5-Aza Exposure Improves Reprogramming Process Through Embryoid Body Formation in Human Gingival Stem Cells

Bioengineering-tissue strategies to model mammalian implantation in vitro

During mammalian implantation, complex and well-orchestrated interactions between the trophectoderm of implanting blastocysts and the maternal endometrium lead to a successful pregnancy. On the other hand, alteration in endometrium-blastocyst crosstalk often causes implantation failure, pregnancy loss, and complications that result in overall infertility. In domestic animals, this represents one of the major causes of economic losses and the understanding of the processes taking place during the early phases of implantation, in both healthy and pathological conditions, is of great importance, to enhance livestock system efficiency. Here we develop highly predictive and reproducible functional tridimensional (3D) in vitro models able to mimic the two main actors that play a key role at this developmental stage: the blastocyst and the endometrium. In particular, we generate a 3D endometrial model by co-culturing primary epithelial and stromal cells, isolated from sow uteri, onto highly porous polystyrene scaffolds. In parallel, we chemically reprogram porcine adult dermal fibroblasts and encapsulate them into micro-bioreactors to create trophoblast (TR) spheroids. Finally, we combine the generated artificial endometrium with the TR spheroids to model mammalian implantation in vitro and mimic the embryo-maternal interactions. The protocols here described allow the generation of reproducible and functional 3D models of both the maternal compartment as well as the implanting embryo, able to recreate in vitro the architecture and physiology of the two tissues in vivo. We suggest that these models can find useful applications to further elucidate early implantation mechanisms and to study the complex interactions between the maternal tissue and the developing embryos.

Combination of epigenetic erasing and mechanical cues to generate human epiBlastoids from adult dermal fibroblasts

PURPOSE

This study is to develop a new protocol that combines the use of epigenetic cues and mechanical stimuli to assemble 3D spherical structures, arbitrarily defined "epiBlastoids," whose phenotype is remarkably similar to natural embryos.

METHODS

A 3-step approach is used to generate epiBlastoids. In the first step, adult dermal fibroblasts are converted into trophoblast (TR)-like cells, combining the use of 5-azacytidine, to erase the original phenotype, with an ad hoc induction protocol, to drive cells towards TR lineage. In the second step, epigenetic erasing is applied once again, in combination with mechanosensing-related cues, to generate inner cell mass (ICM)-like organoids. Specifically, erased cells are encapsulated into micro-bioreactors to promote 3D cell rearrangement and boost pluripotency. In the third step, TR-like cells are co-cultured with ICM-like spheroids in the same micro-bioreactors. Subsequently, the newly generated embryoids are transferred to microwells to favor epiBlastoid formation.

RESULTS

Adult dermal fibroblasts are successfully readdressed towards TR lineage. Cells subjected to epigenetic erasing and encapsulated into micro-bioreactors rearrange in 3D ICM-like structures. Co-culture of TR-like cells and ICM-like spheroids into micro-bioreactors and microwells induces the formation of single structures with uniform shape reminiscent in vivo embryos. CDX2+ cells localized in the out layer of the spheroids, while OCT4+ cells in the inner of the structures. TROP2+ cells display YAP nuclear accumulation and actively transcribed for mature TR markers, while TROP2- cells showed YAP cytoplasmic compartmentalization and expressed pluripotency-related genes.

CONCLUSION

We describe the generation of epiBlastoids that may find useful application in the assisted reproduction field.

Synergistic Effect of miR-200 and Young Extracellular Matrix-based Bio-scaffolds to Reduce Signs of Aging in Senescent Fibroblasts

Aging is defined as a complex, multifaceted degenerative process that causes a gradual decline of physiological functions and a rising mortality risk with time. Stopping senescence or even rejuvenating the body represent one of the long-standing human dreams. Somatic cell nuclear transfer as well as cell reprogramming have suggested the possibility to slow or even reverse signs of aging. We exploited miR-200 family ability to induce a transient high plasticity state in human skin fibroblasts isolated from old individuals and we investigated whether this ameliorates cellular and physiological hallmarks of senescence. In addition, based on the assumption that extracellular matrix (ECM) provides biomechanical stimuli directly influencing cell behavior, we examine whether ECM-based bio-scaffolds, obtained from decellularized ovaries of young swine, stably maintain the rejuvenated phenotype acquired by cells after miR-200 exposure. The results show the existence of multiple factors that cooperate to control a unique program, driving the cell clock. In particular, miR-200 family directly regulates the molecular mechanisms erasing cell senescence. However, this effect is transient, reversible, and quickly lost. On the other hand, the use of an adequate young microenvironment stabilizes the miR-200-mediated rejuvenating effects, suggesting that synergistic interactions occur among molecular effectors and ECM-derived biomechanical stimuli. The model here described is a useful tool to better characterize these complex regulations and to finely dissect the multiple and concurring biochemical and biomechanical cues driving the cell biological clock.

Epigenetic Regulation of Methylation in Determining the Fate of Dental Mesenchymal Stem Cells

Dental mesenchymal stem cells (DMSCs) are crucial in tooth development and periodontal health, and their multipotential differentiation and self-renewal ability play a critical role in tissue engineering and regenerative medicine. Methylation modifications could promote the appropriate biological behavior by postsynthetic modification of DNA or protein and make the organism adapt to developmental and environmental prompts by regulating gene expression without changing the DNA sequence. Methylation modifications involved in DMSC fate include DNA methylation, RNA methylation, and histone modifications, which have been proven to exert a significant effect on the regulation of the fate of DMSCs, such as proliferation, self-renewal, and differentiation potential. Understanding the regulation of methylation modifications on the behavior and the immunoinflammatory responses involved in DMSCs contributes to further study of the mechanism of methylation on tissue regeneration and inflammation. In this review, we briefly summarize the key functions of histone methylation, RNA methylation, and DNA methylation in the differentiation potential and self-renewal of DMSCs as well as the opportunities and challenges for their application in tissue regeneration and disease therapy.

Periodontal ligament stem cells as a promising therapeutic target for neural damage

BACKGROUND

The damaged neuronal cells of adult mammalian lack the regenerative ability to replace the neuronal connections. Periodontal ligament stem cells (PDLSCs) are the promising source for neuroregenerative applications that can improve the injured microenvironment of the damaged neural system. They provide neuronal progenitors and neurotrophic, anti-apoptotic and anti-inflammatory factors. In this study, we aimed to comprehensively explore the various neuronal differentiation potentials of PDLSCs for application in neural regeneration therapy.

MAIN TEXT

PDLSCs have superior potential to differentiate into various neural-like cells through a dedifferentiation stage followed by differentiation process without need for cell division. Diverse combination of nutritional factors can be used to induce the PDLSCs toward neural lineage. PDLSCs when coupled with biomaterials could have significant implications for neural tissue repair. PDLSCs can be a new clinical research target for Alzheimer's disease treatment, multiple sclerosis and cerebral ischemia. Moreover, PDLSCs have beneficial effects on retinal ganglion cell regeneration and photoreceptor survival. PDLSCs can be a great source for the repair of injured peripheral nerve through the expression of several neural growth factors and differentiation into Schwann cells.

CONCLUSION

In conclusion, these cells are an appealing source for utilizing in clinical treatment of the neuropathological disorders. Although significant in vitro and in vivo investigations were carried out in order for neural differentiation evaluation of these cells into diverse types of neurons, more preclinical and clinical studies are needed to elucidate their therapeutic potential for neural diseases.

A Narrative Review: Gingival Stem Cells as a Limitless Reservoir for Regenerative Medicine

The gingival tissue can be collected in an easy way and represent an accessible source to isolate gingival-derived mesenchymal stem cells (GMSCs). GMSCs are a subpopulation of dental-derived mesenchymal stem cells that show the mesenchymal stem cells (MSCs) features, such as differentiation abilities and immunomodulatory properties. Dental-derived stem cells are also expandable in vitro with genomic stability and the possibility to maintain the stemness properties over a prolonged period of passages. Moreover, several preclinical studies have documented that the extracellular vesicles (EVs) released from GMSCs possess similar biological functions and therapeutic effects. The EVs may represent a promising tool in the cell-free regenerative therapy approach. The present review paper summarized the GMSCs, their multi-lineage differentiation capacities, immunomodulatory features, and the potential use in the treatment of several diseases in order to stimulate tissue regeneration. GMSCs should be considered a good stem cell source for potential applications in tissue engineering and regenerative dentistry.

Decellularized Dental Pulp, Extracellular Vesicles, and 5-Azacytidine: A New Tool for Endodontic Regeneration

Dental pulp is a major component of the dental body that serves to maintain the tooth life and function. The aim of the present work was to develop a system that functions as a growth-permissive microenvironment for dental pulp regeneration using a decellularized dental pulp (DDP) matrix, 5-Aza-2′-deoxycytidine (5-Aza), and Extracellular Vesicles (EVs) derived from human Dental Pulp Stem Cells (hDPSCs). Human dental pulps extracted from healthy teeth, scheduled to be removed for orthodontic purpose, were decellularized and then recellularized with hDPSCs. The hDPSCs were seeded on DDP and maintained under different culture conditions: basal medium (CTRL), EVs, 5-Aza, and EVs+-5-Aza. Immunofluorescence staining and Western blot analyses were performed to evaluate the proteins’ expression related to dentinogenesis, such as ALP, RUNX2, COL1A1, Vinculin, DMP1, and DSPP. Protein contents found in the DDP recellularized with hDPSCs were highly expressed in samples co-treated with EVs and 5-Aza compared to other culture conditions. This study developed a DDP matrix loaded by hDPSCs in co-treatment with EVs, which might enhance the dentinogenic differentiation with a high potentiality for endodontic regeneration.

Deciphering the Epigenetic Code of Stem Cells Derived From Dental Tissues

Stem cells derived from dental tissues (DSCs) exhibit multipotent regenerative potential in pioneering tissue engineering regimens. The multipotency of DSCs is critically regulated by an intricate range of factors, of which the epigenetic influence is considered vital. To gain a better understanding of how epigenetic alterations are involved in the DSC fate determination, the present review overviews the current knowledge relating to DSC epigenetic modifications, paying special attention to the landscape of epigenetic modifying agents as well as the related signaling pathways in DSC regulation. In addition, insights into the future opportunities of epigenetic targeted therapies mediated by DSCs are discussed to hold promise for the novel therapeutic interventions in future translational medicine.

Enhanced Extracellular Matrix Deposition on Titanium Implant Surfaces: Cellular and Molecular Evidences

The surface structure of the titanium dental implants can modulate the activity of mesenchymal stem cells in order to promote the upregulation of osteoblastic related genes and the release of extracellular matrix (ECM) components. The present work was focused on the in vitro evaluation of the interaction of human periodontal ligament stem cells (hPDLSCs) and two different implant titanium surfaces topography (CTRL and TEST). This study was aimed at analyzing the cytotoxicity of the dental implant surfaces, the cellular adhesion capacity, and the improvement in the release of ECM molecules in an in vitro model. These parameters were carried out by means of the microscopic evaluation, viability assays, immunofluorescence, Western blot and RT-PCR investigations. The knowledge of the cell/implant interaction is essential for implant healing in order to obtain a more performing surfaces that promote the ECM release and provide the starting point to initiate the osseointegration process.

Human Periodontal Ligament Stem Cells Response to Titanium Implant Surface: Extracellular Matrix Deposition

The major challenge for dentistry is to provide the patient an oral rehabilitation to maintain healthy bone conditions in order to reduce the time for loading protocols. Advancement in implant surface design is necessary to favour and promote the osseointegration process. The surface features of titanium dental implant can promote a relevant influence on the morphology and differentiation ability of mesenchymal stem cells, induction of the osteoblastic genes expression and the release of extracellular matrix (ECM) components. The present study aimed at evaluating the in vitro effects of two different dental implants with titanium surfaces, TEST and CTRL, to culture the human periodontal ligament stem cells (hPDLSCs). Expression of ECM components such as Vimentin, Fibronectin, N-cadherin, Laminin, Focal Adhesion Kinase (FAK) and Integrin beta-1 (ITGB1), and the osteogenic related markers, as runt related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP), were investigated. Human PDLSCs cultured on the TEST implant surface demonstrated a better cell adhesion capability as observed by Scanning Electron Microscopy (SEM) and immunofluorescence analysis. Moreover, immunofluorescence and Western blot experiments showed an over expression of Fibronectin, Laminin, N-cadherin and RUNX2 in hPDLSCs seeded on TEST implant surface. The gene expression study by RT-PCR validated the results obtained in protein assays and exhibited the expression of RUNX2, ALP, Vimentin (VIM), Fibronectin (FN1), N-cadherin (CDH2), Laminin (LAMB1), FAK and ITGB1 in hPDLSCs seeded on TEST surface compared to the CTRL dental implant surface. Understanding the mechanisms of ECM components release and its regulation are essential for developing novel strategies in tissue engineering and regenerative medicine. Our results demonstrated that the impact of treated surfaces of titanium dental implants might increase and accelerate the ECM apposition and provide the starting point to initiate the osseointegration process.

Ovarian Decellularized Bioscaffolds Provide an Optimal Microenvironment for Cell Growth and Differentiation In Vitro

Ovarian failure is the most common cause of infertility. Although numerous strategies have been proposed, a definitive solution for recovering ovarian functions and restoring fertility is currently unavailable. One innovative alternative may be represented by the development of an “artificial ovary” that could be transplanted in patients for re-establishing reproductive activities. Here, we describe a novel approach for successful repopulation of decellularized ovarian bioscaffolds in vitro. Porcine whole ovaries were subjected to a decellularization protocol that removed the cell compartment, while maintaining the macrostructure and microstructure of the original tissue. The obtained bioscaffolds were then repopulated with porcine ovarian cells or with epigenetically erased porcine and human dermal fibroblasts. The results obtained demonstrated that the decellularized extracellular matrix (ECM)-based scaffold may constitute a suitable niche for ex vivo culture of ovarian cells. Furthermore, it was able to properly drive epigenetically erased cell differentiation, fate, and viability. Overall, the method described represents a powerful tool for the in vitro creation of a bioengineered ovary that may constitute a promising solution for hormone and fertility restoration. In addition, it allows for the creation of a suitable 3D platform with useful applications both in toxicological and transplantation studies.

Generation of Trophoblast-Like Cells From Hypomethylated Porcine Adult Dermal Fibroblasts

The first differentiation event in mammalian embryos is the formation of the trophectoderm, which is the progenitor of the outer epithelial components of the placenta, and which supports the fetus during the intrauterine life. However, the epigenetic and paracrine controls at work in trophectoderm differentiation are still to be fully elucidated and the creation of dedicated in vitro models is desirable to increase our understanding. Here we propose a novel approach based on the epigenetic conversion of adult dermal fibroblasts into trophoblast-like cells. The method combines the use of epigenetic erasing with an ad hoc differentiation protocol. Dermal fibroblasts are erased with 5-azacytidine (5-aza-CR) that confers cells a transient high plasticity state. They are then readdressed toward the trophoblast (TR) phenotype, using MEF conditioned medium, supplemented with bone morphogenetic protein 4 (BMP4) and inhibitors of the Activin/Nodal and FGF2 signaling pathways in low O₂ conditions. The method here described allows the generation of TR-like cells from easily accessible material, such as dermal fibroblasts, that are very simply propagated in vitro. Furthermore, the strategy proposed is free of genetic modifications that make cells prone to instability and transformation. The TR model obtained may also find useful application in order to better characterize embryo implantation mechanisms and developmental disorders based on TR defects.

Key Markers and Epigenetic Modifications of Dental-Derived Mesenchymal Stromal Cells

As a novel research hotspot in tissue regeneration, dental-derived mesenchymal stromal cells (MSCs) are famous for their accessibility, multipotent differentiation ability, and high proliferation. However, cellular heterogeneity is a major obstacle to the clinical application of dental-derived MSCs. Here, we reviewed the heterogeneity of dental-derived MSCs firstly and then discussed the key markers and epigenetic modifications related to the proliferation, differentiation, immunomodulation, and aging of dental-derived MSCs. These messages help to control the composition and function of dental-derived MSCs and thus accelerate the translation of cell therapy into clinical practice.

Calreticulin as a special marker to distinguish dental pulp stem cells from gingival mesenchymal stem cells

The construction of protein abundance profiles helps to interpret the clinical applications of stem cells. Dental pulp stem cells (DPSCs) and gingival mesenchymal stem cells (GMSCs) can be isolated from teeth and used as a highly convenient clinical potential material. Here, we aimed to explore commonalities and differences of DPSCs and GMSCs at the protein level. TMT-based quantitative proteomics and two-dimensional gel electrophoresis technology were used in combination to describe the protein profile of DPSCs and GMSCs extracted from the same donor. A total of 2821 proteins were identified by LC-MS/MS, of which 248 differentially abundant proteins (DAPs) were highly expressed in GMSCs while 782 proteins were highly expressed in DPSCs. The biological functions and molecular pathways of DAPs were annotated with GO enrichment and KEGG analysis. The relationship between molecular abundance and cell characteristics including source, proliferation, angiogenesis and inflammation were connected by WGCNA. Special markers, including Calreticulin (CALR), Annexin A5 (ANXA5) and Rho GDP dissociation inhibitor alpha (GDIR1), were proposed to distinguish DPSCs from GMSCs. Our results provide a molecular basis for in-depth understanding of the protein composition and special functions of dental stem cells, and promote the potential clinical application.

Ascorbic Acid: A New Player of Epigenetic Regulation in LPS-gingivalis Treated Human Periodontal Ligament Stem Cells

Periodontitis is usually sustained from microorganism of oral cavity, like Porphyromonas gingivalis (P. gingivalis). Periodontal disease is an infectious disease that afflicts a large number of people. Researches are investigating on the mesenchymal stem cells (MSCs) response to inflammatory events in combination with antioxidant substances. In particular, ascorbic acid (AA) increased cell proliferation, upregulated the cells pluripotency marker expression, provide a protection from inflammation, and induced the regeneration of periodontal ligament tissue. The purpose of the present research was to investigate the effects of AA in primary culture of human periodontal ligament stem cells (hPDLSCs) exposed to P. gingivalis lipopolysaccharide (LPS-G). The effect of AA on hPDLSCs exposed to LPS-G was determined through the cell proliferation assay. The molecules involved in the inflammatory pathway and epigenetic regulation have been identified using immunofluorescence and Western blot analyses. miR-210 level was quantified by qRT-PCR, and the ROS generation was finally studied. Cells co-treated with LPS-G and AA showed a restoration in terms of cell proliferation. The expression of NFκB, MyD88, and p300 was upregulated in LPS-G exposed cells, while the expression was attenuated in the co-treatment with AA. DNMT1 expression is attenuated in the cells exposed to the inflammatory stimulus. The level of miR-210 was reduced in stimulated cells, while the expression was evident in the hPDLSCs co-treated with LPS-G and AA. In conclusion, the AA could enhance a protective effect in in vitro periodontitis model, downregulating the inflammatory pathway and ROS generation and modulating the miR-210 level.

Differential genetic mutations of ectoderm, mesoderm, and endoderm-derived tumors in TCGA database

Background

In terms of biological behavior, gene regulation, or signaling pathways, there is a certain similarity between tumorigenesis and embryonic development of humans. Three germ layer structure exhibits the distinct ability to form specific tissues and organs.

Methods

The present study set out to investigate the genetic mutation characteristics of germ layer differentiation-related genes using the tumor cases of the cancer genome atlas (TCGA) database.

Results

These tumor samples were divided into three groups, including the ectoderm, mesoderm, and endoderm. Children cases less than 9 years old accounted for a larger proportion for the cases in the ectoderm and mesoderm groups; whereas the middle-aged and elderly individuals (from 50 to 89 years old) were more susceptible to tumors of endoderm. There was a better prognosis for the cases of mesoderm, especially the male with the race of White, compared with the other groups. A missense mutation was frequently detected for the cases of ectoderm and endoderm, while deletion mutation was common for that of mesoderm. We could not identify the ectoderm, mesoderm, or endoderm-specific mutated genes or variants with high mutation frequency. However, there was a relatively higher mutation incidence of endoderm markers (GATA6, FOXA2, GATA4, AFP) in the endoderm group, compared with the groups of ectoderm and mesoderm. Additionally, four members (SMO, GLI1, GLI2, GLI3) within the Hedgehog signaling pathway genes showed a relatively higher mutation rate in the endoderm group than the other two groups.

Conclusions

TCGA tumors of ectoderm, mesoderm, and endoderm groups exhibit the distinct subject distribution, survival status, and genomic alteration characteristics. The synergistic mutation effect of specific genes closely related to embryonic development may contribute to the tumorigenesis of tissues or organs derived from the specific germ layers. This study provides a novel reference for exploring the functional connection between embryogenesis and tumorigenesis.

Short ELF-EMF Exposure Targets SIRT1/Nrf2/HO-1 Signaling in THP-1 Cells

Extremely low frequency electromagnetic fields (ELF-EMFs) have been known to modulate inflammatory responses by targeting signal transduction pathways and influencing cellular redox balance through the generation of oxidants and antioxidants. Here, we studied the molecular mechanism underlying the anti-oxidative effect of ELF-EMF in THP-1 cells, particularly with respect to antioxidant enzymes, such as heme oxygenase-1 (HO-1), regulated transcriptionally through nuclear factor E2-related factor 2 (Nrf2) activation. Cells treated with lipopolysaccharides (LPS) were exposed to a 50 Hz, 1 mT extremely low frequency electromagnetic fields for 1 h, 6 h and, 24 h. Our results indicate that ELF-EMF induced HO-1 mRNA and protein expression in LPS-treated THP-1 cells, with peak expression at 6 h, accompanied with a concomitant migration to the nucleus of a truncated HO-1 protein form. The immunostaining analysis further verified a nuclear enrichment of HO-1. Moreover, ELF-EMF inhibited the protein expressions of the sirtuin1 (SIRT1) and nuclear factor kappa B (NF-kB) pathways, confirming their anti-inflammatory/antioxidative role. Pretreatment with LY294002 (Akt inhibitor) and PD980559 (ERK inhibitor) inhibited LPS-induced Nrf2 nuclear translocation and HO-1 protein expression in ELF-EMF-exposed cells. Taken together, our results suggest that short ELF-EMF exposure exerts a protective role in THP-1 cells treated with an inflammatory/oxidative insult such as LPS, via the regulation of Nrf-2/HO-1 and SIRT1 /NF-kB pathways associated with intracellular glutathione (GSH) accumulation.

5-Azacytidine-Induced Cardiomyocyte Differentiation of Very Small Embryonic-Like Stem Cells

The use of stem cells in generating cell-based pacemaker therapies for bradyarrhythmia is currently being considered. Due to the propensity of stem cells to form tumors, as well as ethical issues surrounding their use, the seed cells used in cardiac biological pacemakers have limitations. Very small embryonic-like stem cells (VSELs) are a unique and rare adult stem cell population, which have the same structural, genetic, biochemical, and functional characteristics as embryonic stem cells without the ethical controversy. In this study, we investigated the ability of rat bone marrow- (BM-) derived VSELs to differentiate in vitro into cardiomyocytes by 5-Azacytidine (5-AzaC) treatment. The morphology of VSELs treated with 10 μM 5-AzaC increased in volume and gradually changed to cardiomyocyte-like morphology without massive cell death. Additionally, mRNA expression of the cardiomyocyte markers cardiac troponin-T (cTnT) and α-sarcomeric actin (α-actin) was significantly upregulated after 5-AzaC treatment. Conversely, stem cell markers such as Nanog, Oct-4, and Sox2 were continuously downregulated posttreatment. On day 14 post-5-AzaC treatment, the positive expression rates of cTnT and α-actin were 18.41 ± 1.51% and 19.43 ± 0.51%, respectively. Taken together, our results showed that rat BM-VSELs have the ability to differentiate into cardiomyocytes in vitro. These findings suggest that VSELs would be useful as seed cells in exploring the mechanism of biological pacemaker activity.

Stem Cells Secretome from Oral Tissue Could Represent a Promising Therapeutic Approach in COVID-19-Disease?

At present, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has quickly become a health emergency because no specifics vaccines or drugs, at this moment, are available. Recent studies have shown that the transplantation of mesenchymal stem cells (MSCs) into Coronavirus Disease 2019 (COVID-19) patients could represent a promising strategy for the development of new therapeutic methods. We speculate and suggest that the secretome of human Oral Tissue Stem Cells (hOTSCs), for their immunomodulatory and anti-inflammatory specific properties, could exert beneficial effects on the COVID-19 patients through an innovative aerosolisation technique. This non-invasive technique can offer multiple advantages in prophylaxis, as well as the prevention and treatment of severe epidemic respiratory syndrome with minimum risk and optimal therapeutic effects. This has the potential to create a novel pathway towards immunomodulatory therapy for the treatment of COVID-19 positive patients.

Enhanced VEGF/VEGF-R and RUNX2 Expression in Human Periodontal Ligament Stem Cells Cultured on Sandblasted/Etched Titanium Disk

Bone formation, in skeletal development or in osseointegration processes, is the result of interaction between angiogenesis and osteogenesis. To establish osseointegration, cells must attach to the implant in a direct way without any deposition of soft tissue. Structural design and surface topography of dental implants enhance the cell attachment and can affect the biological response. The aim of the study was to evaluate the cytocompatibility, osteogenic and angiogenic markers involved in bone differentiation of human periodontal ligament stem cells (hPDLSCs) on different titanium disks surfaces. The hPDLSCs were cultured on pure titanium surfaces modified with two different procedures, sandblasted (Control—CTRL) and sandblasted/etched (Test—TEST) as experimental titanium surfaces. After 1 and 8 weeks of culture VEGF, VEGF-R, and RUNX2 expression was evaluated under confocal laser scanning microscopy. To confirm the obtained data, RT-PCR and WB analyses were performed in order to evaluate the best implant surface performance. TEST surfaces compared to CTRL titanium surfaces enhanced cell adhesion and increased VEGF and RUNX2 expression. Moreover, titanium TEST surfaces showed a different topographic morphology that promoted cell adhesion, proliferation, and osteogenic/angiogenic commitment. To conclude, TEST surfaces performed more efficiently than CTRL surfaces; furthermore, TEST surface results showed them to be more biocompatible, better tolerated, and appropriate for allowing hPDLSC growth and proliferation. This fact could also lead to more rapid bone–titanium integration.

Functional Relationship between Osteogenesis and Angiogenesis in Tissue Regeneration

Bone tissue renewal can be outlined as a complicated mechanism centered on the interaction between osteogenic and angiogenic events capable of leading to bone formation and tissue renovation. The achievement or debacle of bone regeneration is focused on the primary role of vascularization occurrence; in particular, the turning point is the opportunity to vascularize the bulk scaffolds, in order to deliver enough nutrients, growth factors, minerals and oxygen for tissue restoration. The optimal scaffolds should ensure the development of vascular networks to warrant a positive suitable microenvironment for tissue engineering and renewal. Vascular Endothelial Growth Factor (VEGF), a main player in angiogenesis, is capable of provoking the migration and proliferation of endothelial cells and indirectly stimulating osteogenesis, through the regulation of the osteogenic growth factors released and through paracrine signaling. For this reason, we concentrated our attention on two principal groups involved in the renewal of bone tissue defects: the cells and the scaffold that should guarantee an effective vascularization process. The application of Mesenchymal Stem Cells (MSCs), an excellent cell source for tissue restoration, evidences a crucial role in tissue engineering and bone development strategies. This review aims to provide an overview of the intimate connection between blood vessels and bone formation that appear during bone regeneration when MSCs, their secretome-Extracellular Vesicles (EVs) and microRNAs (miRNAs) -and bone substitutes are used in combination.

Wnt-3a Induces Epigenetic Remodeling in Human Dental Pulp Stem Cells

Dental pulp stem cells (DPSCs) from adult teeth show the expression of a very complete repertoire of stem pluripotency core factors and a high plasticity for cell reprogramming. Canonical Wnt and Notch signaling pathways regulate stemness and the expression of pluripotency core factors in DPSCs, and even very short-term (48 h) activations of the Wnt pathway induce a profound remodeling of DPSCs at the physiologic and metabolic levels. In this work, DPSC cultures were exposed to treatments modulating Notch and Wnt signaling, and also induced to differentiate to osteo/adipocytes. DNA methylation, histone acetylation, histone methylation, and core factor expression levels where assessed by mass spectroscopy, Western blot, and qPCR. A short-term activation of Wnt signaling by WNT-3A induced a genomic DNA demethylation, and increased histone acetylation and histone methylation in DPSCs. The efficiency of cell reprogramming methods relies on the ability to surpass the epigenetic barrier, which determines cell lineage specificity. This study brings important information about the regulation of the epigenetic barrier by Wnt signaling in DPSCs, which could contribute to the development of safer and less aggressive reprogramming methodologies with a view to cell therapy.

AEDG Peptide (Epitalon) Stimulates Gene Expression and Protein Synthesis during Neurogenesis: Possible Epigenetic Mechanism

It was shown that AEDG peptide (Ala-Glu-Asp-Gly, Epitalon) regulates the function of the pineal gland, the retina, and the brain. AEDG peptide increases longevity in animals and decreases experimental cancerogenesis. AEDG peptide induces neuronal cell differentiation in retinal and human periodontal ligament stem cells. The aim of the study was to investigate the influence of AEDG peptide on neurogenic differentiation gene expression and protein synthesis in human gingival mesenchymal stem cells, and to suggest the basis for the epigenetic mechanism of this process. AEDG peptide increased the synthesis of neurogenic differentiation markers: Nestin, GAP43, β Tubulin III, Doublecortin in hGMSCs. AEDG peptide increased Nestin, GAP43, β Tubulin III and Doublecortin mRNA expression by 1.6–1.8 times in hGMSCs. Molecular modelling method showed, that AEDG peptide preferably binds with H1/6 and H1/3 histones in His-Pro-Ser-Tyr-Met-Ala-His-Pro-Ala-Arg-Lys and Tyr-Arg-Lys-Thr-Gln sites, which interact with DNA. These results correspond to previous experimental data. AEDG peptide and histones H1/3, H1/6 binding may be one of the mechanisms which provides an increase of Nestin, GAP43, β Tubulin III, and Doublecortin neuronal differentiation gene transcription. AEDG peptide can epigenetically regulate neuronal differentiation gene expression and protein synthesis in human stem cells.

Extracellular Vesicles Derived from Human Gingival Mesenchymal Stem Cells: A Transcriptomic Analysis

Human gingival mesenchymal stem cells (hGMSCs) have outstanding characteristics of proliferation and are able to differentiate into osteogenic, chondrogenic, adipogenic, and neurogenic cell lineages. The extracellular vesicles (EVs) secreted by hGMSCs contain proteins, lipids, mRNA and microRNA have emerged as important mediators of cell-to-cell communication. In this study, we analyzed the transcriptome of hGMSCs-derived EVs using Next Generation Sequencing (NGS). The functional evaluation of the transcriptome highlighted 26 structural protein classes and the presence of "non-coding RNAs". Our results showed that EVs contain several growth factors such as Transforming Growth Factor-β (TGF-β), Fibroblast Growth Factor (FGF), and Vascular Endothelial Growth Factors (VEGF) implicated in osteoblast differentiation and in angiogenetic process. Furthermore, the transcriptomic analysis showed the presence of glial cell-derived neurotrophic factor (GDNF) family ligands and neurotrophins involved in neuronal development. The NGS analysis also identified the presence of several interleukins among which some with anti-inflammatory action. Moreover, the transcriptome profile of EVs contained members of the Wnt family, involved in several biological processes, such as cellular proliferation and tissue regeneration. In conclusion, the huge amount of growth factors included in the hGMSCs-derived EVs could make them a big resource in regenerative medicine.

A Novel Role of Ascorbic Acid in Anti-Inflammatory Pathway and ROS Generation in HEMA Treated Dental Pulp Stem Cells

Resin (co)monomers issued from restorative dental materials are able to distribute in the dental pulp or the gingiva, to get to the saliva and to the flowing blood. Many authors have recently shown that methacrylate-based resins, in particular 2-hydroxyethylmethacrylate (HEMA), are responsible of inflammatory and autophagic processes in human dental pulp stem cells (hDPSCs) while ascorbic acid (AS), an antioxidant molecule, can assume a protective role in cell homeostasis. The purpose of the current work was to study if 50 µg/mL AS can affect the inflammatory status induced by 2 mM HEMA in hDPSCs, a tissue–specific cell population. Cell proliferation, cytokine release, morphological arrangement and reactive oxygen species (ROS) formation were determined respectively by MTT, ELISA, morphological analysis and dichlorofluorescein assay. The hDPSCs exposed to HEMA let to an increment of ROS formation and in the expression of high levels of inflammatory mediators such as nuclear factor-κB (NFkB), inflammatory cytokines such as interleukin IL6, IL8, interferon (IFN)ɣ and monocyte chemoattractant protein (MCP)1. Moreover, HEMA induced the up-regulation of pospho-extracellular signal–regulated kinases (pERK)/ERK signaling pathway associated to the nuclear translocation. AS treatment significantly down-regulated the levels of pro-inflammatory mediators. Then, the natural product AS reduced the detrimental result promoted by methacrylates in clinical dentistry, in fact restore cell proliferation, reduce the pro-inflammatory cytokine, downregulate ROS production and of NFkB/pERK/ERK signaling path. In synthesis, AS, could improve the quality of dental care and play a strategic role as innovative endodontic compound easy to use and with reasonable cost.

Transcriptomic Analysis of Stem Cells Treated with Moringin or Cannabidiol: Analogies and Differences in Inflammation Pathways

Inflammation is a common feature of many neurodegenerative diseases. The treatment of stem cells as a therapeutic approach to repair damage in the central nervous system represents a valid alternative. In this study, using Next-Generation Sequencing (NGS) technology, we analyzed the transcriptomic profile of human Gingival Mesenchymal Stem Cells (hGMSCs) treated with Moringin [4-(α-l-ramanosyloxy)-benzyl isothiocyanate] (hGMSCs-MOR) or with Cannabidiol (hGMSCs-CBD) at dose of 0.5 or 5 µM, respectively. Moreover, we compared their transcriptomic profiles in order to evaluate analogies and differences in pro- and anti-inflammatory pathways. The hGMSCs-MOR selectively downregulate TNF-α signaling from the beginning, reducing the expression of TNF-α receptor while hGMSCs-CBD limit its activity after the process started. The treatment with CBD downregulates the pro-inflammatory pathway mediated by the IL-1 family, including its receptor while MOR is less efficient. Furthermore, both the treatments are efficient in the IL-6 signaling. In particular, CBD reduces the effect of the pro-inflammatory JAK/STAT pathway while MOR enhances the pro-survival PI3K/AKT/mTOR. In addition, both hGMSCs-MOR and hGMSCs-CBD improve the anti-inflammatory activity enhancing the TGF-β pathway.

Human Oral Stem Cells, Biomaterials and Extracellular Vesicles: A Promising Tool in Bone Tissue Repair

Tissue engineering and/or regenerative medicine are fields of life science exploiting both engineering and biological fundamentals to originate new tissues and organs and to induce the regeneration of damaged or diseased tissues and organs. In particular, de novo bone tissue regeneration requires a mechanically competent osteo-conductive/inductive 3D biomaterial scaffold that guarantees the cell adhesion, proliferation, angiogenesis and differentiation into osteogenic lineage. Cellular components represent a key factor in tissue engineering and bone growth strategies take advantage from employment of mesenchymal stem cells (MSCs), an ideal cell source for tissue repair. Recently, the application of extracellular vesicles (EVs), isolated from stem cells, as cell-free therapy has emerged as a promising therapeutic strategy. This review aims at summarizing the recent and representative research on the bone tissue engineering field using a 3D scaffold enriched with human oral stem cells and their derivatives, EVs, as a promising therapeutic potential in the reconstructing of bone tissue defects.

Bovine pericardium membrane, gingival stem cells, and ascorbic acid: a novel team in regenerative medicine

Recently, the development and the application of 3D scaffold able to promote stem cell differentiation represented an essential field of interest in regenerative medicine. In particular, functionalized scaffolds improve bone tissue formation and promote bone defects repair. This research aims to evaluate the role of ascorbic acid (AS) supplementation in an in vitro model, in which a novel 3D-scaffold, bovine pericardium collagen membrane called BioRipar (BioR) was functionalized with human Gingival Mesenchymal Stem Cells (hGMSCs). As extensively reported in the literature, AS is an essential antioxidant molecule involved in the extracellular matrix secretion and in the osteogenic induction. Specifically, hGMSCs were seeded on BioR and treated with 60 and 90 μg/mL of AS in order to assess their growth behavior, the expression of bone specific markers involved in osteogenesis (runt-related transcription factor 2, RUNX2; collagen1A1, COL1A1; osteopontin, OPN; bone morphogenetic protein2/4, BMP2/4), and de novo deposition of calcium. The expression of COL1A1, RUNX2, BMP2/4 and OPN was evaluated by RT-PCR, Western blotting and immunocytochemistry, and proved to be upregulated. Our results demonstrate that after three weeks of treatment AS at 60 and 90 μg/mL operates as an osteogenic inductor in hGMSCs. These data indicate that the AS supplementation produces an enhancement of osteogenic phenotype commitment in an in vitro environment. For this reason, AS could represent a valid support for basic and translational research in tissue engineering and regenerative medicine.

Moringin Pretreatment Inhibits the Expression of Genes Involved in Mitophagy in the Stem Cell of the Human Periodontal Ligament

Moringin [4-(α-L-rhamnosyloxy) benzyl isothiocyanate] is an isothiocyanate extracted from Moringa oleifera seeds. It is an antioxidant known for several biological properties useful in the treatment of neurodegenerative diseases. Several neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases are linked to dysfunctional mitochondria due to the resulting increase of Reactive Oxygen Species (ROS). Stem cell-based therapeutic treatments in neurodegenerative diseases provide an alternative strategy aimed to replace the impaired tissue. In this study were investigated the deregulated genes involved in mitophagy in the human periodontal ligament stem cells pretreated with moringin. The RNA-seq study reveals the downregulation of PINK1, with a fold change (FC) of −0.56, such as the genes involved in the phagophore formation (MAP1LC3B FC: −0.73, GABARAP FC: −0.52, GABARAPL1 FC: −0.70, GABARAPL2 FC: −0.39). The moringin pretreatment downregulates the pro−apoptotic gene BAX (−0.66) and upregulates the anti-apoptotic genes BCL2L12 (FC: 1.35) and MCL1 (FC: 0.36). The downregulation of the most of the caspases (CASP1 FC: −1.43, CASP4 FC: −0.18, CASP6 FC: −1.34, CASP7 FC: −0.46, CASP8 FC: −0.65) implies the inactivation of the apoptotic process. Our results suggest that mitochondrial dysfunctions induced by oxidative stress can be inhibited by moringin pretreatment in human periodontal ligament stem cells (hPDLSCs).

HEMA Effects on Autophagy Mechanism in Human Dental Pulp Stem Cells

Autophagy is a complex mechanism that permits the degradation of cellular components in order to enhance cell homeostasis, recycling the damaged, dysfunctional, or unnecessary components. In restorative dentistry practice, free resin monomers of 2-hydroxyethyl methacrylate (HEMA) can be released. The aim of this study was to investigate the effect of HEMA on proliferation and autophagy in human dental pulp stem cells (hDPSCs). Human DPSCs were treated with different concentrations of HEMA (3 and 5 mmol L⁻¹). To evaluate the proliferation rate, MTT and trypan blue assays were used. Autophagic markers such as microtubule-associated protein 1 light chain 3 (LC3-I/II) and ubiquitin-binding protein (p62) were analyzed through immunofluorescence observations. Beclin1, LC3-I/II, and p62 were evaluated by means of Western blotting detection. Considering that activity of extracellular signal–regulated kinase (ERK) and its phosphorylated form (pERK) mediates several cellular processes, such as apoptosis, autophagy, and senescence, the involvement of ERK/pERK signaling was also evaluated. Obtained results showed a decreased cell proliferation associated with morphological changes in HEMA-treated cells. The Western blot results showed that the expression levels of Beclin1, LC3-I/II, and ERK were significantly elevated in HEMA-treated cells and in cells co-treated with rapamycin, an autophagic promoter. The expression levels of p62 were significantly reduced compared to the untreated samples. Protein levels to the autophagic process, observed at confocal microscopy confirmed the data obtained from the Western blot. The up-regulation of ERK and pERK levels, associated with nuclear translocation, revealed that ERK pathway signaling could act as a promoter of autophagy in dental pulp stem cells treated with HEMA.

3D Human Periodontal Stem Cells and Endothelial Cells Promote Bone Development in Bovine Pericardium-Based Tissue Biomaterial

Bone defects repair represents a public and urgent problem in clinical practice, in fact, every year, more than two million patients required new treatments for bone injuries. Today a complete vascularization is strategic in bone formation, representing a new frontier for clinical application. Aim of this research has been developed a three-dimensional (3D) coculture platform using a bovine pericardium collagen membrane (BioR) loaded with human periodontal ligament stem cells (hPDLSCs) and endothelial differentiated cells from hPDLSCs (E-hPDLSCs) able to undergo toward osteoangiogenesis differentiation process. First, we have characterized at confocal laser scanning microscopy (CLSM) level the E-hPDLSCs phenotype profile, through CD31 and CD34 markers expression and the ability to tube vessel formation. Real Time-Polimerase Chain Reaction (RT-PCR) and western blotting analyses revealed the upregulation of Runt-related transcription factor 2 (RUNX2), Collagen 1A1 (COL1A1), Vascular Endothelial Growth Factor-A (VEGF-A) genes and proteins in the living construct composed by hPDLSCs + E-hPDSCs/BioR. Human PDLSCs + E-hPDLSCs/BioR construct showed also an enhacement of de novo synthesis of osteocalcin. Given that, the extracellular-signal-regulated kinase (ERK)/mitogen activated protein kinase (MAPK) transduction signaling was involved in the osteogenesis and angiogenesis process, the ERK1/2 protein level at biochemical level, in our experimental model, has been investigated. Our results evidenced an upregulation of ERK1/2 proteins level born in the living construct. In conclusion, we believe that the use of the hPDLSCs and E-hPDLSCs coculture togheter with BioR as substrate, could represent an efficient model able to activate through ERK1/2 signaling pathway the osteoangiogenesis process, and then representing a new potential engineered platform for surgeons during the repair and the healing of bone defects.

3D Printing PLA/Gingival Stem Cells/ EVs Upregulate miR-2861 and -210 during Osteoangiogenesis Commitment

Bone tissue regeneration strategies require approaches that provide an osteogenic and angiogenic microenvironment able to drive the bone growth. Recently, the development of 3D printing biomaterials, including poly(lactide) (3D-PLA), enriched with mesenchymal stem cells (MSCs) and/or their derivatives, such as extracellular vesicles (EVs) has been achieving promising results. In this study, in vitro results showed an increased expression of osteogenic and angiogenic markers, as RUNX2, VEGFA, OPN and COL1A1 in the living construct 3D-PLA/human Gingival MSCs (hGMSCs)/EVs. Considering that EVs carry and transfer proteins, mRNA and microRNA into target cells, we evaluated miR-2861 and miR-210 expression related to osteoangiogenesis commitment. Histological examination of rats implanted with 3D-PLA/hGMSCs/EVs evidenced the activation of bone regeneration and of the vascularization process, confirmed also by MicroCT. In synthesis, an upregulation of miR-2861 and -210 other than RUNX2, VEGFA, OPN and COL1A1 was evident in cells cultured in the presence of the biomaterial and EVs. Then, these results evidenced that EVs may enhance bone regeneration in calvaria defects, in association with an enhanced vascularization offering a novel regulatory system in the osteoangiogenesis evolution. The application of new strategies to improve biomaterial engraftment is of great interest in the regenerative medicine and can represent a way to promote bone regeneration.

Human gingival mesenchymal stem cells pretreated with vesicular moringin nanostructures as a new therapeutic approach in a mouse model of spinal cord injury

Spinal cord injury (SCI) is a neurological disorder that arises from a primary acute mechanical lesion, followed by a pathophysiological cascade of events that leads to further spinal cord tissue damage. Several preclinical and clinical studies have highlighted the ability of stem cell therapy to improve long-term functional recovery in SCI. Previously, we demonstrated that moringin (MOR) treatment accelerates the differentiation process in mesenchymal stem cells inducing an early up-regulation of neural development associated genes. In the present study, we investigated the anti-inflammatory, anti-apoptotic, and regenerative effects of gingival mesenchymal stem cells (GMSCs) pretreated with nanostructured liposomes enriched with MOR in an animal model of SCI. SCI was produced by extradural compression of the spinal cord at levels T6-T7 in ICR (CD-1) mice. Animals were randomly assigned to the following groups: Sham, SCI, SCI + GMSCs (1 × 106  cell/i.v.), SCI + MOR-GMSCs (1 × 106  cell/i.v.). Our data show that MOR-treated GMSCs exert anti-inflammatory and anti-apoptotic activities. In particular, MOR-treated GMSCs are able to reduce the spinal cord levels of COX-2, GFAP, and inflammatory cytokines IL-1β and IL-6 and to restore spinal cord normal morphology. Also, MOR-treated GMSCs influenced the apoptotic pathway, by reducing Bax, caspase 3, and caspase 9 expressions.

MRAP2 regulates endometrial receptivity and function

A successful embryo implantation depends on the synchronization between a competent blastocyst and a receptive endometrium. Recently, potential modulators of endometrial receptivity (OVGP1, MRAP2, ZCCHC12, and HAP1) have been reported likely with a functional role during embryo implantation. The aim of this study was to evaluate the gene expression of these genes in the endometrium of infertile women. Eighteen endometrial biopsies, during secretory lutheal phase, were recruited from women with unexplained infertility and women who cannot conceive due to their partners' fertility problems. qRT-PCR was carried out to evaluate MRAP2, OVGP1, ZCCHC12 and HAP1 gene expression. MRAP2 expression was also detected by western blot and it was localized by immunohistochemistry. Morphological analysis was performed by light microscopy. MRAP2 was significantly up-regulated in study vs. control group. Western blot analysis confirmed the observed MRAP2 up-expression. MRAP2 resulted mainly localized in the epithelial cells of uterine glands. Morphological analysis displayed that the epithelium of the uterine glands undergo hypertrophy in women with unexplained infertility in respect to women with male infertility factor. MRAP2 could be considered a mediator of endometrial receptivity likely acting on endometrial stability by binding to MCRs and PKR1.

Curcumin/Liposome Nanotechnology as Delivery Platform for Anti-inflammatory Activities via NFkB/ERK/pERK Pathway in Human Dental Pulp Treated With 2-HydroxyEthyl MethAcrylate (HEMA)

Curcumin, primary component of the spice turmeric extracted from the rhizomes of Curcuma longa, represents the major anti-oxidant and anti-inflammatory substance found in turmeric, acting thought various mechanisms not completely understood. Curcumin modulates cytokines, growth factors, transcription factors, inflammatory molecules and cell signaling pathways. During restorative dentistry practice, free resin monomers of 2-hydroxyethyl methacrylate (HEMA) propagate through dentin micro-channel and pulp into the bloodstream affecting cellular integrity. The study highlights the significance of application of curcumin bioactive component into liposomal formulations (CurLIP) to restore the homeostasis of dental pulp stem cells (hDPSCs) in response to 3 and 5 mmol L^–1 HEMA treatment. Cell proliferation in combination with changes of the morphological features, proinflammatory cytokines secretion as Interleukin (IL) 6, IL8, Monocyte Chemoattractant Protein-1 (MCP1) and Interferon-gamma (IFNγ) were assayed along with the nuclear factor (NF)-kB, an inducible transcription factor involved in the activation of several cell processes associated to extracellular signal-regulated kinases (ERK) and posphorylated (p-) ERK pathway. Our results showed a decreased cell proliferation, morphological changes and upregulation of IL6, IL8, MCP1 and IFNγ in presence of 3 and 5 mmol L^–1 HEMA treatment. CurLIP therapy in hDPSCs provokes an increase in cell proliferation and the block of inflammatory cytokines secretion through the inhibitory regulation of NFkB/ERK and pERK signaling cascade. The natural nanocarrier CurLIP influences numerous biochemical and molecular cascades causing anti-inflammatory properties in response to HEMA treatment in human dental pulp stem cells, representing an innovative endodontic formulation able to improve the quality of dental care with a major human community impact.

Effect of short peptides on neuronal differentiation of stem cells

It has been demonstrated that short peptides play an important role in the transmission of biological information, modulation of transcription, and restoring genetically conditioned alterations occurring with age. Peptidergic regulation of homeostasis occupies an important place in physiological processes, which lead to the aging of cells, tissues, and organs, consisting in the involution of major regulatory systems-the nervous, the endocrine, and the immune. The effect of AED (Ala-Glu-Asp), KED (Lys-Glu-Asp), KE (Lys-Glu), AEDG (Ala-Glu-Asp-Gly) peptides and their compound on neuronal differentiation of human periodontal ligament stem cells (hPDLSCs) was studied by immunofluorescence and western blot analysis. Growth-Associated Protein 43 (GAP43), which implements neurotransmission mechanisms and neuroplasticity, demonstrated an increased expression in hPDLSCs cultured with a compound of all studied peptides and with KED alone. The peptide compound and KED, increase the expression of Nestin (neurofilament protein), expressed in early neuronal precursors in hPDLSCs cultures. Thus, the compound of peptides AEDG, KE, AED, and KED could promote the neuronal differentiation of hPDLSCs and be a promising tool for the study of peptides as a modulator of neurogenesis in neurodegenerative diseases studied in animal models.

Periodontal Ligament Stem Cells: Current Knowledge and Future Perspectives

Teeth represent a fascinating area of study in regenerative medicine, because of their unique and complex developmental origin. Several types of mesenchymal stem cells (MSCs) have been characterized in the oral cavity, and those derived from the periodontal ligament (PDL) first isolated by our group in 2005, can be expanded in a xeno-free medium preserving morphological features and markers associated with pluripotency. These postnatal MSCs can be easily recovered by noninvasive procedures and cultured. This could facilitate the use of adult stem cells in human clinical regeneration therapy. In this review we summarize the results of our studies describing morphofunctional features, surface markers, and multilineage differentiation capacity in vitro of PDL MSCs obtained in our laboratories. In vivo characterization of PDL stem cell (PDLSC) location and heterogeneity are still lacking. However, we describe studies exploring the potential use of PDLSC to treat both periodontal diseases and regeneration of other tissues. These MSCs may have an advantage in possessing also angiogenetic, immunoregulatory, and anti-inflammatory properties. The secretome of such cells contains several interesting molecules mimicking the effects of the producer cells. We describe some recent studies from our group on the use of conditioned medium from PDL MSCs, and purified extracellular vesicles therein contained, in animal models of experimental autoimmune encephalomyelitis and their potential application to human disease.

Exosomes from Human Gingiva-Derived Mesenchymal Stem Cells Combined with Biodegradable Chitin Conduits Promote Rat Sciatic Nerve Regeneration

At present, repair methods for peripheral nerve injury often fail to get satisfactory result. Although various strategies have been adopted to investigate the microenvironment after peripheral nerve injury, the underlying molecular mechanisms of neurite outgrowth remain unclear. In this study, we evaluate the effects of exosomes from gingival mesenchymal stem cells (GMSCs) combined with biodegradable chitin conduits on peripheral nerve regeneration. GMSCs were isolated from human gingival tissue and characterized by surface antigen analysis and in vitro multipotent differentiation. The cell supernatant was collected to isolate the exosomes. The exosomes were characterized by transmission electron microscopy, Western blot, and size distribution analysis. The effects of exosomes on peripheral nerve regeneration in vitro were evaluated by coculture with Schwann cells and DRGs. The chitin conduit was prepared and combined with the exosomes to repair rat sciatic nerve defect. Histology, electrophysiology, and gait analysis were used to test the effects of exosomes on sciatic nerve function recovery in vivo. We have successfully cultured GMSCs and isolated exosomes. The exosomes from GMSCs could significantly promote Schwann cell proliferation and DRG axon growth. The in vivo studies showed that chitin conduit combined with exosomes from GMSCs could significantly increase the number and diameter of nerve fibers and promote myelin formation. In addition, muscle function, nerve conduction function, and motor function were also obviously recovered. In summary, this study suggests that GMSC-derived exosomes combined with biodegradable chitin conduits are a useful and novel therapeutic intervention in peripheral nerve repair.

Engineered Extracellular Vesicles From Human Periodontal-Ligament Stem Cells Increase VEGF/VEGFR2 Expression During Bone Regeneration

Bone regeneration represents still a challenge, in particular for calvarium defects. Recently, the development of biomaterials with the addiction of stem cells is giving promising results for the treatment of bone defects. In particular, it was demonstrated that scaffolds enriched with mesenchymal stem cells (MSCs) and/or their derivatives, such as conditioned medium (CM) and extracellular vesicles (EVs), may improve bone regeneration. Moreover, given the deep link between osteogenesis and angiogenesis, a successful approach must also take into consideration the development of vascularization. In this work we evaluated the bone regeneration capacity of a collagen membrane (3D-COL) enriched with human periodontal-ligament stem cells (hPDLSCs) and CM or EVs or EVs engineered with polyethylenimine (PEI-EVs) in rats subjected to a calvarial defect. We evaluated also their capacity to induce angiogenic factors. At first, in vitro results showed an increased expression of osteogenic markers in hPDLSCs cultured with the 3D-COL and PEI-EVs, associated also with the increased protein levels of Vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2). The increased expression of these proteins was confirmed also in vivo in rats implanted with the 3D-COL enriched with hPDLSCs and PEI-EVs. Moreover, histological examination evidenced in this group of rats the activation of bone regeneration and of the vascularization process. Also MicroCT imaging with morphometric analysis confirmed in rats transplanted with 3D-COL enriched with hPDLSCs and PEI-EVs an important regenerative process and a better integration level. All together, these results evidenced that the 3D-COL enriched with hPDLSCs and PEI-EVs may promote bone regeneration of calvaria defects, associated also with an increased vascularization.

Physiological Expression of Ion Channel Receptors in Human Periodontal Ligament Stem Cells

The etiopathogenesis of neurodegenerative diseases is characterized by the death of neurons. Human periodontal ligament stem cells (hPDLSCs), coming from neuronal crest, can potentially become neuronal cells because of their embryologic origin. In this study, we performed an RNA-seq analysis of hPDLSCs in order to determine whether their transcriptomic profile revealed genes encoded for ion channel receptors. Next, each found gene was enriched by the information of pathways stored in the Reactome database. Our results show that the hPDLSCs express GABBR1 and GABBR2, CHRNA1, GRINA genes, respectively associated with GABA_B, NMDA and nACh receptors. In particular, the two subunits of GABA_B receptor are expressed in hPDLSCs. Further, the proteic extract for GABA_BR1, GABA_BR2 and AChRα1 confirmed their expression in hPDLSCs. Our results show that hPDLSCs express physiologically genes associated with ion channel receptors maintaining multipotent features which are useful for neurogenesis.

Hypermethylation of Frizzled1 is associated with Wnt/β-catenin signaling inactivation in mesenchymal stem cells of patients with steroid-associated osteonecrosis

The Wnt/β-catenin signaling pathway is associated with the pathogenesis of steroid-induced osteonecrosis. Our investigation studied whether aberrant CpG island hypermethylation of the FZD1 gene was present in patients with osteonecrosis of the femoral head (ONFH), which results in Wnt/β-catenin signaling inactivation and subsequent cell dysfunction. Bone marrow was collected from the proximal femurs of patients with steroid-associated ONFH (n = 21) and patients with new femoral neck fractures (n = 22), and then mesenchymal stem cells (MSCs) were isolated. We investigated cell viability, the transcription and translation levels of Wnt/β-catenin signaling-related genes, the extent of methylation at CpG islands of the FZD1 promoter, and the osteogenic and adipogenic differentiation abilities of MSCs from the control group and from the ONFH group treated with or without 5′-Aza-dC. According to the results, MSCs from the ONFH group showed a reduced proliferation ability, low transcription and translation levels of FZD1, inhibition of the Wnt/β-catenin signaling pathway, weakened osteogenesis and enhanced adipogenesis ability. Aberrant CpG island hypermethylation of FZD1 was observed in the ONFH group. Treatment with 5’-Aza-dC resulted in de novo FZD1 expression, reactivation of the Wnt/β-catenin signaling pathway and promotion of osteogenesis. Taken together, our study not only provides novel insights into the regulation of the Wnt/β-catenin signaling pathway in this disease but also reveals potential for the use of demethylating agents for the treatment of GC-associated ONFH.

Studies of genetic and molecular signaling processes in the bone disease osteonecrosis, when it is associated with steroid use, reveal insights into disease development and suggest new approaches for treatment. Steroid drugs increase the risk of osteonecrosis, in which bone tissue dies due to insufficient blood supply, but the mechanism of this effect is unclear. Researchers in China, led by Zhibo Sun at Wuhan University, investigated a link between the aberrant addition of methyl groups (CH₃) to the DNA of a specific gene and the onset of the disease. They identified an important molecular signaling pathway in cultured bone marrow cells from patients that is inhibited by the gene methylation. Treating these cells with a drug that inhibits methylation led to reactivation of the gene and the associated signalling pathway that promotes healthy bone formation.

The Role of Hypoxia on the Neuronal Differentiation of Gingival Mesenchymal Stem Cells: A Transcriptional Study

Mesenchymal stem cells (MSCs) are widely used in stem cell therapy for regenerative purposes. Oral-derived MSCs, such as gingival MSCs (GMSCs), deriving from the neural crest seem more suitable to differentiate toward the neuronal lineage. In addition, the preconditioning of MSCs may improve their beneficial effects. Since it is known that hypoxia may influence stem cell properties, we were interested in evaluating the effects of hypoxia preconditioning on the neuronal differentiation of GMSCs. With this aim, we evaluated the transcriptional profile of GMSCs exposed to basal and neuroinductive medium both in normoxia and in cells preconditioned for 48 h in hypoxia. We compared their transcriptional profile using Next Generation Sequencing. At first we observed that hypoxia did not alter cell morphology compared with the GMSCs cultured in a normoxic condition. In order to understand hypoxia preconditioning effects on neuronal differentiation, we screened genes with Log2 fold change ≥2 using the database Cortecon, that collects gene expression data set of in vitro corticogenesis. We observed that hypoxia preconditioning induced the expression of more genes associated with different stages of cortical development. The common genes, expressed both in normoxia and hypoxia preconditioning, were involved in developmental and neuronal processes. Interestingly, a larger number of genes associated with development biology and neuronal process was expressed in GMSCs differentiated after hypoxia preconditioning compared with those in normoxia. In addition, hypoxic-preconditioned differentiated GMSCs showed a higher expression of nestin, PAX6, and GAP43. Our data demonstrated that hypoxia preconditioning enhanced the differentiation potential of GMSCs and induced the activation of a higher number of genes associated with neuronal development. In conclusion, hypoxia may be used to improve MSCs’ properties for stem cell therapy.

MicroRNA 210 Mediates VEGF Upregulation in Human Periodontal Ligament Stem Cells Cultured on 3DHydroxyapatite Ceramic Scaffold

The aim of the present research was the evaluation of the behavior of human periodontal ligament stem cells (hPDLSCs), cultured in presence of Endobon^® Xenograft Granules (G), a fully deproteinated hydroxyapatite ceramic scaffold derived from cancellous bovine bone. hPDLSCs were seeded with and without G for 24 h to 1 week. The cell growth, morphological features, adhesiveness, differentiation ability, modulation of miR-210 and Vascular Endothelial Growth Factor (VEGF) secretion were analyzed by means of MTT assay, Scanning Electron Microscopy (SEM), Confocal Laser Scanning Microscopy (CLSM), Alizarin Red S assay, RT-PCR and ELISA test, respectively. hPDLSCs grown on the biomaterial showed the ability to form focal adhesion on the substrate, as demonstrated by vinculin expression. These data were supported by SEM analysis showing that an adhesiveness process associated to cell growth occurs between cells and biomaterials. The osteogenic differentiation, evaluated by morphological, biochemical, and RT-PCR analysis, was pronounced in the hPDLSCs grown in the three-dimensional inorganic bovine bone substitute in the presence of osteoinductive conditions. In addition, an upregulation of miR-210 and VEGF was evident in cells cultured in presence of the biomaterial. Our results inspire us to consider granules not only an adequate biocompatible three-dimensional biomaterial, but also an effective inductor of miR-210 and VEGF; in fact, the involvement of miR-210 in VEGF secretion could offer a novel regulatory system in the early steps of the bone-regeneration process.