Vasculogenesis from Human Dental Pulp Stem Cells Grown in Matrigel with Fully Defined Serum-Free Culture Media

Functional differentiation of human dental pulp stem cells into neuron-like cells exhibiting electrophysiological activity

BACKGROUND AND AIM

Human dental pulp stem cells (hDPSCs) constitute a promising alternative for central nervous system (CNS) cell therapy. Unlike other human stem cells, hDPSCs can be differentiated, without genetic modification, to neural cells that secrete neuroprotective factors. However, a better understanding of their real capacity to give rise to functional neurons and integrate into synaptic networks is still needed. For that, ex vivo differentiation protocols must be refined, especially to avoid the use of fetal animal serum. The aim of our study is to improve existing differentiation protocols of hDPSCs into neuron-like cells.

METHODS

We compared the effects of the (1) absence or presence of fetal serum during the initial expansion phase as a step prior to switching cultures to neurodifferentiation media. We (2) improved hDPSC neurodifferentiation by adding retinoic acid (RA) and potassium chloride (KCl) pulses for 21 or 60 days and characterized the results by immunofluorescence, digital morphometric analysis, RT-qPCR and electrophysiology.

RESULTS

We found that neural markers like Nestin, GFAP, S100β and p75NTR were expressed differently in neurodifferentiated hDPSC cultures depending on the presence or absence of serum during the initial cell expansion phase. In addition, hDPSCs previously grown as spheroids in serum-free medium exhibited in vitro expression of neuronal markers such as doublecortin (DCX), neuronal nuclear antigen (NeuN), Ankyrin-G and MAP2 after neurodifferentiation. Presynaptic vGLUT2, Synapsin-I, and excitatory glutamatergic and inhibitory GABAergic postsynaptic scaffold proteins and receptor subunits were also present in these neurodifferentiated hDPSCs. Treatment with KCl and RA increased the amount of both voltage-gated Na+ and K+ channel subunits in neurodifferentiated hDPSCs at the transcript level. Consistently, these cells displayed voltage-dependent K+ and TTX-sensitive Na+ currents as well as spontaneous electrophysiological activity and repetitive neuronal action potentials with a full baseline potential recovery.

CONCLUSION

Our study demonstrates that hDPSCs can be differentiated to neuronal-like cells that display functional excitability and thus evidence the potential of these easily accessible human stem cells for nerve tissue engineering. These results highlight the importance of choosing an appropriate culture protocol to successfully neurodifferentiate hDPSCs.

Human dental pulp stem cells modulate pro-inflammatory macrophages both through cell-to-cell contact and paracrine signaling

Introduction

Macrophages play a key role in most of the inflammatory diseases such as Rheumatoid Arthritis (RA), but the mechanism underlying their pathogenesis is still under study. Among stem cells, human dental pulp stem cells (hDPSCs) have attracted attention due to their easy accessibility and immunomodulatory properties, making them a promising adjuvant therapy. In this study, we aimed to evaluate the capacity of hDPSCs to modulate the phenotypes of primary human macrophages. Additionally, we sought to observe the differences induced on macrophages when cultured directly with hDPSCs or through a cell culture insert, mimicking the paracrine communication pathway.

Methods

Monocytes, isolated from buffy coats, were differentiated into pro-inflammatory M1 and anti-inflammatory M2 macrophages. Subsequently, they were cultured with hDPSCs either directly or via a cell-culture insert for 48 hours. Finally, they were analyzed for protein, gene expression, cytokines levels and immunofluorescence.

Results

In our study, we have demonstrated that, hDPSCs, even without priming, can reduce TNFα levels and enhancing IL-10 release in pro-inflammatory macrophages, both through direct contact and paracrine signaling. Furthermore, we found that their effects are more pronounced when in cell-to-cell contact through the decrease of NF-kB and COX-2 expression and of CD80/PD-L1 colocalization. HDPSCs, when in contact with macrophages, showed enhanced expression of NF-kB, COX-2, ICAM-1, PD-L1, FAS-L, TNFα and IFNγ.

Conclusion

We showed that hDPSCs exert immunomodulatory effects on pro-inflammatory macrophages, with cell-to-cell contact yielding a more pronounced outcome compared to paracrine signaling. Our work highlights the immunomodulatory properties of hDPSCs on activated pro-inflammatory macrophages and the potential therapeutic role in inflamed tissue.

Angiogenic Potential of Various Oral Cavity-Derived Mesenchymal Stem Cells and Cell-Derived Secretome: A Systematic Review and Meta-Analysis

Recent evidence suggests the immense potential of human mesenchymal stem cell (hMSC) secretome conditioned medium-mediated augmentation of angiogenesis. However, angiogenesis potential varies from source and origin. The hMSCs derived from the oral cavity share an exceptional quality due to their origin from a hypoxic environment. Our systematic review aimed to compare the mesenchymal stem cells (MSCs) derived from various oral cavity sources and cell-derived secretomes, and evaluate their angiogenic potential. A literature search was conducted using PubMed and Scopus from January 2000 to September 2020. Source-wise outcomes were systematically analyzed using in vitro, in vivo, and in ovo studies, emphasizing endothelial cell migration, tube formation, and blood vessel formation. Ninety-four studies were included in the systematic review, out of which 4 studies were subsequently included in the meta-analysis. Prominent growth factors and other bioactive components implicated in improving angiogenesis were included in the respective studies. The findings suggest that oral tissues are a rich source of hMSCs. The meta-analysis revealed a positive correlation between dental pulp-derived MSCs (DPMSCs) and stem cells derived from apical papilla (SCAP) compared to human umbilical cord-derived endothelial cell lines as a control. It shows a statistically significant positive correlation between the co-culture of human umbilical vein endothelial cells (HUVECs) and DPMSCs with tubule length formation and total branching points. Our meta-analysis revealed that oral-derived MSCs (dental pulp stem cells and SCAP) carry a better angiogenic potential in vitro than endothelial cell lines alone. The reviewed literature illustrates that oral cavity-derived MSCs (OC-MSCs) increased angiogenesis. The present literature reveals a dearth of investigations involving sources other than dental pulp. Even though OC-MSCs have revealed more significant potential than other MSCs, more comprehensive, target-oriented interinstitutional prospective studies are warranted to determine whether oral cavity-derived stem cells are the most excellent sources of significant angiogenic potential.

The potential therapeutic roles of dental pulp stem cells in spinal cord injury

Spinal cord injury (SCI) can lead to serious functional disorders, which have serious impacts on patients and society. The current traditional treatments of SCI are not effective the injured spinal cord is difficult to repair and regenerate. In recent years, stem cell transplantation for the treatment of SCI has been a hot research topic. Dental pulp stem cells have strong abilities of self-renewal and multi-directional differentiation, and have been applied for tissue engineering and regenerative medicine. And dental pulp stem cells have certain advantages in neuro-regenetation, bringing new hope to biotherapy for SCI. This article reviews the characteristics of dental pulp stem cells and their research progress in the treatment of SCI.

Bioengineering Cell Therapy for Treatment of Peripheral Artery Disease

Peripheral artery disease is an atherosclerotic disease associated with limb ischemia that necessitates limb amputation in severe cases. Cell therapies comprised of adult mononuclear or stromal cells have been clinically tested and show moderate benefits. Bioengineering strategies can be applied to modify cell behavior and function in a controllable fashion. Using mechanically tunable or spatially controllable biomaterials, we highlight examples in which biomaterials can increase the survival and function of the transplanted cells to improve their revascularization efficacy in preclinical models. Biomaterials can be used in conjunction with soluble factors or genetic approaches to further modulate the behavior of transplanted cells and the locally implanted tissue environment in vivo. We critically assess the advances in bioengineering strategies such as 3-dimensional bioprinting and immunomodulatory biomaterials that can be applied to the treatment of peripheral artery disease and then discuss the current challenges and future directions in the implementation of bioengineering strategies.

Dental Pulp Cell Transplantation Combined with Regenerative Endodontic Procedures Promotes Dentin Matrix Formation in Mature Mouse Molars

Regenerative endodontic procedures (REPs) are promising for dental pulp tissue regeneration; however, their application in permanent teeth remains challenging. We assessed the potential combination of an REP and local dental pulp cell (DPC) transplantation in the mature molars of C57BL/6 mice with (REP + DPC group) or without (REP group) transplantation of DPCs from green fluorescent protein (GFP) transgenic mice. After 4 weeks, the regenerated tissue was evaluated by micro-computed tomography and histological analyses to detect odontoblasts, vasculogenesis, and neurogenesis. DPCs were assessed for mesenchymal and pluripotency markers. Four weeks after the REP, the molars showed no signs of periapical lesions, and both the REP and REP + DPC groups exhibited a pulp-like tissue composed of a cellular matrix with vessels surrounded by an eosin-stained acellular matrix that resembled hard tissue. However, the REP + DPC group had a broader cellular matrix and uniquely contained odontoblast-like cells co-expressing GFP. Vasculogenesis and neurogenesis were detected in both groups, with the former being more prominent in the REP + DPC group. Overall, the REP was achieved in mature mouse molars and DPC transplantation improved the outcomes by inducing the formation of odontoblast-like cells and greater vasculogenesis.

Improved Cell Properties of Human Dental Pulp Stem Cells (hDPSCs) Isolated and Expanded in a GMP Compliant and Xenogeneic Serum-free Medium

BACKGROUND/AIM

Human dental pulp mesenchymal stem cells (hDPSCs) are considered to be a good cell source for cell-based clinical therapy, due to the advantages of high proliferation capacity, multilineage differentiation potential, immune regulation abilities, less ethnic concerns and non-invasive access. However, hDPSCs were traditionally isolated and expanded in medium containing fetal bovine serum (FBS), which is a barrier for clinical application due to the safety issues (virus transmission and allergy). Although many studies make efforts to screen out a suitable culture medium, the results are not promising so far. Therefore, a standard good manufacturing practice (GMP) compliant culture system is urgently required for the large-scale cell production. This study aimed to find suitable culture conditions for producing clinical grade hDPSCs to meet the requirements for clinical cell-based therapy and further to promote the application of hDPSCs into tissue regeneration or disease cure.

MATERIALS AND METHODS

We derived hDPSCs from nine orthodontic teeth expanded in two different media: a GMP compliant and xenogeneic serum-free medium (AMMS) and a serum containing medium (SCM). Cell propterties including morphology, proliferation, marker expression, differentiation, stemness, senescence and cytokine secretion between these two media were systematically compared.

RESULTS

hDPSCs cultured in both media exhibited the typical characteristics of mesenchymal stem cells (MSCs). However, we found that more cell colonies formed in the primary culture in AMMS, and the hDPSCs displayed higher proliferation capacity, differentiation potential and better stemness maintenance during sub-culturing in AMMS.

CONCLUSION

Cell properties of hDPSCs could be improved when they were isolated and expanded in AMMS, which might provide a good candidate of culture medium for large-scale cell manufacturing.

Prevascularization techniques for dental pulp regeneration: potential cell sources, intercellular communication and construction strategies

One of the difficulties of pulp regeneration is the rapid vascularization of transplanted engineered tissue, which is crucial for the initial survival of the graft and subsequent pulp regeneration. At present, prevascularization techniques, as emerging techniques in the field of pulp regeneration, has been proposed to solve this challenge and have broad application prospects. In these techniques, endothelial cells and pericytes are cocultured to induce intercellular communication, and the cell coculture is then introduced into the customized artificial vascular bed or induced to self-assembly to simulate the interaction between cells and extracellular matrix, which would result in construction of a prevascularization system, preformation of a functional capillary network, and rapid reconstruction of a sufficient blood supply in engineered tissue after transplantation. However, prevascularization techniques for pulp regeneration remain in their infancy, and there remain unresolved problems regarding cell sources, intercellular communication and the construction of prevascularization systems. This review focuses on the recent advances in the application of prevascularization techniques for pulp regeneration, considers dental stem cells as a potential cell source of endothelial cells and pericytes, discusses strategies for their directional differentiation, sketches the mechanism of intercellular communication and the potential application of communication mediators, and summarizes construction strategies for prevascularized systems. We also provide novel ideas for the extensive application and follow-up development of prevascularization techniques for dental pulp regeneration.

Notch and Wnt Signaling Modulation to Enhance DPSC Stemness and Therapeutic Potential

The Dental Pulp of permanent human teeth is home to stem cells with remarkable multilineage differentiation ability: human Dental Pulp Stem Cells (DPSCs). These cells display a very notorious expression of pluripotency core factors, and the ability to give rise to mature cell lineages belonging to the three embryonic layers. For these reasons, several researchers in the field have long considered human DPSCs as pluripotent-like cells. Notably, some signaling pathways such as Notch and Wnt contribute to maintaining the stemness of these cells through a complex network involving metabolic and epigenetic regulatory mechanisms. The use of recombinant proteins and selective pharmacological modulators of Notch and Wnt pathways, together with serum-free media and appropriate scaffolds that allow the maintenance of the non-differentiated state of hDPSC cultures could be an interesting approach to optimize the potency of these stem cells, without a need for genetic modification. In this review, we describe and integrate findings that shed light on the mechanisms responsible for stemness maintenance of hDPSCs, and how these are regulated by Notch/Wnt activation, drawing some interesting parallelisms with pluripotent stem cells. We summarize previous work on the stem cell field that includes interactions between epigenetics, metabolic regulations, and pluripotency core factor expression in hDPSCs and other stem cell types.

In vitro, ex vivo, and in vivo models for dental pulp regeneration

Based on the concept of tissue engineering (Cells-Scaffold-Bioactive molecules), regenerative endodontics appeared as a new notion for dental endodontic treatment. Its approaches aim to preserve dental pulp vitality (pulp capping) or to regenerate a vascularized pulp-like tissue inside necrotic root canals by cell homing. To improve the methods of tissue engineering for pulp regeneration, numerous studies using in vitro, ex vivo, and in vivo models have been performed. This review explores the evolution of laboratory models used in such studies and classifies them according to different criteria. It starts from the initial two-dimensional in vitro models that allowed characterization of stem cell behavior, through 3D culture matrices combined with dental tissue and finally arrives at the more challenging ex vivo and in vivo models. The travel which follows the elaboration of such models reveals the difficulty in establishing reproducible laboratory models for dental pulp regeneration. The development of well-established protocols and new laboratory ex vivo and in vivo models in the field of pulp regeneration would lead to consistent results, reduction of animal experimentation, and facilitation of the translation to clinical practice.

Metabolic shift and the effect of mitochondrial respiration on the osteogenic differentiation of dental pulp stem cells

Background

Metabolism shifts from glycolysis to mitochondrial oxidative phosphorylation are vital during the differentiation of stem cells. Mitochondria have a direct function in differentiation. However, the metabolic shift and the effect of mitochondria in regulating the osteogenic differentiation of human dental pulp stem cells (hDPSCs) remain unclear.

Methods

Human dental pulp stem cells were collected from five healthy donors. Osteogenic differentiation was induced by osteogenic induction medium. The activities of alkaline phosphatase, hexokinase, pyruvate kinase, and lactate dehydrogenase were analyzed by enzymatic activity kits. The extracellular acidification rate and the mitochondrial oxygen consumption rate were measured. The mRNA levels of COL-1, ALP, TFAM, and NRF1 were analyzed. The protein levels of p-AMPK and AMPK were detected by western blotting.

Results

Glycolysis decreased after a slight increase, while mitochondrial oxidative phosphorylation continued to increase when cells grew in osteogenic induction medium. Therefore, the metabolism of differentiating cells switched to mitochondrial respiration. Next, inhibiting mitochondrial respiration with carbonyl cyanide-chlorophenylhydrazone, a mitochondrial uncoupler inhibited hDPSCs differentiation with less ALP activity and decreased ALP and COL-1 mRNA expression. Furthermore, mitochondrial uncoupling led to AMPK activation. 5-Aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, simulated the effect of mitochondrial uncoupling by inhibiting osteogenic differentiation, mitochondrial biogenesis, and mitochondrial morphology. Mitochondrial uncoupling and activation of AMPK depressed mitochondrial oxidative phosphorylation and inhibited differentiation, suggesting that they may serve as regulators to halt osteogenic differentiation from impaired mitochondrial oxidative phosphorylation.

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.

Poly-ε-caprolactone/poly(rotaxane) seeded with human dental pulp stem cells or osteoblasts promotes angiogenesis: a chorioallantoic membrane assay

Biomaterials used for tissue regeneration should ideally provide a favorable environment for cell proliferation and differentiation. Angiogenesis is crucial for supplying oxygen and nutrients necessary for cellular survival at implantation sites. The aim of this study was to evaluate the overall angiogenesis response of a poly ε-caprolactone/poly (rotaxane) blend (poly-blend) carried by human dental pulp stem cells (hDPSCs) or osteoblasts (OB) seeded in the chorioallantoic membranes (CAM) of fertilized chicken eggs on embryonic day 7. They were classified into the following intervention groups: (a) poly(polymeric blend disks free of cells); (b) hDPSC seeded onto CAM; (c) poly/hDPSC (where hDPSCs were seeded onto poly-blend); (d) poly/OB (where osteoblasts were seeded onto poly); (e) OB (where hDPSCs differentiated into osteoblasts were seeded onto CAM); and (f) a negative control when a sterilized silicone ring free of cells or polymer was inserted into CAM. On embryonic day 14, the quantitative and qualitative characteristics of the blood vessels in the CAMs were analyzed macroscopically and microscopically. Macroscopic examination showed that the Poly/hDPSC samples exhibited an increased medium vessel density. Additionally, microscopic observations showed that the Poly/hDPSC group and poly alone resulted in a large lumen area of vascularization. Thus, poly ε-caprolactone/poly (rotaxane) did not impair angiogenesis. Furthermore, poly-blend carried by stem cells of dental pulp origin shows a better vasculogenic potential, which is essential for regenerative therapies.

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

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

In Vitro Induction of Human Dental Pulp Stem Cells to Lymphatic Endothelial Cells

Lymphedema is a progressive and irreversible disease due to the lymphatic system disorder. Conservative and surgical therapies are either ineffective or impractical. Currently, mesenchymal stem cells (MSCs)-based therapies seem to be the most promising treatment for lymphedema. The MSCs promote lymphangiogenesis through the paracrine approach or by directly differentiating into lymphatic endothelial cells (LECs) under the induction of growth factors. Human dental pulp stem cells (hDPSCs) have been suggested to play important roles in tissue regeneration, making it an attractive candidate for the lymphedema treatment. In this study, to evaluate the potential role of hDPSCs in the clinical application for lymphedema treatment, we induced the hDPSCs with vascular endothelial growth factor-C (VEGF-C) and investigated the lymphangiogenic differentiation potential of hDPSCs in vitro. We found that under the VEGF-C induction, hDPSCs demonstrated upregulated LECs specific markers, promoted cell proliferation and migration, and increased tube formation, all of which contributed to their differentiation into LECs in vitro.

Meeting the challenges and clinical requirements for dental regeneration; the New Zealand experience

Disease and trauma leading to tooth loss and destruction of supporting bone is a significant oral handicap, which may be addressed through surgical therapies that aim to regenerate the lost tissue. Whilst complete regeneration of teeth is still aspirational, regeneration of supporting structures (dental pulp, cementum, periodontal ligament, bone) is becoming commonplace, both for teeth and for titanium dental implants that are used to replace teeth. Most grafting materials are essentially passive, however the next generation of oral regenerative devices will combine non-antibiotic antimicrobials and/or osteogenic or inductive factors and/or appropriate multipotential stem cells. The review gives an overview of the approaches taken, including fabrication of novel scaffolds, incorporation of growth factors and cell-based therapies, and discusses the preclinical animal models we employ in the development pathway.

Application of dental stem cells in three-dimensional tissue regeneration

Dental stem cells can differentiate into different types of cells. Dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, stem cells from apical papilla, and dental follicle progenitor cells are five different types of dental stem cells that have been identified during different stages of tooth development. The availability of dental stem cells from discarded or removed teeth makes them promising candidates for tissue engineering. In recent years, three-dimensional (3D) tissue scaffolds have been used to reconstruct and restore different anatomical defects. With rapid advances in 3D tissue engineering, dental stem cells have been used in the regeneration of 3D engineered tissue. This review presents an overview of different types of dental stem cells used in 3D tissue regeneration, which are currently the most common type of stem cells used to treat human tissue conditions.

Metformin pre-conditioning enhances the angiogenic ability of the secretome of dental pulp stem cells

The aim of the present study was to assess the influence of metformin on the angiogenic ability of secretomes from dental pulp stem cells. The stem cells were obtained from the dental pulp (DPSCs) (n = 3) using the explant culture method. We treated the DPSCs with different concentrations of metformin and assessed the expression of the angiogenesis-related genes. We also tested the angiogenic effect of the secretomes on the yolk sac membrane of the chick embryos by counting the quaternary blood vessel formations on the yolk sac membrane. We found that metformin treatment enhanced the angiogenic potential of the stem cell secretome in a dose-dependent manner. This was evidenced by the increase in the quaternary blood vessel formations in the yolk sac membrane with lower to higher concentrations of metformin. Pre-treatment with metformin modulates the angiogenic potential of the stem cell-conditioned media in a dose-dependent manner. The augmentation of the angiogenic potential of the DPSCs can aid regeneration, especially in scenarios requiring the regeneration of vacuoles.

Inverse and reciprocal regulation of p53/p21 and Bmi-1 modulates vasculogenic differentiation of dental pulp stem cells

Dental pulp stem cells (DPSC) are capable of differentiating into vascular endothelial cells. Although the capacity of vascular endothelial growth factor (VEGF) to induce endothelial differentiation of stem cells is well established, mechanisms that maintain stemness and prevent vasculogenic differentiation remain unclear. Here, we tested the hypothesis that p53 signaling through p21 and Bmi-1 maintains stemness and inhibits vasculogenic differentiation. To address this hypothesis, we used primary human DPSC from permanent teeth and Stem cells from Human Exfoliated Deciduous (SHED) teeth as models of postnatal mesenchymal stem cells. DPSC seeded in biodegradable scaffolds and transplanted into immunodeficient mice generated mature human blood vessels invested with smooth muscle actin-positive mural cells. Knockdown of p53 was sufficient to induce vasculogenic differentiation of DPSC (without vasculogenic differentiation medium containing VEGF), as shown by increased expression of endothelial markers (VEGFR2, Tie-2, CD31, VE-cadherin), increased capillary sprouting in vitro; and increased DPSC-derived blood vessel density in vivo. Conversely, induction of p53 expression with small molecule inhibitors of the p53-MDM2 binding (MI-773, APG-115) was sufficient to inhibit VEGF-induced vasculogenic differentiation. Considering that p21 is a major downstream effector of p53, we knocked down p21 in DPSC and observed an increase in capillary sprouting that mimicked results observed when p53 was knocked down. Stabilization of ubiquitin activity was sufficient to induce p53 and p21 expression and reduce capillary sprouting. Interestingly, we observed an inverse and reciprocal correlation between p53/p21 and the expression of Bmi-1, a major regulator of stem cell self-renewal. Further, direct inhibition of Bmi-1 with PTC-209 resulted in blockade of capillary-like sprout formation. Collectively, these data demonstrate that p53/p21 functions through Bmi-1 to prevent the vasculogenic differentiation of DPSC.

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.

Periodontitis-compromised dental pulp stem cells secrete extracellular vesicles carrying miRNA-378a promote local angiogenesis by targeting Sufu to activate the Hedgehog/Gli1 signalling

Objectives

Previously, our investigations demonstrated robust pro‐angiogenic potentials of extracellular vesicles secreted by periodontitis‐compromised dental pulp stem cells (P‐EVs) when compared to those from healthy DPSCs (H‐EVs), but the underlying mechanism remains unknown.

Materials and methods

Here, circulating microRNAs (miRNAs) specifically found in P‐EVs (compared with H‐EVs) were identified by Agilent miRNA microarray analysis, and the roles of the candidate miRNA in P‐EV‐enhanced cell angiogenesis were confirmed by cell transfection and RNA interference methods. Next, the direct binding affinity between the candidate miRNA and its target gene was evaluated by luciferase reporter assay. CCK‐8, transwell/scratch wound healing and tube formation assays were established to investigate the proliferation, migration, and tube formation abilities of endothelial cells (ECs). Western blot was employed to measure the protein levels of Hedgehog/Gli1 signalling pathway components and angiogenesis‐related factors.

Results

The angiogenesis‐related miRNA miR‐378a was found to be enriched in P‐EVs, and its role in P‐EV‐enhanced cell angiogenesis was confirmed, wherein Sufu was identified as a downstream target gene of miR‐378a. Functionally, silencing of Sufu stimulated EC proliferation, migration and tube formation by activating Hedgehog/Gli1 signalling. Further, we found that incubation with P‐EVs enabled the transmission of P‐EV‐contained miR‐378a to ECs. Subsequently, the expressions of Sufu, Gli1 and vascular endothelial growth factor in ECs were significantly influenced by P‐EV‐mediated miR‐378a transmission.

Conclusions

These data suggest that P‐EVs carrying miR‐378a promote EC angiogenesis by downregulating Sufu to activate the Hedgehog/Gli1 signalling pathway. Our findings reveal a crucial role for EV‐derived miR‐378a in cell angiogenesis and hence offer a new target for modifying stem cells and their secreted EVs to enhance vessel regenerative potential.

Growth Factors VEGF-A165 and FGF-2 as Multifunctional Biomolecules Governing Cell Adhesion and Proliferation

Vascular endothelial growth factor-A165 (VEGF-A165) and fibroblast growth factor-2 (FGF-2) are currently used for the functionalization of biomaterials designed for tissue engineering. We have developed a new simple method for heterologous expression and purification of VEGF-A165 and FGF-2 in the yeast expression system of Pichia pastoris. The biological activity of the growth factors was assessed in cultures of human and porcine adipose tissue-derived stem cells (ADSCs) and human umbilical vein endothelial cells (HUVECs). When added into the culture medium, VEGF-A165 stimulated proliferation only in HUVECs, while FGF-2 stimulated the proliferation of both cell types. A similar effect was achieved when the growth factors were pre-adsorbed to polystyrene wells. The effect of our recombinant growth factors was slightly lower than that of commercially available factors, which was attributed to the presence of some impurities. The stimulatory effect of the VEGF-A165 on cell adhesion was rather weak, especially in ADSCs. FGF-2 was a potent stimulator of the adhesion of ADSCs but had no to negative effect on the adhesion of HUVECs. In sum, FGF-2 and VEGF-A165 have diverse effects on the behavior of different cell types, which maybe utilized in tissue engineering.