Stem cells isolated from human dental pulp and amniotic fluid improve skeletal muscle histopathology in mdx/SCID mice

A comprehensive review on the role of mesenchymal stromal/stem cells in the management of rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease with systemic manifestations. Although the success of immune modulatory drug therapy is considerable, about 40% of patients do not respond to treatment. Mesenchymal stromal/stem cells (MSCs) have been demonstrated to have therapeutic potential for inflammatory diseases.

AREAS COVERED

This review provides an update on RA disease and on pre-clinical and clinical studies using MSCs from bone marrow, umbilical cord, adipose tissue, and dental pulp, to regulate the immune response. Moreover, the clinical use, safety, limitations, and future perspective of MSCs in RA are discussed. Using the PubMed database and ClincalTrials.gov, peer-reviewed full-text papers, abstracts and clinical trials were identified from 1985 through to April 2023.

EXPERT OPINION

MSCs demonstrated a satisfactory safety profile and potential for clinical efficacy. However, it is mandatory to deepen the investigations on how MSCs affect the proinflammatory deregulated RA patients' cells. MSCs are potentially good candidates for severe RA patients not responding to conventional therapies but a long-term follow-up after stem cells treatment and standardized protocols are needed. Future research should focus on well-designed multicenter randomized clinical trials with adequate sample sizes and properly selected patients satisfying RA criteria for a valid efficacy evaluation.

Mesenchymal Stromal Cells: Heterogeneity and Therapeutical Applications

Mesenchymal stromal cells nowadays emerge as a major player in the field of regenerative medicine and translational research. They constitute, with their derived products, the most frequently used cell type in different therapies. However, their heterogeneity, including different subpopulations, the anatomic source of isolation, and high donor-to-donor variability, constitutes a major controversial issue that affects their use in clinical applications. Furthermore, the intrinsic and extrinsic molecular mechanisms underlying their self-renewal and fate specification are still not completely elucidated. This review dissects the different heterogeneity aspects of the tissue source associated with a distinct developmental origin that need to be considered when generating homogenous products before their usage for clinical applications.

DNA-PKcs regulates myogenesis in an Akt-dependent manner independent of induced DNA damage

Skeletal muscle regeneration relies on muscle stem (satellite) cells. We previously demonstrated that satellite cells efficiently and accurately repair radiation-induced DNA double-strand breaks (DSBs) via the DNA-dependent kinase DNA-PKcs. We show here that DNA-PKcs affects myogenesis independently of its role in DSB repair. Consequently, this process does not require the accumulation of DSBs and it is also independent of caspase-induced DNA damage. We report that in myogenic cells DNA-PKcs is essential for the expression of the differentiation factor Myogenin in an Akt2-dependent manner. DNA-PKcs interacts with the p300-containing complex that activates Myogenin transcription. We show also that SCID mice that are deficient in DNA-PKcs, and are used for transplantation and muscle regeneration studies, display altered myofiber composition and delayed myogenesis upon injury. These defects are exacerbated after repeated injury/regeneration events resulting in reduced muscle size. We thus identify a novel, caspase-independent, regulation of myogenic differentiation, and define a differentiation phase that does not involve the DNA damage/repair process.

Stem cell sources from human biological waste material: a role for the umbilical cord and dental pulp stem cells for regenerative medicine

Stem cell research with biological waste material is an area that holds promise to revolutionize treatment modalities and clinical practice. The interest in surgical remnants is increasing with time as research on human embryonic stem cells remains controversial due to legal and ethical issues. Perhaps, these restrictions are the motivation for the use of alternative mesenchymal stem cell (MSC) sources in the regenerative field. Stem cells (SCs) of Umbilical Cord (UC) and Dental Pulp (DP) have almost similar biological characteristics to other MSCs and can differentiate into a number of cell lineages with enormous potential future prospects. A concise critical observation of UC-MSCs and DP-MSCs is presented here reviewing articles from the last two decades along with other stem cell sources from different biological waste materials.

Neurological Disease Modeling Using Pluripotent and Multipotent Stem Cells: A Key Step towards Understanding and Treating Mucopolysaccharidoses

Despite extensive research, the links between the accumulation of glycosaminoglycans (GAGs) and the clinical features seen in patients suffering from various forms of mucopolysaccharidoses (MPSs) have yet to be further elucidated. This is particularly true for the neuropathology of these disorders; the neurological symptoms are currently incurable, even in the cases where a disease-specific therapeutic approach does exist. One of the best ways to get insights on the molecular mechanisms driving that pathogenesis is the analysis of patient-derived cells. Yet, not every patient-derived cell recapitulates relevant disease features. For the neuronopathic forms of MPSs, for example, this is particularly evident because of the obvious inability to access live neurons. This scenario changed significantly with the advent of induced pluripotent stem cell (iPSC) technologies. From then on, a series of differentiation protocols to generate neurons from iPSC was developed and extensively used for disease modeling. Currently, human iPSC and iPSC-derived cell models have been generated for several MPSs and numerous lessons were learnt from their analysis. Here we review most of those studies, not only listing the currently available MPS iPSC lines and their derived models, but also summarizing how they were generated and the major information different groups have gathered from their analyses. Finally, and taking into account that iPSC generation is a laborious/expensive protocol that holds significant limitations, we also hypothesize on a tempting alternative to establish MPS patient-derived neuronal cells in a much more expedite way, by taking advantage of the existence of a population of multipotent stem cells in human dental pulp to establish mixed neuronal and glial cultures.

Flow-dependent shear stress affects the biological properties of pericyte-like cells isolated from human dental pulp

BACKGROUND

Human dental pulp stem cells represent a mesenchymal stem cell niche localized in the perivascular area of dental pulp and are characterized by low immunogenicity and immunomodulatory/anti-inflammatory properties. Pericytes, mural cells surrounding the endothelium of small vessels, regulate numerous functions including vessel growth, stabilization and permeability. It is well established that pericytes have a tight cross talk with endothelial cells in neoangiogenesis and vessel stabilization, which are regulated by different factors, i.e., microenvironment and flow-dependent shear stress. The aim of this study was to evaluate the effects of a pulsatile unidirectional flow in the presence or not of an inflammatory microenvironment on the biological properties of pericyte-like cells isolated from human dental pulp (hDPSCs).

METHODS

Human DPSCs were cultured under both static and dynamic conditions with or without pre-activated peripheral blood mononuclear cells (PBMCs). Pulsatile unidirectional flow shear stress was generated by using a specific peristaltic pump. The angiogenic potential and inflammatory properties of hDPSCs were evaluated through reverse phase protein microarrays (RPPA), confocal immunofluorescence and western blot analyses.

RESULTS

Our data showed that hDPSCs expressed the typical endothelial markers, which were up-regulated after endothelial induction, and were able to form tube-like structures. RPPA analyses revealed that these properties were modulated when a pulsatile unidirectional flow shear stress was applied to hDPSCs. Stem cells also revealed a downregulation of the immune-modulatory molecule PD-L1, in parallel with an up-regulation of the pro-inflammatory molecule NF-kB. Immune-modulatory properties of hDPSCs were also reduced after culture under flow-dependent shear stress and exposure to an inflammatory microenvironment. This evidence was strengthened by the detection of up-regulated levels of expression of pro-inflammatory cytokines in PBMCs.

CONCLUSIONS

In conclusion, the application of a pulsatile unidirectional flow shear stress induced a modulation of immunomodulatory/inflammatory properties of dental pulp pericyte-like cells.

Stem Cell Application for Stress Urinary Incontinence: From Bench to Bedside

Stress urinary incontinence (SUI) is a common urinary system disease worldwide. Nowadays, medical therapy and surgery can control the symptoms and improve the life quality of patients. However, they might also bring about complications as the standard therapy fails to address the underlying problem of urethral sphincter dysfunction. Recent advances in cell technology have aroused interest in the use of autologous stem cell therapy to restore the ability of urinary control. The present study reviewed several types of stem cells for the treatment of SUI in the experimental and clinical stages.

Human dental pulp stem cells (hDPSCs) promote the lipofibroblast transition in the early stage of a fibro-inflammatory process

Introduction: In autoimmune diseases, particularly in systemic sclerosis and chronic periaortitis, a strict correlation between chronic inflammation and fibrosis exists. Since the currently used drugs prove mostly effective in suppressing inflammation, a better comprehension of the molecular mechanisms exerted by cell types implicated in fibro-inflammation is needed to develop novel therapeutic strategies. Mesenchymal stromal/stem cells (MSCs) are being matter of deep investigation to unveil their role in the evolution of fibrogenetic process. Several findings pointed out the controversial implication of MSCs in these events, with reports lining at a beneficial effect exerted by external MSCs and others highlighting a direct contribution of resident MSCs in fibrosis progression. Human dental pulp stem cells (hDPSCs) have demonstrated to hold promise as potential therapeutic tools due to their immunomodulatory properties, which strongly support their contribution to tissue regeneration. Methods: Our present study evaluated hDPSCs response to a fibro-inflammatory microenvironment, mimicked in vitro by a transwell co-culture system with human dermal fibroblasts, at early and late culture passages, in presence of TGF-β1, a master promoter of fibrogenesis. Results and Discussion: We observed that hDPSCs, exposed to acute fibro-inflammatory stimuli, promote a myofibroblast-to-lipofibroblast transition, likely based on BMP2 dependent pathways. Conversely, when a chronic fibro-inflammatory microenvironment is generated, hDPSCs reduce their anti-fibrotic effect and acquire a pro-fibrotic phenotype. These data provide the basis for further investigations on the response of hDPSCs to varying fibro-inflammatory conditions.

Botanicals and Oral Stem Cell Mediated Regeneration: A Paradigm Shift from Artificial to Biological Replacement

Stem cells are a well-known autologous pluripotent cell source, having excellent potential to develop into specialized cells, such as brain, skin, and bone marrow cells. The oral cavity is reported to be a rich source of multiple types of oral stem cells, including the dental pulp, mucosal soft tissues, periodontal ligament, and apical papilla. Oral stem cells were useful for both the regeneration of soft tissue components in the dental pulp and mineralized structure regeneration, such as bone or dentin, and can be a viable substitute for traditionally used bone marrow stem cells. In recent years, several studies have reported that plant extracts or compounds promoted the proliferation, differentiation, and survival of different oral stem cells. This review is carried out by following the PRISMA guidelines and focusing mainly on the effects of bioactive compounds on oral stem cell-mediated dental, bone, and neural regeneration. It is observed that in recent years studies were mainly focused on the utilization of oral stem cell-mediated regeneration of bone or dental mesenchymal cells, however, the utility of bioactive compounds on oral stem cell-mediated regeneration requires additional assessment beyond in vitro and in vivo studies, and requires more randomized clinical trials and case studies.

Clinical Potential of Dental Pulp Stem Cells in Pulp Regeneration: Current Endodontic Progress and Future Perspectives

Dental caries is a common disease that not only destroys the rigid structure of the teeth but also causes pulp necrosis in severe cases. Once pulp necrosis has occurred, the most common treatment is to remove the damaged pulp tissue, leading to a loss of tooth vitality and increased tooth fragility. Dental pulp stem cells (DPSCs) isolated from pulp tissue exhibit mesenchymal stem cell-like characteristics and are considered ideal candidates for regenerating damaged dental pulp tissue owing to their multipotency, high proliferation rate, and viability after cryopreservation. Importantly, DPSCs do not elicit an allogeneic immune response because they are non-immunogenic and exhibit potent immunosuppressive properties. Here, we provide an up-to-date review of the clinical applicability and potential of DPSCs, as well as emerging trends in the regeneration of damaged pulp tissue. In addition, we suggest the possibility of using DPSCs as a resource for allogeneic transplantation and provide a perspective for their clinical application in pulp regeneration.

Application of dental pulp stem cells in oral maxillofacial tissue engineering

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

Therapeutic Potential of Dental Pulp Stem Cells According to Different Transplant Types

Stem cells are unspecialised cells capable of perpetual self-renewal, proliferation and differentiation into more specialised daughter cells. They are present in many tissues and organs, including the stomatognathic system. Recently, the great interest of scientists in obtaining stem cells from human teeth is due to their easy availability and a non-invasive procedure of collecting the material. Three key components are required for tissue regeneration: stem cells, appropriate scaffold material and growth factors. Depending on the source of the new tissue or organ, there are several types of transplants. In this review, the following division into four transplant types is applied due to genetic differences between the donor and the recipient: xenotransplantation, allotransplantation, autotransplantation and isotransplantation (however, due to the lack of research, type was not included). In vivo studies have shown that Dental Pulp Stem Cells (DPSCs)can form a dentin-pulp complex, nerves, adipose, bone, cartilage, skin, blood vessels and myocardium, which gives hope for their use in various biomedical areas, such as immunotherapy and regenerative therapy. This review presents the current in vivo research and advances to provide new biological insights and therapeutic possibilities of using DPSCs.

Role of PD-L1 in licensing immunoregulatory function of dental pulp mesenchymal stem cells

Background

Dental pulp stem cells (DPSCs) are low immunogenic and hold immunomodulatory properties that, along with their well-established multi-potency, might enhance their potential application in autoimmune and inflammatory diseases. The present study focused on the ability of DPSCs to modulate the inflammatory microenvironment through PD1/PD-L1 pathway.

Methods

Inflammatory microenvironment was created in vitro by the activation of T cells isolated from healthy donors and rheumatoid arthritis (RA) patients with anti-CD3 and anti-CD28 antibodies. Direct and indirect co-cultures between DPSCs and PBMCs were carried out to evaluate the activation of immunomodulatory checkpoints in DPSCs and the inflammatory pattern in PBMCs.

Results

Our data suggest that the inflammatory stimuli trigger DPSCs immunoregulatory functions that can be exerted by both direct and indirect contact. As demonstrated by using a selective PD-L1 inhibitor, DPSCs were able to activate compensatory pathways targeting to orchestrate the inflammatory process by modulating pro-inflammatory cytokines in pre-activated T lymphocytes. The involvement of PD-L1 mechanism was also observed in autologous inflammatory status (pulpitis) and after direct exposure to pre-activated T cells from RA patients suggesting that immunomodulatory/anti-inflammatory properties are strictly related to their stemness status.

Conclusions

Our findings point out that the communication with the inflammatory microenvironment is essential in licensing their immunomodulatory properties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02664-4.

Shikonin induces odontoblastic differentiation of dental pulp stem cells via AKT-mTOR signaling in the presence of CD44

Purpose: In our previous study, we demonstrated that hyaluronan induces odontoblastic differentiation of dental pulp stem cells via interactions with CD44. However, it remains unclear whether CD44 expression by dental pulp stem cells is required for odontoblastic differentiation.Methods: We searched for a compound other than hyaluronan that induces odontoblastic differentiation of dental pulp stem cells and used western blotting to determine whether CD44 is involved in the induction of odontoblastic differentiation by the compound. We further validated the cell signaling details of the compound-induced expression of dentin sialophosphoprotein (DSPP), which is known as a marker of odontoblastic differentiation.Results: We investigated shikonin, which is one of the derivatives of naphthoquinone, the skeleton of vitamin K. Shikonin-induced expression of DSPP was inhibited by PI3K, AKT, and mTOR inhibitors. Additionally, shikonin-induced expression of DSPP was inhibited in dental pulp stem cells transfected with siRNA against CD44.Conclusions: Shikonin can stimulate dental pulp stem cells to undergo odontoblastic differentiation through a mechanism involving the AKT-mTOR signaling pathway and CD44. Although expression of CD44 is important for inducing odontoblastic differentiation of dental pulp stem cells, the relationship between the AKT-mTOR signaling pathway and CD44 expression, in the context of shikonin stimulation, has not yet been elucidated. This study suggests that shikonin may be useful for inducing odontoblastic differentiation of dental pulp stem cells, and that it may have clinical applications, including protection of the dental pulp.

Dental Pulp Stem Cells Derived From Adult Human Third Molar Tooth: A Brief Review

The fields of regenerative medicine and stem cell-based tissue engineering have the potential of treating numerous tissue and organ defects. The use of adult stem cells is of particular interest when it comes to dynamic applications in translational medicine. Recently, dental pulp stem cells (DPSCs) have been traced in third molars of adult humans. DPSCs have been isolated and characterized by several groups. DPSCs have promising characteristics including self-renewal capacity, rapid proliferation, colony formation, multi-lineage differentiation, and pluripotent gene expression profile. Nevertheless, genotypic, and phenotypic heterogeneities have been reported for DPSCs subpopulations which may influence their therapeutic potentials. The underlying causes of DPSCs’ heterogeneity remain poorly understood; however, their heterogeneity emerges as a consequence of an interplay between intrinsic and extrinsic cellular factors. The main objective of the manuscript is to review the current literature related to the human DPSCs derived from the third molar, with a focus on their physiological properties, isolation procedures, culture conditions, self-renewal, proliferation, lineage differentiation capacities and their prospective advances use in pre-clinical and clinical applications.

Mesenchymal stem cell therapies for Alzheimer's disease: preclinical studies

Alzheimer's disease (AD) is a chronic, progressive, and fatal neurodegenerative disorder that is characterized by memory failure, cognitive impairment, as well as behavioral and psychological manifestations. Drugs can only moderately manage, but not alleviate, clinical symptoms. Results, based on animal models, have demonstrated that cell therapy is a promising strategy for treating neurodegenerative disorders. The homing effect of mesenchymal stem cells (MSCs) replaces damaged cells, while some scholars believe that the paracrine effects play a crucial role in treating diseases. In fact, these cells have rich sources, exhibit high proliferation rates, low tumorigenicity, and immunogenicity, and have no ethical concerns. Consequently, MSCs have been used across various disease aspects, such as regulating immunity, nourishing nerves, and promoting regeneration. Deterioration of public health status have exposed both Alzheimer's patients and researchers to various difficulties during epidemics. In this review, we discuss the advances and challenges in the application of mesenchymal stem cell therapy for treatment of Alzheimer's disease.

Dentine sialophosphoprotein signal in dentineogenesis and dentine regeneration

Dentineogenesis starts on odontoblasts, which synthesise and secrete non-collagenous proteins (NCPs) and collagen. When dentine is injured, dental pulp progenitors/mesenchymal stem cells (MSCs) can migrate to the injured area, differentiate into odontoblasts and facilitate formation of reactionary dentine. Dental pulp progenitor cell/MSC differentiation is controlled at given niches. Among dental NCPs, dentine sialophosphoprotein (DSPP) is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family, whose members share common biochemical characteristics such as an Arg-Gly-Asp (RGD) motif. DSPP expression is cell- and tissue-specific and highly seen in odontoblasts and dentine. DSPP mutations cause hereditary dentine diseases. DSPP is catalysed into dentine glycoprotein (DGP)/sialoprotein (DSP) and phosphoprotein (DPP) by proteolysis. DSP is further processed towards active molecules. DPP contains an RGD motif and abundant Ser-Asp/Asp-Ser repeat regions. DPP-RGD motif binds to integrin αVβ3 and activates intracellular signalling via mitogen-activated protein kinase (MAPK) and focal adhesion kinase (FAK)-ERK pathways. Unlike other SIBLING proteins, DPP lacks the RGD motif in some species. However, DPP Ser-Asp/Asp-Ser repeat regions bind to calcium-phosphate deposits and promote hydroxyapatite crystal growth and mineralisation via calmodulin-dependent protein kinase II (CaMKII) cascades. DSP lacks the RGD site but contains signal peptides. The tripeptides of the signal domains interact with cargo receptors within the endoplasmic reticulum that facilitate transport of DSPP from the endoplasmic reticulum to the extracellular matrix. Furthermore, the middle- and COOH-terminal regions of DSP bind to cellular membrane receptors, integrin β6 and occludin, inducing cell differentiation. The present review may shed light on DSPP roles during odontogenesis.

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.

Mesenchymal Stromal Cells and Their Secretome: New Therapeutic Perspectives for Skeletal Muscle Regeneration

Mesenchymal stromal cells (MSCs) are multipotent cells found in different tissues: bone marrow, peripheral blood, adipose tissues, skeletal muscle, perinatal tissues, and dental pulp. MSCs are able to self-renew and to differentiate into multiple lineages, and they have been extensively used for cell therapy mostly owing to their anti-fibrotic and immunoregulatory properties that have been suggested to be at the basis for their regenerative capability. MSCs exert their effects by releasing a variety of biologically active molecules such as growth factors, chemokines, and cytokines, either as soluble proteins or enclosed in extracellular vesicles (EVs). Analyses of MSC-derived secretome and in particular studies on EVs are attracting great attention from a medical point of view due to their ability to mimic all the therapeutic effects produced by the MSCs (i.e., endogenous tissue repair and regulation of the immune system). MSC-EVs could be advantageous compared with the parental cells because of their specific cargo containing mRNAs, miRNAs, and proteins that can be biologically transferred to recipient cells. MSC-EV storage, transfer, and production are easier; and their administration is also safer than MSC therapy. The skeletal muscle is a very adaptive tissue, but its regenerative potential is altered during acute and chronic conditions. Recent works demonstrate that both MSCs and their secretome are able to help myofiber regeneration enhancing myogenesis and, interestingly, can be manipulated as a novel strategy for therapeutic interventions in muscular diseases like muscular dystrophies or atrophy. In particular, MSC-EVs represent promising candidates for cell free-based muscle regeneration. In this review, we aim to give a complete picture of the therapeutic properties and advantages of MSCs and their products (MSC-derived EVs and secreted factors) relevant for skeletal muscle regeneration in main muscular diseases.

Bovine-Derived Xenografts Immobilized With Cryopreserved Stem Cells From Human Adipose and Dental Pulp Tissues Promote Bone Regeneration: A Radiographic and Histological Study

Adipose tissue-derived stem cells (ADSCs) and dental pulp stem cells (DPSCs) have become promising sources for bone tissue engineering. Our study aimed at evaluating bone regeneration potential of cryopreserved ADSCs and DPSCs combined with bovine-derived xenografts with 10% porcine collagen. In vitro studies revealed that although DPSCs had higher proliferative abilities, ADSCs exhibited greater mineral depositions and higher osteogenic-related gene expression, indicating better osteogenic differentiation potential of ADSCs. After applying cryopreserved ADSCs and DPSCs in a critical-sized calvarial defect model, both cryopreserved mesenchymal stem cells significantly improved bone volume density and new bone area at 2, 4, and 8 weeks. Furthermore, the combined treatment with ADSCs and xenografts was more efficient in enhancing bone repair processes compared to combined treatment with DPCSs at all-time points. We also evaluated the sequential early bone healing process both histologically and radiographically, confirming a high agreement between these two methods. Based on these results, we propose grafting of the tissue-engineered construct seeded with cryopreserved ADSCs as a useful strategy in accelerating bone healing processes.

Dental pulp stem cells can improve muscle dysfunction in animal models of Duchenne muscular dystrophy

Background

Duchenne muscular dystrophy (DMD) is an inherited progressive disorder that causes skeletal and cardiac muscle deterioration with chronic inflammation. Dental pulp stem cells (DPSCs) are attractive candidates for cell-based strategies for DMD because of their immunosuppressive properties. Therefore, we hypothesized that systemic treatment with DPSCs might show therapeutic benefits as an anti-inflammatory therapy.

Methods

To investigate the potential benefits of DPSC transplantation for DMD, we examined disease progression in a DMD animal model, mdx mice, by comparing them with different systemic treatment conditions. The DPSC-treated model, a canine X-linked muscular dystrophy model in Japan (CXMD_J), which has a severe phenotype similar to that of DMD patients, also underwent comprehensive analysis, including histopathological findings, muscle function, and locomotor activity.

Results

We demonstrated a therapeutic strategy for long-term functional recovery in DMD using repeated DPSC administration. DPSC-treated mdx mice and CXMD_J showed no serious adverse events. MRI findings and muscle histology suggested that DPSC treatment downregulated severe inflammation in DMD muscles and demonstrated a milder phenotype after DPSC treatment. DPSC-treated models showed increased recovery in grip-hand strength and improved tetanic force and home cage activity. Interestingly, maintenance of long-term running capability and stabilized cardiac function was also observed in 1-year-old DPSC-treated CXMD_J.

Conclusions

We developed a novel strategy for the safe and effective transplantation of DPSCs for DMD recovery, which included repeated systemic injection to regulate inflammation at a young age. This is the first report on the efficacy of a systemic DPSC treatment, from which we can propose that DPSCs may play an important role in delaying the DMD disease phenotype.

Angiogenesis in Regenerative Dentistry: Are We Far Enough for Therapy?

Angiogenesis is a broad spread term of high interest in regenerative medicine and tissue engineering including the dental field. In the last two decades, researchers worldwide struggled to find the best ways to accelerate healing, stimulate soft, and hard tissue remodeling. Stem cells, growth factors, pathways, signals, receptors, genetics are just a few words that describe this area in medicine. Dental implants, bone and soft tissue regeneration using autologous grafts, or xenografts, allografts, their integration and acceptance rely on their material properties. However, the host response, through its vascularization, plays a significant role. The present paper aims to analyze and organize the latest information about the available dental stem cells, the types of growth factors with pro-angiogenic effect and the possible therapeutic effect of enhanced angiogenesis in regenerative dentistry.

Characteristics and Therapeutic Potential of Human Amnion-Derived Stem Cells

Stem cells including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells (ASCs) are able to repair/replace damaged or degenerative tissues and improve functional recovery in experimental model and clinical trials. However, there are still many limitations and unresolved problems regarding stem cell therapy in terms of ethical barriers, immune rejection, tumorigenicity, and cell sources. By reviewing recent literatures and our related works, human amnion-derived stem cells (hADSCs) including human amniotic mesenchymal stem cells (hAMSCs) and human amniotic epithelial stem cells (hAESCs) have shown considerable advantages over other stem cells. In this review, we first described the biological characteristics and advantages of hADSCs, especially for their high pluripotency and immunomodulatory effects. Then, we summarized the therapeutic applications and recent progresses of hADSCs in treating various diseases for preclinical research and clinical trials. In addition, the possible mechanisms and the challenges of hADSCs applications have been also discussed. Finally, we highlighted the properties of hADSCs as a promising source of stem cells for cell therapy and regenerative medicine and pointed out the perspectives for the directions of hADSCs applications clinically.

Effects of p-Cresol on Senescence, Survival, Inflammation, and Odontoblast Differentiation in Canine Dental Pulp Stem Cells

Aging, defined by a decrease in the physical and functional integrity of the tissues, leads to age-associated degenerative diseases. There is a relation between aged dental pulp and the senescence of dental pulp stem cells (DPSCs). Therefore, it is important to investigate the molecular processes underlying the senescence of DPSCs to elucidate the dental pulp aging mechanisms. p-Cresol (PC), a uremic toxin, is strongly related to cellular senescence. Here, age-related phenotypic changes including senescence, apoptosis, inflammation, and declining odontoblast differentiation in PC-treated canine DPSCs were investigated. Under the PC condition, cellular senescence was induced by decreased proliferation capacity and increased cell size, senescence-associated β-galactosidase (SA-β-gal) activity, and senescence markers p21, IL-1β, IL-8, and p53. Exposure to PC could stimulate inflammation by the increased expression of IL-6 and cause the distraction of the cell cycle by the increased level of Bax protein and decreased Bcl-2. The levels of odontoblast differentiation markers, dentin sialophosphoprotein (DSPP), dentin matrix protein 1, and osterix, were decreased. Consistent with those findings, the alizarin red staining, alkaline phosphatase, and DSPP protein level were decreased during the odontoblast differentiation process. Taken together, these findings indicate that PC could induce cellular senescence in DPSCs, which may demonstrate the changes in aging dental pulp.

Transplantation of human dental pulp stem cells in streptozotocin-induced diabetic rats

Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease caused by the destruction of pancreatic β-cells. Human dental pulp stem cells represent a promising source for cell-based therapies, owing to their easy, minimally invasive surgical access, and high proliferative capacity. It was reported that human dental pulp stem cells can differentiate into a pancreatic cell lineage in vitro; however, few studies have investigated their effects on diabetes. Our study aimed to investigate the therapeutic potential of intravenous and intrapancreatic transplantation of human dental pulp stem cells in a rat model of streptozotocin-induced type 1 diabetes. Forty Sprague Dawley male rats were randomly categorized into four groups: control, diabetic (STZ), intravenous treatment group (IV), and intrapancreatic treatment group (IP). Human dental pulp stem cells (1 × 10⁶ cells) or vehicle were injected into the pancreas or tail vein 7 days after streptozotocin injection. Fasting blood glucose levels were monitored weekly. Glucose tolerance test, rat and human serum insulin and C-peptide, pancreas histology, and caspase-3, vascular endothelial growth factor, and Ki67 expression in pancreatic tissues were assessed 28 days post-transplantation. We found that both IV and IP transplantation of human dental pulp stem cells reduced blood glucose and increased levels of rat and human serum insulin and C-peptide. The cells engrafted and survived in the streptozotocin-injured pancreas. Islet-like clusters and scattered human dental pulp stem cells expressing insulin were observed in the pancreas of diabetic rats with some difference in the distribution pattern between the two injection routes. RT-PCR analyses revealed the expression of the human-specific pancreatic β-cell genes neurogenin 3 (NGN3), paired box 4 (PAX4), glucose transporter 2 (GLUT2), and insulin in the pancreatic tissues of both the IP and IV groups. In addition, the transplanted cells downregulated the expression of caspase-3 and upregulated the expression of vascular endothelial growth factor and Ki67, suggesting that the injected cells exerted pro-angiogenetic and antiapoptotic effects, and promoted endogenous β-cell replication. Our study is the first to show that human dental pulp stem cells can migrate and survive within streptozotocin-injured pancreas, and induce antidiabetic effects through the differentiation and replacement of lost β-cells and paracrine-mediated pancreatic regeneration. Thus, human dental pulp stem cells may have therapeutic potential to treat patients with long term T1DM.

Modulation of Cell Death and Promotion of Chondrogenic Differentiation by Fas/FasL in Human Dental Pulp Stem Cells (hDPSCs)

Human dental pulp stem cells (hDPSCs) are characterized by high proliferation rate, the multi-differentiation ability and, notably, low immunogenicity and immunomodulatory properties exerted through different mechanisms including Fas/FasL pathway. Despite their multipotency, hDPSCs require particular conditions to achieve chondrogenic differentiation. This might be due to the perivascular localization and the expression of angiogenic marker under standard culture conditions. FasL stimulation was able to promote the early induction of chondrogenic commitment and to lead the differentiation at later times. Interestingly, the expression of angiogenic marker was reduced by FasL stimulation without activating the extrinsic apoptotic pathway in standard culture conditions. In conclusion, these findings highlight the peculiar embryological origin of hDPSCs and provide further insights on their biological properties. Therefore, Fas/FasL pathway not only is involved in determining the immunomodulatory properties, but also is implicated in supporting the chondrogenic commitment of hDPSCs.

Pulp stem cells derived from human permanent and deciduous teeth: Biological characteristics and therapeutic applications

Human pulp stem cells (PSCs) include dental pulp stem cells (DPSCs) isolated from dental pulp tissues of human extracted permanent teeth and stem cells from human exfoliated deciduous teeth (SHED). Depending on their multipotency and sensitivity to local paracrine activity, DPSCs and SHED exert therapeutic applications at multiple levels beyond the scope of the stomatognathic system. This review is specifically concentrated on PSC-updated biological characteristics and their promising therapeutic applications in (pre)clinical practice. Biologically, distinguished from conventional mesenchymal stem cell markers in vitro, NG2, Gli1, and Celsr1 have been evidenced as PSC markers in vivo. Both perivascular cells and glial cells account for PSC origin. Therapeutically, endodontic regeneration is where PSCs hold the most promises, attributable of PSCs' robust angiogenic, neurogenic, and odontogenic capabilities. More recently, the interplay between cell homing and liberated growth factors from dentin matrix has endowed a novel approach for pulp-dentin complex regeneration. In addition, PSC transplantation for extraoral tissue repair and regeneration has achieved immense progress, following their multipotential differentiation and paracrine mechanism. Accordingly, PSC banking is undergoing extensively with the intent of advancing tissue engineering, disease remodeling, and (pre)clinical treatments.

Neural crest derived stem cells from dental pulp and tooth-associated stem cells for peripheral nerve regeneration

The peripheral nerve injuries, representing some of the most common types of traumatic lesions affecting the nervous system, are highly invalidating for the patients besides being a huge social burden. Although peripheral nervous system owns a higher regenerative capacity than does central nervous system, mostly depending on Schwann cells intervention in injury repair, several factors determine the extent of functional outcome after healing. Based on the injury type, different therapeutic approaches have been investigated so far. Nerve grafting and Schwann cell transplantation have represented the gold standard treatment for peripheral nerve injuries, however these approaches own limitations, such as scarce donor nerve availability and donor site morbidity. Cell based therapies might provide a suitable tool for peripheral nerve regeneration, in fact, the ability of different stem cell types to differentiate towards Schwann cells in combination with the use of different scaffolds have been widely investigated in animal models of peripheral nerve injuries in the last decade. Dental pulp is a promising cell source for regenerative medicine, because of the ease of isolation procedures, stem cell proliferation and multipotency abilities, which are due to the embryological origin from neural crest. In this article we review the literature concerning the application of tooth derived stem cell populations combined with different conduits to peripheral nerve injuries animal models, highlighting their regenerative contribution exerted through either glial differentiation and neuroprotective/neurotrophic effects on the host tissue.

CRISPR/Cas9-Based Dystrophin Restoration Reveals a Novel Role for Dystrophin in Bioenergetics and Stress Resistance of Muscle Progenitors

Although the lack of dystrophin expression in muscle myofibers is the central cause of Duchenne muscular dystrophy (DMD), accumulating evidence suggests that DMD may also be a stem cell disease. Recent studies have revealed dystrophin expression in satellite cells and demonstrated that dystrophin deficiency is directly related to abnormalities in satellite cell polarity, asymmetric division, and epigenetic regulation, thus contributing to the manifestation of the DMD phenotype. Although metabolic and mitochondrial dysfunctions have also been associated with the DMD pathophysiology profile, interestingly, the role of dystrophin with respect to stem cells dysfunction has not been elucidated. In the past few years, editing of the gene that encodes dystrophin has emerged as a promising therapeutic approach for DMD, although the effects of dystrophin restoration in stem cells have not been addressed. Herein, we describe our use of a clustered regularly interspaced short palindromic repeats/Cas9‐based system to correct the dystrophin mutation in dystrophic (mdx) muscle progenitor cells (MPCs) and show that the expression of dystrophin significantly improved cellular properties of the mdx MPCs in vitro. Our findings reveal that dystrophin‐restored mdx MPCs demonstrated improvements in cell proliferation, differentiation, bioenergetics, and resistance to oxidative and endoplasmic reticulum stress. Furthermore, our in vivo studies demonstrated improved transplantation efficiency of the corrected MPCs in the muscles of mdx mice. Our results indicate that changes in cellular energetics and stress resistance via dystrophin restoration enhance muscle progenitor cell function, further validating that dystrophin plays a role in stem cell function and demonstrating the potential for new therapeutic approaches for DMD. stem cells2019;37:1615–1628

Regenerative potential of human dental pulp stem cells in the treatment of stress urinary incontinence: In vitro and in vivo study

Objectives

To evaluate the regenerative potential of human dental pulp stem cells (hDPSCs) in an animal model of stress urinary incontinence (SUI). SUI, an involuntary leakage of urine, is due to physical stress involving an increase in bladder pressure and a damage of external urethral sphincter affecting muscles and nerves. Conventional therapies can only relieve the symptoms. Human DPSCs are characterized by peculiar stemness and immunomodulatory properties and might provide an alternative tool for SUI therapy.

Materials and methods

In vitro phase: hDPSCs were induced towards the myogenic commitment following a 24 hours pre‐conditioning with 5‐aza‐2′‐deoxycytidine (5‐Aza), then differentiation was evaluated. In vivo phase: pudendal nerve was transected in female rats to induce stress urinary incontinence; then, pre‐differentiated hDPSCs were injected in the striated urethral sphincter. Four weeks later, urethral sphincter regeneration was assayed through histological, functional and immunohistochemical analyses.

Results

Human DPSCs were able to commit towards myogenic lineage in vitro and, four weeks after cell injection, hDPSCs engrafted in the external urethral sphincter whose thickness was almost recovered, committed towards myogenic lineage in vivo, promoted vascularization and an appreciable recovery of the continence. Moreover, hDPSCs were detected within the nerve, suggesting their participation in repair of transected nerve.

Conclusions

These promising data and further investigations on immunomodulatory abilities of hDPSCs would allow to make them a potential tool for alternative therapies of SUI.

Clinical Potential and Current Progress of Dental Pulp Stem Cells for Various Systemic Diseases in Regenerative Medicine: A Concise Review

Dental pulp stem cells (DPSCs) are mesenchymal stem cells (MSCs) that have multipotent differentiation and a self-renewal ability. They have been useful not only for dental diseases, but also for systemic diseases. Extensive studies have suggested that DPSCs are effective for various diseases, such as spinal cord injuries, Parkinson's disease, Alzheimer's disease, cerebral ischemia, myocardial infarction, muscular dystrophy, diabetes, liver diseases, eye diseases, immune diseases, and oral diseases. DPSCs have the potential for use in a cell-therapeutic paradigm shift to treat these diseases. It has also been reported that DPSCs have higher regenerative potential than the bone marrow-derived mesenchymal stem cells known as representative MSCs. Therefore, DPSCs have recently gathered much attention. In this review, the therapeutic potential of DPSCs, the latest progress in the pre-clinical study for treatment of these various systemic diseases, and the clinical applications of DPSCs in regenerative medicine, are all summarized. Although challenges, including mechanisms of the effects and establishment of cell processing and transplantation methods for clinical use, still remain, DPSCs could be promising stem cells sources for various clinical applications, because of their easy isolation by a noninvasive procedure without ethical concerns.

The Regenerative Potential of Amniotic Fluid Stem Cell Extracellular Vesicles: Lessons Learned by Comparing Different Isolation Techniques

Extracellular vesicles (EVs) derived from amniotic fluid stem cells (AFSCs) mediate anti-apoptotic, pro-angiogenic, and immune-modulatory effects in multiple disease models, such as skeletal muscle atrophy and Alport syndrome. A source of potential variability in EV biological functions is how EV are isolated from parent cells. Currently, a comparative study of different EV isolation strategies using conditioned medium from AFSCs is lacking. Herein, we examined different isolation strategies for AFSC-EVs, using common techniques based on differential sedimentation (ultracentrifugation), solubility (ExoQuick, Total Exosome Isolation Reagent, Exo-PREP), or size-exclusion chromatography (qEV). All techniques isolated AFSC-EVs with typical EV morphology and protein markers. In contrast, AFSC-EV size, protein content, and yield varied depending on the method of isolation. When equal volumes of the different AFSC-EV preparations were used as treatment in a model of lung epithelial injury, we observed a significant variation in how AFSC-EVs were able to protect against cell death. AFSC-EV enhancement of cell survival appeared to be dose dependent, and largely uninfluenced by variation in EV-size distributions, relative EV-purity, or their total protein content. The variation in EV-mediated cell survival obtained with different isolation strategies emphasizes the importance of testing alternative isolation techniques in order to maximize EV regenerative capacity.

Use of a 3D Floating Sphere Culture System to Maintain the Neural Crest-Related Properties of Human Dental Pulp Stem Cells

Human dental pulp is considered an interesting source of adult stem cells, due to the low-invasive isolation procedures, high content of stem cells and its peculiar embryological origin from neural crest. Based on our previous findings, a dental pulp stem cells sub-population, enriched for the expression of STRO-1, c-Kit, and CD34, showed a higher neural commitment. However, their biological properties were compromised when cells were cultured in adherent standard conditions. The aim of this study was to evaluate the ability of three dimensional floating spheres to preserve embryological and biological properties of this sub-population. In addition, the expression of the inwardly rectifying potassium channel Kir4.1, Fas and FasL was investigated in 3D-sphere derived hDPSCs. Our data showed that 3D sphere-derived hDPSCs maintained their fibroblast-like morphology, preserved stemness markers expression and proliferative capability. The expression of neural crest markers and Kir4.1 was observed in undifferentiated hDPSCs, furthermore this culture system also preserved hDPSCs differentiation potential. The expression of Fas and FasL was observed in undifferentiated hDPSCs derived from sphere culture and, noteworthy, FasL was maintained even after the neurogenic commitment was reached, with a significantly higher expression compared to osteogenic and myogenic commitments. These data demonstrate that 3D sphere culture provides a favorable micro-environment for neural crest-derived hDPSCs to preserve their biological properties.

Supplementation with IL-6 and Muscle Cell Culture Conditioned Media Enhances Myogenic Differentiation of Adipose Tissue-Derived Stem Cells through STAT3 Activation

Mature skeletal muscle cells cannot be expanded in culture systems. Therefore, it is difficult to construct an in vitro model for muscle diseases. To establish an efficient protocol for myogenic differentiation of human adipose tissue-derived stem cells (hADSCs), we investigated whether addition of IL-6 and/or myocyte-conditioned media (CM) to conventional differentiation media can shorten the differentiation period. hADSCs were differentiated to myocytes using the conventional protocol or modified with the addition of 25 pg/mL IL-6 and/or C2C12 CM (25% v/v). The expression of MyoD and myogenine mRNA was significantly higher at 5⁻6 days after differentiation using the modified protocol than with the conventional protocol. mRNA and protein expression of myosin heavy chain, a marker of myotubes, was significantly upregulated at 28 and 42 days of differentiation using the modified protocol, and the level achieved after a 4-week differentiation period was similar to that achieved at 6 weeks using the conventional protocol. The expression of p-STAT3 was significantly increased when the modified protocol was used. Similarly, addition of colivelin, a STAT3 activator, instead of IL-6 and C2C12 CM, promoted the myogenic differentiation of ADSCs. The modified protocol improved differentiation efficiency and reduced the time required for differentiation of myocytes. It might be helpful to save cost and time when preparing myocytes for cell therapies and drug discovery.

Dental Mesenchymal Stem Cell-Based Translational Regenerative Dentistry: From Artificial to Biological Replacement

Dentistry is a continuously changing field that has witnessed much advancement in the past century. Prosthodontics is that branch of dentistry that deals with replacing missing teeth using either fixed or removable appliances in an attempt to simulate natural tooth function. Although such "replacement therapies" appear to be easy and economic they fall short of ever coming close to their natural counterparts. Complications that arise often lead to failures and frequent repairs of such devices which seldom allow true physiological function of dental and oral-maxillofacial tissues. Such factors can critically affect the quality of life of an individual. The market for dental implants is continuously growing with huge economic revenues. Unfortunately, such treatments are again associated with frequent problems such as peri-implantitis resulting in an eventual loss or replacement of implants. This is particularly influential for patients having co-morbid diseases such as diabetes or osteoporosis and in association with smoking and other conditions that undoubtedly affect the final treatment outcome. The advent of tissue engineering and regenerative medicine therapies along with the enormous strides taken in their associated interdisciplinary fields such as stem cell therapy, biomaterial development, and others may open arenas to enhancing tissue regeneration via designing and construction of patient-specific biological and/or biomimetic substitutes. This review will overview current strategies in regenerative dentistry while overviewing key roles of dental mesenchymal stem cells particularly those of the dental pulp, until paving the way to precision/translational regenerative medicine therapies for future clinical use.

Anterior Capsule of the Lens: Comparison of Morphological Properties and Apoptosis Induction following FLACS and Standard Phacoemulsification Surgery

Purpose

Comparative evaluation of morphological features of anterior capsules and apoptosis induction in epithelial cells after femtosecond laser-assisted cataract surgery (FLACS) and standard phacoemulsification surgery.

Methods

Group 1: 30 FLACS anterior capsulotomies and Group 2: 30 manual anterior continuous curvilinear capsulorhexes. All patients were operated on by the same experienced surgeon. Morphological features of the anterior capsules and apoptosis induction in epithelial cells were evaluated.

Results

All patients revealed a significant mean best-corrected visual acuity (BCVA) improvement 3 months after surgery, and no major intraoperative nor postoperative complications occurred. The capsular epithelium appeared to be preserved in both groups. Scanning electron microscopy analysis revealed irregular saw-tooth shaped edges in capsules from Group 1 whereas capsules from Group 2 showed regular and smooth edges. A statistically significant higher expression of the downstream apoptotic effector cleaved caspase 3 was observed in Group 1.

Conclusions

The saw-tooth appearance was likely due to the progressive sequence of laser pulses on the capsule. The low energy/high frequency properties of the laser pulse, combined with an overlapped pulse pattern, resulted in highly continuous morphology of capsule edges. The higher apoptosis induction in FLACS group might be due to photodisruption-dependent plasma generation and formation of cavitation bubbles.

Transplantation of Allogeneic PW1pos/Pax7neg Interstitial Cells Enhance Endogenous Repair of Injured Porcine Skeletal Muscle

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Allogeneic PICs express and secrete an array of pro-regenerative paracrine factors that stimulate a regenerative response in a preclinical muscle injury model applicable to humans.

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Paracrine factors secreted by allogeneic PICs stimulate endogenous progenitor cell activation and differentiation, leading to accelerated and improved myofiber regeneration and microvessel formation.

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Allogeneic PICs survive long enough to exert their action before being cleared by the host immune system. Therefore, the cells transplanted are allogeneic but the regeneration is completely autologous.

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Administration of HGF and IGF-1 improves skeletal muscle regeneration, but not to the same extent as PIC transplantation.

Skeletal muscle-derived PW1^pos/Pax7^neg interstitial cells (PICs) express and secrete a multitude of proregenerative growth factors and cytokines. Utilizing a porcine preclinical skeletal muscle injury model, delivery of allogeneic porcine PICs (pPICs) significantly improved and accelerated myofiber regeneration and neocapillarization, compared with saline vehicle control-treated muscles. Allogeneic pPICs did not contribute to new myofibers or capillaries and were eliminated by the host immune system. In conclusion, allogeneic pPIC transplantation stimulated the endogenous stem cell pool to bring about enhanced autologous skeletal muscle repair and regeneration. This allogeneic cell approach is considered a cost-effective, easy to apply, and readily available regenerative therapeutic strategy.

Stem Cells from Dental Pulp: What Epigenetics Can Do with Your Tooth

Adult stem cells have attracted scientific attention because they are able to self-renew and differentiate into several specialized cell types. In this context, human dental tissue-derived mesenchymal stem cells (hDT-MSCs) have emerged as a possible solution for repairing or regenerating damaged tissues. These cells can be isolated from primary teeth that are naturally replaced, third molars, or other dental tissues and exhibit self-renewal, a high proliferative rate and a great multilineage potential. However, the cellular and molecular mechanisms that determine lineage specification are still largely unknown. It is known that a change in cell fate requires the deletion of existing transcriptional programs, followed by the establishment of a new developmental program to give rise to a new cell lineage. Increasing evidence indicates that chromatin structure conformation can influence cell fate. In this way, reversible chemical modifications at the DNA or histone level, and combinations thereof can activate or inactivate cell-type-specific gene sequences, giving rise to an alternative cell fates. On the other hand, miRNAs are starting to emerge as a possible player in establishing particular somatic lineages. In this review, we discuss two new and promising research fields in medicine and biology, epigenetics and stem cells, by summarizing the properties of hDT-MSCs and highlighting the recent findings on epigenetic contributions to the regulation of cellular differentiation.

Dental stem cells: recent progresses in tissue engineering and regenerative medicine

Since the disclosure of adult mesenchymal stem cells (MSCs), there have been an intense investigation on the characteristics of these cells and their potentialities. Dental stem cells (DSCs) are MSC-like populations with self-renewal capacity and multidifferentiation potential. Currently, there are five main DSCs, dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHED), stem cells from apical papilla (SCAP), periodontal ligament stem cells (PDLSCs) and dental follicle precursor cells (DFPCs). These cells are extremely accessible, prevail during all life and own an amazing multipotency. In the past decade, DPSCs and SHED have been thoroughly studied in regenerative medicine and tissue engineering as autologous stem cells therapies and have shown amazing therapeutic abilities in oro-facial, neurologic, corneal, cardiovascular, hepatic, diabetic, renal, muscular dystrophy and auto-immune conditions, in both animal and human models, and most recently some of them in human clinical trials. In this review, we focus the characteristics, the multiple roles of DSCs and its potential translation to clinical settings. These new insights of the apparently regenerative aptitude of these DSCs seems quite promising to investigate these cells abilities in a wide variety of pathologies. Key messages Dental stem cells (DSCs) have a remarkable self-renewal capacity and multidifferentiation potential; DSCs are extremely accessible and prevail during all life; DSCs, as stem cells therapies, have shown amazing therapeutic abilities in oro-facial, neurologic, corneal, cardiovascular, hepatic, diabetic, renal, muscular dystrophy and autoimmune conditions; DSCs are becoming extremely relevant in tissue engineering and regenerative medicine.

Activation of Fas/FasL pathway and the role of c-FLIP in primary culture of human cholangiocarcinoma cells

Intrahepatic cholangiocarcinoma (iCCA) represents a heterogeneous group of malignancies emerging from the biliary tree, often in the context of chronic bile ducts inflammation. The immunological features of iCCA cells and their capability to control the lymphocytes response have not yet been investigated. The aims of the present study were to evaluate the interaction between iCCA cells and human peripheral blood mononuclear cells (PBMCs) and the role of Fas/FasL in modulating T-cells and NK-cells response after direct co-culture. iCCA cells express high levels of Fas and FasL that increase after co-culture with PBMCs inducing apoptosis in CD4⁺, CD8⁺ T-cells and in CD56⁺ NK-cells. In vitro, c-FLIP is expressed in iCCA cells and the co-culture with PBMCs induces an increase of c-FLIP in both iCCA cells and biliary tree stem cells. This c-FLIP increase does not trigger the caspase cascade, thus hindering apoptotis of iCCA cells which, instead, underwent proliferation. The increased expression of Fas, FasL and c-FLIP is confirmed in situ, in human CCA and in primary sclerosing cholangitis. In conclusion our data indicated that iCCA cells have immune-modulatory properties by which they induce apoptosis of T and NK cells, via Fas/FasL pathway, and escape inflammatory response by up-regulating c-FLIP system.

Osteogenic Differentiation of hDPSCs on Biogenic Bone Apatite Thin Films

A previous study reported the structural characterization of biogenic apatite (BAp) thin films realized by a pulsed electron deposition system by ablation of deproteinized bovine bone. Thin films annealed at 400°C exhibited composition and crystallinity degree very close to those of biogenic apatite; this affinity is crucial for obtaining faster osseointegration compared to conventional, thick hydroxyapatite (HA) coatings, for both orthopedics and dentistry. Here, we investigated the adhesion, proliferation, and osteogenic differentiation of human dental pulp stem cells (hDPCS) on as-deposited and heat-treated BAp and stoichiometric HA. First, we showed that heat-treated BAp films can significantly promote hDPSC adhesion and proliferation. Moreover, hDPSCs, while initially maintaining the typical fibroblast-like morphology and stemness surface markers, later started expressing osteogenic markers such as Runx-2 and OSX. Noteworthy, when cultured in an osteogenic medium on annealed BAp films, hDPSCs were also able to reach a more mature and terminal commitment, with respect to HA and as-deposited films. Our findings suggest that annealed BAp films not only preserve the typical biological properties of stemness of, hDPSCs but also improve their ability of osteogenic commitment.

Protein and Molecular Characterization of a Clinically Compliant Amniotic Fluid Stem Cell-Derived Extracellular Vesicle Fraction Capable of Accelerating Muscle Regeneration Through Enhancement of Angiogenesis

The secretome of human amniotic fluid stem cells (AFSCs) has great potential as a therapeutic agent in regenerative medicine. However, it must be produced in a clinically compliant manner before it can be used in humans. In this study, we developed a means of producing a biologically active secretome from AFSCs that is free of all exogenous molecules. We demonstrate that the full secretome is capable of promoting stem cell proliferation, migration, and protection of cells against senescence. Furthermore, it has significant anti-inflammatory properties. Most importantly, we show that it promotes tissue regeneration in a model of muscle damage. We then demonstrate that the secretome contains extracellular vesicles (EVs) that harbor much, but not all, of the biological activity of the whole secretome. Proteomic characterization of the EV and free secretome fraction shows the presence of numerous molecules specific to each fraction that could be key regulators of tissue regeneration. Intriguingly, we show that the EVs only contain miRNA and not mRNA. This suggests that tissue regeneration in the host is mediated by the action of EVs modifying existing, rather than imposing new, signaling pathways. The EVs harbor significant anti-inflammatory activity as well as promote angiogenesis, the latter may be the mechanistic explanation for their ability to promote muscle regeneration after cardiotoxin injury.

Human dental pulp pluripotent-like stem cells promote wound healing and muscle regeneration

Background

Dental pulp represents an easily accessible autologous source of adult stem cells. A subset of these cells, named dental pulp pluripotent-like stem cells (DPPSC), shows high plasticity and can undergo multiple population doublings, making DPPSC an appealing tool for tissue repair or maintenance.

Methods

DPPSC were harvested from the dental pulp of third molars extracted from young patients. Growth factors released by DPPSC were analysed using antibody arrays. Cells were cultured in specific differentiation media and their endothelial, smooth and skeletal muscle differentiation potential was evaluated. The therapeutic potential of DPPSC was tested in a wound healing mouse model and in two genetic mouse models of muscular dystrophy (Scid/mdx and Sgcb-null Rag2-null γc-null).

Results

DPPSC secreted several growth factors involved in angiogenesis and extracellular matrix deposition and improved vascularisation in all three murine models. Moreover, DPPSC stimulated re-epithelialisation and ameliorated collagen deposition and organisation in healing wounds. In dystrophic mice, DPPSC engrafted in the skeletal muscle of both dystrophic murine models and showed integration in muscular fibres and vessels. In addition, DPPSC treatment resulted in reduced fibrosis and collagen content, larger cross-sectional area of type II fast-glycolytic fibres and infiltration of higher numbers of proangiogenic CD206⁺ macrophages.

Conclusions

Overall, DPPSC represent a potential source of stem cells to enhance the wound healing process and slow down dystrophic muscle degeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0621-3) contains supplementary material, which is available to authorized users.

Human dental pulp stem cells expressing STRO-1, c-kit and CD34 markers in peripheral nerve regeneration

Peripheral nerve injuries are a commonly encountered clinical problem and often result in long-term functional defects. The application of stem cells able to differentiate in Schwann cell-like cells in vitro and in vivo, could represent an attractive therapeutic approach for the treatment of nerve injuries. Further, stem cells sources sharing the same embryological origin as Schwann cells might be considered a suitable tool. The aim of this study was to demonstrate the ability of a neuroectodermal subpopulation of human STRO-1⁺ /c-Kit⁺ /CD34⁺ DPSCs, expressing P75^NTR , nestin and SOX-10, to differentiate into Schwann cell-like cells in vitro and to promote axonal regeneration in vivo, which led to functional recovery as measured by sustained gait improvement, in animal rat model of peripheral nerve injury. Transplanted human dental pulp stem cells (hDPSCs) engrafted into sciatic nerve defect, as revealed by the positive staining against human nuclei, showed the expression of typical Schwann cells markers, S100b and, noteworthy, a significant number of myelinated axons was detected. Moreover, hDPSCs promoted axonal regeneration from proximal to distal stumps 1 month after transplantation. This study demonstrates that STRO-1⁺ /c-Kit⁺ /CD34⁺ hDPSCs, associated with neural crest derivation, represent a promising source of stem cells for the treatment of demyelinating disorders and might provide a valid alternative tool for future clinical applications to achieve functional recovery after injury or peripheral neuropathies besides minimizing ethical issues. Copyright © 2016 John Wiley & Sons, Ltd.

Secreted trophic factors of mesenchymal stem cells support neurovascular and musculoskeletal therapies

Adult mesenchymal stem cells (MSCs) represent a subject of intense experimental and biomedical interest. Recently, trophic activities of MSCs have become the topic of a number of revealing studies that span both basic and clinical fields. In this review, we focus on recent investigations that have elucidated trophic mechanisms and shed light on MSC clinical efficacy relevant to musculoskeletal applications. Innate differences due to MSC sourcing may play a role in the clinical utility of isolated MSCs. Pain management, osteochondral, nerve, or blood vessel support by MSCs derived from both autologous and allogeneic sources have been examined. Recent mechanistic insights into the trophic activities of these cells point to ultimate regulation by nitric oxide, nuclear factor-kB, and indoleamine, among other signaling pathways. Classic growth factors and cytokines-such as VEGF, CNTF, GDNF, TGF-β, interleukins (IL-1β, IL-6, and IL-8), and C-C ligands (CCL-2, CCL-5, and CCL-23)-serve as paracrine control molecules secreted or packaged into extracellular vesicles, or exosomes, by MSCs. Recent studies have also implicated signaling by microRNAs contained in MSC-derived exosomes. The response of target cells is further regulated by their microenvironment, involving the extracellular matrix, which may be modified by MSC-produced matrix metalloproteinases (MMPs) and tissue inhibitor of MMPs. Trophic activities of MSCs, either resident or introduced exogenously, are thus intricately controlled, and may be further fine-tuned via implant material modifications. MSCs are actively being investigated for the repair and regeneration of both osteochondral and other musculoskeletal tissues, such as tendon/ligament and meniscus. Future rational and effective MSC-based musculoskeletal therapies will benefit from better mechanistic understanding of MSC trophic activities, for example using analytical "-omics" profiling approaches.