Human adult dental pulp stem cells enhance poststroke functional recovery through non-neural replacement mechanisms

Pharmacokinetic characteristics of mesenchymal stem cells in translational challenges

Over the past two decades, mesenchymal stem/stromal cell (MSC) therapy has made substantial strides, transitioning from experimental clinical applications to commercial products. MSC therapies hold considerable promise for treating refractory and critical conditions such as acute graft-versus-host disease, amyotrophic lateral sclerosis, and acute respiratory distress syndrome. Despite recent successes in clinical and commercial applications, MSC therapy still faces challenges when used as a commercial product. Current detection methods have limitations, leaving the dynamic biodistribution, persistence in injured tissues, and ultimate fate of MSCs in patients unclear. Clarifying the relationship between the pharmacokinetic characteristics of MSCs and their therapeutic effects is crucial for patient stratification and the formulation of precise therapeutic regimens. Moreover, the development of advanced imaging and tracking technologies is essential to address these clinical challenges. This review provides a comprehensive analysis of the kinetic properties, key regulatory molecules, different fates, and detection methods relevant to MSCs and discusses concerns in evaluating MSC druggability from the perspective of integrating pharmacokinetics and efficacy. A better understanding of these challenges could improve MSC clinical efficacy and speed up the introduction of MSC therapy products to the market.

Priming and Combined Strategies for the Application of Mesenchymal Stem Cells in Ischemic Stroke: A Promising Approach

Ischemic stroke (IS) is a leading cause of death and disability worldwide. Tissue plasminogen activator (tPA) administration and mechanical thrombectomy are the main treatments but have a narrow time window. Mesenchymal stem cells (MSCs), which are easily scalable in vitro and lack ethical concerns, possess the potential to differentiate into various types of cells and secrete a great number of growth factors for neuroprotection and regeneration. Moreover, MSCs have low immunogenicity and tumorigenic properties, showing safety and preliminary efficacy both in preclinical studies and clinical trials of IS. However, it is unlikely that MSC treatment alone will be sufficient to maximize recovery due to the low survival rate of transplanted cells and various mechanisms of ischemic brain damage in the different stages of IS. Preconditioning was used to facilitate the homing, survival, and secretion ability of the grafted MSCs in the ischemic region, while combination therapies are alternatives that can maximize the treatment effects, focusing on multiple therapeutic targets to promote stroke recovery. In this case, the combination therapy can yield a synergistic effect. In this review, we summarize the type of MSCs, preconditioning methods, and combined strategies as well as their therapeutic mechanism in the treatment of IS to accelerate the transformation from basic research to clinical application.

Transfer of miR-877-3p via extracellular vesicles derived from dental pulp stem cells attenuates neuronal apoptosis and facilitates early neurological functional recovery after cerebral ischemia-reperfusion injury through the Bclaf1/P53 signaling pathway

Cerebral ischemia-reperfusion injury (I/RI) is one of the principal pathogenic factors in the poor prognosis of ischemic stroke, for which current therapeutic options to enhance neurological recovery are notably insufficient. Dental pulp stem cell-derived extracellular vesicles (DPSC-EVs) have promising prospects in stroke treatment and the specific underlying mechanisms have yet to be fully elucidated. The present study observed that DPSC-EVs ameliorated the degree of cerebral edema and infarct volume by reducing the apoptosis of neurons. Furthermore, the miRNA sequencing and functional enrichment analysis identified that miR-877-3p as a key component in DPSC-EVs, contributing to neuroprotection and anti-apoptotic effects. Following target prediction and dual-luciferase assay indicated that miR-877-3p interacted with Bcl-2-associated transcription factor (Bclaf1) to play a function. The miR-877-3p inhibitor or Bclaf1 overexpression reversed the neuroprotective effects of DPSC-EVs. The findings reveal a novel therapeutic pathway where miR-877-3p, transferred via DPSC-EVs, confers neuroprotection against cerebral I/RI, highlighting its potential in promoting neuronal survival and recovery post-ischemia.

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.

Human-Induced Pluripotent Stem Cell-Derived Neural Progenitor Cells Showed Neuronal Differentiation, Neurite Extension, and Formation of Synaptic Structures in Rodent Ischemic Stroke Brains

Ischemic stroke is a major cerebrovascular disease with high morbidity and mortality rates; however, effective treatments for ischemic stroke-related neurological dysfunction have yet to be developed. In this study, we generated neural progenitor cells from human leukocyte antigen major loci gene-homozygous-induced pluripotent stem cells (hiPSC-NPCs) and evaluated their therapeutic effects against ischemic stroke. hiPSC-NPCs were intracerebrally transplanted into rat ischemic brains produced by transient middle cerebral artery occlusion at either the subacute or acute stage, and their in vivo survival, differentiation, and efficacy for functional improvement in neurological dysfunction were evaluated. hiPSC-NPCs were histologically identified in host brain tissues and showed neuronal differentiation into vGLUT-positive glutamatergic neurons, extended neurites into both the ipsilateral infarct and contralateral healthy hemispheres, and synaptic structures formed 12 weeks after both acute and subacute stage transplantation. They also improved neurological function when transplanted at the subacute stage with γ-secretase inhibitor pretreatment. However, their effects were modest and not significant and showed a possible risk of cells remaining in their undifferentiated and immature status in acute-stage transplantation. These results suggest that hiPSC-NPCs show cell replacement effects in ischemic stroke-damaged neural tissues, but their efficacy is insufficient for neurological functional improvement after acute or subacute transplantation. Further optimization of cell preparation methods and the timing of transplantation is required to balance the efficacy and safety of hiPSC-NPC transplantation.

Effect of Octamer-Binding Transcription Factor 4 Overexpression on the Neural Induction of Human Dental Pulp Stem Cells

Stem cell-based therapy is a potential alternative strategy for brain repair, with neural stem cells (NSC) presenting as the most promising candidates. Obtaining sufficient quantities of NSC for clinical applications is challenging, therefore alternative cell types, such as neural crest-derived dental pulp stem cells (DPSC), may be considered. Human DPSC possess neurogenic potential, exerting positive effects in the damaged brain through paracrine effects. However, a method for conversion of DPSC into NSC has yet to be developed. Here, overexpression of octamer-binding transcription factor 4 (OCT4) in combination with neural inductive conditions was used to reprogram human DPSC along the neural lineage. The reprogrammed DPSC demonstrated a neuronal-like phenotype, with increased expression levels of neural markers, limited capacity for sphere formation, and enhanced neuronal but not glial differentiation. Transcriptomic analysis further highlighted the expression of genes associated with neural and neuronal functions. In vivo analysis using a developmental avian model showed that implanted DPSC survived in the developing central nervous system and respond to endogenous signals, displaying neuronal phenotypes. Therefore, OCT4 enhances the neural potential of DPSC, which exhibited characteristics aligning with neuronal progenitors. This method can be used to standardise DPSC neural induction and provide an alternative source of neural cell types.

A review of the therapeutic potential of dental stem cells as scaffold-free models for tissue engineering application

In the realm of regenerative medicine, tissue engineering has introduced innovative approaches to facilitate tissue regeneration. Specifically, in pulp tissue engineering, both scaffold-based and scaffold-free techniques have been applied. Relevant articles were meticulously chosen from PubMed, Scopus, and Google Scholar databases through a comprehensive search spanning from October 2022 to December 2022. Despite the inherent limitations of scaffolding, including inadequate mechanical strength for hard tissues, insufficient vents for vessel penetration, immunogenicity, and suboptimal reproducibility-especially with natural polymeric scaffolds-scaffold-free tissue engineering has garnered significant attention. This methodology employs three-dimensional (3D) cell aggregates such as spheroids and cell sheets with extracellular matrix, facilitating precise regeneration of target tissues. The choice of technique aside, stem cells play a pivotal role in tissue engineering, with dental stem cells emerging as particularly promising resources. Their pluripotent nature, non-invasive extraction process, and unique properties render them highly suitable for scaffold-free tissue engineering. This study delves into the latest advancements in leveraging dental stem cells and scaffold-free techniques for the regeneration of various tissues. This paper offers a comprehensive summary of recent developments in the utilization of dental stem cells and scaffold-free methods for tissue generation. It explores the potential of these approaches to advance tissue engineering and their effectiveness in therapies aimed at tissue regeneration.

Public RNA-seq data-based identification and functional analyses reveal that MXRA5 retains proliferative and migratory abilities of dental pulp stem cells

Dental pulp stem cells (DPSC) usually remain quiescent in the dental pulp tissue; however, once the dental pulp tissue is injured, DPSCs potently proliferate and migrate into the injury microenvironment and contribute to immuno-modulation and tissue repair. However, the key molecules that physiologically support the potent proliferation and migration of DPSCs have not been revealed. In this study, we searched publicly available transcriptome raw data sets, which contain comparable (i.e., equivalently cultured) DPSC and mesenchymal stem cell data. Three data sets were extracted from the Gene Expression Omnibus database and then processed and analyzed. MXRA5 was identified as the predominant DPSC-enriched gene associated with the extracellular matrix. MXRA5 is detected in human dental pulp tissues. Loss of MXRA5 drastically decreases the proliferation and migration of DSPCs, concomitantly with reduced expression of the genes associated with the cell cycle and microtubules. In addition to the known full-length isoform of MXRA5, a novel splice variant of MXRA5 was cloned in DPSCs. Recombinant MXRA5 coded by the novel splice variant potently induced the haptotaxis migration of DPSCs, which was inhibited by microtubule inhibitors. Collectively, MXRA5 is a key extracellular matrix protein in dental pulp tissue for maintaining the proliferation and migration of DPSCs.

Effects of ethanol washing and storage duration on primary culture of stem cells from human exfoliated deciduous teeth

Purpose

Since the oral environment harbors various microorganisms, the removal of contaminants during the primary culture process of stem cells from human exfoliated deciduous teeth (SHEDs) is very important. We investigated optimal methods for primary culture of SHEDs with minimal contamination rates.

Materials and methods

Three different storage conditions for deciduous teeth were utilized:1) storing teeth in Hank's Balanced Salt Solution (HBSS) with 3% penicillin and streptomycin (P/S), 2) storing teeth in HBSS with 3% antibiotics and antimycotics (A-A), and 3) storing teeth in HBSS with A-A, and additional washing with 70% ethanol just before primary culture of dental pulp. In addition, the storage time from the extraction of teeth to the primary culture was measured.

Results

The contamination rates were about 70% for HBSS with P/S, 40% for HBSS with A-A, and less than 10% for HBSS with A-A and additional washing with 70% ethanol. When the primary culture was conducted within 12 h after teeth extraction, the contamination rate was the lowest in all conditions. Furthermore, when the teeth were delivered in HBSS with A-A and an additional 70% ethanol washing was performed, the contamination rate was 0% until 48 h after teeth extraction. Ethanol washing had little effect on the cellular characteristics and stemness of SHEDs, including their morphology, growth rate, expression of surface markers, and differentiation potential.

Conclusions

We suggested that both delivering teeth in HBSS with A-A and additional 70% ethanol washing are critical considerations for the successful culture of SHEDs without contamination.

Short-term beneficial effects of human dental pulp stem cells and their secretome in a rat model of mild ischemic stroke

Although cell therapy has been applied in regenerative medicine for decades, recent years have seen greatly increased attention being given to the use of stem cell-based derivatives such as cell-free secretome. Dental pulp stem cells (DPSCs) are widely available, easily accessible, and have high neuroprotective and angiogenic properties. In addition, DPSC-derived secretome contains a rich mixture of trophic factors. The current investigation evaluated the short-term therapeutic effects of human DPSCs and their secretome in a rat model of mild ischemic stroke. Mild ischemic stroke was induced by 30 min middle cerebral artery occlusion, and hDPSCs or their secretome was administered intra-arterially and intranasally. Neurological function, infarct size, spatial working memory, and relative expression of seven target genes in two categories of neurotrophic and angiogenic factors were assessed three days after stroke. In the short-term, all treatments reduced the severity of neurological and histological deficits caused by ischemic stroke. Moreover, transient middle cerebral artery occlusion led to the striatal and cortical over-expression of BDNF, NT-3, and angiogenin, while NGF and VEGF expression was reduced. Almost all interventions were able to modulate the expression of target genes after stroke. The obtained data revealed that single intra-arterial administration of hDPSCs or their secretome, single intranasal transplantation of hDPSCs, or repeated intranasal administration of hDPSC-derived secretome was able to ameliorate the devastating effects of a mild stroke, at least in the short-term.

Effect of Wnt10a/β-catenin signaling pathway on promoting the repair of different types of dentin-pulp injury

How to repair dentin-pulp injury effectively has always been a clinical problem, and the comparative study of repair process between different injuries is unknown. Dental pulp stem cells (DPSCs) often are selected as seed cells for the study of dentin-pulp injury repair due to excellent advantages in odontogenesis and pulp differentiation. Although many previous researches have indicated that the Wnt protein and Wnt/β-catenin signaling pathway were crucial for dental growth, development, and injury repair, the specific mechanism remained unknown. In this study, different dentine-pulp injury models of adult mice were established successfully by abrasion and cutting methods. The gross morphology and micro-CT were used to observe the repair of injured mice incisor in different groups. We found that the repair time of each group was different. The repair time of the cutting group was longer than the abrasion group and the qRT-PCR detection showed that the expression of DSPP in the cutting group was higher than that in the abrasion group, but there was no significant difference in proliferation among the groups. In vivo and cell experiments showed that activation of Wnt/β-catenin signaling pathway can promote the proliferation and odontoblast differentiation of DPSCs. In addition, by using RNAscope staining, we observed that Wnt10a was mainly expressed in the proliferative region and partially expressed in the odontoblast region. The Western blotting results showed that in the early stage of repair, the expression of Wnt10a increased with the extension of days after injury in both abrasion and cutting group and the increase of Wnt10a was tested obviously on the 5th day after injury. But on the 7th day after injury, the expression of Wnt10a was still obvious in the cutting group, while the expression of Wnt10a was significantly reduced in the abrasion group, which was close to the control group. It is suggested that Wnt10a acts as a repair-related protein and has an important role in tooth injury repair. Wnt10a was activated by R-spondin and LiCl, and Wnt10a-siRNA DPSCs were constructed to inhibit Wnt10a. The results showed that Wnt10a/β-catenin signaling pathway promoted the proliferation and odontoblast differentiation of DPSCs. It plays a crucial role in the repair process of different injuries. This study enriched the mechanisms of Wnt10a /β-catenin signaling pathways in different types of dentin-pulp injury repair, which could provide experimental evidences for the target gene screening and also give some new ideas for the subsequent research on the molecular mechanisms of tooth regeneration.

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.

The NG2-glia is a potential target to maintain the integrity of neurovascular unit after acute ischemic stroke

The neurovascular unit (NVU) plays a critical role in health and disease. In the current review, we discuss the critical role of a class of neural/glial antigen 2 (NG2)-expressing glial cells (NG2-glia) in regulating NVU after acute ischemic stroke (AIS). We first introduce the role of NG2-glia in the formation of NVU during development as well as aging-induced damage to NVU and accompanying NG2-glia change. We then discuss the reciprocal interactions between NG2-glia and the other component cells of NVU, emphasizing the factors that could influence NG2-glia. Damage to the NVU integrity is the pathological basis of edema and hemorrhagic transformation, the most dreaded complication after AIS. The role of NG2-glia in AIS-induced NVU damage and the effect of NG2-glia transplantation on AIS-induced NVU damage are summarized. We next discuss the role of NG2-glia and the effect of NG2-glia transplantation in oligodendrogenesis and white matter repair as well as angiogenesis which is associated with the outcome of the patients after AIS. Finally, we review the current strategies to promote NG2-glia proliferation and differentiation and propose to use the dental pulp stem cells (DPSC)-derived exosome as a promising strategy to reduce AIS-induced injury and promote repair through maintaining the integrity of NVU by regulating endogenous NG2-glia proliferation and differentiation.

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.

The Immunomodulatory and Regenerative Effect of Biodentine™ on Human THP-1 Cells and Dental Pulp Stem Cells: In Vitro Study

Background

Pulp tissue affected by deep caries and trauma can be protected by vital pulp therapies in which pulp regeneration success depends on the degree of pulp inflammation and the presence of regenerative signals. Reparative dentinogenesis requires dental pulp stem cell (DPSC) activity which can be stimulated by many bioactive molecules to repair the dentine, mediating a balance between the inflammatory response and the reparative events. Therefore, this study was performed in order to investigate the immune-inflammatory effect of Biodentine capping material on DPSCs and macrophages.

Method

THP-1, a human monocytic cell line, was differentiated to macrophages, and flow cytometry was used to analyze the expressions of specific macrophage markers. LPS-mediated infection was created for macrophages and DPSCs followed by treatment with Biodentine. CBA array was used to investigate the cytokine secretion followed by qPCR. Migration potential of treated DPSCs was also determined.

Results

Our results showed that THP-1 cell line was successfully differentiated into macrophages as shown by surface marker expression. CBA array and qPCR results showed that Biodentine-treated DPSCs and macrophages upregulated anti-inflammatory cytokines and downregulated proinflammatory cytokines. Also, Biodentine enhances the migration potential of treated DPSCs.

Conclusion

Biodentine capping material mediated the polarization of M1 to M2 macrophages suggestive of tissue repair properties of macrophages and enhanced the anti-inflammatory cytokines of DPSCs responsible for dentine-pulp regeneration.

Combination stem cell therapy using dental pulp stem cells and human umbilical vein endothelial cells for critical hindlimb ischemia

Narrowing of arteries supplying blood to the limbs provokes critical hindlimb ischemia (CLI). Although CLI results in irreversible sequelae, such as amputation, few therapeutic options induce the formation of new functional blood vessels. Based on the proangiogenic potentials of stem cells, in this study, it was examined whether a combination of dental pulp stem cells (DPSCs) and human umbilical vein endothelial cells (HUVECs) could result in enhanced therapeutic effects of stem cells for CLI compared with those of DPSCs or HUVECs alone. The DPSCs+ HUVECs combination therapy resulted in significantly higher blood flow and lower ischemia damage than DPSCs or HUVECs alone. The improved therapeutic effects in the DPSCs+ HUVECs group were accompanied by a significantly higher number of microvessels in the ischemic tissue than in the other groups. In vitro proliferation and tube formation assay showed that VEGF in the conditioned media of DPSCs induced proliferation and vessel-like tube formation of HUVECs. Altogether, our results demonstrated that the combination of DPSCs and HUVECs had significantly better therapeutic effects on CLI via VEGF-mediated crosstalk. This combinational strategy could be used to develop novel clinical protocols for CLI proangiogenic regenerative treatments.

Combination stem cell therapy using dental pulp stem cells and human umbilical vein endothelial cells for critical hindlimb ischemia

Narrowing of arteries supplying blood to the limbs provokes critical hindlimb ischemia (CLI). Although CLI results in irreversible sequelae, such as amputation, few therapeutic options induce the formation of new functional blood vessels. Based on the proangiogenic potentials of stem cells, in this study, it was examined whether a combination of dental pulp stem cells (DPSCs) and human umbilical vein endothelial cells (HUVECs) could result in enhanced therapeutic effects of stem cells for CLI compared with those of DPSCs or HUVECs alone. The DPSCs+ HUVECs combination therapy resulted in significantly higher blood flow and lower ischemia damage than DPSCs or HUVECs alone. The improved therapeutic effects in the DPSCs+ HUVECs group were accompanied by a significantly higher number of microvessels in the ischemic tissue than in the other groups. In vitro proliferation and tube formation assay showed that VEGF in the conditioned media of DPSCs induced proliferation and vessel-like tube formation of HUVECs. Altogether, our results demonstrated that the combination of DPSCs and HUVECs had significantly better therapeutic effects on CLI via VEGF-mediated crosstalk. This combinational strategy could be used to develop novel clinical protocols for CLI proangiogenic regenerative treatments. [BMB Reports 2022; 55(7): 336-341].

Ischemic Brain Stroke and Mesenchymal Stem Cells: An Overview of Molecular Mechanisms and Therapeutic Potential

Ischemic brain injury is associated with a high rate of mortality and disability with no effective therapeutic strategy. Recently, a growing number of studies are focusing on mesenchymal stem cell-based therapies for neurodegenerative disorders. However, despite having the promising outcome of preclinical studies, the clinical application of stem cell therapy remained elusive due to little or no progress in clinical trials. The objective of this study was to provide a generalized critique for the role of mesenchymal stem cell therapy in ischemic stroke injury, its underlying mechanisms, and constraints on its preclinical and clinical applications. Thus, we attempted to present an overview of previously published reports to evaluate the progress and provide molecular basis of mesenchymal stem cells (MSCs) therapy and its application in preclinical and clinical settings, which could aid in designing an effective regenerative therapeutic strategy in the future.

Dental-derived cells for regenerative medicine: stem cells, cell reprogramming, and transdifferentiation

Embryonic stem cells have been a popular research topic in regenerative medicine owing to their pluripotency and applicability. However, due to the difficulty in harvesting them and their low yield efficiency, advanced cell reprogramming technology has been introduced as an alternative. Dental stem cells have entered the spotlight due to their regenerative potential and their ability to be obtained from biological waste generated after dental treatment. Cell reprogramming, a process of reverting mature somatic cells into stem cells, and transdifferentiation, a direct conversion between different cell types without induction of a pluripotent state, have helped overcome the shortcomings of stem cells and raised interest in their regenerative potential. Furthermore, the potential of these cells to return to their original cell types due to their epigenetic memory has reinforced the need to control the epigenetic background for successful management of cellular differentiation. Herein, we discuss all available sources of dental stem cells, the procedures used to obtain these cells, and their ability to differentiate into the desired cells. We also introduce the concepts of cell reprogramming and transdifferentiation in terms of genetics and epigenetics, including DNA methylation, histone modification, and non-coding RNA. Finally, we discuss a novel therapeutic avenue for using dental-derived cells as stem cells, and explain cell reprogramming and transdifferentiation, which are used in regenerative medicine and tissue engineering.

Dental-Pulp Stem Cells as a Therapeutic Strategy for Ischemic Stroke

Regenerative medicine aims to restore human functions by regenerating organs and tissues using stem cells or living tissues for the treatment of organ and tissue defects or dysfunction. Clinical trials investigating the treatment of cerebral infarction using mesenchymal stem cells, a type of somatic stem cell therapy, are underway. The development and production of regenerative medicines using somatic stem cells is expected to contribute to the treatment of cerebral infarction, a central nervous system disease for which there is no effective treatment. Numerous experimental studies have shown that cellular therapy, including the use of human dental pulp stem cells, is an attractive strategy for patients with ischemic brain injury. This review describes the basic research, therapeutic mechanism, clinical trials, and future prospects for dental pulp stem cell therapy, which is being investigated in Japan in first-in-human clinical trials for the treatment of patients with acute cerebral ischemia.

Neurogenic and cognitive enhancing effects of human dental pulp stem cells and its secretome in animal model of hippocampal neurodegeneration

Progressive hippocampal neuronal losses, neuroinflammation, declined neurogenesis and impaired hippocampal functions are pathological features of Alzheimer's disease and temporal lobe epilepsy (TLE). Halting neuroinflammation and progressive neurodegeneration in the hippocampus is a major challenge in treating such disease conditions which, if unsuccessful would lead to learning/memory dysfunction and co-morbidities like anxiety/depression. Mesenchymal stem cells (MSCs) therapy provides hope for treating neurodegenerative diseases by either replacing lost neurons by transplantation of MSCs which might differentiate into appropriate neuronal phenotypes or by stimulating the resident neural stem cells for proliferation/differentiation. In this current study, we demonstrate that the intrahippocampal transplantation of ectoderm originated dental pulp stem cells (DPSCs) or intrahippocampal injection of DPSCs condition medium (DPSCs-CM) in a mouse model of hippocampal neurodegeneration could efficiently prevent neurodegeneration, neuroinflammation, enhance hippocampal neurogenesis and spatial learning and memory functions much superior to commonly used bone marrow mesenchymal stem cells (BM-MSCs) or its secretome. Probing the possible mechanisms of neuroprotection revealed that DPSCs/DPSCs-CM treatment upregulated an array of hosts' endogenous neural survival factors expression, reduced pro-apoptotic caspase activity and upregulated the anti-apoptotic factors BCL-2 and phosphorylated PI3K prominently than BM-MSCs/BM-MSCs-CM, suggesting that among MSCs, neural crest originated DPSCs might be a better adult stem cell candidate for treating neurodegenerative diseases.

G-CSF augments the neuroprotective effect of conditioned medium of dental pulp stem cells against hypoxic neural injury in SH-SY5Y cells

Objective(s):

Dental pulp stem cells (DPSCs) can differentiate into functional neurons and have the potential for cell therapy in neurological diseases. Granulocyte colony-stimulating factor (G-CSF) is a glycoprotein family shown neuroprotective effect in models of nerve damage.

we evaluated the protective effects of G-CSF, conditioned media from DPSCs (DPSCs-CM) and conditioned media from transfected DPSCs with plasmid encoding G-CSF (DPSC-CMT) on SH-SY5Y exposed to CoCl₂ as a model of hypoxia-induced neural damage.

Materials and Methods:

SH-SY5Y exposed to CoCl₂ were treated with DPSCs-CM, G-CSF, simultaneous combination of DPSCs-CM and G-CSF and finally DPSC-CMT. Cell viability and apoptosis were determined by resazurin (or lactate dehydrogenase (LDH) assay alternatively) and propidium iodide (PI) staining. Western blot analysis was performed to detect changes in apoptotic protein levels. The interleukin-6 and interleukin-10 IL6/IL10 levels were measured with Enzyme-Linked Immunosorbent Assay (ELISA).

Results:

DPSCs-CM and G-CSF were able to significantly protect SH-SY5Y against neural cell damage caused by CoCl₂ according to resazurin and LDH analysis. Also, the percentage of apoptotic cells decreased when SH-SY5Y were treated with DPSCs-CM and G-CSF simultaneously. After transfection of DPSCs with G-CSF plasmid, DPSC-CMT could significantly improve the protection. The amount of β-catenin, cleaved PARP and caspase-3 were significantly decreased and the expression of survivin was considerably increased when hypoxic SH-SY5Y treated with DPSCs-CM plus G-CSF according to Western blot. Decreased level of IL-6/IL-10, which exposed to CoCl₂, after treatment with DPSCs-CM indicated the suppression of inflammatory mediators.

Conclusion:

Combination therapy of G-CSF and DPSCs-CM improved the protective activity.

Classification and Characteristics of Mesenchymal Stem Cells and Its Potential Therapeutic Mechanisms and Applications against Ischemic Stroke

Ischemic stroke is a serious cerebral disease that often induces death and long-term disability. As a currently available therapy for recanalization after ischemic stroke, thrombolysis, including intravenous thrombolysis and endovascular therapy, still cannot be applicable to all patients due to the narrow time window. Mesenchymal stem cell (MSC) transplantation therapy, which can trigger neuronal regeneration and repair, has been considered as a significant advance in treatment of ischemic stroke. MSC transplantation therapy has exhibited its potential to improve the neurological function in ischemic stroke. Our review describes the current progress and future perspective of MSC transplantation therapy in ischemic stroke treatment, including cell types, transplantation approaches, therapeutic mechanisms, and preliminary clinical trials of MSC transplantation, for providing us an update role of MSC transplantation in ischemic stroke treatment.

Injectable biomaterial shuttles for cell therapy in stroke

Ischemic stroke (IS) is the leading cause of disability and contributes to a significant socio-economic cost in the western world. Brain repair strategies investigated in the pre-clinical models include the delivery of drug or cell-based therapeutics; which is hindered by the complex anatomy and functional organization of the brain. Biomaterials can be instrumental in alleviating some of these challenges by providing a structural support, localization, immunomodulation and/or modulating cellular cross-talk in the brain. This review addresses the significance of and challenges associated with cell therapy in an ischemic brain. This is followed by a detailed insight into the biomaterial-based delivery systems which have been designed to provide sustained trophic factor delivery for endogenous repair and to support transplanted cell survival and integration. A biomaterial intervention uses a multifaceted approach in enhancing the survival and engraftment of cells during transplantation and this has driven them as potential candidates for the treatment of IS. The biological processes that are activated as a response to the biomaterials and how to modulate them is one of the key factors contributing to the success of the biomaterial-based therapeutic approach. Future perspectives highlight the need of a combinative approach of merging the material design with disease biology to fabricate effective biomaterial-based intervention of stroke.

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.

Potential for Stem Cell-Based Therapy in the Road of Treatment for Neurological Disorders Secondary to COVID-19

Abstract

The severe acute respiratory syndrome coronavirus 2 has led to the worldwide pandemic named coronavirus disease 2019 (COVID-19). It has caused a significant increase in the number of cases and mortalities since its first diagnosis in December 2019. Although COVID-19 primarily affects the respiratory system, neurological involvement of the central and peripheral nervous system has been also reported. Herein, the higher risk of neurodegenerative diseases in COVID-19 patients in future is also imaginable. Neurological complications of COVID-19 infection are more commonly seen in severely ill individuals; but, earlier diagnosis and treatment can lead to better long-lasting results. In this respect, stem cell biotechnologies with considerable self-renewal and differentiation capacities have experienced great progress in the field of neurological disorders whether in finding out their underlying processes or proving them promising therapeutic approaches. Herein, many neurological disorders have been found to benefit from stem cell medicine strategies. Accordingly, in the present review, the authors are trying to discuss stem cell-based biotechnologies as promising therapeutic options for neurological disorders secondary to COVID-19 infection through reviewing neurological manifestations of COVID-19 and current stem cell-based biotechnologies for neurological disorders.

Lay Summary

Due to the substantial burden of neurological disorders in the health, economic, and social system of society, the emergence of neurological manifestations following COVID-19 (as a life-threatening pandemic) creates the need to use efficient and modern methods of treatment. Since stem cell-based methods have been efficient for a large number of neurological diseases, it seems that the use of mentioned methods is also effective in the process of improving neurological disorders caused by COVID-19. Hereupon, the current review aims to address stem cell-based approaches as treatments showing promise to neurological disorders related to COVID-19.

Stem cells from human exfoliated deciduous teeth attenuate mechanical allodynia in mice through distinct from the siglec-9/MCP-1-mediated tissue-repairing mechanism

The effects of stem cells from human exfoliated deciduous teeth (SHED) on mechanical allodynia were examined in mice. A single intravenous injection of SHED and conditioned medium from SHED (SHED-CM) through the left external jugular vein significantly reversed the established mechanical allodynia induced by spinal nerve transection at 6 days after injection. SHED or SHED-CM significantly decreased the mean numbers of activating transcription factor 3-positive neurons and macrophages in the ipsilateral side of the dorsal root ganglion (DRG) at 20 days after spinal nerve transection. SHED or SHED-CM also suppressed activation of microglia and astrocytes in the ipsilateral side of the dorsal spinal cord. A single intravenous injection of secreted ectodomain of sialic acid-binding Ig-like lectin-9 and monocyte chemoattractant protein-1 had no effect on the established mechanical allodynia, whereas a single intravenous injection of protein component(s) contained in SHED-CM with molecular weight of between 30 and 50 kDa reversed the pain. Therefore, it may be concluded that protein component(s) with molecular mass of 30–50 kDa secreted by SHED could protect and/or repair DRG neurons damaged by nerve transection, thereby ameliorating mechanical allodynia.

Induced Neural Cells from Human Dental Pulp Ameliorate Functional Recovery in a Murine Model of Cerebral Infarction

Human mesenchymal stem cells are a promising cell source for the treatment of stroke. Their primary mechanism of action occurs via neuroprotective effects by trophic factors, anti-inflammatory effects, and immunomodulation. However, the regeneration of damaged neuronal networks by cell transplantation remains challenging. We hypothesized that cells induced to neural lineages would fit the niche, replace the lesion, and be more effective in improving symptoms compared with stem cells themselves. We investigated the characteristics of induced neural cells from human dental pulp tissue and compared the transplantation effects between these induced neural cells and uninduced dental pulp stem cells. Induced neural cells or dental pulp stem cells were intracerebrally transplanted 5 days after cerebral infarction induced by permanent middle cerebral artery occlusion in immunodeficient mice. Effects on functional recovery were also assessed through behavior testing. We used immunohistochemistry and neuron tracing to analyze the differentiation, axonal extension, and connectivity of transplanted cells to the host's neural circuit. Transplantation of induced neural cells from human dental pulp ameliorated functional recovery after cerebral infarction compared with dental pulp stem cells. The induced neural cells comprised both neurons and glia and expressed functional voltage, and they were more related to neurogenesis in terms of transcriptomics. Induced neural cells had a higher viability than did dental pulp stem cells in hypoxic culture. We showed that induced neural cells from dental pulp tissue offer a novel therapeutic approach for recovery after cerebral infarction.

Biodegradable and biocompatible graphene-based scaffolds for functional neural tissue engineering: A strategy approach using dental pulp stem cells and biomaterials

Neural tissue engineering aims to restore the function of nervous system tissues using biocompatible cell-seeded scaffolds. Graphene-based scaffolds combined with stem cells deserve special attention to enhance tissue regeneration in a controlled manner. However, it is believed that minor changes in scaffold biomaterial composition, internal porous structure, and physicochemical properties can impact cellular growth and adhesion. The current work aims to investigate in vitro biological effects of three-dimensional (3D) graphene oxide (GO)/sodium alginate (GOSA) and reduced GOSA (RGOSA) scaffolds on dental pulp stem cells (DPSCs) in terms of cell viability and cytotoxicity. Herein, the effects of the 3D scaffolds, coating conditions, and serum supplementation on DPSCs functions are explored extensively. Biodegradation analysis revealed that the addition of GO enhanced the degradation rate of composite scaffolds. Compared to the 2D surface, the cell viability of 3D scaffolds was higher (p < 0.0001), highlighting the optimal initial cell adhesion to the scaffold surface and cell migration through pores. Moreover, the cytotoxicity study indicated that the incorporation of graphene supported higher DPSCs viability. It is also shown that when the mean pore size of the scaffold increases, DPSCs activity decreases. In terms of coating conditions, poly- l-lysine was the most robust coating reagent that improved cell-scaffold adherence and DPSCs metabolism activity. The cytotoxicity of GO-based scaffolds showed that DPSCs can be seeded in serum-free media without cytotoxic effects. This is critical for human translation as cellular transplants are typically serum-free. These findings suggest that proposed 3D GO-based scaffolds have favorable effects on the biological responses of DPSCs.

Dental pulp stem cell-derived exosomes alleviate cerebral ischaemia-reperfusion injury through suppressing inflammatory response

Objectives

The study aimed to determine whether dental pulp stem cell‐derived exosomes (DPSC‐Exos) exert protective effects against cerebral ischaemia‐reperfusion (I/R) injury and explore its underlying mechanism.

Materials and Methods

Exosomes were isolated from the culture medium of human DPSC. Adult male C57BL/6 mice were subjected to 2 hours transient middle cerebral artery occlusion (tMCAO) injury followed by 2 hours reperfusion, after which singular injection of DPSC‐Exos via tail vein was administrated. Brain oedema, cerebral infarction and neurological impairment were measured on day 7 after exosomes injection. Then, oxygen‐glucose deprivation–reperfusion (OGD/R) induced BV2 cells were studied to analyse the therapeutic effects of DPSC‐Exos on I/R injury in vitro. Protein levels of TLR4, MyD88, NF‐κB p65, HMGB1, IL‐6, IL‐1β and TNF‐α were determined by western blot or enzyme‐linked immunosorbent assay. The cytoplasmic translocation of HMGB1 was detected by immunofluorescence staining.

Results

DPSC‐Exos alleviated brain oedema, cerebral infarction and neurological impairment in I/R mice. DPSC‐Exos inhibited the I/R‐mediated expression of TLR4, MyD88 and NF‐κB significantly. DPSC‐Exos also reduced the protein expression of IL‐6, IL‐1β and TNF‐α compared with those of the control both in vitro and in vivo. Meanwhile, DPSC‐Exos markedly decreased the HMGB1 cytoplasmic translocation induced by I/R damage.

Conclusions

DPSC‐Exos can ameliorate I/R‐induced cerebral injury in mice. Its anti‐inflammatory mechanism might be related with the inhibition of the HMGB1/TLR4/MyD88/NF‐κB pathway.

Progress in Mesenchymal Stem Cell Therapy for Ischemic Stroke

Ischemic stroke (IS) is a serious cerebrovascular disease with high morbidity and disability worldwide. Despite the great efforts that have been made, the prognosis of patients with IS remains unsatisfactory. Notably, recent studies indicated that mesenchymal stem cell (MSCs) therapy is becoming a novel research hotspot with large potential in treating multiple human diseases including IS. The current article is aimed at reviewing the progress of MSC treatment on IS. The mechanism of MSCs in the treatment of IS involved with immune regulation, neuroprotection, angiogenesis, and neural circuit reconstruction. In addition, nutritional cytokines, mitochondria, and extracellular vesicles (EVs) may be the main mediators of the therapeutic effect of MSCs. Transplantation of MSCs-derived EVs (MSCs-EVs) affords a better neuroprotective against IS when compared with transplantation of MSCs alone. MSC therapy can prolong the treatment time window of ischemic stroke, and early administration within 7 days after stroke may be the best treatment opportunity. The deliver routine consists of intraventricular, intravascular, intranasal, and intraperitoneal. Furthermore, several methods such as hypoxic preconditioning and gene technology could increase the homing and survival ability of MSCs after transplantation. In addition, MSCs combined with some drugs or physical therapy measures also show better neurological improvement. These data supported the notion that MSC therapy might be a promising therapeutic strategy for IS. And the application of new technology will promote MSC therapy of IS.

Peripheral-neuron-like properties of differentiated human dental pulp stem cells (hDPSCs)

Elucidating the mechanisms underlying human pain sensation requires the establishment of an in vitro model of pain reception comprising human cells expressing pain-sensing receptors and function properly as neurons. Human dental pulp stem cells (hDPSCs) are mesenchymal stem cells and a promising candidate for producing human neuronal cells, however, the functional properties of differentiated hDPSCs have not yet been fully characterized. In this study, we demonstrated neuronal differentiation of hDPSCs via both their expression of neuronal marker proteins and their neuronal function examined using Ca²⁺ imaging. Moreover, to confirm the ability of nociception, Ca²⁺ responses in differentiated hDPSCs were compared to those of rat dorsal root ganglion (DRG) neurons. Those cells showed similar responses to glutamate, ATP and agonists of transient receptor potential (TRP) channels. Since TRP channels are implicated in nociception, differentiated hDPSCs provide a useful in vitro model of human peripheral neuron response to stimuli interpreted as pain.

Transplantation of rat dental pulp stem cells facilities post-lesion recovery in the somatosensory whisker cortex of male Wistar rats

Damage to somatosensory "barrel" cortex reduces the rats' behavioral sensitivity in discrimination of tactile stimuli. Here, we examined how transplantation of stem cells into the lesioned barrel cortex can help in recovery of sensory capacities. We induced mechanical lesions in the right barrel cortex area of male rats. Three days after lesioning, rats received one of three transplantation types: un-differentiated dental pulp stem cells (U-DPSCs) or differentiated dental pulp stem cells (D-DPSCs), or cell medium (vehicle). A fourth group of rats were control without any Surgery. For 4 consecutive weeks, starting one week after transplantation, we evaluated the rats' preference to explore novel textures as a measure of sensory discrimination ability, also measured the expression of glial fibrillary acidic protein (GFAP), Olig 2, nestin, neuronal nuclei (NeuN), brain-derived neurotrophic factor (BDNF) and neuroligin1 by immunohistochemistry and western blotting. Unilateral mechanical lesion decreased the rats' preferential exploration of novel textures compared to the control group across the 4-week behavioral tests. Following stem cell therapy, the rats' performance significantly improved at week 2-4 compared to the vehicle group. Compared to the control group, there was a significant decrease in the expression of nestin, NeuN, Olig 2, BDNF, neuroligin1 and a significant increase in the expression of GFAP in the vehicle group. The expression of the neural markers was significantly higher in DPSCs compared with the vehicle group whereas GFAP level was lower in DPSCs compared to vehicle. We found that DPSCs therapy affected a range of neuronal markers in the barrel cortex post lesion, and improved the rats' recovery for sensory discrimination.

Safety and Homing of Human Dental Pulp Stromal Cells in Head and Neck Cancer

BACKGROUND

Head and neck cancer (HNC) is one of the most common cancers, associated with a huge mortality and morbidity. In order to improve patient outcomes, more efficient and targeted therapies are essential. Bone marrow-derived mesenchymal stromal cells (BM-MSCs) express tumour homing capacity, which could be exploited to target anti-cancer drug delivery to the tumour region and reduce adverse side-effects. Nevertheless, dental pulp stromal cells (DPSCs), an MSC-like population present in teeth, could offer important clinical benefits because of their easy isolation and superior proliferation compared to BM-MSCs. Therefore, we aimed to elucidate the tumour homing and safe usage of DPSCs to treat HNC.

METHODS

The in vivo survival as well as the effect of intratumourally administered DPSCs on tumour aggressiveness was tested in a HNC xenograft mouse model by using bioluminescence imaging (BLI), (immuno)histology and qRT-PCR. Furthermore, the in vitro and in vivo tumour homing capacity of DPSCs towards a HNC cell line were evaluated by a transwell migration assay and BLI, respectively.

RESULTS

Intratumourally injected DPSCs survived for at least two weeks in the tumour micro-environment and had no significant influence on tumour morphology, growth, angiogenesis and epithelial-to-mesenchymal transition. In addition, DPSCs migrated towards tumour cells in vitro, which could not be confirmed after their in vivo intravenous, intraperitoneal or peritumoural injection under the tested experimental conditions.

CONCLUSIONS

Our research suggests that intratumourally delivered DPSCs might be used as safe factories for the continuous delivery of anti-cancer drugs in HNC. Nevertheless, further optimization as well as efficacy studies are necessary to understand and improve in vivo tumour homing and determine the optimal experimental set-up of stem cell-based cancer therapies, including dosing and timing.

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.

Sivelestat-loaded nanostructured lipid carriers modulate oxidative and inflammatory stress in human dental pulp and mesenchymal stem cells subjected to oxygen-glucose deprivation

Stroke remains the leading cause of morbidity and mortality. Stem cell-based therapy offers promising hope for survivors and their families. Despite the clinical translation of stem cell-based therapies in stroke patients for almost two decades, results of these randomized controlled trials are not very optimistic. In these lines, an amalgamation of nanocarriers based drug delivery with stem cells holds great promise in enhancing stroke recovery. In the present study, we treated oxygen-glucose deprivation (OGD) exposed dental pulp stem cells (DPSCs) and mesenchymal stem cells (MSCs) with sivelestat-loaded nanostructured lipid carriers (NLCs). Various physicochemical limitations associated with sivelestat drug applications and its recent inefficacy in the clinical trials necessitates the development of novel delivery approaches for sivelestat. Therefore, to improve its efficacy on the survival of DPSCs and MSCs cell types under OGD insult, the current NLCs were formulated and characterized. Resulting NLCs exhibited a hydrodynamic diameter of 160-180 nm by DLS technique and possessed good PDI values of 0.2-0.3. Their shape, size and surface morphology were corroborated with microscopic techniques like TEM, SEM, and AFM. FTIR and UV-Vis techniques confirmed nanocarrier's loading capacity, encapsulation efficiency of sivelestat, and drug release profile. Oxidative stress in DPSCs and MSCs was assessed by DHE and DCFDA staining, and cell viability was assessed by Trypan blue exclusion test and MTT assay. Results indicated that sivelestat-loaded NLCs protected the loss of cell membrane integrity and restored cell morphology. Furthermore, NLCs successfully defended human DPSCs and MSCs against OGD-induced oxidative and inflammatory stress. In conclusion, modulation of oxidative and inflammatory stress by treatment with sivelestat-loaded NLCs in DPSCs and MSCs provides a novel strategy to rescue stem cells during ischemic stroke.

Delayed Treatment with Human Dental Pulp Stem Cells Accelerates Functional Recovery and Modifies Responses of Peri-Infarct Astrocytes Following Photothrombotic Stroke in Rats

Dental pulp contains multipotent mesenchymal stem cells that improve outcomes when administered early after temporary middle cerebral artery occlusion in rats. To further assess the therapeutic potential of these cells, we tested whether functional recovery following stroke induced by photothrombosis could be modified by a delayed treatment that was initiated after the infarct attained maximal volume. Photothrombosis induces permanent focal ischemia resulting in tissue changes that better reflect key aspects of the many human strokes in which early restoration of blood flow does not occur. Human dental pulp stem cells (approximately 400 × 10³ viable cells) or vehicle were injected into the infarct and adjacent brain tissue of Sprague-Dawley rats at 3 days after the induction of unilateral photothrombotic stroke in the sensorimotor cortex. Forepaw function was tested up to 28 days after stroke. Cellular changes in peri-infarct tissue at 28 days were assessed using immunohistochemistry. Rats treated with the stem cells showed faster recovery compared with vehicle-treated animals in a test of forelimb placing in response to vibrissae stimulation and in first attempt success in a skilled forelimb reaching test. Total success in the skilled reaching test and forepaw use during exploration in a Perspex cylinder were not significantly different between the 2 groups. At 28 days after stroke, rats treated with the stem cells showed decreased immunolabeling for glial fibrillary acidic protein in tissue up to 1 mm from the infarct, suggesting decreased reactive astrogliosis. Synaptophysin, a marker of synapses, and collagen IV, a marker of capillaries, were not significantly altered at this time by the stem-cell treatment. These results indicate that dental pulp stem cells can accelerate recovery without modifying initial infarct formation. Decreases in reactive astrogliosis in peri-infarct tissue could have contributed to the change by promoting adaptive responses in neighboring neurons.

Human Dental Pulp Stem Cells (DPSCs) Therapy in Rescuing Photoreceptors and Establishing a Sodium Iodate-Induced Retinal Degeneration Rat Model

BACKGROUND

Different methods have been used to inject stem cells into the eye for research. We previously explored the intravitreal route. Here, we investigate the efficacy of intravenous and subretinal-transplanted human dental pulp stem cells (DPSCs) in rescuing the photoreceptors of a sodium iodate-induced retinal degeneration model.

METHODS

Three groups of Sprague Dawley rats were used: intervention, vehicle group and negative control groups (n = 6 in each). Intravenous injection of 60 mg/kg sodium iodate (day 0) induced retinal degeneration. On day 4 post-injection of sodium iodate, the rats in the intervention group received intravenous DPSC and subretinal DPSC in the right eye; rats in the vehicle group received subretinal Hank's balance salt solution and intravenous normal saline; while negative control group received nothing. Electroretinogram (ERG) was performed to assess the retinal function at day 0 (baseline), day 4, day 11, day 18, day 26, and day 32. By the end of the study at day 32, the rats were euthanized, and both their enucleated eyes were sent for histology.

RESULTS

No significant difference in maximal ERG a-wave (p = 0.107) and b-wave, (p = 0.153) amplitude was seen amongst the experimental groups. However, photopic 30 Hz flicker amplitude of the study eye showed significant differences in the 3 groups (p = 0.032). Within the intervention group, there was an improvement in 30 Hz flicker ERG response of all 6 treated right eyes, which was injected with subretinal DPSC; while the 30 Hz flicker ERG of the non-treated left eyes remained flat. Histology showed improved outer nuclear layer thickness in intervention group; however, findings were not significant compared to the negative and vehicle groups.

CONCLUSION

Combination of subretinal and intravenous injection of DPSCs may have potential to rescue cone function from a NaIO₃-induced retinal injury model.

Transplantation of human dental pulp stem cells compensates for striatal atrophy and modulates neuro-inflammation in 3-nitropropionic acid rat model of Huntington's disease

Stem cell-based therapy has recently offered a promising alternative for the remedy of neurodegenerative disorders like Huntington's disease (HD). Herein, we investigated the potential ameliorative effects of implantation of dental pulp stem cells (DPSCs) in 3-nitropropionic acid (3-NP) rat models of HD. In this regard, human DPSCs were isolated, culture-expanded and implanted in rats lesioned with 3-NP. Post-transplantation examinations revealed that DPSCs were able to survive and augment motor skills and muscle activity. Histological analysis showed DPSCs treatment hampered the shrinkage of the striatum along with the inhibition of gliosis and microgliosis in the striatum of 3-NP rat models. We also detected the downregulation of Caspase-3 and pro-inflammatory cytokines such as TNF and IL-1β upon DPSCs grafting. Overall, these findings imply that the grafting of DPSCs could repair motor-skill impairment and induce neurogenesis, probably through the secretion of neurotrophic factors and the modulation of neuroinflammatory response in HD animal models.

Clinical Application of Bone Marrow Mesenchymal Stem/Stromal Cells to Repair Skeletal Tissue

There has been an escalation in reports over the last decade examining the efficacy of bone marrow derived mesenchymal stem/stromal cells (BMSC) in bone tissue engineering and regenerative medicine-based applications. The multipotent differentiation potential, myelosupportive capacity, anti-inflammatory and immune-modulatory properties of BMSC underpins their versatile nature as therapeutic agents. This review addresses the current limitations and challenges of exogenous autologous and allogeneic BMSC based regenerative skeletal therapies in combination with bioactive molecules, cellular derivatives, genetic manipulation, biocompatible hydrogels, solid and composite scaffolds. The review highlights the current approaches and recent developments in utilizing endogenous BMSC activation or exogenous BMSC for the repair of long bone and vertebrae fractures due to osteoporosis or trauma. Current advances employing BMSC based therapies for bone regeneration of craniofacial defects is also discussed. Moreover, this review discusses the latest developments utilizing BMSC therapies in the preclinical and clinical settings, including the treatment of bone related diseases such as Osteogenesis Imperfecta.

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.

The Effects and Underlying Mechanisms of Cell Therapy on Blood-Brain Barrier Integrity After Ischemic Stroke

Ischemic stroke is one of the main causes of mortality and disability worldwide. However, efficient therapeutic strategies are still lacking. Stem/progenitor cell-based therapy, with its vigorous advantages, has emerged as a promising tool for the treatment of ischemic stroke. The mechanisms involve new neural cells and neuronal circuitry formation, antioxidation, inflammation alleviation, angiogenesis, and neurogenesis promotion. In the past decades, in-depth studies have suggested that cell therapy could promote vascular stabilization and decrease blood-brain barrier (BBB) leakage after ischemic stroke. However, the effects and underlying mechanisms on BBB integrity induced by the engrafted cells in ischemic stroke have not been reviewed yet. Herein, we will update the progress in research on the effects of cell therapy on BBB integrity after ischemic stroke and review the underlying mechanisms. First, we will present an overview of BBB dysfunction under the ischemic condition and cells engraftment for ischemic treatment. Then, we will summarize and discuss the current knowledge about the effects and underlying mechanisms of cell therapy on BBB integrity after ischemic stroke. In particular, we will review the most recent studies in regard to the relationship between cell therapy and BBB in tissue plasminogen activator (t-PA)-mediated therapy and diabetic stroke.

Long non-coding RNA maternally expressed gene 3 inhibits osteogenic differentiation of human dental pulp stem cells via microRNA-543/smad ubiquitin regulatory factor 1/runt-related transcription factor 2 axis

OBJECTIVE

The aim of the present study was to investigate the biological roles and underlying mechanism of the long non-coding RNA maternally expressed gene 3 (MEG3) on osteogenic differentiation of human dental pulp stem cells (hDPSCs).

METHODS

The expression levels of MEG3, microRNA-543 (miR-543), osterix, osteopontin, osteocalcin and runt-related transcription factor 2 (RUNX2) were measured by quantitative real-time PCR (qRT-PCR). Alkaline phosphatase (ALP) activity assay and alizarin red S staining (ARS) were used to measure the impacts exerted by MEG3, miR-543 on osteogenic differentiation. Cell proliferation was measured by MTT assay. In addition, the targeted relationships between miR-543, MEG3, and Smad ubiquitin regulatory factor 1 (SMURF1) were assessed through dual luciferase reporter assay.

RESULTS

During osteogenic induction, the expression of MEG3 was gradually reduced, whereas the expression of miR-543, osterix, osteopontin, osteocalcin and RUNX2 were gradually increased. Functional analysis implied that MEG3 overexpression or miR-543 inhibition reduced the cell proliferation, ALP activity, ARS levels, and decreased the expression of osteoblast-related proteins. Moreover, MEG3 promoted SMURF1 expression by directly targeting miR-543 as a competing endogenous RNA. Furthermore, overexpression of miR-543 or silencing SMURF1 could reverse the inhibitory effects of MEG3 on the osteogenic differentiation of hDPSCs.

CONCLUSIONS

In conclusion, our study revealed that overexpression of MEG3 inhibited hDPSCs osteogenic differentiation via miR-543/SMURF1/RUNX2 regulatory network, which may contribute to the functional regulation and clinical applications of hDPSCs.

Recent Advances in Cell-Based Therapies for Ischemic Stroke

Stroke is the most prevalent cardiovascular disease worldwide, and is still one of the leading causes of death and disability. Stem cell-based therapy is actively being investigated as a new potential treatment for certain neurological disorders, including stroke. Various types of cells, including bone marrow mononuclear cells, bone marrow mesenchymal stem cells, dental pulp stem cells, neural stem cells, inducible pluripotent stem cells, and genetically modified stem cells have been found to improve neurological outcomes in animal models of stroke, and there are some ongoing clinical trials assessing their efficacy in humans. In this review, we aim to summarize the recent advances in cell-based therapies to treat stroke.

Cell-Based Therapy for Stroke: Musing With Muse Cells

Stem cell-based regenerative therapies may rescue the central nervous system following ischemic stroke. Mesenchymal stem cells exhibit promising regenerative capacity in in vitro studies but display little to no incorporation in host tissue after transplantation in in vivo models of stroke. Despite these limitations, clinical trials using mesenchymal stem cells have produced some functional benefits ascribed to their ability to modulate the host's inflammatory response coupled with their robust safety profile. Regeneration of ischemic brain tissue using stem cells, however, remains elusive in humans. Multilineage-differentiating stress-enduring (Muse) cells are a distinct subset of mesenchymal stem cells found sporadically in connective tissue of nearly every organ. Since their discovery in 2010, these endogenous reparative stem cells have been investigated for their therapeutic potential against a variety of diseases, including acute myocardial infarction, stroke, chronic kidney disease, and liver disease. Preclinical studies have exemplified Muse cells' unique ability mobilize, differentiate, and engraft into damaged host tissue. Intravenously transplanted Muse cells in mouse lacunar stroke models afforded functional recovery and long-term engraftment into the host neural network. This mini-review article highlights these biological properties that make Muse cells an exceptional candidate donor source for cell therapy in ischemic stroke. Elucidating the mechanism behind the therapeutic potential of Muse cells will undoubtedly help optimize stem cell therapy for stroke and advance the field of regenerative medicine.

Dental Pulp Stem Cells in Neuroregeneration

Neurological diseases and injuries affect the routine life of patients. Current medical and surgical treatment has not improved the quality of life to desired limits. Neural regeneration through stem cells may be ideal choice in current scenario. Dental pulp stem cells (DPSCs), which are isolated from dental pulp, have shown excellent neuroregenerative properties in various animal studies. This review outlines the clinical perspective of DPSCs in neuroregeneration.

Multilineage Differentiation Potential of Human Dental Pulp Stem Cells-Impact of 3D and Hypoxic Environment on Osteogenesis In Vitro

Human dental pulp harbours unique stem cell population exhibiting mesenchymal stem/stromal cell (MSC) characteristics. This study aimed to analyse the differentiation potential and other essential functional and morphological features of dental pulp stem cells (DPSCs) in comparison with Wharton’s jelly-derived MSCs from the umbilical cord (UC-MSCs), and to evaluate the osteogenic differentiation of DPSCs in 3D culture with a hypoxic microenvironment resembling the stem cell niche. Human DPSCs as well as UC-MSCs were isolated from primary human tissues and were subjected to a series of experiments. We established a multiantigenic profile of DPSCs with CD45⁻/CD14⁻/CD34⁻/CD29⁺/CD44⁺/CD73⁺/CD90⁺/CD105⁺/Stro-1⁺/HLA-DR⁻ (using flow cytometry) and confirmed their tri-lineage osteogenic, chondrogenic, and adipogenic differentiation potential (using qRT-PCR and histochemical staining) in comparison with the UC-MSCs. The results also demonstrated the potency of DPSCs to differentiate into osteoblasts in vitro. Moreover, we showed that the DPSCs exhibit limited cardiomyogenic and endothelial differentiation potential. Decreased proliferation and metabolic activity as well as increased osteogenic differentiation of DPSCs in vitro, attributed to 3D cell encapsulation and low oxygen concentration, were also observed. DPSCs exhibiting elevated osteogenic potential may serve as potential candidates for a cell-based product for advanced therapy, particularly for bone repair. Novel tissue engineering approaches combining DPSCs, 3D biomaterial scaffolds, and other stimulating chemical factors may represent innovative strategies for pro-regenerative therapies.