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

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.

Advances in oral mesenchymal stem cell-derived extracellular vesicles in health and disease

Extracellular vesicles (EVs) are nano-size vesicles secreted naturally by all cells into the extracellular space and have been recognized as important cell-cell mediators in multicellular organisms. EVs contain nucleic acids, proteins, lipids, and other cellular components, regulating many basic biological processes and playing an important role in regenerative medicine and diseases. EVs can be traced to their cells of origin and exhibit a similar function. Moreover, EVs demonstrate low immunogenicity, good biocompatibility, and fewer side effects, compared to their parent cells. Mesenchymal stem cells (MSCs) are one of the most important resource cells for EVs, with a great capacity for self-renewal and multipotent differentiation, and play an essential role in stem cell therapy. The mechanism of MSC therapy was thought to be attributed to the differentiation of MSCs after targeted migration, as previously noted. However, emerging evidence shows the previously unknown role of MSC-derived paracrine factors in stem cell therapy. Especially EVs derived from oral tissue MSCs (OMSC-EVs), show more advantages than those of all other MSCs in tissue repair and regeneration, due to their lower invasiveness and easier accessibility for sample collection. Here, we systematically review the biogenesis and biological characteristics of OMSC-EVs, as well as the role of OMSC-EVs in intercellular communication. Furthermore, we discuss the potential therapeutic roles of OMSC-EVs in oral and systemic diseases. We highlight the current challenges and future directions of OMSC-EVs to focus more attention on clinical translation. We aim to provide valuable insights for the explorative clinical application of OMSC-EVs.

Differential Expression of MicroRNA (MiR-27, MiR-145) among Dental Pulp Stem Cells (DPSCs) Following Neurogenic Differentiation Stimuli

This study sought to evaluate the expression of previously identified microRNAs known to regulate neuronal differentiation in mesenchymal stem cells (MSCs), including miR-27, miR-125, miR-128, miR-135, miR-140, miR-145, miR-218 and miR-410, among dental pulp stem cells (DPSCs) under conditions demonstrated to induce neuronal differentiation. Using an approved protocol, n = 12 DPSCs were identified from an existing biorepository and treated with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF), which were previously demonstrated to induce neural differentiation markers including Sox1, Pax6 and NFM among these DPSCs. This study revealed that some microRNAs involved in the neuronal differentiation of MSCs were also differentially expressed among the DPSCs, including miR-27 and miR-145. In addition, this study also revealed that administration of bFGF and EGF was sufficient to modulate miR-27 and miR-145 expression in all of the stimulus-responsive DPSCs but not among all of the non-responsive DPSCs-suggesting that further investigation of the downstream targets of these microRNAs may be needed to fully evaluate and understand these observations.

KLF2 Regulates Neural Differentiation of Dental Pulp-derived Stem Cells by Modulating Autophagy and Mitophagy

BACKGROUND

Transplantation of stem cells for treating neurodegenerative disorders is a promising future therapeutic approach. However, the molecular mechanism underlying the neuronal differentiation of dental pulp-derived stem cells (DPSC) remains inadequately explored. The current study aims to define the regulatory role of KLF2 (Kruppel-like factor 2) during the neural differentiation (ND) of DPSC.

METHODS

We first investigated the transcriptional and translational expression of KLF2, autophagy, and mitophagy-associated markers during the ND of DPSC by using quantitative RT-PCR and western blot methods. After that, we applied the chemical-mediated loss- and gain-of-function approaches using KLF2 inhibitor, GGPP (geranylgeranyl pyrophosphate), and KLF2 activator, GGTI-298 (geranylgeranyl transferase inhibitor-298) to delineate the role of KLF2 during ND of DPSC. The western blot, qRT-PCR, and immunocytochemistry were performed to determine the molecular changes during ND after KLF2 deficiency and KLF2 sufficiency. We also analyzed the oxygen consumption rate (OCR) and the extracellular acidification rate (ECAR) using the Seahorse XFe24 analyzer.

RESULTS

Our study demonstrated that the expression level of KLF2, autophagy, and mitophagy-associated markers were significantly elevated during the ND of DPSC. Next, we found that the KLF2 inhibitor, GGPP significantly reduced the ND of DPSC. Inversely, KLF2 overexpression accelerated the molecular phenomenon of DPSC's commitment towards ND, indicating the crucial role of KLF2 in neurogenesis. Moreover, we found that the KLF2 positively regulated autophagy, mitophagy, and the Wnt5a signaling pathway during neurogenesis. Seahorse XFe24 analysis revealed that the ECAR and OCR parameters were significantly increased during ND, and inhibition of KLF2 marginally reversed them towards DPSC's cellular bioenergetics. However, KLF2 overexpression shifted the cellular energy metabolism toward the quiescent stage.

CONCLUSION

Collectively, our findings provide the first evidence that the KLF2 critically regulates the neurogenesis of DPSC by inducing autophagy and mitophagy.

Therapeutic Potential of Oral-Derived Mesenchymal Stem Cells in Retinal Repair

The retina has restricted regeneration ability to recover injured cell layer because of reduced production of neurotrophic factors and increased inhibitory molecules against axon regrowth. A diseased retina could be regenerated by repopulating the damaged tissue with functional cell sources like mesenchymal stem cells (MSCs). The cells are able to release neurotrophic factors (NFs) to boost axonal regeneration and cell maintenance. In the current study, we comprehensively explore the potential of various types of stem cells (SCs) from oral cavity as promising therapeutic options in retinal regeneration. The oral MSCs derived from cranial neural crest cells (CNCCs) which explains their broad neural differentiation potential and secret rich NFs. They are comprised of dental pulp SCs (DPSCs), SCs from exfoliated deciduous teeth (SHED), SCs from apical papilla (SCAP), periodontal ligament-derived SCs (PDLSCs), gingival MSCs (GMSCs), and dental follicle SCs (DFSCs). The Oral MSCs are becoming a promising source of cells for cell-free or cell-based therapeutic approach to recover degenerated retinal. These cells have various mechanisms of action in retinal regeneration including cell replacement and the paracrine effect. It was demonstrated that they have more neuroprotective and neurotrophic effects on retinal cells than immediate replacement of injured cells in retina. This could be the reason that their therapeutic effects would be weakened over time. It can be concluded that neuronal and retinal regeneration through these cells is most likely due to their NFs that dramatically suppress oxidative stress, inflammation, and apoptosis. Although, oral MSCs are attractive therapeutic options for retinal injuries, more preclinical and clinical investigations are required.

Potential of dental pulp stem cells and their products in promoting peripheral nerve regeneration and their future applications

Peripheral nerve injury (PNI) seriously affects people's quality of life. Stem cell therapy is considered a promising new option for the clinical treatment of PNI. Dental stem cells, particularly dental pulp stem cells (DPSCs), are adult pluripotent stem cells derived from the neuroectoderm. DPSCs have significant potential in the field of neural tissue engineering due to their numerous advantages, such as easy isolation, multidifferentiation potential, low immunogenicity, and low transplant rejection rate. DPSCs are extensively used in tissue engineering and regenerative medicine, including for the treatment of sciatic nerve injury, facial nerve injury, spinal cord injury, and other neurodegenerative diseases. This article reviews research related to DPSCs and their advantages in treating PNI, aiming to summarize the therapeutic potential of DPSCs for PNI and the underlying mechanisms and providing valuable guidance and a foundation for future research.

Metal-Organic Frameworks-Based Nanoplatforms for the Theranostic Applications of Neurological Diseases

Neurological diseases are the foremost cause of disability and the second leading cause of death worldwide. Owing to the special microenvironment of neural tissues and biological characteristics of neural cells, a considerable number of neurological disorders are currently incurable. In the past few years, the development of nanoplatforms based on metal-organic frameworks (MOFs) has broadened opportunities for offering sensitive diagnosis/monitoring and effective therapy of neurology-related diseases. In this article, the obstacles for neurotherapeutics, including delayed diagnosis and misdiagnosis, the existence of blood brain barrier (BBB), off-target treatment, irrepressible inflammatory storm/oxidative stress, and irreversible nerve cell death are summarized. Correspondingly, MOFs-based diagnostic/monitoring strategies such as neuroimaging and biosensors (electrochemistry, fluorometry, colorimetry, electrochemiluminescence, etc.) and MOFs-based therapeutic strategies including higher BBB permeability, targeting specific lesion sites, attenuation of neuroinflammation/oxidative stress as well as regeneration of nerve cells, are extensively highlighted for the management of neurological diseases. Finally, the challenges of the present research from perspective of clinical translation are discussed, hoping to facilitate interdisciplinary studies at the intersections between MOFs-based nanoplatforms and neurotheranostics.

Immunomodulatory properties of mesenchymal stem cells/dental stem cells and their therapeutic applications

Mesenchymal stem/stromal cells (MSCs) are widely distributed in the body and play essential roles in tissue regeneration and homeostasis. MSCs can be isolated from discarded tissues, expanded in vitro and used as therapeutics for autoimmune diseases and other chronic disorders. MSCs promote tissue regeneration and homeostasis by primarily acting on immune cells. At least six different types of MSCs have been isolated from postnatal dental tissues and have remarkable immunomodulatory properties. Dental stem cells (DSCs) have been demonstrated to have therapeutic effects on several systemic inflammatory diseases. Conversely, MSCs derived from nondental tissues such as the umbilical cord exhibit great benefits in the management of periodontitis in preclinical studies. Here, we discuss the main therapeutic uses of MSCs/DSCs, their mechanisms, extrinsic inflammatory cues and the intrinsic metabolic circuitries that govern the immunomodulatory functions of MSCs/DSCs. Increased understanding of the mechanisms underpinning the immunomodulatory functions of MSCs/DSCs is expected to aid in the development of more potent and precise MSC/DSC-based therapeutics.

VEGFA-modified DPSCs combined with LC-YE-PLGA NGCs promote facial nerve injury repair in rats

Objective

The aim of this research was to investigate the effect of vascular endothelial growth factor A (VEGFA)-overexpressing rat dental pulp stem cells (rDPSCs) combined with laminin-coated and yarn-encapsulated poly(_l-lactide-co-glycolide) (PLGA) nerve guidance conduit (LC-YE-PLGA NGC) in repairing 10 mm facial nerve injury in rats.

Study Design

rDPSCs isolated from rat mandibular central incisor were cultured and identified in vitro and further transfected with the lentiviral vectors (Lv-VEGFA). To investigate the role and mechanisms of VEGFA in neurogenic differentiation in vitro, semaxanib (SU5416), Cell Counting Kit-8 (CCK-8), real-time quantitative polymerase chain reaction (qPCR) and Western blotting were performed. Ten-millimeter facial nerve defect models in rats were established and bridged by LC-YE-PLGA NGCs. The repair effects were detected by transmission electron microscopy (TEM), compound muscle action potential (CMAP), immunohistochemistry and immunofluorescence.

Results

Extracted cells exhibited spindle-shaped morphology, presented typical markers (CD44⁺CD90⁺CD34^-CD45^-), and presented multidirectional differentiation potential. The DPSCs with VEGFA overexpression were constructed successfully. VEGFA enhanced the proliferation and neural differentiation ability of rDPSCs, and the expression of neuron-specific enolase (NSE) and βIII-tubulin was increased. However, these trends were reversed with the addition of SU5416. This suggests that VEGFA mediates the above effects mainly through vascular endothelial growth factor receptor 2 (VEGFR2) binding. The LC-YE-NGC basically meet the requirements of facial nerve repair. For the in vivo experiment, the CMAP latency period was shorter in DPSCS-VEGFA-NGC group in comparison with other experimental groups, while the amplitude was increased. Such functional recovery correlated well with an increase in histological improvement. Further study suggested that VEGFA-modified DPSCs could increase the myelin number, thickness and axon diameter of facial nerve. NSE, βIII-tubulin and S100 fluorescence intensity and immunohistochemical staining intensity were significantly enhanced.

Conclusion

VEGFA-modified rDPSCs combined with LC-YE-PLGA NGCs have certain advantages in the growth and functional recovery of facial nerves in rats.

Neural Regeneration in Regenerative Endodontic Treatment: An Overview and Current Trends

Pulpal and periapical diseases are the most common dental diseases. The traditional treatment is root canal therapy, which achieves satisfactory therapeutic outcomes-especially for mature permanent teeth. Apexification, pulpotomy, and pulp revascularization are common techniques used for immature permanent teeth to accelerate the development of the root. However, there are obstacles to achieving functional pulp regeneration. Recently, two methods have been proposed based on tissue engineering: stem cell transplantation, and cell homing. One of the goals of functional pulp regeneration is to achieve innervation. Nerves play a vital role in dentin formation, nutrition, sensation, and defense in the pulp. Successful neural regeneration faces tough challenges in both animal studies and clinical trials. Investigation of the regeneration and repair of the nerves in the pulp has become a serious undertaking. In this review, we summarize the current understanding of the key stem cells, signaling molecules, and biomaterials that could promote neural regeneration as part of pulp regeneration. We also discuss the challenges in preclinical or clinical neural regeneration applications to guide deep research in the future.

Human gingival mesenchymal stem cells improve movement disorders and tyrosine hydroxylase neuronal damage in Parkinson disease rats

BACKGROUND AIMS

Gingival mesenchymal stem cells (GMSCs) demonstrate high proliferation, trilineage differentiation and immunomodulatory properties. Parkinson disease (PD) is the second most common type of neurodegenerative disease. This study aimed to explore the effect and mechanism of GMSC-based therapy in 6-hydroxydopamine-induced PD rats.

METHODS

RNA sequencing and quantitative proteomics technology was used to validate the neuroprotective role of GMSCs therapeutic in 6-Hydroxydopamine -induced PD model in vitro and in vivo. Western blotting, immunofluorescence and real-time quantitative PCR verified the molecular mechanism of GMSCs treatment.

RESULTS

Intravenous injection of GMSCs improved rotation and forelimb misalignment behavior, enhanced the anti-apoptotic B-cell lymphoma 2/B-cell lymphoma 2-associated X axis, protected tyrosine hydroxylase neurons, decreased the activation of astrocytes and reduced the astrocyte marker glial fibrillary acidic protein and microglia marker ionized calcium-binding adaptor molecule 1 in the substantia nigra and striatum of PD rats. The authors found that GMSCs upregulated nerve regeneration-related molecules and inhibited metabolic disorders and the activation of signal transducer and activator of transcription 3. GMSCs showed a strong ability to protect neurons and reduce mitochondrial membrane potential damage and reactive oxygen species accumulation. The safety of GMSC transplantation was confirmed by the lack of tumor formation following subcutaneous transplantation into nude mice for up to 8 weeks.

CONCLUSIONS

The authors' research helps to explain the mechanism of GMSC-based therapeutic strategies and promote potential clinical application in Parkinson disease.

MZF1 alleviates oxidative stress and apoptosis induced by rotenone in SH-SY5Y cells by promoting RBM3 transcription

OBJECTIVE

To investigate the protective effect of MZF1/RBM3 on rotenone-induced neuronal injury.

METHODS

Rotenone (1 μM) was used to treat SH-SY5Y cells for 24 hr to simulate the cellular model of Parkinson's disease (PD), followed by detection of SH-SY5Y cell activities using MTT assay. MZF1 expression in rotenone-treated SH-SY5Y cells was detected by qRT-PCR and Western blot. MZF1 overexpression plasmid or MZF1 overexpression plasmid and RBM3 siRNA was transfected into SH-SY5Y cells, and then the expressions of MZF1 and RBM3 were detected. Oxidative stress (OS) in SH-SY5Y cells was detected using CMH2DCF-DA probes. Cell apoptosis rate was detected by flow cytometry. CHIP assay and dual-luciferase reporter assay were used to detect the binding between MZF1 and RBM3 promoter.

RESULTS

The expression of MZF1 was significantly lower in the rotenone-induced SH-SY5Y cells. Overexpression of MZF1 significantly reduced OS and apoptosis in rotenone-induced SH-SY5Y cells. MZF1 was a transcription factor of RBM3, which promoted the transcription of RBM3, and knockdown of RBM3 inhibited the protective effect of MZF1 overexpression on SH-SY5Y cells.

CONCLUSION

MZF1 alleviates OS and apoptosis induced by rotenone in SH-SY5Y cells by promoting RBM3 transcription.