Neuroimmunomodulatory properties of DPSCs in anin vitromodel of Parkinson's disease

Molars to Medicine: A Focused Review on the Pre-Clinical Investigation and Treatment of Secondary Degeneration following Spinal Cord Injury Using Dental Stem Cells

Spinal cord injury (SCI) can result in the permanent loss of mobility, sensation, and autonomic function. Secondary degeneration after SCI both initiates and propagates a hostile microenvironment that is resistant to natural repair mechanisms. Consequently, exogenous stem cells have been investigated as a potential therapy for repairing and recovering damaged cells after SCI and other CNS disorders. This focused review highlights the contributions of mesenchymal (MSCs) and dental stem cells (DSCs) in attenuating various secondary injury sequelae through paracrine and cell-to-cell communication mechanisms following SCI and other types of neurotrauma. These mechanistic events include vascular dysfunction, oxidative stress, excitotoxicity, apoptosis and cell loss, neuroinflammation, and structural deficits. The review of studies that directly compare MSC and DSC capabilities also reveals the superior capabilities of DSC in reducing the effects of secondary injury and promoting a favorable microenvironment conducive to repair and regeneration. This review concludes with a discussion of the current limitations and proposes improvements in the future assessment of stem cell therapy through the reporting of the effects of DSC viability and DSC efficacy in attenuating secondary damage after SCI.

Comparative analysis of uninduced and neuronally-induced human dental pulp stromal cells in a 6-OHDA model of Parkinson's disease

BACKGROUND

In recent years, dental pulp stromal cells (DPSCs) have emerged as a promising therapeutic approach for Parkinson's disease (PD), owing to their inherent neurogenic potential and the lack of neuroprotective treatments for this condition. However, uncertainties persist regarding the efficacy of these cells in an undifferentiated state versus a neuronally-induced state. This study aims to delineate the distinct therapeutic potential of uninduced and neuronally-induced DPSCs in a rodent model of PD induced by 6-Hydroxydopamine (6-OHDA).

METHODS

DPSCs were isolated from human teeth, characterized as mesenchymal stromal cells, and induced to neuronal differentiation. Neuronal markers were assessed before and after induction. DPSCs were transplanted into the substantia nigra pars compacta (SNpc) of rats 7 days following the 6-OHDA lesion. In vivo tracking of the cells, evaluation of locomotor behavior, dopaminergic neuron survival, and the expression of essential proteins within the dopaminergic system were conducted 7 days postgrafting.

RESULTS

Isolated DPSCs exhibited typical characteristics of mesenchymal stromal cells and maintained a normal karyotype. DPSCs consistently expressed neuronal markers, exhibiting elevated expression of βIII-tubulin following neuronal induction. Results from the animal model showed that both DPSC types promoted substantial recovery in dopaminergic neurons, correlating with enhanced locomotion. Additionally, neuronally-induced DPSCs prevented GFAP elevation, while altering DARPP-32 phosphorylation states. Conversely, uninduced DPSCs reduced JUN levels. Both DPSC types mitigated the elevation of glycosylated DAT.

CONCLUSIONS

Our results suggested that uninduced DPSCs and neuronally-induced DPSCs exhibit potential in reducing dopaminergic neuron loss and improving locomotor behavior, but their underlying mechanisms differ.

Exploring the neurogenic differentiation of human dental pulp stem cells

Human dental pulp stem cells (hDPSCs) have increasingly gained interest as a potential therapy for nerve regeneration in medicine and dentistry, however their neurogenic potential remains a matter of debate. This study aimed to characterize hDPSC neuronal differentiation in comparison with the human SH-SY5Y neuronal stem cell differentiation model. Both hDPSCs and SH-SY5Y could be differentiated to generate typical neuronal-like cells following sequential treatment with all-trans retinoic acid (ATRA) and brain-derived neurotrophic factor (BDNF), as evidenced by significant expression of neuronal proteins βIII-tubulin (TUBB3) and neurofilament medium (NF-M). Both cell types also expressed multiple neural gene markers including growth-associated protein 43 (GAP43), enolase 2/neuron-specific enolase (ENO2/NSE), synapsin I (SYN1), nestin (NES), and peripherin (PRPH), and exhibited measurable voltage-activated Na⁺ and K⁺ currents. In hDPSCs, upregulation of acetylcholinesterase (ACHE), choline O-acetyltransferase (CHAT), sodium channel alpha subunit 9 (SCN9A), POU class 4 homeobox 1 (POU4F1/BRN3A) along with a downregulation of motor neuron and pancreas homeobox 1 (MNX1) indicated that differentiation was more guided toward a cholinergic sensory neuronal lineage. Furthermore, the Extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor U0126 significantly impaired hDPSC neuronal differentiation and was associated with reduction of the ERK1/2 phosphorylation. In conclusion, this study demonstrates that extracellular signal-regulated kinase/Mitogen-activated protein kinase (ERK/MAPK) is necessary for sensory cholinergic neuronal differentiation of hDPSCs. hDPSC-derived cholinergic sensory neuronal-like cells represent a novel model and potential source for neuronal regeneration therapies.

Alzheimer’s disease: Pathophysiology and dental pulp stem cells therapeutic prospects

Alzheimer’s disease (AD) is a destructive neurodegenerative disease with the progressive dysfunction, structural disorders and decreased numbers of neurons in the brain, which leads to long-term memory impairment and cognitive decline. There is a growing consensus that the development of AD has several molecular mechanisms similar to those of other neurodegenerative diseases, including excessive accumulation of misfolded proteins and neurotoxic substances produced by hyperactivated microglia. Nonetheless, there is currently a lack of effective drug candidates to delay or prevent the progression of the disease. Based on the excellent regenerative and reparative capabilities of stem cells, the application of them to repair or replace injured neurons carries enormous promise. Dental pulp stem cells (DPSCs), originated from ectomesenchyme of the cranial neural crest, hold a remarkable potential for neuronal differentiation, and additionally express a variety of neurotrophic factors that contribute to a protective effect on injured neuronal cells. Notably, DPSCs can also express immunoregulatory factors to control neuroinflammation and potentiate the regeneration and recovery of injured neurons. These extraordinary features along with accessibility make DPSCs an attractive source of postnatal stem cells for the regeneration of neurons or protection of existing neural circuitry in the neurodegenerative diseases. The present reviews the latest research advance in the pathophysiology of AD and elaborate the neurodifferentiation and neuroprotective properties of DPSCs as well as their application prospects in AD.

Promising Role of Oral Cavity Mesenchymal Stem Cell-Derived Extracellular Vesicles in Neurodegenerative Diseases

Mesenchymal stem cells (MSCs) and mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been regarded as the beneficial and available tools to treat various hereditary, multifactorial, acute, and chronic diseases. Mesenchymal stem cells can be extracted from numerous sources for clinical purposes while oral cavity-derived mesenchymal stem cells seem to be more effective in neuroregeneration than other sources due to their similar embryonic origins to neuronal tissues. In various studies and different neurodegenerative diseases (NDs), oral cavity mesenchymal stem cells have been applied to prove their promising capacities in disease improvement. Moreover, oral cavity mesenchymal stem cells' secretion is regarded as a novel and practical approach to neuroregeneration; hence, extracellular vesicles (EVs), especially exosomes, may provide promising results to improve CNS defects. This review article focuses on how oral cavity-derived stem cells and their extracellular vesicles can improve neurodegenerative conditions and tries to show which molecules are involved in the recovery process.

A New Target of Dental Pulp-Derived Stem Cell-Based Therapy on Recipient Bone Marrow Niche in Systemic Lupus Erythematosus

Recent advances in mesenchymal stem/stromal cell (MSC) research have led us to consider the feasibility of MSC-based therapy for various diseases. Human dental pulp-derived MSCs (hDPSCs) have been identified in the dental pulp tissue of deciduous and permanent teeth, and they exhibit properties with self-renewal and in vitro multipotency. Interestingly, hDPSCs exhibit superior immunosuppressive functions toward immune cells, especially T lymphocytes, both in vitro and in vivo. Recently, hDPSCs have been shown to have potent immunomodulatory functions in treating systemic lupus erythematosus (SLE) in the SLE MRL/lpr mouse model. However, the mechanisms underlying the immunosuppressive efficacy of hDPSCs remain unknown. This review aims to introduce a new target of hDPSC-based therapy on the recipient niche function in SLE.

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.

Immunomodulatory functions of oral mesenchymal stem cells: Novel force for tissue regeneration and disease therapy

Mesenchymal stem cells (MSCs)-based therapeutic strategies have achieved remarkable efficacies. Oral tissue-derived MSCs, with powerful self-renewal and multilineage differentiation abilities, possess the features of abundant sources and easy accessibility and hold great potential in tissue regeneration and disease therapies. Oral MSCs mainly consist of periodontal ligament stem cells, gingival mesenchymal stem cells, dental pulp stem cells, stem cells from human exfoliated deciduous teeth, stem cells from the apical papilla, dental follicle stem cells, and alveolar bone-derived mesenchymal stem. Early immunoinflammatory response stage is the prerequisite phase of healing process. Besides the potent capacities of differentiation and regeneration, oral MSCs are capable of interacting with various immune cells and function as immunomodulatory regulators. Consequently, the immunomodulatory effects of oral MSCs during damage repair seem to be crucial for exploring novel immunomodulatory strategies to achieve disease recovery and tissue regeneration. Herein, we reviewed various oral MSCs with their immunomodulatory properties and the potential mechanism, as well as their effects on immunomodulation-mediated disease therapies and tissue regeneration.

Advances and Perspectives in Dental Pulp Stem Cell Based Neuroregeneration Therapies

Human dental pulp stem cells (hDPSCs) are some of the most promising stem cell types for regenerative therapies given their ability to grow in the absence of serum and their realistic possibility to be used in autologous grafts. In this review, we describe the particular advantages of hDPSCs for neuroregenerative cell therapies. We thoroughly discuss the knowledge about their embryonic origin and characteristics of their postnatal niche, as well as the current status of cell culture protocols to maximize their multilineage differentiation potential, highlighting some common issues when assessing neuronal differentiation fates of hDPSCs. We also review the recent progress on neuroprotective and immunomodulatory capacity of hDPSCs and their secreted extracellular vesicles, as well as their combination with scaffold materials to improve their functional integration on the injured central nervous system (CNS) and peripheral nervous system (PNS). Finally, we offer some perspectives on the current and possible future applications of hDPSCs in neuroregenerative cell therapies.

Neural Basis of Dental Pulp Stem Cells and its Potential Application in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. Though significant insights into the molecular-biochemical-cellular-behavioral basis of PD have been understood, there is no appreciable treatment available till date. Current therapies provide symptomatic relief without any influence on the progression of the disease. Stem cell therapy has been vigorously explored to treat PD. In this comprehensive review, we analyze various stem cell candidates for treating PD and discuss the possible mechanisms. We advocate the advantage of using neural crest originated dental pulp stem cells (DPSC) due to their predisposition towards neural differentiation and their potential to regenerate neurons far better than commonly used bone marrow derived mesenchymal stem cells (BM-MSCs). Eventually, we highlight the current challenges in the field and the strategies which may be used for overcoming the impediments.

The potential therapy with dental tissue-derived mesenchymal stem cells in Parkinson's disease

Parkinson’s disease (PD), the second most common neurodegenerative disease worldwide, is caused by the loss of dopaminergic (DAergic) neurons in the substantia nigra resulting in a series of motor or non-motor disorders. Current treatment methods are unable to stop the progression of PD and may bring certain side effects. Cell replacement therapy has brought new hope for the treatment of PD. Recently, human dental tissue-derived mesenchymal stem cells have received extensive attention. Currently, dental pulp stem cells (DPSCs) and stem cells from human exfoliated deciduous teeth (SHED) are considered to have strong potential for the treatment of these neurodegenerative diseases. These cells are considered to be ideal cell sources for the treatment of PD on account of their unique characteristics, such as neural crest origin, immune rejection, and lack of ethical issues. In this review, we briefly describe the research investigating cell therapy for PD and discuss the application and progress of DPSCs and SHED in the treatment of PD. This review offers significant and comprehensive guidance for further clinical research on PD.

Biodistribution of Intramuscularly-Transplanted Human Dental Pulp Stem Cells in Immunocompetent Healthy Rats through NIR Imaging

Owing to their neural crest origin, dental pulp stem cells (DPSCs) are increasingly gaining prominence in treating nervous system disease conditions. However, as per the regulatory bodies [European-Medicines Agency (EMA), Indian-Council of Medical-Research (ICMR)], their biodistribution after transplantation needs to be evaluated for them to be considered for cell-based therapy for clinical trials. There are yet no studies describing the dynamic distribution of human origin DPSCs (hDPSCs) after transplantation in an immunocompetent, physiologically healthy animal model. Here, using near-infrared (NIR)-based whole animal and ex vivo tissue imaging, we assessed the biodistribution of intramuscularly transplanted hDPSCs in immunocompetent healthy Wistar rats. Further validation was done by quantifying gene expression of the human Alu gene in rat tissues. After 24 h of transplantation, an increase in signal intensity and area of signal was observed in the muscle of administration compared to 30 min and 6 h. At hour 24, neither increase in human Alu nor human Ki67 gene expression was seen in the rat muscle, thus confirming that the increase in signal area and intensity at hour 24 was not due to proliferation of the transplanted cells. Rather at hour 24, the NIR-signal intensity in bone marrow increased, suggesting that the NIR-tagged DPSCs have started entering into the blood vessels adjacent to the muscle, and the blood vessels being placed just beneath the subcutaneous layer might be responsible for an increase in signal intensity. Signal intensity increased distinctly in all organs at this timepoint, confirming that the cells entered the bloodstream by hour 24. Lung entrapment of DPSCs was not observed, since signal intensity was least in lungs as compared to the site of injection. Cells were retained for up to 28 days at the site of injection. These findings lay the basis to design the dosage for intramuscular delivery of hDPSCs for degenerative disease models and for future clinical trials.

Are human dental pulp stem cells the future of neurodegenerative diseases and nerve injury therapy?*

This review summarizes results from in vitro and in vivo studies which provide evidence that human dental pulp stem cells (hDPSCs) might be a novel treatment strategy for nervous system injuries and neurodegenerative diseases because of their high potential for neurogenic differentiation and secretion of neuron-related trophic factors. It is also worth underlining that hDPSCs are neural crest-derived cells that possess biological properties of mesenchymal stem cells (MSCs). Induced hDPSCs have a high ability to differentiate into neuron-like cells, which show functional activity. hDPSCs express immunomodulatory factors that enhance regeneration and repair of nerve injury. These specific features of undifferentiated and differentiated hDPSCs make these cells promising for the therapy of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s diseases, stroke, spinal cord injury as well as peripheral nerve injury. Recently, investigators propose that the tissue engineering technology, including scaffold, stem cells and growth factor, should provide a new strategy for spinal cord and peripheral nerve injury treatment. hDPSCs should be considered as a good choice for peripheral nerve injury therapy, because they have better potential to differentiate into neural and glial cells than stem cells coming from other sources through the expression of neuronal makers and wide range of neurotropic factors secretion. Unique properties of hDPSCs, such as high proliferation rate, trophic factors expression and stronger neuroprotective effects, indicate that these stem cells may be beneficial in neural disease therapy.

Neuro-regenerative potential of dental stem cells: a concise review

This review will summarize the research information regarding the regenerative potential of dental stem cells for the treatment of neurodegenerative disorders. As compared to existing treatment modalities, the stem cell therapy seems promising, and accumulating evidences about the differentiation of stem cells into various lineages are proving it. The incidence of neurodegenerative diseases such as Alzheimer's, Parkinson's, stroke, and peripheral neuropathy is increasing due to the rise in life expectancies of people which have put a huge burden on economies. Finding a promising treatment could benefit not only the patients but also the communities. Dental stem cells hold a great potential to differentiate into neuronal cells. Many studies have reported the differentiation potential of the dental stem cells with the presence of neuronal lineage markers. In this review, we conferred how the use of dental stem cells can benefit the above-mentioned bedridden diseases.

Characteristics and Therapeutic Potential of Dental Pulp Stem Cells on Neurodegenerative Diseases

To evaluate the therapeutic potential of stem cells for neurodegenerative diseases, emphasis should be placed on clarifying the characteristics of the various types of stem cells. Among stem cells, dental pulp stem cells (DPSCs) are a cell population that is rich in cell proliferation and multipotency. It has been reported that transplantation of DPSCs has protective effects against models of neurodegenerative diseases. The protective effects are not only through differentiation into the target cell type for the disease but are also related to trophic factors released from DPSCs. Recently, it has been reported that serum-free culture supernatant of dental pulp stem cell-conditioned medium (DPCM) contains various trophic factors and cytokines and that DPCM is effective for models of neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and Amyotrophic Lateral Sclerosis (ALS). Moreover, the use of stem cells from human exfoliated deciduous teeth (SHEDs) has been considered. SHEDs are derived from deciduous teeth that have been disposed of as medical waste. SHEDs have higher differentiation capacity and proliferation ability than DPSCs. In addition, the serum-free culture supernatant of SHEDs (SHED-CM) contains more trophic factors, cytokines, and biometals than DPCM and also promotes neuroprotection. The neuroprotective effect of DPSCs, including those from deciduous teeth, will be used as the seeds of therapeutic drugs for neurodegenerative diseases. SHEDs will be used for further cell therapy of neurodegenerative diseases in the future. In this paper, we focused on the characteristics of DPSCs and their potential for neurodegenerative diseases.

Method for Evaluating Neuromodulatory Properties of Dental Pulp Stem Cell as an In Vitro Model for Parkinson's Disease

Several research groups have utilized dental pulp stem cells for numerous studies as treatment modality for Parkinson's disease (PD). However, the roles of dental pulp stem cells in governing the Parkinson's disease inflammatory microenvironment remain to be evaluated. In this article, we elaborate the method where we can investigate the effects of dental pulp stem cells on neurons and microglia in an in vitro inflammatory microenvironment.

Dopaminergic induction of human dental pulp stem cells by photobiomodulation: comparison of 660nm laser light and polychromatic light in the nir

Human dental pulp stem cells (hDPSCs) are able to differentiate into dopaminergic neurons and help the maintenance of partially degenerated neurons, which makes them as an alternative cell source for treatment of Parkinsons' disease (PD) patients. Here, the effect of photobiomodulation with polychromatic light source in the near infrared (NIR) range (600-1200 nm) or low level 660 nm diode laser light on hDPSCs during dopaminergic induction was investigated. Real time RT-qPCR analysis indicated that expressions of brain derived neurotrophic factor (BDNF), glial cell line derived neurotropic factor (GNDF), matrix associated protein 2 (MAP2), nuclear receptor related 1 protein (NURR1) and dopamine transporter (DAT) were increased, especially in the first 7 days of dopaminergic induction when 660 nm laser light was applied with a total energy density of 1.6 J/cm². The activity of polychromatic light on hDPSCs depended on the differentiation media and protein type. BDNF, GDNF, NURR-1 and MAP2 expressions were increased in the presence of pre-induction factors, and decreased when the post-induction factors were added into the culture medium. In contrast with all these promising results, the dopaminergically induced hDPSCs did not show any functional characteristics of dopaminergic neurons and died after they were transferred to a new laminin coated culture plates. In conclusion, the expression of dopaminergic neuron protective protein mRNAs in hDPSCs was increased by photobiomodulation in defined conditions. However, the cells were not able to differentiate into functional dopaminergic neurons either in control or in photobiomodulated groups that are prone to cell death and exhibit immature dopaminergic neuron characteristics.

Dental mesenchymal stem cells and neuro-regeneration: a focus on spinal cord injury

Regenerative medicine is a branch of translational research that aims to reestablish irreparably damaged tissues and organs by stimulating the body's own repair mechanisms via the implantation of stem cells differentiated into specialized cell types. A rich source of adult stem cells is located inside the tooth and is represented by human dental pulp stem cells, or hDPSCs. These cells are characterized by a high proliferative rate, have self-renewal and multi-lineage differentiation properties and are often used for tissue engineering and regenerative medicine. The present review will provide an overview of hDPSCs and related features with a special focus on their potential applications in regenerative medicine of the nervous system, such as, for example, after spinal cord injury. Recent advances in the identification and characterization of dental stem cells and in dental tissue engineering strategies suggest that bioengineering approaches may successfully be used to regenerate districts of the central nervous system, previously considered irreparable.

Mechanisms underlying dental-derived stem cell-mediated neurorestoration in neurodegenerative disorders

BACKGROUND

Neurodegenerative disorders have a complex pathology and are characterized by a progressive loss of neuronal architecture in the brain or spinal cord. Neuroprotective agents have demonstrated promising results at the preclinical stage, but this has not been confirmed at the clinical stage. Thus far, no neuroprotective drug that can prevent neuronal degeneration in patients with neurodegenerative disorders is available.

MAIN BODY

Recent studies have focused on neurorestorative measures, such as cell-based therapy, rather than neuroprotective treatment. The utility of cell-based approaches for the treatment of neurodegenerative disorders has been explored extensively, and the results have been somewhat promising with regard to reversing the outcome. Because of their neural crest origin, ease of harvest, accessibility, ethical suitability, and potential to differentiate into the neurogenic lineage, dental-derived stem cells (DSCs) have become an attractive source for cell-based neurorestoration therapies. In the present review, we summarize the possible use of DSC-based neurorestoration therapy as an alternative treatment for neurodegenerative disorders, with a particular emphasis on the mechanism underlying recovery in neurodegenerative disorders.

CONCLUSION

Transplantation research in neurodegenerative diseases should aim to understand the mechanism providing benefits both at the molecular and functional level. Due to their ease of accessibility, plasticity, and ethical suitability, DSCs hold promise to overcome the existing challenges in the field of neurodegeneration through multiple mechanisms, such as cell replacement, bystander effect, vasculogenesis, synaptogenesis, immunomodulation, and by inhibiting apoptosis.

Potential Roles of Dental Pulp Stem Cells in Neural Regeneration and Repair

This review summarizes current advances in dental pulp stem cells (DPSCs) and their potential applications in the nervous diseases. Injured adult mammalian nervous system has a limited regenerative capacity due to an insufficient pool of precursor cells in both central and peripheral nervous systems. Nerve growth is also constrained by inhibitory factors (associated with central myelin) and barrier tissues (glial scarring). Stem cells, possessing the capacity of self-renewal and multicellular differentiation, promise new therapeutic strategies for overcoming these impediments to neural regeneration. Dental pulp stem cells (DPSCs) derive from a cranial neural crest lineage, retain a remarkable potential for neuronal differentiation, and additionally express multiple factors that are suitable for neuronal and axonal regeneration. DPSCs can also express immunomodulatory factors that stimulate formation of blood vessels and enhance regeneration and repair of injured nerve. These unique properties together with their ready accessibility make DPSCs an attractive cell source for tissue engineering in injured and diseased nervous systems. In this review, we interrogate the neuronal differentiation potential as well as the neuroprotective, neurotrophic, angiogenic, and immunomodulatory properties of DPSCs and its application in the injured nervous system. Taken together, DPSCs are an ideal stem cell resource for therapeutic approaches to neural repair and regeneration in nerve diseases.