 1 in C3H10T1/2 cells were significantly increased in shCkip-1 cells following 7-day osteoinduction compared with shCtrl cells. Moreover, the involvement of Lrp5 in shCkip-1-induced osteogenic differentiation of C3H10T1/2 cells was further verified. The results indicated that Ckip-1 reduced C3H10T1/2 MSC proliferation and osteogenic differentiation via the canonical Wnt-signaling receptor Lrp5, which is essential for the improvement of bone tissue engineering.

Nanotherapeutics for regeneration of degenerated tissue infected by bacteria through the multiple delivery of bioactive ions and growth factor with antibacterial/angiogenic and osteogenic/odontogenic capacity

Therapeutic options are quite limited in clinics for the successful repair of infected/degenerated tissues. Although the prevalent treatment is the complete removal of the whole infected tissue, this leads to a loss of tissue function and serious complications. Herein the dental pulp infection, as one of the most common dental problems, was selected as a clinically relevant case to regenerate using a multifunctional nanotherapeutic approach. For this, a mesoporous bioactive glass nano-delivery system incorporating silicate, calcium, and copper as well as loading epidermal growth factor (EGF) was designed to provide antibacterial/pro-angiogenic and osteo/odontogenic multiple therapeutic effects. Amine-functionalized Cu-doped bioactive glass nanospheres (Cu-BGn) were prepared to be 50-60 nm in size, mesoporous, positive-charged and bone-bioactive. The Cu-BGn could release bioactive ions (copper, calcium and silicate ions) with therapeutically-effective doses. The Cu-BGn treatment to human umbilical vein endothelial cells (HUVEC) led to significant enhancement of the migration, tubule formation and expression of angiogenic gene (e.g. vascular endothelial growth factor, VEGF). Furthermore, the EGF-loaded Cu-BGn (EGF@Cu-BGn) showed pro-angiogenic effects with antibacterial activity against E. faecalis, a pathogen commonly involved in the pulp infection. Of note, under the co-culture condition of HUVEC with E. faecalis, the secretion of VEGF was up-regulated. In addition, the osteo/odontogenic stimulation of the EGF@Cu-BGn was evidenced with human dental pulp stem cells. The local administration of the EGF@Cu-BGn in a rat molar tooth defect infected with E. faecalis revealed significant in vivo regenerative capacity, highlighting the nanotherapeutic uses of the multifunctional nanoparticles for regenerating infected/damaged hard tissues.

Comparing the osteogenic potential of schneiderian membrane and dental pulp mesenchymal stem cells: an in vitro study

Mesenchymal stem cells, being characterized by high self-renewal capacity and multi-lineage differentiation potential, are widely used in regenerative medicine especially for repair of bone defects in patients with poor bone regenerative capacity. In this study, we aimed to compare the osteogenic potential of human maxillary schneiderian sinus membrane (hMSSM)-derived stem cells versus permanent teeth dental pulp stem cells (DPSCs). Both cells types were cultivated in osteogenic and non-osteogenic inductive media. Alkaline phosphatase (ALP) activity assay and quantitative real-time PCR analysis were carried out to assess osteogenic differentiation. We showed that ALP activity and osteoblastic markers transcription levels were more striking in hMSSM-derived stem cells than DPSCs. Our results highlight hMSSM-derived stem cells as a recommended stem cell type for usage during bone tissue regenerative therapy.

Immunohistochemical analysis of stem cells from human exfoliated deciduous teeth seeded in carbonate apatite scaffold for the alveolar bone defect in Wistar rats ( Rattus novergicus)

Background: Stem cells from human exfoliated deciduous teeth (SHED) seeded in carbonate apatite scaffold (CAS) may have multiple functions that could be used to regenerate the alveolar bone defects. The purpose of this study is to examine the ability of SHED and CAS in alveolar bone defects using an immunohistochemical analysis.

Methods: ten three-month-old healthy male Wistar rats (R. novergicus) that weighed between 150–250 grams (g) were used as animal models. A simple blind random sampling method was used to select the sample that was assigned to the study group for CAS and SHED seeded in CAS (n=5). The animal study model of the alveolar bone was established by extracting the anterior mandible teeth. Rodent anesthesia was applied to relieve the pain during the procedure for all test animals. Immunohistochemistry was performed after seven days to facilitate the examination of the receptor activator of NF-κβ ligand (RANKL), osteoprotegrin (OPG), transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin, and osteopontin expression. The data was analyzed using the unpaired t-test (p<0.01) and Pearson’s correlation test (p<0.05).

Results: The OPG, RUNX2, TGF-β, VEGF, ALP, osteocalcin, and ostepontin expressions were higher in SHED seeded in CAS than CAS only with a significant difference between the groups (p<0.01). Furthermore, the RANKL expression was lower in SHED seeded in CAS compared to CAS only. There was a strong reverse significant correlation between OPG and RANKL expression (p<0.05).

Conclusions: The number of osteogenic marker expressing cells, such as OPG, RUNX2, TGF-β, VEGF, ALP, osteocalcin, and ostepontin, increased. However, RANKL expression in the alveolar bone defects that were implanted with SHED seeded in CAS did not increase after seven days.

Long non-coding RNA maternally expressed gene 3 inhibits osteogenic differentiation of human dental pulp stem cells via microRNA-543/smad ubiquitin regulatory factor 1/runt-related transcription factor 2 axis

OBJECTIVE

The aim of the present study was to investigate the biological roles and underlying mechanism of the long non-coding RNA maternally expressed gene 3 (MEG3) on osteogenic differentiation of human dental pulp stem cells (hDPSCs).

METHODS

The expression levels of MEG3, microRNA-543 (miR-543), osterix, osteopontin, osteocalcin and runt-related transcription factor 2 (RUNX2) were measured by quantitative real-time PCR (qRT-PCR). Alkaline phosphatase (ALP) activity assay and alizarin red S staining (ARS) were used to measure the impacts exerted by MEG3, miR-543 on osteogenic differentiation. Cell proliferation was measured by MTT assay. In addition, the targeted relationships between miR-543, MEG3, and Smad ubiquitin regulatory factor 1 (SMURF1) were assessed through dual luciferase reporter assay.

RESULTS

During osteogenic induction, the expression of MEG3 was gradually reduced, whereas the expression of miR-543, osterix, osteopontin, osteocalcin and RUNX2 were gradually increased. Functional analysis implied that MEG3 overexpression or miR-543 inhibition reduced the cell proliferation, ALP activity, ARS levels, and decreased the expression of osteoblast-related proteins. Moreover, MEG3 promoted SMURF1 expression by directly targeting miR-543 as a competing endogenous RNA. Furthermore, overexpression of miR-543 or silencing SMURF1 could reverse the inhibitory effects of MEG3 on the osteogenic differentiation of hDPSCs.

CONCLUSIONS

In conclusion, our study revealed that overexpression of MEG3 inhibited hDPSCs osteogenic differentiation via miR-543/SMURF1/RUNX2 regulatory network, which may contribute to the functional regulation and clinical applications of hDPSCs.

Dental stem cells: The role of biomaterials and scaffolds in developing novel therapeutic strategies

Dental stem cells (DSCs) are self-renewable cells that can be obtained easily from dental tissues, and are a desirable source of autologous stem cells. The use of DSCs for stem cell transplantation therapeutic approaches is attractive due to their simple isolation, high plasticity, immunomodulatory properties, and multipotential abilities. Using appropriate scaffolds loaded with favorable biomolecules, such as growth factors, and cytokines, can improve the proliferation, differentiation, migration, and functional capacity of DSCs and can optimize the cellular morphology to build tissue constructs for specific purposes. An enormous variety of scaffolds have been used for tissue engineering with DSCs. Of these, the scaffolds that particularly mimic tissue-specific micromilieu and loaded with biomolecules favorably regulate angiogenesis, cell-matrix interactions, degradation of extracellular matrix, organized matrix formation, and the mineralization abilities of DSCs in both in vitro and in vivo conditions. DSCs represent a promising cell source for tissue engineering, especially for tooth, bone, and neural tissue restoration. The purpose of the present review is to summarize the current developments in the major scaffolding approaches as crucial guidelines for tissue engineering using DSCs and compare their effects in tissue and organ regeneration.

Cellulose acetate-gelatin-coated boron-bioactive glass biocomposite scaffolds for bone tissue engineering

In this study, we aimed to prepare and characterize porous scaffolds composed of pure and boron oxide (B₂O₃)-doped bioactive glass (BG) that were infiltrated by cellulose acetate-gelatin (CA-GE) polymer solution for bone tissue engineering applications. Composite scaffolds were cross-linked with glutaraldehyde after polymer coating to protect the structural integrity of the polymeric-coated scaffolds. The impact of B₂O₃ incorporation into BG-polymer porous scaffolds on the cross-sectional morphology, porosity, mechanical properties, degradation and bioactivity of the scaffolds was investigated. Human dental pulp stem cells (hDPSCs) were enzymatically isolated and used for cell culture studies. According to scanning electron microscope analysis, the porous structure of the scaffolds was preserved after polymer coating. After polymer infiltration, the porosity of the scaffolds decreased from 64.2% to 59.35% for pure BG scaffolds and from 67.3% to 58.9% for B₂O₃-doped scaffolds. Meanwhile, their compressive strengths increased from 0.13 to 0.57 MPa and from 0.20 to 0.82 MPa, respectively. After polymer infiltration, 7% B₂O₃-incorporated BG scaffolds had higher weight loss and Ca-P layer deposition than pure BG scaffolds, after 14 d of incubation in simulated body fluid at 37 °C. Higher attachment and proliferation of hDPSCs were observed on 7% B₂O₃-BG-CA/GE scaffolds. In addition, the alkaline phosphatase activity of the cells was about 1.25-fold higher in this group than that observed on BG-CA/GE scaffolds after 14 d of incubation in osteogenic medium, while their intracellular calcium amounts were 1.7-fold higher than observed on BG-CA/GE after 7 d of incubation in osteogenic medium. Our results suggested that porous cellulose acetate-gelatin-coated boron-BG scaffolds hold promise for bone tissue engineering applications.

Immunohistochemical analysis of stem cells from human exfoliated deciduous teeth seeded in carbonate apatite scaffold for the alveolar bone defect in Wistar rats ( Rattus novergicus)

Background: Stem cells from human exfoliated deciduous teeth (SHED) seeded in carbonate apatite scaffold (CAS) may have multiple functions that could be used to regenerate the alveolar bone defects. The purpose of this study is to examine the ability of SHED and CAS in alveolar bone defects using an immunohistochemical analysis. Methods: ten three-month-old healthy male Wistar rats (R. novergicus) that weighed between 150-250 grams (g) were used as animal models. A simple blind random sampling method was used to select the sample that was assigned to the study group for CAS and SHED seeded in CAS (n=5). The animal study model of the alveolar bone was established by extracting the anterior mandible teeth. Rodent anesthesia was applied to relieve the pain during the procedure for all test animals. Immunohistochemistry was performed after seven days to facilitate the examination of the receptor activator of NF-κβ ligand (RANKL), osteoprotegrin (OPG), transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin, and osteopontin expression. The data was analyzed using the unpaired t-test (p<0.01) and Pearson's correlation test (p<0.05). Results: The OPG, RUNX2, TGF-β, VEGF, ALP, osteocalcin, and ostepontin expressions were higher in SHED seeded in CAS than CAS only with a significant difference between the groups (p<0.01). Furthermore, the RANKL expression was lower in SHED seeded in CAS compared to CAS only. There was a strong reverse significant correlation between OPG and RANKL expression (p<0.05). Conclusions: The number of osteogenic marker expressing cells, such as OPG, RUNX2, TGF-β, VEGF, ALP, osteocalcin, and ostepontin, increased. However, RANKL expression in the alveolar bone defects that were implanted with SHED seeded in CAS did not increase after seven days.

Mesenchymal Stromal Cell Immunology for Efficient and Safe Treatment of Osteoarthritis

Mesenchymal stem cell (MSC) therapy represents a promising approach for the treatment of osteoarthritis (OA). MSCs can be readily isolated from multiple sources and expanded ex vivo for possible clinical application. They possess a unique immunological profile and regulatory machinery that underline their therapeutic effects. They also have the capacity to sense the changes within the tissue environment to display the adequate response. Indeed, there is a close interaction between MSCs and the host cells. Accordingly, MSCs demonstrate encouraging results for a variety of diseases including OA. However, their effectiveness needs to be improved. In this review, we selected to discuss the importance of the immunological features of MSCs, including the type of transplantation and the immune and blood compatibility. It is important to consider MSC immune evasive rather than immune privileged. We also highlighted some of the actions/mechanisms that are displayed during tissue healing including the response of MSCs to injury signals, their interaction with the immune system, and the impact of their lifespan. Finally, we briefly summarized the results of clinical studies reporting on the application of MSCs for the treatment of OA. The research field of MSCs is inspiring and innovative but requires more knowledge about the immunobiological properties of these cells. A better understanding of these features will be key for developing a safe and efficient medicinal product for clinical use in OA.

Biopolymers-calcium phosphate antibacterial coating reduces the pathogenicity of internalized bacteria by mesenchymal stromal cells

A multifunctional material system that kills bacteria and drives bone healing is urgently sought to improve bone prosthesis. Herein, the osteoinductive coating made of calcium phosphate/chitosan/hyaluronic acid, named Hybrid, was proposed as an antibacterial substrate for stromal cell adhesion. This Hybrid coating possesses a contact-killing effect reducing by 90% the viability of Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) strains after 48 h of contact. In addition to the production of immunomodulatory mediators, Wharton's jelly (WJ-SCs), dental pulp (DPSCs) and bone marrow (BM-MSCs) derived stromal cells were able to release antibacterial and antibiofilm agents effective against S. aureus and P. aeruginosa strains, respectively. Studying the effect of the Hybrid coating on the internalization of S. aureus by the stromal cells, in acute-mimicking bone infection, highlighted an increase in the bacteria internalization by DPSCs and BM-MSCs when cultured on the Hybrid coating versus uncoated glass. Despite the internalization, Hybrid coating showed a beneficial effect by reducing the pathogenicity of the internalized bacteria. The formation of biofilm was reduced by at least 50% in comparison to internalized bacteria by stromal cells on uncoated glass. This work opens the route for the development of innovative antibacterial coatings by taking into account the internalization of bacteria by stromal cells.

Superior CKIP-1 sensitivity of orofacial bone-derived mesenchymal stem cells in proliferation and osteogenic differentiation compared to long bone-derived mesenchymal stem cells

Maxillofacial bone defects caused by multiple factors, including congenital deformations and tumors, have become a research focus in the field of oral medicine. Bone tissue engineering is increasingly regarded as a potential approach for maxillofacial bone repair. Mesenchymal stem cells (MSCs) with different origins display various biological characteristics. The aim of the present study was to investigate the effects of casein kinase‑2 interaction protein‑1 (CKIP‑1) on MSCs, including femoral bone marrow‑derived MSCs (BMMSCs) and orofacial bone‑derived MSCs (OMSCs), isolated from the femoral and orofacial bones of wild‑type (WT) and CKIP‑1 knockout (KO) mice. MSCs were isolated using collagenase II and the main biological characteristics, including proliferation, apoptosis and osteogenic differentiation, were investigated. Subcutaneous transplantation of MSCs in mice was also performed to assess ectopic bone formation. MTT and clone formation assay results indicated that cell proliferation in the KO group was increased compared with the WT group, and OMSCs exhibited significantly increased levels of proliferation compared with BMMSCs. However, the proportion of apoptotic cells was not significantly different between CKIP‑1 KO OMSCs and BMMSCs. Furthermore, it was revealed that osteogenic differentiation was increased in CKIP‑1 KO MSCs compared with WT MSCs, particularly in OMSCs. Consistent with the in vitro results, enhanced ectopic bone formation was observed in CKIP‑1 KO mice compared with WT mice, particularly in OMSCs compared with BMMSCs. In conclusion, the present results indicated that OMSCs may have a superior sensitivity to CKIP‑1 in promoting osteogenesis compared with BMMSCs; therefore, CKIP‑1 KO in OMSCs may serve as an efficient strategy for maxillofacial bone repair.

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.

LncRNA CALB2 sponges miR-30b-3p to promote odontoblast differentiation of human dental pulp stem cells via up-regulating RUNX2

Illuminating the mechanisms of odontoblast differentiation of human dental pulp stem cells (hDPSCs) is the key to find therapeutic clues to promote odontogenesis. LncRNAs play a regulatory role in odontoblast differentiation. Here, we identified a novel lncRNA, named lncRNA CALB2. It was up-regulated in odontoblast-differentiated hDPSCs and potentially interacted with miR-30b-3p and RUNX2. Via gain- and loss-of-function approaches, we found lncRNA CALB2 significantly promoted the odontoblast differentiation of hDPSCs. Then, dual luciferase reporter assay and RNA immunoprecipitation assay revealed that both lncRNA CALB2 and RUNX2 mRNA could directly bind to miR-30b-3p via the same binding sites. Interestingly, miR-30b-3p in hDPSCs was down-regulated and RUNX2 was up-regulated during odontoblast differentiation. Moreover, lncRNA CALB2 knockdown significantly reduced the protein level of RUNX2, DSPP and DMP-1, while miR-30b-3p inhibitor rescued the reduction. Furthermore, miR-30b-3p exerted an inhibitory effect on odontoblast differentiation, which could be reversed by lncRNA CALB2. Collectively, these findings indicate that the newly identified lncRNA CALB2 acts as a miR-30b-3p sponge to regulate RUNX2 expression, thus promoting the odontoblast differentiation of hDPSCs. LncRNA CALB2/miR-30b-3p/RUNX2 axis could be a novel therapeutic target for accelerating odontogenesis.

LncRNA H19 promotes odontoblastic differentiation of human dental pulp stem cells by regulating miR-140-5p and BMP-2/FGF9

BACKGROUND

Increasing evidence has revealed that long non-coding RNAs (lncRNAs) exert critical roles in biological mineralization. As a critical process for dentin formation, odontoblastic differentiation is regulated by complex signaling networks. The present study aimed to investigate the biological role and regulatory mechanisms of lncRNA-H19 (H19) in regulating the odontoblastic differentiation of human dental pulp stem cells (hDPSCs).

METHODS

We performed lncRNA microarray assay to reveal the expression patterns of lncRNAs involved in odontoblastic differentiation. H19 was identified and verified as a critical factor by qRT-PCR. The gain- and loss-of-function studies were performed to investigate the biological role of H19 in regulating odontoblastic differentiation of hDPSCs in vitro and in vivo. Odontoblastic differentiation was evaluated through qRT-PCR, Western blot, and Alizarin Red S staining. Bioinformatics analysis identified that H19 could directly interact with miR-140-5p, which was further verified by luciferase reporter assay. After overexpression of miR-140-5p in hDPSCs, odontoblastic differentiation was determined. Moreover, the potential target genes of miR-140-5p were investigated and the biological functions of BMP-2 and FGF9 in hDPSCs were verified. Co-transfection experiments were conducted to validate miR-140-5p was involved in H19-mediated odontoblastic differentiation in hDPSCs.

RESULTS

The expression of H19 was significantly upregulated in hDPSCs undergoing odontoblastic differentiation. Overexpression of H19 stimulated odontoblastic differentiation in vitro and in vivo, whereas downregulation of H19 revealed the opposite effect. H19 binds directly to miR-140-5p and overexpression of miR-140-5p inhibited odontoblastic differentiation of hDPSCs. H19 acted as a miR-140-5p sponge, resulting in regulated the expression of BMP-2 and FGF9. Overexpression of H19 abrogated the inhibitory effect of miR-140-5p on odontoblastic differentiation.

CONCLUSION

Our data revealed that H19 plays a positive regulatory role in odontoblastic differentiation of hDPSCs through miR-140-5p/BMP-2/FGF9 axis, suggesting that H19 may be a stimulatory regulator of odontogenesis.

Osteogenic and odontogenic differentiation potential of dental pulp stem cells isolated from inflamed dental pulp tissues (I-DPSCs) by two different methods

Objective: The objective of the present study is to isolate stem cells from inflamed dental pulp tissues (I-DPSCs) and study the characteristic such as surface markers, osteo/odontogenic differentiation potential between the outgrowth (OG) and enzymatic digestion (COL) methods.Materials and methods: I-DPSCs harvested by both methods were analysed for Mesenchymal Stem Cell marker expression by flow cytometry. The metabolic activity of the isolated cells was assessed by MTT assay. The Alkaline Phosphatase (ALP) and Alizarin red staining was done to analyse the osteogenic potential of isolated cells. The osteo/odontogenic differentiation was done by checking the expression of Dentine Matrix Protein 1 (DMP1), Dentine Sialophosphoprotein (DSPP), ALP and Bone Gamma-Carboxyglutamate Protein (BGLAP) by Real time PCR.Results: The isolated cells were positive for MSC markers such as CD-90, CD-105 and CD-73 and negative for CD-14, CD-45 and STRO-1. MTT assay indicated that the I-DPSCs from OG method showed higher metabolic activity than cells from COL. However, the osteo/odontogenic differentiation was in favour of cells isolated by COL method.Conclusion: Although the cell metabolic rate was more in OG, the osteo/odontogenic differentiation was higher in COL, suggesting that the isolation method and culture conditions do affect the differentiation capacity of isolated cells.

Effect of parathyroid hormone-related protein on odontogenic differentiation in human dental pulp cells

BACKGROUND

Parathyroid hormone-related protein (PTHrP) plays an important role in many physiological processes, including bone regeneration. The function of PTHrP is similar to PTH. It promotes osteogenic differentiation in MC3T3-E1 cells. The aim of this study was to investigate whether PTHrP might have odontogenic differentiation ability in human dental pulp cells (hDPCs).

METHODS

The viability of hDPCs after stimulation with PTHrP was measured. Real-time polymerase chain reaction and Western blot analysis were performed to evaluate the expression levels of odontogenic markers and activation of protein kinase B (PKB/AKT), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK). To evaluate mineralized nodule formation, alkaline phosphatase (ALP) staining and alizarin red S staining were performed.

RESULTS

PTHrP promoted odontogenic differentiation as evidenced by the formation of mineralized nodules, the induction of ALP activity, and the upregulation of odontogenic markers (dentin sialophosphoprotein and dentin matrix protein-1). The phosphorylation of AKT, ERK, JNK, and p38 was increased by PTHrP. However, an AKT inhibitor (LY294002), an ERK inhibitor (U0126), a JNK inhibitor (SP600125), and a p38 inhibitor (SB203580) inhibited the increase of mineralization induced by PTHrP.

CONCLUSION

The present study revealed that PTHrP could promote odontogenic differentiation and mineralization through activating the AKT, ERK, JNK, and p38 signaling pathways. These results provide novel insights into the odontogenic action of PTHrP.

Controlled release of basic fibroblast growth factor from a peptide biomaterial for bone regeneration

Self-assembled peptide scaffolds based on D-RADA16 are an important matrix for controlled drug release and three-dimensional cell culture. In this work, D-RADA16 peptide hydrogels were coated on artificial bone composed of nano-hydroxyapatite/polyamide 66 (nHA/PA66) to obtain a porous drug-releasing structure for treating bone defects. The developed materials were characterized via transmission electron microscopy and scanning electron microscopy. The proliferation and adhesion of bone mesenchymal stem cells (BMSCs) were examined by confocal laser microscopy and CCK-8 experiments. The osteogenic ability of the porous materials towards bone BMSCs was examined in vitro by staining with Alizarin Red S and alkaline phosphatase, and bioactivity was evaluated in vivo. The results revealed that nHA/PA66/D-RADA16/bFGF reduces the degradation rate of D-RADA16 hydrogels and prolongs sustained release of bFGF, which would promote BMSCs proliferation, adhesion and osteogenesis in vitro and bone repair in vivo. Thus, it deserves more attention and is worthy of further research.

Calcium phosphate enriched synthetic tyrosine-derived polycarbonate - dicalcium phosphate dihydrate polymer scaffolds for enhanced bone regeneration

Optimal repair of large craniomaxillofacial (CMF) defects caused by trauma or disease requires the development of new, synthetic osteoconductive materials in combination with cell-based therapies, to overcome the limitations of traditionally used bone graft substitutes. In this study, tyrosine-derived polycarbonate, E1001(1k) scaffolds were fabricated to incorporate the osteoinductive coating, Dicalcium phosphate dihydrate (DCPD). The biocompatibility of E1001(1k)-DCPD, E1001(1k)-βTCP and E1001(1k) scaffolds was compared using in vitro culture with human dental pulp stem cells (hDPSCs). We found that the DCPD coating was converted to carbonated hydroxyapatite over time in in vitro culture in Osteogenic Media, while the βTCP did not. hDPSCs exhibited slow initial attachment and proliferation on DCPD E1001(1k) scaffolds, but subsequently improved over time in culture, and promoted osteogenic differentiation. To the best of our knowledge, this study highlights for the first time the effects of Osteogenic Media on phase changes of DCPD, and on DCPD scaffold cytocompatibility with hDPSCs. DCPD showed similar hDPSC biocompatibility and osteoconductivity as compared to βTCP, and osteogenic differentiation of seeded hDPSCs. These studies suggest that E1001(1k)-DCPD scaffolds are a superior tool for craniofacial bone regeneration and provide the foundation for future in vivo testing.

Mesenchymal Stem Cells from Human Exfoliated Deciduous Teeth and the Orbicularis Oris Muscle: How Do They Behave When Exposed to a Proinflammatory Stimulus?

Mesenchymal stem cells (MSCs) have been studied as a promising type of stem cell for use in cell therapies because of their ability to regulate the immune response. Although they are classically isolated from the bone marrow, many studies have sought to isolate MSCs from noninvasive sources. The objective of this study was to evaluate how MSCs isolated from the dental pulp of human exfoliated deciduous teeth (SHED) and fragments of the orbicularis oris muscle (OOMDSCs) behave when treated with an inflammatory IFN-γ stimulus, specifically regarding their proliferative, osteogenic, and immunomodulatory potentials. The results demonstrated that the proliferation of SHED and OOMDSCs was inhibited by the addition of IFN-γ to their culture medium and that treatment with IFN-γ at higher concentrations resulted in a greater inhibition of the proliferation of these cells than treatment with IFN-γ at lower concentrations. SHED and OOMDSCs maintained their osteogenic differentiation potential after stimulation with IFN-γ. Additionally, SHED and OOMDSCs have been shown to have low immunogenicity because they lack expression of HLA-DR and costimulatory molecules such as CD40, CD80, and CD86 before and after IFN-γ treatment. Last, SHED and OOMDSCs expressed the immunoregulatory molecule HLA-G, and the expression of this antigen increased after IFN-γ treatment. In particular, an increase in intracellular HLA-G expression was observed. The results obtained suggest that SHED and OOMDSCs lack immunogenicity and have immunomodulatory properties that are enhanced when they undergo inflammatory stimulation with IFN-γ, which opens new perspectives for the therapeutic use of these cells.

Systematic Review of Human Dental Pulp Stem Cells for Cartilage Regeneration

Background: Symptomatic cartilage lesions and early osteoarthritis produce significant clinical and economic burdens. Cartilage repair can improve the symptoms and delay arthroplasty. The complete healing of damaged cartilage with the consistent reproduction of normal hyaline cartilage has not yet been achieved. The choice of harvesting site might influence the cells' abilities to modulate immunologic and inflammatory responses. Recently, dental pulp has been shown to contain a stem cell niche consisting of dental pulp stem cells (DPSCs) that maintain their self-renewal capacity due to the active environment in the dental pulp of deciduous teeth. Objective: The aim of this study was to critically review the current literature on the potential and limitations of the use of dental pulp-derived mesenchymal stem cells in cell-based therapies for cartilage regeneration. Methods: An electronic, customized search of scientific articles was conducted using the PubMed/MEDLINE and EMBASE databases from their inception to December 2018. The inclusion criteria were applied, and the articles that described the use of DPSC in cartilage treatment were selected for complete evaluation. The articles were classified according to the scaffold used, experimental model, chondrogenic differentiation features, defect location, cartilage evaluation, and results. After the application of the eligibility criteria, a total of nine studies were selected and fully analyzed. Results: A variety of animal models were used, including mice, rats, rabbits, and miniature pigs, to evaluate the quality and safety of human DPSCs in the repair of cartilage defects. Among the articles, two studies focused on preclinical models of cartilage tissue engineering. Five studies implanted DPSCs in other animal sites. Conclusion: The use of DPSCs is a potential new stem cell therapy for articular cartilage repair. The preclinical evidence discussed in this article provides a solid foundation for future clinical trials. Impact statement Osteoarthritis presents an ever-increasing clinical and socioeconomic burden. While cartilage repair has the potential to improve symptoms and delay joint replacement, complete regeneration of hyaline cartilage has been an elusive goal. Dental pulp has been shown to contain a niche that protects dental pulp stem cells (DPSCs) from the cumulative effects of genetic and environmental factors and maintains their self-renewal capacity due to the active environment. Transplantation and preclinical trials have demonstrated the strong potential of regenerative tissue-engineering protocols using DPSCs.

Evaluation of growth, stemness, and angiogenic properties of dental pulp stem cells cultured in cGMP xeno-/serum-free medium

This study was aimed to investigate the effects of cGMP xeno-/serum-free medium (XSF, Irvine Scientific) on the properties of human dental pulp stem cells (DPSCs). DPSCs, from passage 2, were cultured in XSF or fetal bovine serum (FBS)-supplemented medium, and sub-cultured up to passage 8. Cumulative population doublings (PDs) and the number of colony-forming-units (CFUs) were determined. qRT-PCR, ELISA, and in vitro assays were used to assess angiogenic capacity. Flow cytometry was used to measure CD73, CD90, and CD105 expression. Differentiation into osteo-, adipo-, and chondrogenic cell lineages was performed. DPSCs showed more elongated morphology, a reduced rate of proliferation at later passages, and lower CFU counts in XSF compared with FBS. Expression of angiogenic factors at the gene and protein levels varied in the two media and with passage number, but cells grown in XSF had more in vitro angiogenic activity. The majority of early and late passage DPSCs cultured in XSF expressed CD73 and CD90. In contrast, the percentage of CD105 positive DPSCs in XSF medium was significantly lower with increased passage whereas the majority of cells cultured in FBS were CD105 positive. Switching XSF-cultured DPSCs to medium supplemented with human serum restored the expression of CD105. The tri-lineage differentiation of DPSCs cultured under XSF and FBS conditions was similar. We showed that despite reduced CD105 expression levels, DPSCs expanded in XSF medium maintained a functional MSC phenotype. Furthermore, restoration of CD105 expression is likely to occur upon in vivo transplantation, when cells are exposed to human serum.