Bone repair by periodontal ligament stem cellseeded nanohydroxyapatite-chitosan scaffold

Osteogenic Differentiation and Proliferation of Apical Papilla Stem Cells Using Chitosan-Coated Nanohydroxyapatite and Bioactive Glass Nanoparticles

OBJECTIVE

 The aim of this study was to evaluate the osteogenic differentiation ability and proliferation of apical papilla stem cells (SCAPs) using chitosan-coated nanohydroxyapatite and bioactive glass nanoparticles.

MATERIALS AND METHODS

 Hydroxyapatite, chitosan-coated nanohydroxyapatite, and bioactive glass 45S5 nanoparticles were prepared and characterized using a transmission electron microscope and X-ray diffraction. SCAPs were harvested from freshly extracted impacted wisdom teeth, cultured, and characterized using flow cytometric analysis. Tested nanomaterials were mixed and samples were classified into five equal groups as follows: negative control group: SCAP with Dulbecco's modified eagle's medium, positive control group: SCAP with inductive media, first experimental group: nanohydroxyapatite with SCAP, second experimental group: chitosan-coated nanohydroxyapatite with SCAP, third experimental group: bioactive glass nanoparticles with SCAP. Osteoblastic differentiation was assessed using an alkaline phosphatase (ALP) assay. Receptor activator of nuclear factor kappa beta ligand (RANKL) expression was evaluated using specific polyclonal antibodies by fluorescence microscope. The proliferation of SCAP was assessed using cell count and viability of trypan blue in addition to an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

RESULTS

 Isolated SCAP showed a nonhematopoietic origin. Chitosan-coated nanohydroxyapatite showed the highest ALP concentration followed by nanobioactive glass, nanohydroxyapatite, and negative control. Chitosan-coated nanohydroxyapatite showed the highest H score followed by nanobioactive glass, nanohydroxyapatite, and negative control in RANKL expression. Chitosan-coated nanohydroxyapatite showed the highest viable cell count.

CONCLUSION

 SCAP isolation is achievable from extracted fully impacted immature third molars. All tested biomaterials have the ability to induce osteogenic differentiation and proliferation of SCAP. Composite nanoparticle materials show better osteogenic differentiation and proliferation of SCAP than single nanoparticles.

Effects of Improper Mechanical Force on the Production of Sonic Hedgehog, RANKL, and IL-6 in Human Periodontal Ligament Cells In Vitro

Improper mechanical stress may induce side effects during orthodontic treatment. If the roots and alveolar bones are extensively resorbed following excess mechanical stress, unplanned tooth mobility and inflammation can occur. Although multiple factors are believed to contribute to the development of side effects, the cause is still unknown. Sonic hedgehog (Shh), one of the hedgehog signals significantly associated with cell growth and cancer development, promotes osteoclast formation in the jawbone. Shh may be associated with root and bone resorptions during orthodontic treatment. In this study, we investigated the relationships between Shh, RANKL, and IL-6 in human periodontal ligament (hPDL) cells exposed to improper mechanical force. Weights were placed on hPDL cells and human gingival fibroblasts (HGFs) for an optimal orthodontic force group (1.0 g/cm2) and a heavy orthodontic force group (4.0 g/cm2). A group with no orthodontic force was used as a control group. Real-time PCR, SDS-PAGE, and Western blotting were performed to examine the effects of orthodontic forces on the expression of Shh, RANKL, and IL-6 at 2, 4, 6, 8, 12, and 24 h after the addition of pressure. The protein expression of Shh was not clearly induced by orthodontic forces of 1.0 and 4.0 g/cm2 compared with the control in HGFs and hPDL cells. In contrast, RANKL and IL-6 gene and protein expression was significantly induced by 1.0 and 4.0 g/cm2 in hPDL cells for forces lasting 6~24 h. However, neither protein was expressed in HGFs. RANKL and IL-6 expressions in response to orthodontic forces and in the control were clearly inhibited by Shh inhibitor RU-SKI 43. Shh did not directly link to RANKL and IL-6 for root and bone resorptions by orthodontic force but was associated with cell activities to be finally guided by the production of cytokines in hPDL cells.

Alveolar ridge preservation in rat tooth extraction model by chitosan-derived epigenetic modulation scaffold

PURPOSE

Alveolar ridge preservation is a surgical technique used to prevent dimensional changes in the alveolar bone by dressing biomaterials in the extraction socket. Recently, a chitosan biphasic calcium phosphate loaded with trichostatin A (CS/BCP/TSA) scaffold was introduced as an excellent bone-regeneration material. This study aimed to explore the biological properties of released trichostatin A (TSA) and evaluate the potential of the CS/BCP/TSA scaffold in preserving the alveolar ridge in a rat tooth extraction model.

METHODS

In vitro biocompatibility, histone deacetylase (HDAC) activity, and osteogenic differentiation of MC3T3-E1 cells were tested. For in vivo studies, the maxillary first molars (M1) of Wistar rats were extracted, and alveolar ridge preservation was performed using a CS/BCP/TSA scaffold or commercial bone graft. Micro-Computed Tomography (micro-CT), polyfluorochrome labeling, and histological analysis were used to evaluate the ridge-preservation ability.

RESULTS

The released TSA was cytocompatible. Inhibition of histone deacetylase (HDAC) activity and induction of osteogenic differentiation in MC3T3-E1 cells were confirmed. The socket dressing with the CS/BCP/TSA scaffold showed increased socket bone fill and preserved the buccal and middle aspects of the alveolar ridge compared with the conventional graft. Further analysis of the bone regeneration ability by histomorphometric and histological analyses demonstrated that CS/BCP/TSA showed a significantly higher potential to induce bone formation and complete healing in the extraction socket than the other groups.

CONCLUSIONS

The CS/BCP/TSA scaffold is a novel candidate for alveolar ridge preservation.

Stem Cells in the Periodontium-Anatomically Related Yet Physiologically Diverse

Periodontitis is a complex chronic disease discernible by the deterioration of periodontal tissue. The goal of periodontal therapy is to achieve complete tissue regeneration, and one of the most promising treatment options is to harness the regenerative potential of stem cells available within the periodontal complex. Periodontal ligament stem cells, gingival mesenchymal stem cells, oral periosteal stem cells, and dental follicle stem cells have structural similarities, but their immunological responses and features differ. The qualities of diverse periodontal stem cells, their immune-modulatory effects, and variances in their phenotypes and characteristics will be discussed in this review. Although there is evidence on each stem cell population in the periodontium, understanding the differences in markers expressed, the various research conducted so far on their regenerative potential, will help in understanding which stem cell population will be a better candidate for tissue engineering. The possibility of selecting the most amenable stem cell population for optimal periodontal regeneration and the development and current application of superior tissue engineering treatment options such as autologous transplantation, three-dimensional bioengineered scaffolds, dental stem cell-derived extracellular vesicles will be explored.

The Osteogenic Role of Biomaterials Combined with Human-Derived Dental Stem Cells in Bone Tissue Regeneration

The use of stem cells in regenerative medicine had great potential for clinical applications. However, cell delivery strategies have critical importance in stimulating the differentiation of stem cells and enhancing their potential to regenerate damaged tissues. Different strategies have been used to investigate the osteogenic potential of dental stem cells in conjunction with biomaterials through in vitro and in vivo studies. Osteogenesis has a broad implication in regenerative medicine, particularly for maxillofacial defects. This review summarizes some of the most recent developments in the field of tissue engineering using dental stem cells.

Investigation on mechanical properties of AZ31B magnesium alloy manufactured by stir casting process

- Nanocomposites of AZ31B with varying compositions of nano-hydroxyapatite and nano alumina were cast by the stir casting process. The primary goal of this research is to investigate and assess if it is feasible to fabricate magnesium metal matrix nano-composites (MMNCs) utilizing the stir casting process for biomedical applications. In this study AZ31B used as matrix and nano alumina (Al2O3) and nano hydroxyapatite (nHA) as a reinforcement. Due to its low weight as a structural metal and excellent strength-to-weight ratio, magnesium is commonly employed in engineering designs in addition to the development of composite materials. Mg alloys are widely used in biomedical due to their lower density. The Brinell hardness test was conducted to examine materials made by casting and forging processes that have a structure which is too coarse or rough for another test. It was observed that AZ31B-5nHa among the others has the highest hardness number. Compression tests were conducted to check the behavior of the MMNC under an applied load. AZ31B-0.5(Al2O3)-0.3nHa among the others has the highest compressive strength. It was observed that adding nHA reinforcement in AZ31B affects the microstructure and mechanical characteristics of a nanocomposite made of magnesium metal matrix, including compressive strength, hardness, corrosion resistance and biocompatibility. This study aims to investigate the effects of reinforcement on a magnesium metal matrix nanocomposite's microstructure and mechanical properties.

A Novel Perspective on Tissue Engineering Potentials of Periodontal Ligament Stem Cells

It is challenging to completely and predictably regenerate the missing periodontal tissues caused by the trauma or disease. To regenerate the periodontium, there is a need to consider several aspects that co-occur with periodontal development. This study provides an overview of the most up-to-date investigations on the characteristics and immunomodulatory features of Periodontal Ligament Stem Cells (PDLSCs) and the recent interventions performed using these cells, focusing on cell survival, proliferation, and differentiation. Keeping in mind the relationship between age and potency of PDLSCs, this work also demonstrates the necessity of establishing dental-derived stem cell banks for tissue regeneration applications. The data were collected from Pubmed and Google Scholar databases with the keywords of periodontal ligament stem cells, tissue engineering, characteristics, and stem cell therapy. The results showed the presence of wide-ranging research reports supporting the usability of PDLSCs for periodontal reconstruction. However, a better understanding of self-restoration for adequate regulation of adult stem cell growth is needed for various applied purposes.

Periodontal ligament stem cell-based bioactive constructs for bone tissue engineering

Objectives: Stem cell-based tissue engineering approaches are promising for bone repair and regeneration. Periodontal ligament stem cells (PDLSCs) are a promising cell source for tissue engineering, especially for maxillofacial bone and periodontal regeneration. Many studies have shown potent results via PDLSCs in bone regeneration. In this review, we describe recent cutting-edge researches on PDLSC-based bone regeneration and periodontal tissue regeneration. Data and sources: An extensive search of the literature for papers related to PDLSCs-based bioactive constructs for bone tissue engineering was made on the databases of PubMed, Medline and Google Scholar. The papers were selected by three independent calibrated reviewers. Results: Multiple types of materials and scaffolds have been combined with PDLSCs, involving xeno genic bone graft, calcium phosphate materials and polymers. These PDLSC-based constructs exhibit the potential for bone and periodontal tissue regeneration. In addition, various osteo inductive agents and strategies have been applied with PDLSCs, including drugs, biologics, gene therapy, physical stimulation, scaffold modification, cell sheets and co-culture. Conclusoin: This review article demonstrates the great potential of PDLSCs-based bioactive constructs as a promising approach for bone and periodontal tissue regeneration.

Challenges of Periodontal Tissue Engineering: Increasing Biomimicry through 3D Printing and Controlled Dynamic Environment

In recent years, tissue engineering studies have proposed several approaches to regenerate periodontium based on the use of three-dimensional (3D) tissue scaffolds alone or in association with periodontal ligament stem cells (PDLSCs). The rapid evolution of bioprinting has sped up classic regenerative medicine, making the fabrication of multilayered scaffolds-which are essential in targeting the periodontal ligament (PDL)-conceivable. Physiological mechanical loading is fundamental to generate this complex anatomical structure ex vivo. Indeed, loading induces the correct orientation of the fibers forming the PDL and maintains tissue homeostasis, whereas overloading or a failure to adapt to mechanical load can be at least in part responsible for a wrong tissue regeneration using PDLSCs. This review provides a brief overview of the most recent achievements in periodontal tissue engineering, with a particular focus on the use of PDLSCs, which are the best choice for regenerating PDL as well as alveolar bone and cementum. Different scaffolds associated with various manufacturing methods and data derived from the application of different mechanical loading protocols have been analyzed, demonstrating that periodontal tissue engineering represents a proof of concept with high potential for innovative therapies in the near future.

Calcium Orthophosphate (CaPO4)-Based Bioceramics: Preparation, Properties, and Applications

Various types of materials have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A short time later, such synthetic biomaterials were called bioceramics. Bioceramics can be prepared from diverse inorganic substances, but this review is limited to calcium orthophosphate (CaPO4)-based formulations only, due to its chemical similarity to mammalian bones and teeth. During the past 50 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the CaPO4-based implants would remain biologically stable once incorporated into the skeletal structure or whether they would be resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed, and such formulations became an integrated part of the tissue engineering approach. Now, CaPO4-based scaffolds are designed to induce bone formation and vascularization. These scaffolds are usually porous and harbor various biomolecules and/or cells. Therefore, current biomedical applications of CaPO4-based bioceramics include artificial bone grafts, bone augmentations, maxillofacial reconstruction, spinal fusion, and periodontal disease repairs, as well as bone fillers after tumor surgery. Prospective future applications comprise drug delivery and tissue engineering purposes because CaPO4 appear to be promising carriers of growth factors, bioactive peptides, and various types of cells.

Comparison of Osteoblastic Differentiation of Human Periodontal Ligament Stem Cells through Application of Two β-tricalcium Phosphate Products: An in vitro Study

Statement of the Problem

Osteoblastic differentiation of periodontal ligament stem cells (PLSCs) is essential for alveolar bone regeneration.

Purpose

The purpose of this study was to compare the potential of two β-tricalcium phosphate (βTCP) products to induce osteoblastic differentiation of human PLSCs.

Materials and Method

In this in vitro study, human PLSCs were cultured in mediums supplemented with Guidor Easy-Graft [βTCP+polylactide-co-glycolide (PLCG)+n-methyl-2-pyrrolidone (NMP)] [Sunstar Company, Swiss] or Sorbone [βTCP] [Meta Company, South Korea] as two alloplasts experimental groups, mesenchymal cells differentiated into osteoblasts without alloplast as positive control group, and mesenchymal cells without osteoblastic induction as negative control group. Osteoblastic differentiation was evaluated using Alizarine Red staining and spectrophotometry to assay calcium deposits and real-time polymerase chain reaction to examine expression of alkaline phosphatase (ALP) and osteopontin (OPN) antigens on day 21. Data were analyzed by using SPSS 22 software and one-way ANOVA and Bonferoni tests (p< 0.05).

Results

Spectrophotometry confirmed that calcium deposits were higher in Guidor Easy-Graft group compared to Sorbone group (p< 0.001) and higher in two experimental groups than controls (p< 0.05). According to real-time polymerase chain reaction, level of ALP expression was higher in Sorbone than Guidor and the levels of Guidor, positive control and negative control were equal; OPN levels of the positive control were more than the other groups. OPN levels of Sobone, Guidor and negative control were the same.

Conclusion

These findings indicated that Guidor Easy-Graft and Sorbone enhanced differentiation of human PLSCs to osteoblasts, and could be employed as appropriate bone-graft materials.

Krüppel-like factor 5 -mediated Sirtuin6 promotes osteogenic differentiation and inhibits inflammatory injury of lipopolysaccharide-induced periodontal membrane stem cells by inhibiting nuclear factor kappa-B pathway

Periodontitis is a chronic infectious disease that causes inflammation and immune response and has an ultimate impact on the health of the whole body. Sirtuin6 (SIRT6) and Krüppel-like factor 5 (KLF5) have been reported to regulate the inflammatory response and play an important role in the development of periodontitis. LPS was adopted to induce periodontal ligament stem cells (PDLSCs) to construct a periodontitis cell model. SIRT6 expression was assayed through RT-qPCR and Western blot. Subsequently, after SIRT6 was overexpressed, CCK8 was to appraise cell viability. ELISA analysis was used to estimate inflammatory response. ALP staining, ARS staining, and Western blot were used to detect osteogenic differentiation. The JASPAR website then predicts the binding of transcription factor KLF5 to SIRT6 promoter. The interaction between KLF5 and SIRT6 was verified by a luciferase reporter and ChIP assays. Additionally, the osteogenic differentiation and inflammation in LPS-induced PDLSCs transfected with Ov-SIRT6 and si-KIF5 were also explored. Finally, the protein levels of the nuclear factor kappa-B (NF-κB) pathway-related factors were detected by Western blot to further explore the mechanism. There was a marked decrease in SIRT6 expression in LPS-induced PDLSCs. SITR6 overexpression prevented LPS-induced cell viability loss and inflammation, while promoting osteogenic differentiation. In addition, KLF5 could transcriptionally activate SIRT6. Further, KLF5 knockdown reversed the impacts of SIRT6 on the proliferation, inflammation, and osteogenic differentiation of LPS-induced PDLSCs via mediating NF-κB pathway. Overall, KLF5-mediated SIRT6 promoted the viability and osteogenic differentiation, while inhibiting the inflammatory response of LPS-induced PDLSCs by inhibiting NF-κB pathway.

A Non-thermal Biocompatible Plasma-Modified Chitosan Scaffold Enhances Osteogenic Differentiation in Bone Marrow Stem Cells

Non-thermal biocompatible plasma (NBP) was considered as an efficient tool in tissue engineering to modify the surface of biomaterials. Three-dimensional chitosan scaffolds have been extensively used in different ways because it holds some remarkable properties, including biodegradability and biocompatibility. In this study, we evaluated the osteogenic potential of NBP-treated chitosan scaffolds using two different plasma sources: a dielectric barrier discharge (NBP-DBD) and a soft jet (NBP-J). The surface modification of the scaffold was evaluated using scanning electron microscopy. For osteogenic differentiation of cells, proliferation and differentiation were tested by using bone marrow-derived stem cells (BMSCs). We observed that cell viability using NBP-DBD and NBP-J treated chitosan scaffolds yielded significant improvements in cell viability and differentiation. The results obtained with MTT and live/dead assays showed that NBP-modified scaffold increases cell metabolic by MTT assay and live/dead assay. It also observed that the NBP treatment is more effective at 5 min with DBD and was selected for further investigations. Enhanced osteogenic differentiation was observed using NBP-treated scaffolds, as reflected by increased alkaline phosphatase activity. Our findings showed that NBP is an innovative and beneficial tool for modifying chitosan scaffolds to increase their activity, making them suitable as biocompatible materials and for bone tissue engineering.

Mesenchymal stem cell-based nanoparticles and scaffolds in regenerative medicine

Mesenchymal stem cells (MSCs) are adult stem cells owing to their regenerative potential and multilineage potency. MSCs have wide-scale applications either in their native cellular form or in conjugation with specific biomaterials as nanocomposites. Majorly, these natural or synthetic biomaterials are being used in the form of metallic and non-metallic nanoparticles (NPs) to encapsulate MSCs within hydrogels like alginate or chitosan or drug cargo loading into MSCs. In contrast, nanofibers of polymer scaffolds such as polycaprolactone (PCL), poly-lactic-co-glycolic acid (PLGA), poly-L-lactic acid (PLLA), silk fibroin, collagen, chitosan, alginate, hyaluronic acid (HA), and cellulose are used to support or grow MSCs directly on it. These MSCs based nanotherapies have application in multiple domains of biomedicine including wound healing, bone and cartilage engineering, cardiac disorders, and neurological disorders. This study focused on current approaches of MSCs-based therapies and has been divided into two major sections. The first section elaborates on MSC-based nano-therapies and their plausible applications including exosome engineering and NPs encapsulation. The following section focuses on the various MSC-based scaffold approaches in tissue engineering. Conclusively, this review mainly focused on MSC-based nanocomposite's current approaches and compared their advantages and limitations for building effective regenerative medicines.

Efficacy of biocompatible trilayers nanofibrous scaffold with/without allogeneic adipose-derived stem cells on class II furcation defects of dogs' model

OBJECTIVE

This study aimed to evaluate the regenerative capacity of a newly-developed polycaprolactone (PCL)-based nanofibrous composite scaffold either alone or in combination with adipose-derived mesenchymal stem cells (ADSCs) as a treatment modality for class II furcation defects.

MATERIALS AND METHODS

After ADSCs isolation and scaffold characterization, the mandibular premolars of adult male mongrel dogs were selected and randomly assigned into three equal groups. In group I, class II furcation defects were surgically induced to the inter-radicular bone. While class II furcation defects of group II were induced as in group I. In addition, the defects were filled with the prefabricated scaffold. Moreover, class II furcation defects of group III were induced as in group II and instead the defects were filled with the prefabricated scaffold seeded with ADSCs. The dogs were sacrificed at 30 days or at 60 days. Periodontal wound healing/regeneration was evaluated by radiological examination using cone beam computed tomography and histologically using ordinary, histochemical, and immunohistochemical staining.

RESULTS

In the two examination periods, group II defects compared to group I, and group III compared to the other groups showed a decrease in defect dimensions radiographically. Histologically, histochemically, and immunohistochemically, they significantly demonstrated better periodontal wound healing/regeneration, predominant collagen type I of newly formed bone and periodontal ligament with a significant increase in the immunoreactivity of vascular endothelial growth factor and osteopontin.

CONCLUSIONS

The newly fabricated nanofibrous scaffold has enhanced periodontal wound healing/regeneration of class II furcation defects with further enhancement achieved when ADSCs seeded onto the scaffold before implantation.

CLINICAL RELEVANCE

The implementation of our newly-developed PCL-based nanofibrous composite scaffolds in class II furcation defect either alone or in conjunction with ADSCs can be considered as a suitable treatment modality to allow periodontal tissues regeneration.

Therapeutic potential of periodontal ligament stem cells

Inflammatory periodontal disease known as periodontitis is one of the most common conditions that affect human teeth and often leads to tooth loss. Due to the complexity of the periodontium, which is composed of several tissues, its regeneration and subsequent return to a homeostatic state is challenging with the therapies currently available. Cellular therapy is increasingly becoming an alternative in regenerative medicine/dentistry, especially therapies using mesenchymal stem cells, as they can be isolated from a myriad of tissues. Periodontal ligament stem cells (PDLSCs) are probably the most adequate to be used as a cell source with the aim of regenerating the periodontium. Biological insights have also highlighted PDLSCs as promising immunomodulator agents. In this review, we explore the state of knowledge regarding the properties of PDLSCs, as well as their therapeutic potential, describing current and future clinical applications based on tissue engineering techniques.

Multidifferentiation potential of dental-derived stem cells

Tooth-related diseases and tooth loss are widespread and are a major public health issue. The loss of teeth can affect chewing, speech, appearance and even psychology. Therefore, the science of tooth regeneration has emerged, and attention has focused on tooth regeneration based on the principles of tooth development and stem cells combined with tissue engineering technology. As undifferentiated stem cells in normal tooth tissues, dental mesenchymal stem cells (DMSCs), which are a desirable source of autologous stem cells, play a significant role in tooth regeneration. Researchers hope to reconstruct the complete tooth tissues with normal functions and vascularization by utilizing the odontogenic differentiation potential of DMSCs. Moreover, DMSCs also have the ability to differentiate towards cells of other tissue types due to their multipotency. This review focuses on the multipotential capacity of DMSCs to differentiate into various tissues, such as bone, cartilage, tendon, vessels, neural tissues, muscle-like tissues, hepatic-like tissues, eye tissues and glands and the influence of various regulatory factors, such as non-coding RNAs, signaling pathways, inflammation, aging and exosomes, on the odontogenic/osteogenic differentiation of DMSCs in tooth regeneration. The application of DMSCs in regenerative medicine and tissue engineering will be improved if the differentiation characteristics of DMSCs can be fully utilized, and the factors that regulate their differentiation can be well controlled.

Characteristics and biologic effects of thermosensitive quercetin-chitosan/collagen hydrogel on human periodontal ligament stem cells

Thermosensitive hydrogels could function as scaffolds and delivery vehicle of natural flavonoids. The current study aimed to investigate effects of chitosan/collagen ratios on properties of thermosensitive beta-glycerophosphate (bGP) chitosan/collagen hydrogels as delivery vehicle of quercetin and then examined effects of quercetin-hydrogels on growth and cell viability of human periodontal ligament stem cells (hPDLSCs). Microstructure and physical, mechanical and antioxidant properties and quercetin release profiles of the hydrogels were investigated. Fourier transform infrared spectroscopy and X-ray powder diffraction analyses were performed to examine gelation process of the hydrogels. Antioxidant assays were conducted to measure antioxidant capacity of quercetin-hydrogels. It was found that bGP-chitosan/collagen hydrogels exhibited porous structures with interconnected pore architecture and could sustain quercetin release. Chitosan content improved well defined porous structure, increased porosity of the hydrogels and decreased releasing rate of quercetin from the hydrogels. The quercetin-bGP-2:1 (wt/wt) chitosan/collagen hydrogels exhibited antioxidant capacity and were able to promote growth of hPDLSCs in a dose dependent manner. In conclusion, the thermosensitive quercetin-bGP-2:1 (wt/wt) chitosan/collagen hydrogel demonstrated optimal properties of scaffolds for bone tissue engineering and sustained release of natural flavonoids. Incorporating quercetin in the chitosan/collagen hydrogel enhanced bioactive microenvironment that supported stem cell encapsulation.

The osteogenic differentiation of human dental pulp stem cells in alginate-gelatin/Nano-hydroxyapatite microcapsules

Background

Microcapsule is considered as a promising 3D microenvironment for Bone Tissue Engineering (BTE) applications. Microencapsulation of cells in an appropriate scaffold not only protected the cells against excess stress but also promoted cell proliferation and differentiation. Through the current study, we aimed to microcapsulate the human Dental Pulp Stem Cells (hDPSCs) and evaluated the proliferation and osteogenic differentiation of those cells by using MTT assay, qRT-PCR, Alkaline phosphatase, and Alizarine Red S.

Results

The SEM results revealed that Alg/Gel microcapsules containing nHA showed a rough and more compact surface morphology in comparison with the Alg/Gel microcapsules. Moreover, the microencapsulation by Alg/Gel/nHA could improve cell proliferation and induce osteogenic differentiation. The cells cultured in the Alg/Gel and Alg/Gel/nHA microcapsules showed 1.4-fold and 1.7-fold activity of BMP-2 gene expression more in comparison with the control group after 21 days. The mentioned amounts for the BMP-2 gene were 2.5-fold and 4-fold more expression for the Alg/Gel and Alg/Gel/nHA microcapsules after 28 days. The nHA, addition to hDPSCs-laden Alg/Gel microcapsule, could up-regulate the bone-related gene expressions of osteocalcin, osteonectin, and RUNX-2 during the 21 and 28 days through the culturing period, too. Calcium deposition and ALP activities of the cells were observed in accordance with the proliferation results as well as the gene expression analysis.

Conclusion

The present study demonstrated that microencapsulation of the hDPSCs inside the Alg/Gel/nHA hydrogel could be a potential approach for regenerative dentistry in the near future.

Graphical abstract

Periodontal Ligament Stem Cells: Regenerative Potency in Periodontium

Periodontium is consisted of root cementum, bone lining the tooth socket, gingiva facing the tooth, and periodontal ligament (PDL). Its primary functions are support of the tooth and protection of tooth, nerve, and blood vessels from injury by mechanical loading. Severe periodontitis induces the destruction of periodontium and results in a significant cause of tooth loss among adults. Unfortunately, conventional therapies such as scaling and root planning are often only palliative. Therefore, the ultimate goal of the treatment for periodontitis is to restore disrupted periodontium to its original shape and function. Tissue engineering refers to the process of combining cells, scaffolds, and signaling molecules for the production of functional tissues to restore, maintain, and improve damaged organs. The discovery of periodontal ligament stem cells (PDLSCs) highlighted the possibility for development of tissue engineering technology-based therapeutics for disrupted periodontium. PDLSCs are a kind of somatic stem cells that show potential to differentiate into multiple cell types and undergo robust clonal self-renewal. Therefore, PDLSCs are considered a highly promising stem cell population for regenerative therapy in periodontium; however, their rarity prevents the progression of basic and clinical researches. In this review, we summarize recent research advancement and accumulated information regarding the self-renewal capacity, multipotency, and immunomodulatory effect of PDLSCs, as well as their contribution to repair and regeneration of periodontium and other tissues. We also discuss the possibility of PDLSCs for clinical application of regenerative medicine and provide an outline of the genetic approaches to overcome the issue about the rarity of PDLSCs.

Nanomaterials for Periodontal Tissue Engineering: Chitosan-Based Scaffolds. A Systematic Review

Introduction. Several biomaterials are used in periodontal tissue engineering in order to obtain a three-dimensional scaffold, which could enhance the oral bone regeneration. These novel biomaterials, when placed in the affected area, activate a cascade of events, inducing regenerative cellular responses, and replacing the missing tissue. Natural and synthetic polymers can be used alone or in combination with other biomaterials, growth factors, and stem cells. Natural-based polymer chitosan is widely used in periodontal tissue engineering. It presents biodegradability, biocompatibility, and biological renewability properties. It is bacteriostatic and nontoxic and has hemostatic and mucoadhesive capacity. The aim of this systematic review is to obtain an updated overview of the utilization and effectiveness of chitosan-based scaffold (CS-bs) in the alveolar bone regeneration process. Materials and Methods. During database searching (using PubMed, Cochrane Library, and CINAHL), 72 items were found. The title, abstract, and full text of each study were carefully analyzed and only 22 articles were selected. Thirteen articles were excluded based on their title, five after reading the abstract, twenty-six after reading the full text, and six were not considered because of their publication date (prior to 2010). Quality assessment and data extraction were performed in the twelve included randomized controlled trials. Data concerning cell proliferation and viability (CPV), mineralization level (M), and alkaline phosphatase activity (ALPA) were recorded from each article Results. All the included trials tested CS-bs that were combined with other biomaterials (such as hydroxyapatite, alginate, polylactic-co-glycolic acid, polycaprolactone), growth factors (basic fibroblast growth factor, bone morphogenetic protein) and/or stem cells (periodontal ligament stem cells, human jaw bone marrow-derived mesenchymal stem cells). Values about the proliferation of cementoblasts (CB) and periodontal ligament cells (PDLCs), the activity of alkaline phosphatase, and the mineralization level determined by pure chitosan scaffolds resulted in lower than those caused by chitosan-based scaffolds combined with other molecules and biomaterials. Conclusions. A higher periodontal regenerative potential was recorded in the case of CS-based scaffolds combined with other polymeric biomaterials and bioceramics (bio compared to those provided by CS alone. Furthermore, literature demonstrated that the addition of growth factors and stem cells to CS-based scaffolds might improve the biological properties of chitosan.

Towards osteogenic differentiation of human dental pulp stem cells on PCL-PEG-PCL/zeolite nanofibrous scaffolds

Presently, tissue engineering has been developed as an effective option in the restoration and repair of tissue defects. One of the tissue engineering strategies is to use both biodegradable scaffolds and stimulating factors for enhancing cell responses. In this study, the effect of zeolite was assessed on cell viability, proliferation, osteo/odontogenic differentiation, and mineralization of human dental pulp stem cells (hDPSCs) cultured on poly (ε-coprolactone) - poly (ethylene glycol)-poly (ε-caprolactone) (PCL-PEG-PCL) nanofibers. For this purpose, PCL-PEG-PCL nanofibrous scaffolds incorporated with zeolite were prepared via electrospinning. Both PCL-PEG-PCL and PCL-PEG-PCL/Zeolite nanofibrous scaffolds revealed bead-less constructions with average diameters of 430 nm and 437 nm, respectively. HDPSCs were transferred to PCL-PEG-PCL nanofibrous scaffolds containing zeolite nanoparticles. Cell adhesion and proliferation of hDPSCs and their osteo/odontogenic differentiation on these scaffolds were evaluated using MTT assay, Alizarin red S staining, and qRT-PCR assay. The results revealed that PCL-PEG-PCL/Zeolite nanofibrous scaffolds could support better cell adhesion, proliferation and osteogenic differentiation of hDPSCs and as such is expected to be a promising scaffold for bone tissue engineering applications.

Mesenchymal stem cells and biologic factors leading to bone formation

BACKGROUND

Physiological bone formation and bone regeneration occurring during bone repair can be considered distinct but similar processes. Mesenchymal stem cells (MSC) and associated biologic factors are crucial to both bone formation and bone regeneration.

AIM

To perform a narrative review of the current literature regarding the role of MSC and biologic factors in bone formation with the aim of discussing the clinical relevance of in vitro and in vivo animal studies.

METHODS

The literature was searched for studies on MSC and biologic factors associated with the formation of bone in the mandible and maxilla. The search specifically targeted studies on key aspects of how stem cells and biologic factors are important in bone formation and how this might be relevant to bone regeneration. The results are summarized in a narrative review format.

RESULTS

Different types of MSC and many biologic factors are associated with bone formation in the maxilla and mandible.

CONCLUSION

Bone formation and regeneration involve very complex and highly regulated cellular and molecular processes. By studying these processes, new clinical opportunities will arise for therapeutic bone regenerative treatments.

Oral Bone Tissue Engineering: Advanced Biomaterials for Cell Adhesion, Proliferation and Differentiation

The advancements made in biomaterials have an important impact on oral tissue engineering, especially on the bone regeneration process. Currently known as the gold standard in bone regeneration, grafting procedures can sometimes be successfully replaced by a biomaterial scaffold with proper characteristics. Whether natural or synthetic polymers, biomaterials can serve as potential scaffolds with major influences on cell adhesion, proliferation and differentiation. Continuous research has enabled the development of scaffolds that can be specifically designed to replace the targeted tissue through changes in their surface characteristics and the addition of growth factors and biomolecules. The progress in tissue engineering is incontestable and research shows promising contributions to the further development of this field. The present review aims to outline the progress in oral tissue engineering, the advantages of biomaterial scaffolds, their direct implication in the osteogenic process and future research directions.

Promotion of osteogenic differentiation by non-thermal biocompatible plasma treated chitosan scaffold

Non-thermal biocompatible plasma (NBP) has recently emerged as an attractive tool for surface modification of biomaterials in tissue engineering. Three dimensional chitosan scaffolds have been widely used in bone tissue engineering due to biodegradable and biocompatible properties. The present study aimed to evaluate osteogenic potential of NBP treated chitosan scaffold. The surface characteristics of scaffolds were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), cell proliferation and differentiation was tested with osteoprogenitor cell line MC3T3-E1. The results show that NBP modified scaffold increase cell metabolic by MTT assay and live/dead assay. More importantly, we evidenced enhancement of osteogenic differentiation on NBP treated scaffolds by an increase of alkaline phosphatase (ALP) activity, high degree of extracellular mineralization and up-regulated osteogenic marker genes expression level. The findings in our study highlighted NBP as the innovative method to modified chitosan scaffold and to fine-tuning the scaffold a more suitable and beneficial biomaterial for in vivo bone tissue engineering and clinical bone defects therapies.

Dental pulp stem cells in chitosan/gelatin scaffolds for enhanced orofacial bone regeneration

OBJECTIVE

Biomimetic chitosan/gelatin (CS/Gel) scaffolds have attracted great interest in tissue engineering of several tissues. However, limited information exists regarding the potential of combining CS/Gel scaffolds with oral cells, such as dental pulp stem cells (DPSCs), to produce customized constructs targeting alveolar/orofacial bone reconstruction, which has been the aim of the present study.

METHODS

Two scaffold types, designated as CS/Gel-0.1 and CS/Gel-1, were fabricated using 0.1 and 1% (v/v) respectively of the crosslinker glutaraldehyde (GTA). Scaffolds (n=240) were seeded with DPSCs with/without pre-exposure to recombinant human BMP-2. In vitro assessment included DPSCs characterization (flow cytometry), evaluation of viability/proliferation (live/dead staining, metabolic-based tests), osteo/odontogenic gene expression analysis (qRT-PCR) and structural/chemical characterization (scanning electron microscopy, SEM; energy dispersive X-ray spectroscopy, EDX; X-ray powder diffraction, XRD; thermogravimetry, TG). In vivo assessment included implantation of DPSC-seeded scaffolds in immunocompromised mice, followed by histology and SEM-EDX. Statistical analysis employed one/two-way ANOVA and Tukey's post-hoc tests (significance for p<0.05).

RESULTS

Both scaffolds supported cell viability/proliferation over 14 days in culture, showing extensive formation of a hydroxyapatite-rich nanocrystalline calcium phosphate phase. Differential expression patterns indicated GTA concentration to significantly affect the expression of osteo/odontogenic genes, with CS/Gel-0.1 scaffolds being more effective in upregulating DSPP, IBSP and Osterix. In vivo analysis demonstrated time-dependent production of a nanocrystalline, mineralized matrix at 6, 8 and 10 weeks, being more prominent in constructs bearing rhBMP-2 pre-treated cells. The latter showed higher amounts of osteoid and fully mineralized bone, as well as empty space reduction.

SIGNIFICANCE

These results reveal a promising strategy for orofacial bone tissue engineering.

Amino acid composition of nanofibrillar self-assembling peptide hydrogels affects responses of periodontal tissue cells in vitro

Background

The regeneration of tissue defects at the interface between soft and hard tissue, eg, in the periodontium, poses a challenge due to the divergent tissue requirements. A class of biomaterials that may support the regeneration at the soft-to-hard tissue interface are self-assembling peptides (SAPs), as their physicochemical and mechanical properties can be rationally designed to meet tissue requirements.

Materials and methods

In this work, we investigated the effect of two single-component and two complementary β-sheet forming SAP systems on their hydrogel properties such as nanofibrillar architecture, surface charge, and protein adsorption as well as their influence on cell adhesion, morphology, growth, and differentiation.

Results

We showed that these four 11-amino acid SAP (P11-SAP) hydrogels possessed physico-chemical characteristics dependent on their amino acid composition that allowed variabilities in nanofibrillar network architecture, surface charge, and protein adsorption (eg, the single-component systems demonstrated an ~30% higher porosity and an almost 2-fold higher protein adsorption compared with the complementary systems). Cytocompatibility studies revealed similar results for cells cultured on the four P11-SAP hydrogels compared with cells on standard cell culture surfaces. The single-component P11-SAP systems showed a 1.7-fold increase in cell adhesion and cellular growth compared with the complementary P11-SAP systems. Moreover, significantly enhanced osteogenic differentiation of human calvarial osteoblasts was detected for the single-component P11-SAP system hydrogels compared with standard cell cultures.

Conclusion

Thus, single-component system P11-SAP hydrogels can be assessed as suitable scaffolds for periodontal regeneration therapy, as they provide adjustable, extracellular matrix-mimetic nanofibrillar architecture and favorable cellular interaction with periodontal cells.

Detection, Characterization, and Clinical Application of Mesenchymal Stem Cells in Periodontal Ligament Tissue

Mesenchymal stem cells (MSCs) are a kind of somatic stem cells that exert a potential to differentiate into multiple cell types and undergo robust clonal self-renewal; therefore, they are considered as a highly promising stem cell population for tissue engineering. MSCs are identified in various adult organs including dental tissues. Periodontal ligament (PDL) is a highly specialized connective tissue that surrounds the tooth root. PDL also contains MSC population, and many researchers have isolated them and performed their detailed characterization. Here, we review the current understanding of the features and functions of MSC population in PDL tissues and discuss their possibility for the application of PDL regeneration.

Exendin-4 relieves the inhibitory effects of high glucose on the proliferation and osteoblastic differentiation of periodontal ligament stem cells

BACKGROUND

With the impaired regenerative potential in patients with diabetes mellitus (DM), Periodontal ligament stem cells (PDLSCs) are regarded as an attractive source of stem cells for periodontal cytotherapy. Recent studies have shown that Exendin-4 (Ex-4) exerts cell-protective effects and bone remodeling ability on many types of cells. The aim of this study was to investigate whether Ex-4 alleviates the inhibition of high glucose on the proliferation and osteogenic differentiation of PDLSCs.

METHODS

PDLSCs were incubated in medium supplemented with 5.5 mM d-glucose (NG), 30 mM d-glucose (HG), NG plus Ex-4, and HG plus different concentration (1, 10, 20, 100 nM) of Ex-4 respectively. Cell proliferation was detected by CCK-8 assay and cell cycle analysis. Osteogenesis was assessed by Alizarin Red S staining and evaluation of the mRNA expression of Runx2, ALP and Osx at day 7, 14 and 21. Intracellular level of reactive oxygen species (ROS) was detected using 5-(and-6)-chloromethyl-2',7'-dichlorodihydro-fluorescein diacetate (CMH2DCF-DA).

RESULTS

The proliferation ability, mineralized nodules forming capacity and the mRNA expression of Runx2, ALP and Osx of PDLSCs in HG group were decreased, the ROS level was increased compared to NG group. With the treatment of Ex-4, the HG-inhibited proliferation ability and osteogenic differentiation ability of PDLSCs were significantly reversed, the HG-increased ROS level could be down-regulated. Moreover, Ex-4 enhanced the osteogenic differentiation of normal PDLSCs.

CONCLUSIONS

Ex-4 alleviates the inhibitory effect of HG on the proliferation and osteoblastic differentiation of PDLSCs, and has a significant enhance in the osteoblastic differentiation of normal PDLSCs, giving new insights into the possible therapeutic method of diabetic periodontitis.

Gelatin/Nanohyroxyapatite Cryogel Embedded Poly(lactic-co-glycolic Acid)/Nanohydroxyapatite Microsphere Hybrid Scaffolds for Simultaneous Bone Regeneration and Load-Bearing

It is desirable to combine load-bearing and bone regeneration capabilities in a single bone tissue engineering scaffold. For this purpose, we developed a high strength hybrid scaffold using a sintered poly(lactic-co-glycolic acid) (PLGA)/nanohydroxyapatite (nHAP) microsphere cavity fitted with gelatin/nHAP cryogel disks in the center. Osteo-conductive/osteo-inductive nHAP was incorporated in 250⁻500 μm PLGA microspheres at 40% (w/w) as the base matrix for the high strength cavity-shaped microsphere scaffold, while 20% (w/w) nHAP was incorporated into gelatin cryogels as an embedded core for bone regeneration purposes. The physico-chemical properties of the microsphere, cryogel, and hybrid scaffolds were characterized in detail. The ultimate stress and Young's modulus of the hybrid scaffold showed 25- and 21-fold increases from the cryogel scaffold. In vitro studies using rabbit bone marrow-derived stem cells (rBMSCs) in cryogel and hybrid scaffolds through DNA content, alkaline phosphatase activity, and mineral deposition by SEM/EDS, showed the prominence of both scaffolds in cell proliferation and osteogenic differentiation of rBMSCs in a normal medium. Calcium contents analysis, immunofluorescent staining of collagen I (COL I), and osteocalcin (OCN) and relative mRNA expression of COL I, OCN and osteopontin (OPN) confirmed in vitro differentiation of rBMSCs in the hybrid scaffold toward the bone lineage. From compression testing, the cell/hybrid scaffold construct showed a 1.93 times increase of Young's modulus from day 14 to day 28, due to mineral deposition. The relative mRNA expression of osteogenic marker genes COL I, OCN, and OPN showed 5.5, 18.7, and 7.2 folds increase from day 14 to day 28, respectively, confirming bone regeneration. From animal studies, the rBMSCs-seeded hybrid constructs could repair mid-diaphyseal tibia defects in rabbits, as evaluated by micro-computed tomography (μ-CT) and histological analyses. The hybrid scaffold will be useful for bone regeneration in load-bearing areas.

Porous Chitosan/Nano-Hydroxyapatite Composite Scaffolds Incorporating Simvastatin-Loaded PLGA Microspheres for Bone Repair

The combination of bone tissue scaffolds with osteogenic induction factors is an effective strategy to facilitate bone healing processes. Here, chitosan (CS)/nano-hydroxyapatite (HA) scaffolds containing simvastatin (SIM)-loaded PLGA microspheres were fabricated by combining a freeze-drying technique with a modified water-oil-water emulsion method. The CS/HA weight ratio of 1:2 was selected by analyzing the effect of HA content on the micro-architecture, mechanical strength, and biocompatibility of the scaffold. Drug release kinetics showed that the SIM encapsulated in the scaffold was released in a sustained manner for up to 30 days. In vitro bioactivity study in rat bone marrow-derived mesenchymal stem cells showed that the SIM-loaded scaffolds had a strong ability in accelerating cell proliferation and inducing osteogenic differentiation. Moreover, an in vivo experiment using a rat calvarial defect model also documented that the SIM-loaded scaffolds had a remarkable effect on bone-promoting regeneration. The results of this study suggest that the SIM-loaded CS/HA scaffold is feasible and effective in bone repair and thus may provide a promising route for the treatment of critical-sized bone defects.

Allogenic human serum, a clinical grade serum supplement for promoting human periodontal ligament stem cell expansion

Exposing human periodontal ligament stem cells (hPDLSCs) to animal proteins during cell expansion would compromise quality and safety of the hPDLSCs for clinical applications. The current study aimed to evaluate the replacement of animal-based serum by human serum for the expansion of hPDLSCs. hPDLSCs were cultured in culture media supplemented with four types of serums: Group A: fetal bovine serum (FBS); Group B: allogeneic human male AB serum (HS); Group C: in-house autologous (Auto-HS); and Group D: in-house allogeneic human serums (Allo-HS). Exhibitions of mesenchymal stem cell characteristics of hPDLSCs were examined. Then, growth and osteogenic (OS) differentiation potential of hPDLSCs in FBS and HS at passages 5 and 15 were compared to investigate the effects of serum supplements on growth and expansion stability of the expanded hPDLSCs. After that, growth and OS differentiation of hPDLSCs in Auto- and Allo-HS were investigated. Flow cytometrical analyses, functional differentiations, cell growth kinetic, cytogenetic analysis, alkaline phosphatase and calcium content assays, and oil red O and von Kossa staining were performed. Results showed that at passage 5, HS promoted growth and OS differentiation of hPDLSCs and extensive cell expansion, decreased growth and differentiation potential of the expanded hPDLSCs, particularly in HS. Growth and OS differentiation of hPDLSCs in Auto-HS and Allo-HS were not different. In summary, allogeneic human serum could be a replacement to FBS for hPDLSC expansion. In vitro cell expansion of hPDLSCs should be minimal to ensure optimal cell quality. Copyright © 2016 John Wiley & Sons, Ltd.

Injectable nanoparticles/hydrogels composite as sustained release system with stromal cell-derived factor-1α for calvarial bone regeneration

Repair of craniofacial bony defects remains a challenge for surgeons due to the delicate and complex anatomy of the craniofacial skeleton. Stromal cell-derived factor-1α (SDF-1α) is an important chemokine which plays a critical role in the homing of mesenchymal stem cells (MSC), while, the shortcomings including short half-life and easy degradation by enzymes made it in relatively low efficacy. In this work, SDF-1α/chitosan/carboxymeymethy-chitosan nanoparticles (SDF-1α/CS/CMCS NPs) were prepared and characterized for various parameters including morphology, particle size, zeta potential, loading efficiency and the release characteristics from thermosensitive chitosan/β-glycerol phosphate disodium salt (CS/GP) hydrogels. The SDF-1α encapsulated in CS/CMCS NPs within CS/GP hydrogels showed significantly sustained release effect. The cumulative release of SDF-1α was only 40% during 28d. The data from rat calvarial defects model revealed that the SDF-1α/CS/CMCS NPs embedded hydrogels group could significantly promote the new bone formation (38.5±4.5%), compared to that of the SDF-1α embedded hydrogels group (26.3±7.25%, p<0.05) and the control group (8.64±4.8%, p<0.01). Histological data also confirmed this difference. This study demonstrated the potential applications of nanoparticulate injectable hydrogels for sustained release SDF-1α on bone tissue regeneration.

PTH/SDF-1α cotherapy promotes proliferation, migration and osteogenic differentiation of human periodontal ligament stem cells

OBJECTIVES

Stromal cell-derived factor-1α (SDF-1α) plays an important role in tissue regeneration in various tissues including the periodontium. A potential limitation for its use derives from its sensitivity to cleavage by dipeptidyl peptidase-IV (DPP-IV). Parathyroid hormone (PTH) reduces enzymatic activity of DPP-IV and is suggested to be a promising agent for periodontal tissue repair. The purpose of this study was to provide insight into how SDF-1α and intermittent PTH treatment might affect proliferation, migration and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) in vitro.

MATERIALS AND METHODS

PDLSCs were isolated by the limiting dilution method. Surface markers were quantified by flow cytometry. Cell-counting kit-8 (CCK8), cell migration assay, alkaline phosphatase (ALP) activity assay, alizarin red staining and RT-PCR were used to determine viability, migration and osteogenic differentiation of PDLSCs.

RESULTS

PDLSCs were positive for CD44, CD73, CD90, CD105, CD166 and STRO-1 and negative for CD14, CD34 and CD45. PTH/SDF-1α cotherapy significantly promoted cell proliferation, chemotactic capability, ALP activity and mineral deposition (P<.05). Gene expression level of bone sialoprotein (BSP), runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) were all up-regulated (P<.05).

CONCLUSIONS

PTH/SDF-1α cotherapy promoted proliferation, migration and osteogenic differentiation of PDLSCs in vitro. Cotherapy seemed to have potential to promote periodontal tissue regeneration by facilitating chemotaxis of PDLSCs to the injured site, followed by promoting proliferation and osteogenic differentiation of these cells.

Influence of porosity and pore shape on structural, mechanical and biological properties of poly ϵ-caprolactone electro-spun fibrous scaffolds

Background: Electro-spun scaffolds are utilized in a diverse spectrum of clinical targets, with an ever-increasing quantity of work progressing to clinical studies and commercialization. The limited number of conformations in which the scaffolds can be fabricated hampers their wide acceptance in clinical practice. Materials & methods: Herein, we assessed a single-strep fabrication process for predesigned electro-spun scaffold preparation and the ramifications of the introduction of porosity (0, 30, 50, 70%) and pore shape (circle, rhomboid, square) on structural, mechanical (tensile and ball burst) and biological (dermal fibroblast and THP-1) properties. Results: The collector design did not affect the fibrous nature of the scaffold. Modulation of the porosity and pore shape offered control over the mechanical properties of the scaffolds. Neither the porosity nor the pore shape affected cellular (dermal fibroblast and THP-1) response. Conclusion: Overall, herein we provide evidence that electro-spun scaffolds of controlled architecture can be fabricated with fibrous fidelity, adequate mechanical properties and acceptable cytocompatibility for a diverse range of clinical targets.

Cytokines during periodontal wound healing: potential application for new therapeutic approach

Regeneration of periodontal tissues is one of the main goals of periodontal therapy. However, current treatment, including surgical approach, use of membrane to allow maturation of all periodontal tissues, or use of enamel matrix derivatives, presents limitations in their indications and outcomes leading to the development of new tissue engineering strategies. Several cytokines are considered as key molecules during periodontal destruction process. However, their role during each phase of periodontal wound healing remains unclear. Control and modulation of the inflammatory response and especially, release of cytokines or activation/inhibition in a time- and spatial-controlled manner may be a potential perspective for periodontal tissue engineering. The aim of this review was to summarize the specific role of several cytokines during periodontal wound healing and the potential therapeutic interest of inflammatory modulation for periodontal regeneration especially related to the expression sequence of cytokines.

Bioactivity of periodontal ligament stem cells on sodium titanate coated with graphene oxide

As a biocompatible and low cytotoxic nanomaterial, graphene oxide (GO) has captured tremendous interests in tissue engineering. However, little is known about the behavior of dental stem cells on GO. This study was to evaluate the bioactivity of human periodontal ligament stem cells (PDLSCs) on GO coated titanium (GO-Ti) substrate in vitro as compared to sodium titanate (Na-Ti) substrate. By scanning electron microscope (SEM), confocal laser scanning microscope (CLSM), methylthiazol tetrazolium (MTT) assay, alkaline phosphatase (ALP) activity, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis, we investigated the attachment, morphology, proliferation and osteogenic differentiation of PDLSCs on these two substrates. When seeded on GO-Ti substrate, PDLSCs exhibited significantly higher proliferation rate, ALP activity and up-regulated gene expression level of osteogenesis-related markers of collagen type I (COL-I), ALP, bone sialoprotein (BSP), runt related transcription factor 2 (Runx2) and osteocalcin (OCN) compared with those on Na-Ti substrate. Moreover, GO promoted the protein expression of BSP, Runx2 and OCN. These findings suggest that the combination of GO and PDLSCs provides a promising construct for regenerative dentistry.

Regenerative Applications Using Tooth Derived Stem Cells in Other Than Tooth Regeneration: A Literature Review

Tooth derived stem cells or dental stem cells are categorized according to the location from which they are isolated and represent a promising source of cells for regenerative medicine. Originally, as one kind of mesenchymal stem cells, they are considered an alternative of bone marrow stromal cells. They share many commonalties but maintain differences. Considering their original function in development and the homeostasis of tooth structures, many applications of these cells in dentistry have aimed at tooth structure regeneration; however, the application in other than tooth structures has been attempted extensively. The availability from discarded or removed teeth can be an innate benefit as a source of autologous cells. Their origin from the neural crest results in exploitation of neurological and numerous other applications. This review briefly highlights current and future perspectives of the regenerative applications of tooth derived stem cells in areas beyond tooth regeneration.

Genipin-Crosslinked Chitosan Gels and Scaffolds for Tissue Engineering and Regeneration of Cartilage and Bone

The present review article intends to direct attention to the technological advances made since 2009 in the area of genipin-crosslinked chitosan (GEN-chitosan) hydrogels. After a concise introduction on the well recognized characteristics of medical grade chitosan and food grade genipin, the properties of GEN-chitosan obtained with a safe, spontaneous and irreversible chemical reaction, and the quality assessment of the gels are reviewed. The antibacterial activity of GEN-chitosan has been well assessed in the treatment of gastric infections supported by Helicobacter pylori. Therapies based on chitosan alginate crosslinked with genipin include stem cell transplantation, and development of contraction free biomaterials suitable for cartilage engineering. Collagen, gelatin and other proteins have been associated to said hydrogels in view of the regeneration of the cartilage. Viability and proliferation of fibroblasts were impressively enhanced upon addition of poly-l-lysine. The modulation of the osteocytes has been achieved in various ways by applying advanced technologies such as 3D-plotting and electrospinning of biomimetic scaffolds, with optional addition of nano hydroxyapatite to the formulations. A wealth of biotechnological advances and know-how has permitted reaching outstanding results in crucial areas such as cranio-facial surgery, orthopedics and dentistry. It is mandatory to use scaffolds fully characterized in terms of porosity, pore size, swelling, wettability, compressive strength, and degree of acetylation, if the osteogenic differentiation of human mesenchymal stem cells is sought: in fact, the novel characteristics imparted by GEN-chitosan must be simultaneously of physico-chemical and cytological nature. Owing to their high standard, the scientific publications dated 2010-2015 have met the expectations of an interdisciplinary audience.

Chitosan-PLGA polymer blends as coatings for hydroxyapatite nanoparticles and their effect on antimicrobial properties, osteoconductivity and regeneration of osseous tissues

Composite biomaterials comprising nanostructured hydroxyapatite (HAp) have an enormous potential for natural bone tissue reparation, filling and augmentation. Chitosan (Ch) as a naturally derived polymer has many physicochemical and biological properties that make it an attractive material for use in bone tissue engineering. On the other hand, poly-D,L-lactide-co-glycolide (PLGA) is a synthetic polymer with a long history of use in sustained drug delivery and tissue engineering. However, while chitosan can disrupt the cell membrane integrity and may induce blood thrombosis, PLGA releases acidic byproducts that may cause tissue inflammation and interfere with the healing process. One of the strategies to improve the biocompatibility of Ch and PLGA is to combine them with compounds that exhibit complementary properties. In this study we present the synthesis and characterization, as well as in vitro and in vivo analyses of a nanoparticulate form of HAp coated with two different polymeric systems: (a) Ch and (b) a Ch-PLGA polymer blend. Solvent/non-solvent precipitation and freeze-drying were used for synthesis and processing, respectively, whereas thermogravimetry coupled with mass spectrometry was used for phase identification purposes in the coating process. HAp/Ch composite particles exhibited the highest antimicrobial activity against all four microbial strains tested in this work, but after the reconstruction of the bone defect they also caused inflammatory reactions in the newly formed tissue where the defect had lain. Coating HAp with a polymeric blend composed of Ch and PLGA led to a decrease in the reactivity and antimicrobial activity of the composite particles, but also to an increase in the quality of the newly formed bone tissue in the reconstructed defect area.

Chitosan and Its Potential Use as a Scaffold for Tissue Engineering in Regenerative Medicine

Tissue engineering is an important therapeutic strategy to be used in regenerative medicine in the present and in the future. Functional biomaterials research is focused on the development and improvement of scaffolding, which can be used to repair or regenerate an organ or tissue. Scaffolds are one of the crucial factors for tissue engineering. Scaffolds consisting of natural polymers have recently been developed more quickly and have gained more popularity. These include chitosan, a copolymer derived from the alkaline deacetylation of chitin. Expectations for use of these scaffolds are increasing as the knowledge regarding their chemical and biological properties expands, and new biomedical applications are investigated. Due to their different biological properties such as being biocompatible, biodegradable, and bioactive, they have given the pattern for use in tissue engineering for repair and/or regeneration of different tissues including skin, bone, cartilage, nerves, liver, and muscle. In this review, we focus on the intrinsic properties offered by chitosan and its use in tissue engineering, considering it as a promising alternative for regenerative medicine as a bioactive polymer.