Long term explant culture for harvesting homogeneous population of human dental pulp stem cells

Decellularized leaf-based biomaterial supports osteogenic differentiation of dental pulp mesenchymal stem cells

Decellularized tissues are an attractive scaffolds for 3D tissue engineering. Decellularized animal tissues have certain limitations such as the availability of tissue, high costs and ethical concerns related to the use of animal sources. Plant-based tissue decellularized scaffolds could be a better option to overcome the problem. The leaves of different plants offer a unique opportunity for the development of tissue-specific scaffolds, depending on the reticulate or parallel veination. Herein, we decellularized spinach leaves and employed these for the propagation and osteogenic differentiation of dental pulp stem cells (DPSCs). DPSCs were characterized by using mesenchymal stem cell surface markers CD90, CD105 and CD73 and CD34, CD45 and HLA-DR using flow cytometry. Spinach leaves were decellularized using ethanol, NaOH and HCL. Cytotoxicity of spinach leaf scaffolds were analysed by MTT assay. Decellularized spinach leaves supported dental pulp stem cell adhesion, proliferation and osteogenic differentiation. Our data demonstrate that the decellularized spinach cellulose scaffolds can stimulate the growth, proliferation and osteogenic differentiation of DPSCs. In this study, we showed the versatile nature of decellularized plant leaves as a biological scaffold and their potential for bone regeneration in vitro.

Long-term cryopreservation of whole gingival tissue

Stem cells obtained from the body tissue, such as adipose tissue, dental pulp and gingival tissue. Fresh tissue is often used to isolate and culture for regenerative medicine. However, availability of tissue as and when required is one of the measure issue in regenerative medicine. Cryopreservation of tissue provides benefit over tissue availability, storage for significant amount of period and helps preserve the original cell structures. The effects of cryopreservation of gingival tissue for mesenchymal stem cell (MSC) are not well documented; however this process is of increasing importance for regenerative therapies. This study examined the effect of cryopreservation on the long term survival the whole gingival biopsy tissue. We studied cell outgrowth, cell morphology, MSC surface-markers and differentiation of mesenchymal stem cells derived from cryopreserved gingiva. In this study, gingival tissue was cryopreserved for 3, 6, 9 months. Cryopreserved tissue has been thawed and cells were isolated by using explant culture method. The fresh and cryopreserved gingival tissue cells were cultured and characterized for surface marker analysis, CFU-f, population doubling time, and osteogenic, chondrogenic and adipogenic differentiation. The fresh and cryopreserved tissue has similar stem cell properties. Results indicate that cryopreservation of the entire gingival tissue does not affect the properties of stem cells. This opens door for gingival tissue banking for future use in periodontology and regenerative medicine.

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.

How to make full use of dental pulp stem cells: an optimized cell culture method based on explant technology

Introduction

Dental pulp stem cells from humans possess self-renewal and versatile differentiation abilities. These cells, known as DPSC, are promising for tissue engineering due to their outstanding biological characteristics and ease of access without significant donor site trauma. Existing methods for isolating DPSC mainly include enzyme digestion and explant techniques. Compared with the enzymatic digestion technique, the outgrowth method is less prone to cell damage and loss during the operation, which is essential for DPSC with fewer tissue sources.

Methods

In order to maximize the amount of stem cells harvested while reducing the cost of DPSC culture, the feasibility of the optimized explant technique was evaluated in this experiment. Cell morphology, minimum cell emergence time, the total amount of cells harvested, cell survival, and proliferative and differentiation capacity of DPSC obtained with different numbers of explant attachments (A1-A5) were evaluated.

Results

There was a reduction in the survival rate of the cells in groups A2-A5, and the amount of harvested DPSC decreased in A3-A5 groups, but the DPSC harvested in groups A1-A4 had similar proliferative and differentiation abilities. However, starting from group A5, the survival rate, proliferation and differentiation ability of DPSC decreased significantly, and the adipogenic trend of the cells became more apparent, indicating that the cells had begun to enter the senescence state.

Discussion

The results of our study demonstrated that the DPSC obtained by the optimized explant method up to 4 times had reliable biological properties and is available for tissue engineering.

The Migration and the Fate of Dental Pulp Stem Cells

Human dental pulp stem cells (hDPSCs) are adult mesenchymal stem cells (MSCs) obtained from dental pulp and derived from the neural crest. They can differentiate into odontoblasts, osteoblasts, chondrocytes, adipocytes and nerve cells, and they play a role in tissue repair and regeneration. In fact, DPSCs, depending on the microenvironmental signals, can differentiate into odontoblasts and regenerate dentin or, when transplanted, replace/repair damaged neurons. Cell homing depends on recruitment and migration, and it is more effective and safer than cell transplantation. However, the main limitations of cell homing are the poor cell migration of MSCs and the limited information we have on the regulatory mechanism of the direct differentiation of MSCs. Different isolation methods used to recover DPSCs can yield different cell types. To date, most studies on DPSCs use the enzymatic isolation method, which prevents direct observation of cell migration. Instead, the explant method allows for the observation of single cells that can migrate at two different times and, therefore, could have different fates, for example, differentiation and self-renewal. DPSCs use mesenchymal and amoeboid migration modes with the formation of lamellipodia, filopodia and blebs, depending on the biochemical and biophysical signals of the microenvironment. Here, we present current knowledge on the possible intriguing role of cell migration, with particular attention to microenvironmental cues and mechanosensing properties, in the fate of DPSCs.

Spheroid Culture System, a Promising Method for Chondrogenic Differentiation of Dental Mesenchymal Stem Cells

The objective of the present work was to develop a three-dimensional culture model to evaluate, in a short period of time, cartilage tissue engineering protocols. The spheroids were compared with the gold standard pellet culture. The dental mesenchymal stem cell lines were from pulp and periodontal ligament. The evaluation used RT-qPCR and Alcian Blue staining of the cartilage matrix. This study showed that the spheroid model allowed for obtaining greater fluctuations of the chondrogenesis markers than for the pellet one. The two cell lines, although originating from the same organ, led to different biological responses. Finally, biological changes were detectable for short periods of time. In summary, this work demonstrated that the spheroid model is a valuable tool for studying chondrogenesis and the mechanisms of osteoarthritis, and evaluating cartilage tissue engineering protocols.

Insulin-producing cell clusters derived from human gingival mesenchymal stem cells as a model for diabetes research

BACKGROUND

The human gingiva-derived mesenchymal stem cells (hGMSCs) possess a great potential to develop the cell-based therapy for diabetes due to its unscarred healing capacity and reparative potential. In this current study, we isolated, cultured and characterised the GMSCs and explored their potential to differentiate into Insulin Producing Cell Clusters (IPCCs).

METHODS

The cells derived from gingival tissues exhibited fibroblast-like morphology. The flow cytometric analysis revealed positive expression of CD73(97.43%), CD90(95.05%), and CD105(93.17%) and negative expression of CD34(0.05%), CD45(0.09%), and HLA-DR (0.025) surface markers. We then converted this adherent fibroblast-like GMSCs into floating IPCCs using a sequential three-step protocol containing a different combination of differentiating agents. Initially, the presence of insulin in IPCCs was confirmed by dithizone staining. Glucose-stimulated insulin secretion (GSIS) assay confirmed that IPCCs secrete insulin in response to glucose.

RESULTS

Generated IPCCs express pancreatic markers such as insulin, pdx1, glucagon, GLUT4 and GLUT2 as evidenced by RT-PCR analysis. Our results unequivocally showed that IPCCs can be generated from gingiva which is a potential source of postnatal MSCs. Our results offer the IPCCs generated from hGMSCs a platform for screening anti-diabetic drugs and a new autologous source of tissue for islet transplantation for the treatment of diabetes.

CONCLUSIONS

Our results unequivocally demonstrate for the first time that hGMSCs can be used as an attractive non-invasive tissue source for generating IPCCs, which can be employed in diabetes research for screening antidiabetic agents and also for transplantation in type 1 diabetic patients as autologous source without the need of immunosuppression.

Therapeutic potential of dental pulp stem cells and their derivatives: Insights from basic research toward clinical applications

For more than 20 years, researchers have isolated and identified postnatal dental pulp stem cells (DPSCs) from different teeth, including natal teeth, exfoliated deciduous teeth, healthy teeth, and diseased teeth. Their mesenchymal stem cell (MSC)-like immunophenotypic characteristics, high proliferation rate, potential for multidirectional differentiation and biological features were demonstrated to be superior to those of bone marrow MSCs. In addition, several main application forms of DPSCs and their derivatives have been investigated, including stem cell injections, modified stem cells, stem cell sheets and stem cell spheroids. In vitro and in vivo administration of DPSCs and their derivatives exhibited beneficial effects in various disease models of different tissues and organs. Therefore, DPSCs and their derivatives are regarded as excellent candidates for stem cell-based tissue regeneration. In this review, we aim to provide an overview of the potential application of DPSCs and their derivatives in the field of regenerative medicine. We describe the similarities and differences of DPSCs isolated from donors of different ages and health conditions. The methodologies for therapeutic administration of DPSCs and their derivatives are introduced, including single injections and the transplantation of the cells with a support, as cell sheets, or as cell spheroids. We also summarize the underlying mechanisms of the regenerative potential of DPSCs.

The effect of implants loaded with stem cells from human exfoliated deciduous teeth on early osseointegration in a canine model

Background

This in vivo experimental study investigated the effect of stem cells from human exfoliated deciduous teeth (SHEDs) on early osteogenesis around implants.

Methods

In four healthy adult male Beagle dogs, the left mandibular received implants and SHED as the experimental group, and the right mandibular received implants and phosphate-buffered saline as the control group. The Beagle dogs were randomly divided into groups A and B, which were sacrificed at 2 and 4 weeks after implantation. Micro-computed tomography and histological analysis were used to investigate the effect of SHED-loading on the early osseointegration around the implants.

Results

The total bone-to-implant contact (BIC%) and interthread bone improved significantly. The analysis of the bone volume fraction and trabecular thickness showed that the bone trabecula around the implants in the SHEDs group was thicker and denser than that in the control group, suggesting a better osseointegration.

Conclusions

The application of implants pre-adhered with SHEDs improved and accelerated early osseointegration around the implant, resulting in thicker and denser trabecular bone.

Human Umbilical Cord Mesenchymal Stem Cell-Based in vitro Model for Neurotoxicity Testing

Neurotoxicity (NT) testing for regulatory purposes is based on in vivo animal testing. There is general consensus, however, about the need for the development of alternative methodologies to allow researchers to more rapidly and cost effectively screen large numbers of chemicals for their potential to cause NT, or to investigate their mode of action. In vitro assays are considered an important source of information for making regulatory decisions, and human cell-based systems are recommended as one of the most relevant models in toxicity testing, to reduce uncertainty in the extrapolation of results from animal-based models. Human neuronal models range from various neuroblastoma cell lines to stem cell-derived systems, including those derived from mesenchymal stem/stromal cells (hMSC). hMSCs exhibit numerous advantages, including the fact that they can be obtained in high yield from healthy human adult tissues, can be cultured with a minimal laboratory setup and without genetic manipulations, are able of continuous and repeated self-renewal, are nontumorigenic, and can form large populations of stably differentiated cells representative of different tissues, including neuronal cells. hMSCs derived from human umbilical cord (hUC) in particular possess several prominent advantages, including a painless, non-invasive, and ethically acceptable collection procedure, simple and convenient preparation, and high proliferation capacity. In addition, hMSCs can be efficiently differentiated into neuron-like cells (hNLCs), which can then be used for the assessment of neuronal toxicity of potential neurotoxic compounds in humans. Here, we describe a step-by-step procedure to use hMSCs from the umbilical cord for in vitro neurotoxicity testing. First, we describe how to isolate, amplify, and store hMSCs derived from the umbilical cord. We then outline the steps to transdifferentiate these cells into hNLCs, and then use the hNLCs for neurotoxicity testing by employing multiple common cytotoxicity assays after treatment with test compounds. The approach follows the most updated guidance on using human cell-based systems. These protocols will allow investigators to implement an alternative system for obtaining primary NLCs of human origin, and support advancement in neurotoxicity research. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Isolation and maintenance of human mesenchymal stem/stromal cells (hMSCs) obtained from the umbilical cord lining membrane Basic Protocol 2: Transdifferentiation of hMSCs into neuron-like cells (hNLCs) and basic neurotoxicity assessment.

Effect of Different Intracanal Medicaments on the Viability and Survival of Dental Pulp Stem Cells

Background: Stem cells play an important role in the success of regenerative endodontic procedures. They are affected by the presence of medicaments that are used before the induction of bleeding or the creation of a scaffold for endodontic regeneration. This study examines the effects of different intracanal medicaments on the viability and survival of dental pulp stem cells at different doses and over different exposure times. Methods: Dental pulp stem cells were cultured from healthy third molar teeth using the long-term explant culture method and characterized using flow cytometry and exposed to different concentrations of calcium hydroxide, doxycycline, potassium iodide, triamcinolone, and glutaraldehyde, each ranging from 0 (control) to 1000 µg/mL. Exposure times were 6, 24, and 48 h. Cell viability was measured using the MTT assay, and apoptosis was measured using the Annexin V-binding assay. Results: All medicaments significantly reduced cell viability at different concentrations over different exposure times. Calcium hydroxide and triamcinolone favored cell viability at higher concentrations during all exposure times compared to other medicaments. The apoptosis assay showed a significant increase in cell death on exposure to doxycycline, potassium iodide, and glutaraldehyde. Conclusion: The intracanal medicaments examined in our study affected the viability of dental pulp stem cells in a time and dose-dependent manner. They also adversely affected the survival of dental pulp stem cells. Further studies are needed to better understand the effect of prolonged exposure to medicaments according to clinical protocols and their effect on the stemness of dental pulp stem cells.

In-vitro analysis on the potential use of dental pulp mesenchymal stem cells on arecoline-induced oral epithelial cells

To assess the protective role of the secretome of dental pulp mesenchymal stem cells on arecoline-induced epithelial-mesenchymal transition and senescence on epithelial cells of the oral mucosa. Effect of varying concentrations of arecoline extract and dental pulp mesenchymal stem cell condition media (DPSC-CM) were noted on oral mucosal epithelial cells. MTT assay, Annexin V-FITC/PI assay, and the quantitative gene expressions of BCL2, PUMA, BAD, BAX, CASP3, CASP9, CASP12, TGFB1, CST3, COL1A2, COL3A1, TIMP1, TIMP2, CDH1, and CDH2 were assessed. Oral mucosal epithelial cells exposed only to the arecoline were the control. 50% and 100% DPSC-CM decreased apoptosis-related gene expression in the cells exposed with 25 μM arecoline compared to the control. 50% DPSC-CM attenuated the expression of all fibrotic genes and EMT-related genes. 20% and 100% DPSC-CM showed differential effects on fibrotic and EMT-related genes. DPSC-CM inhibited apoptosis, and attenuated expression of fibrotic and EMT-related genes on arecoline treated human oral epithelial cells.

Long-term explant culture: an improved method for consistently harvesting homogeneous populations of keloid fibroblasts

Explant culture is a more suitable method than enzyme digestion for the isolation of keloid fibroblasts (KFs), but it has a longer isolation period. In this study, we propose a long-term explant culture method. Unlike in the conventional explant culture method, we continued culturing explants to isolate KFs rather than discarding them during passage. We demonstrated that keloid explants could be cultured for more than 4 months to continuously yield enriched KFs, and the KFs from the repeatedly cultured explants had shorter isolation times. The biological behavior and fibrotic phenotypic characteristics of the KFs from the explants cultured long term were investigated, and no statistical differences were found compared with the KFs from the original explants. In conclusion, the long-term explant culture method was shown to be efficient for harvesting a large, homogeneous population of KFs. The high efficiency as well as ease of operation and sample saving make this method convenient for researchers working with KFs.

Assessing the effect of human dental pulp mesenchymal stem cell secretome on human oral, breast, and melanoma cancer cell lines

Background

The secretome of the dental pulp mesenchymal stem cells (DPMSCS-S) have an array of regenerative potential and could aid in the rehabilitation of cancer patients post-therapeutic interventions, although caution is required as DPMSC-S have shown to augment prostate cancer cells. Thus, it is vital to assess if these pro-carcinogenic effects extend to other cancer types.

Objective

To assess if DPMSC-S has any pro-carcinogenic effect on oral cancer, breast cancer, and melanoma cell lines.

Materials and methods

Conditioned media obtained from the isolated and characterized DPMSC (DPMSC-CM) were profiled using bead-based multiplex assay. AW13515 (oral cancer), MDA-MB-231 (breast cancer), and A-375 (melanoma) cell lines were exposed to 20%, 50%, and 100% DPMSC-CM for 24, 48, and 72 h. DPMSC-CM effect on the cancer cell properties and secretome were assessed.

Results

DPMSC-CM augmented invasion, adhesion, multi-drug resistance, DNA repair, and mitochondrial repair in AW13516 through upregulation of growth factors Ang-2, EGF, M−CSF, PDGF-AA, PDGF-BB, pro-inflammatory cytokines TNF-α, IL-2, downregulation of anti-inflammatory cytokine TGF-β1, and pro-inflammatory cytokine IL-4. In MDA-MB-231, invasion, and multi-drug resistance were augmented through upregulation of growth factors EGF, EPO, G-CSF, HGF, M−CSF, PDGF-AA, and pro-inflammatory cytokine TNF-α, CXCL10, IL-12p70. EMT, invasion, migration, and adhesion were augmented in A-375 through upregulation of growth factors Ang-2, EGF, PDGF-BB, TGF-α, pro-inflammatory cytokines TNF-α, and IL-17A.

Conclusion

DPMSC-CM can augment the carcinogenic properties of oral cancer, breast cancer, and melanoma cells, further animal model studies are required to validate our in-vitro findings.

Study of optimal conditions for growth and osteogenic differentiation of dental pulp stem cells based on glucose and serum content

Dental pulp stem cells (DPSCs) have shown promising characteristics in terms of their proliferation and osteogenic differentiation potential, which could be of greater benefit in regenerative dentistry. However, obstacles remain in the in vitro cultivation of DPSCs, which significantly affect their growth and differentiating ability. Therefore in this study, we demonstrated the growth and osteogenic differentiation of DPSCs in the presence of media containing different combinations of serum and glucose to get an optimized combination of both. DPSCs were cultured in media containing combinations of low glucose (LG), low serum (LS), high glucose (HG), and high serum (HS). The proliferation and osteogenic differentiation were assessed in DPSCs cultured with these different combinations of culture conditions. High glucose high serum condition significantly inhibited the proliferation of DPSCs and also affected their clonogenic potential, as evidenced by colony-forming units. Irrespective of the serum content, high glucose in the media also decreased the osteogenic potential of DPSCs confirmed by functional staining, and downregulation of osteogenesis-related genes. High glucose content in the culture media affects the growth and differentiation potential of the DPSCs. Hence, the culture conditions for the DPSCs should be reconsidered to utilize their maximum potential.

The Growth Factors and Cytokines of Dental Pulp Mesenchymal Stem Cell Secretome May Potentially Aid in Oral Cancer Proliferation

BACKGROUND

Growth factors and cytokines responsible for the regenerative potential of the dental pulp mesenchymal stem cell secretome (DPMSC-S) are implicated in oral carcinogenesis. The impact and effects of these secretory factors on cancer cells must be understood in order to ensure their safe application in cancer patients.

OBJECTIVE

We aimed to quantify the growth factors and cytokines in DPMSC-S and assess their effect on oral cancer cell proliferation.

MATERIALS AND METHODS

DPMSCs were isolated from patients with healthy teeth (n = 5) that were indicated for extraction for orthodontic reasons. The cells were characterized using flow cytometry and conditioned medium (DPMSC-CM) was prepared. DPMSC-CM was subjected to a bead-based array to quantify the growth factors and cytokines that may affect oral carcinogenesis. The effect of DPMSC-CM (20%, 50%, 100%) on the proliferation of oral cancer cells (AW123516) was evaluated using a Ki-67-based assay at 48 h. AW13516 cultured in the standard growth medium acted as the control.

RESULTS

VEGF, HCF, Ang-2, TGF-α, EPO, SCF, FGF, and PDGF-BB were the growth factors with the highest levels in the DPMSC-CM. The highest measured pro-inflammatory cytokine was TNF-α, followed by CXCL8. The most prevalent anti-inflammatory cytokine in the DPMSC-CM was IL-10, followed by TGF-β1 and IL-4. Concentrations of 50% and 100% DPMSC-CM inhibited Ki-67 expression in AW13516, although the effect was non-significant. Moreover, 20% DPMSC-CM significantly increased Ki-67 expression compared to the control.

CONCLUSIONS

The increased Ki-67 expression of oral cancer cells in response to 20% DPMSC-CM indicates the potential for cancer progression. Further research is needed to identify their effects on other carcinogenic properties, including apoptosis, stemness, migration, invasion, adhesion, and therapeutic resistance.

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.

Preliminary Evaluation of Proliferation, Wound Healing Properties, Osteogenic and Chondrogenic Potential of Dental Pulp Stem Cells Obtained from Healthy and Periodontitis Affected Teeth

Background: Dental pulp tissue within the central cavity of the tooth is composed of dental pulp stem cells (DPSC). These mesenchymal stem cells have good proliferative as well as differentiation potential. DPSC has been isolated even from teeth with inflamed pulps and is found to retain their proliferative and differentiation potential. Little research is available about the viability and differentiation potential of DPSC obtained from teeth with periodontitis. In the present study, the aim was to compare the morphological features, stem cell marker (MSC) expression, proliferation rate, migratory and wound healing properties, osteogenic and chondrogenic differentiation potential of DPSCs obtained from periodontally healthy teeth (hDPSCs) and periodontitis affected teeth (pDPSCs). Methods: Dental pulp tissue was obtained from periodontally healthy volunteers (n = 3) and patients with periodontitis undergoing extraction of mobile teeth (n = 3). DPSC were isolated using the explant technique and cultured. All the experiments were performed at early passage (Passage 2), late passage (Passage 6) and after cryopreservation. Morphological features of the hDPSCs and pDPSCs were ascertained using microscopy. The expression of cell surface stem cell markers was assessed by the flow cytometry method. The proliferation and growth rate of the cells were assayed by plotting a growth curve from 0–13 days of culture. The migratory characteristics were assessed by wound scratch assay. Osteogenic and chondrogenic differentiation of the cells was assessed using standard protocols with and without induction. Results: DPSCs were successfully obtained from periodontally healthy teeth (hDPSC) and periodontitis-affected teeth (pDPSCs). The data suggests that there were no morphological differences observed in early passage cells between the two cohorts. Cryopreservation did change the morphology of pDSPCs. There was no significant difference in the positive expression of mesenchymal markers CD73, CD90 and CD105 in early passage cells. However, serial passaging and cryopreservation affected the marker expression in pDPSCs. A faint expression of hematopoietic stem cell markers CD34, CD45 and MHC class II antigen HLA-DR was observed in both the cell types. The expression of HLA-DR is upregulated in pDPSCs compared to hDPSC. A significantly slower growth rate and slower wound healing properties was observed in pDPSCs compared to hDPSC. In late passage and after cryopreservation, the migratory ability of pDPSCs was found to be increased drastically. There was no significant difference in osteogenic potential between the two cell types. However, the chondrogenic potential of pDPSCs was significantly lower compared to hDPSc. Yet, pDPSCs showed enhanced osteogenesis and chondrogenesis at late passage as well as after cryopreservation. Conclusion: The results of this novel study shed light on the isolation of viable DPSC from periodontitis-affected teeth. These cells exhibit a slower growth rate and migratory characteristics compared to their healthy counterparts. There was no difference in osteogenic potential but a reduction in chondrogenic potential was seen in pDPSCs compared to hDPSC. The findings reveal that DPSC from periodontitis-affected teeth presents an easy and viable option for regenerative medicine application. Some additional nutritive factors and protocols may be required to attain better regenerative benefits while using pDPSCs.

Dose-Dependent Effect of Cordycepin on Viability, Proliferation, Cell Cycle, and Migration in Dental Pulp Stem Cells

Simple Summary

Cordycepin is an adenosine analogue isolated from the fungus Cordyceps militaris. Cordycepin is a nucleoside antimetabolite that has shown a broad spectrum of biological activity including antineoplastic activity. limited research has been carried out on the effects of Cordycepin on the regenerative potential of stem cells, including dental pulp-derived mesenchymal stem cells. The present study was designed to assess if Cordycepin could enhance the vital properties of dental pulp-derived mesenchymal stem cells for regenerative purposes.

Abstract

Objective: To examine the effect of Cordycepin on the viability, proliferation, and migratory properties of dental pulp-derived mesenchymal stem cells. Materials and methods: The pulp was derived from human premolar teeth extracted for orthodontic purposes after obtaining informed consent. The samples were transferred to the laboratory for processing. DPSCs were expanded and characterized using flow cytometry and differentiation to the bone, adipose, and cartilage cells was examined. MTT Assay was performed using various concentrations of Cordycepin. The growth curve was plotted for 13 days. Cell cycle analysis was performed by flow cytometry. Migratory ability was assessed by wound healing assay. ROS generation was detected by flow cytometry. Gene expression was quantified by RT-qPCR. Statistical analysis was performed. p < 0.05 was considered as significant and p < 0.01 was considered as highly significant (* p < 0.05, and ** p < 0.01). Results: DPSCs expressed characteristic MSC-specific markers and trilineage differentiation. Cordycepin at lower concentrations did not affect the viability of DPSCs. The growth curve of cells showed a dose-dependent increase in cell numbers till the maximum dose. DPSCs treated with 2.5 µM Cordycepin was found to have a reduced G1 phase cell percentage. DPSCs treated with 2.5 µM and 5 µM Cordycepin showed a significant decrease in G2 phase cells. No significant difference was observed for S phase cells. Cordycepin treatment affected the migratory ability in DPSCs in a concentration-dependent manner. Conclusion: Cordycepin can be used at therapeutic doses to maintain stem cells.

Effect of Ascorbic Acid on Differentiation, Secretome and Stemness of Stem Cells from Human Exfoliated Deciduous Tooth (SHEDs)

Stem cells from human exfoliated deciduous teeth (SHEDs) are considered a type of mesenchymal stem cells (MSCs) because of their unique origin from the neural crest. SHEDs can self-renewal and multi-lineage differentiation with the ability to differentiate into odontoblasts, osteoblast, chondrocytes, neuronal cells, hepatocytes, adipocytes, etc. They are emerging as an ideal source of MSCs because of their easy availability and extraordinary cell number. Ascorbic acid, or vitamin C, has many cell-based applications, such as bone regeneration, osteoblastic differentiation, or extracellular matrix production. It also impacts stem cell plasticity and the ability to sustain pluripotent activity. In this study, we evaluate the effects of ascorbic acid on stemness, paracrine secretion, and differentiation into osteoblast, chondrocytes, and adipocytes. SHEDs displayed enhanced multifaceted activity, which may have applications in regenerative therapy.

Taurine Augments Telomerase Activity and Promotes Chondrogenesis in Dental Pulp Stem Cells

Background: Stem cell therapy has become an advanced and state-of-the-art procedure to regenerate lost tissues of the human body. Cartilage repair is a challenging task in which stem cells find potential application. One of the important biologic modifiers that can cause chondrogenic differentiation of stem cells is taurine. However, taurine has not been investigated for its effects on dental pulp derived stem cell (DPSC) chondrogenic differentiation. Objective: The objective of the study was to investigate if taurine administration to DPSCs heralds chondrogenic differentiation as ascertained by expression of SOX9, COL2A1, ACAN, ELN, and COMP. The study also investigated if the differentiated cells synthesized glycosaminoglycans, a marker of cartilage formation. The study also aimed to assess proliferative activity of the cells after taurine administration by measuring the hTERT gene and protein expression. Materials and methods: DPSCs were obtained from a molecular biology laboratory and characterization of stem cell markers was done by flow cytometry. The cells were subjected to a MTT assay using various concentrations of taurine. Following this, hTERT gene and protein estimation was done in the control, telomerase inhibitor treated DPSC (TI-III), 10 μM taurine treated DPSC, and TI-III + 10 μM taurine treated DPSCs. A polymerase chain reaction was done to assess gene expression of SOX9, COL2A1, ACAN, ELN, and COMP genes and glycosaminoglycans were estimated in control cells, Induced DPSCs, induced and TI-III treated DPSCs, and 10 μM taurine treated DPSCs. Results: DPSCs expressed CD73, CD90, and CD105 and did not express CD34, CD45, and HLA-DR, which demonstrated that they were mesenchymal stem cells. The MTT assay revealed that various concentrations of taurine did not affect the cell viability of DPSCs. A concentration of 10 μM of taurine was used for further assays. With regard to the hTERT gene and protein expression, the taurine treated cells expressed the highest levels that were statistically significant compared to the other groups. Taurine was also found to restore hTERT expression in telomerase inhibitor treated cells. With regard to chondrogenesis related genes, taurine administration significantly increased the expression of SOX9, COL2A1, ACAN, and ELN genes in DPSCs and caused a significant increase in glycosaminoglycan production by the cells. Conclusions: Taurine can be regarded a biologic modifier that can significantly augment chondrogenic differentiation of DPSCs and can find potential applications in regenerative medicine in the area of cartilage regeneration.

Viability of Quercetin-Induced Dental Pulp Stem Cells in Forming Living Cellular Constructs for Soft Tissue Augmentation

Autogenous gingival grafts used for root coverage or gingival augmentation procedures often result in donor site morbidity. Living cellular constructs as an exogenous alternative have been proven to be associated with lower morbidity. With the available background information, the present study aims to assess if quercetin-induced living cell constructs, derived from dental pulp stem cells, have the potential to be applied as a tool for soft tissue augmentation. The characterized dental pulp stem cells (positive for CD73, CD90, and negative for CD34, HLA-DR) were expanded in Dulbecco's Modified Eagle's medium (DMEM) supplemented with 10 mM quercetin. The handling properties of the quercetin-induced dental pulp stem cell constructs were assessed by visual, and tactile sensation. A microscopic characterization using hematoxylin and eosin staining, and qRT-PCR-based analysis for stemness-associated genes (OCT4, NANOG, SOX2, and cMyc) was also performed. Dental pulp stem cells without quercetin administration were used as the control. Dental pulp stem cell constructs induced by quercetin easily detached from the surface of the plate, whereas there was no formation in the control cells. It was also simple to transfer the induced cellular construct on the flattened surface. Microscopic characterization of the constructs showed cells embedded in a tissue matrix. Quercetin also increased the expression of stemness-related genes. The use of quercetin-induced DPSC living constructs for soft tissue augmentation could provide an alternative to autogenous soft tissue grafts to lower patient morbidity and improve esthetic outcomes.

Modulation of the Dental Pulp Stem Cell Secretory Profile by Hypoxia Induction Using Cobalt Chloride

The action of stem cells is mediated by their paracrine secretions which comprise the secretory profile. Various approaches can be used to modify the secretory profile of stem cells. Creating a hypoxic environment is one method. The present study aims to demonstrate the influence of CoCl₂ in generating hypoxic conditions in a dental pulp stem cell (DPSCs) culture, and the effect of this environment on their secretory profile. DPSCs that were isolated from human permanent teeth were characterized and treated with different concentrations of CoCl₂ to assess their viability by an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and proliferation by a cell counting kit (CCK)-8 assay. The gene expression level of hypoxia-inducible factor 1-alpha (HIF-1α) was analyzed by quantitative real time polymerase chain reaction (qRT-PCR) to demonstrate a hypoxic environment. Comparative evaluation of the growth factors and cytokines were done by cytometric bead array. Gene expression levels of transcription factors OCT4 and SOX2 were analyzed by qRT-PCR to understand the effect of CoCl₂ on stemness in DPSCs. DPSCs were positive for MSC-specific markers. Doses of CoCl_2, up to 20 µM, did not negatively affect cell viability; in low doses (5 µM), it promoted cell survival. Treatment with 10 µM of CoCl₂ significantly augmented the genetic expression of HIF-1α. Cells treated with 10 µM of CoCl₂ showed changes in the levels of growth factors and cytokines produced. It was very evident that CoCl₂ also increased the expression of OCT4 and SOX2, which is the modulation of stemness of DPSCs. A CoCl₂ treatment-induced hypoxic environment modulates the secretory profile of DPSCs.

Comparative analysis of cytokines and growth factors in the conditioned media of stem cells from the pulp of deciduous, young, and old permanent tooth

Objectives

To compare and analyze the secretome profile of stem cells obtained from the deciduous tooth (SHEDs), young (yDPSCs), and old permanent tooth (oDPSCs).

Methods

All the stem cells were assessed for mesenchymal stem cell markers. The stem cells were differentiated into osteoblasts and chondrocytes using lineage-specific differentiation media. Conditioned media was collected from growing stem cells, and a cytometric bead array was performed to estimate secreted cytokines and growth factor levels by flow cytometry. Gene expresseion levels were assessed by real-time quantitative polymerase chain reaction.

Results

Age did not affect the mesenchymal characteristics of dental stem cells from various age groups. The secretomes of SHEDs and young yDPSCs exhibit more growth factors and lesser pro-inflammatory cytokines than oDPSCs. Osteo and chondrogenic differentiation potential were higher in SHEDs and young yDPSCs than in the oDPSCs. TLR1, TLR2, TLR3 show decreased expression levels with age and TLR5, TLR6 show increased expression with age.

Conclusion

The superior regenerative potential of SHEDs and yDPSCs may be due to the higher growth factors and lower pro-inflammatory cytokine profile.