Cytoprotective effects of melatonin on zoledronic acid-treated human mesenchymal stem cells in vitro

Dental pulp cells cocultured with macrophages aggravate the inflammatory conditions stimulated by LPS

BACKGROUND

Pulp inflammation is complex interactions between different types of cells and cytokines. To mimic the interactions of different types of cells in inflamed dental pulp tissues, dental pulp cells (DPCs) were cocultured with different ratios of macrophages (THP-1) or LPS treatment.

METHODS

DPCs were cocultured with various ratios of THP-1, then photographed cell morphology and determined cell viability by MTT assay at preset times. Total RNA was also extracted to measure the inflammation marker-IL-6 and IL-8 expressions by RT-Q-PCR. The DPCs and THP-1 were treated with 0.01 - 1μg/ml lipopolysaccharide (LPS) and extract RNA at preset times, and detected IL-6 and IL-8 expression. DPCs were cocultured with various ratios of THP-1 with 0.1 μg/mL LPS, and detected IL-6 and IL-8 expression after 24 and 48 h. The data were analyzed by unpaired t-test or Mann-Whitney test. Differences were considered statistically significant when p < 0.05.

RESULTS

THP-1 and DPCs coculture models did not suppress the viability of DPCs and THP-1. Cocultured with various ratios of THP-1 could increase IL-6 and IL-8 expressions of DPCs (p = 0.0056 - p < 0.0001). The expressions of IL-6 and IL-8 were stronger in higher ratio groups (p = 0.0062 - p < 0.0001). LPS treatment also induced IL-6 and IL-8 expressions of DPCs and THP-1 (p = 0.0179 - p < 0.0001 and p = 0.0189 - p < 0.0001, separately). Under the presence of 0.1 μg/mL LPS, DPCs cocultured with THP-1 for 24 h also enhanced IL-6 and IL-8 expression (p = 0.0022). After cocultured with a higher ratio of THP-1 for 48 h, IL-6 and IL-8 expressions were even stronger in the presence of LPS (p = 0.0260).

CONCLUSIONS

Coculturing dental pulp cells and macrophages under LPS treatment aggravate the inflammatory process. The responses of our models were more severe than traditional inflamed dental models and better represented what happened in the real dental pulp. Utilizing our models to explore the repair and regeneration in endodontics will be future goals.

CREB1 alleviates the apoptosis and potentiates the osteogenic differentiation of zoledronic acid-treated human periodontal ligament stem cells via up-regulating VEGF

Periodontitis represents a severe inflammatory illness in tooth supporting tissue. It has been supported that cAMP response element binding protein 1 (CREB1), a common transcription factor, extensively participates in osteogenic differentiation. Here, the current study was to look into the impacts of CREB1 on the process of periodontitis and its possible action mechanism. After human periodontal ligament stem cells (PDLSCs) were challenged with zoledronic acid (ZA), CREB1 expression was examined with RT-qPCR and western blotting. CCK-8 assay appraised cell activity. Following CREB1 elevation or/and vascular endothelial growth factor (VEGF) silencing in ZA-treated PDLSCs, CCK-8 and TUNEL assays separately estimated cell viability and apoptosis. Western blotting tested the expression of apoptosis- and osteogenic differentiation-associated proteins. ALP staining measured PDLSCs osteogenic ability and ARS staining estimated mineralized nodule formation. JASPAR predicted the potential binding of CREB1 with VEGF promoter, which was then testified by ChIP and luciferase reporter assays. RT-qPCR and western blotting tested VEGF expression. CREB1 expression was declined in ZA-exposed PDLSCs and CREB1 elevation exacerbated the viability and osteogenic differentiation while obstructed the apoptosis of PDLSCs. Additionally, CREB1 bond to VEGF promoter and transcriptionally activated VEGF expression. Further, VEGF absence partially stimulated the apoptosis while suppressed the osteogenic differentiation of CREB1-overexpressing PDLSCs treated by ZA. To be concluded, CREB1 might activate VEGF transcription to obstruct the apoptosis while contribute to the osteogenic differentiation of ZA-treated PDLSCs.

In Vitro Cytotoxicity of Antiresorptive and Antiangiogenic Compounds on Oral Tissues Contributing to MRONJ: Systematic Review

BACKGROUND

Invasive dental treatment in patients exposed to antiresorptive and antiangiogenic drugs can cause medication-related osteonecrosis of the jaw (MRONJ). Currently, the exact pathogenesis of this disease is unclear.

METHODS

In March 2022, Medline (Ovid), Embase (Ovid), Scopus, and Web of Science were screened to identify eligible in vitro studies investigating the effects of antiresorptive and antiangiogenic compounds on orally derived cells.

RESULTS

Fifty-nine articles met the inclusion criteria. Bisphosphonates were used in 57 studies, denosumab in two, and sunitinib and bevacizumab in one. Zoledronate was the most commonly used nitrogen-containing bisphosphonate. The only non-nitrogen-containing bisphosphonate studied was clodronate. The most frequently tested tissues were gingival fibroblasts, oral keratinocytes, and alveolar osteoblasts. These drugs caused a decrease in cell proliferation, viability, and migration.

CONCLUSIONS

Antiresorptive and antiangiogenic drugs displayed cytotoxic effects in a dose and time-dependent manner. Additional research is required to further elucidate the pathways of MRONJ.

Low-level laser therapy prevents medication-related osteonecrosis of the jaw-like lesions via IL-1RA-mediated primary gingival wound healing

BACKGROUND

Medication-related osteonecrosis of the jaw (MRONJ) is a serious debilitating disease caused by anti-resorption and anti-angiogenesis drugs, significantly affecting patients' quality of life. Recent studies suggested that primary gingival wound healing may effectively prevent the development of MRONJ. This study aimed to evaluate the effects of low-level light therapy (LLLT) on promoting gingival wound healing in extraction sockets of MRONJ-like mice and preventing the occurrence of MRONJ. Furthermore, we explored underlying mechanisms.

METHODS

Mice were randomly divided into the Ctrl, Zol, and Zol + LLLT groups. Administration of zoledronate and tooth extraction of bilateral maxillary second molars were used to build the MRONJ model, and LLLT was locally administered into the tooth sockets to examine the effect of LLLT. Next, to explore the function of IL-1RA, we performed LLLT with interleukin-1 receptor antagonist (IL-1RA) neutralizing antibody (named Zol + LLLT + IL-1RA NAb group) or negative control antibodies for tooth extraction in subsequent rescue animal experiments. Stereoscope observations, micro-computed tomography, and histological examination were conducted to evaluate gingival wound healing and bone regeneration in tooth sockets. The effects of LLLT on the migration capacities of zoledronate-treated epithelial cells were assessed in vitro.

RESULTS

LLLT promoted primary gingival wound healing without exposed necrotic bone. Micro-computed tomography results showed higher bone volume and mineral density of the tooth sockets after LLLT. Histology analysis showed complete gingival coverage, obvious bone regeneration, and reduced soft tissue inflammation, with down-regulated pro-inflammation cytokines, like interleukin-1 beta (IL-1β) and tumor necrosis factor-α (TNF-α), and up-regulated IL-1RA expression in the gingival tissue in the LLLT group. The rescue assay further showed that the effects of LLLT promoting gingival wound healing and preventing MRONJ might be partially abolished by IL-1RA neutralizing antibodies. In vitro studies demonstrated that LLLT accelerated zoledronate-treated epithelial cell migration.

CONCLUSIONS

LLLT might promote primary gingival wound healing and contribute to subsequent bone regeneration of the tooth extractions in MRONJ-like lesions via IL-1RA-mediated pro-inflammation signaling suppression.

Dose-Dependent Effects of Melatonin on the Viability, Proliferation, and Differentiation of Dental Pulp Stem Cells (DPSCs)

(1) Background: Dental pulp stem cells (DPSCs) are derived from pulp tissue lodged within human teeth and are mesenchymal in origin. These DPSCs have been demonstrated to dissociate into clusters of various cell lineages and are very easy to isolate, culture, and expand. Melatonin, a multifaceted molecule with a spectrum of effects in the human body, is known to influence stem cell viability, proliferation, and differentiation, but little is known about the impact melatonin has on the capacity of DPSCs to differentiate into adipocytes, osteocytes, and chondrocytes. The primary objective of this research was to explore the impact that melatonin has on proliferation, and the capacity of DPSCs to differentiate into adipocytes, osteocytes, and chondrocytes. (2) Methodology: DPSCs were extracted from 12 healthy human teeth, cultured, and expanded. Flow cytometry was performed to examine the surface stem cell markers. Further, melatonin was added to the cultured DPSCs in various concentrations, to assess cytotoxicity using an MTT assay. Following this, the DPSCs were tested for their proliferative ability, as well as adipogenic, osteogenic, and chondrogenic differentiation capabilities under the influence of variable concentrations of melatonin. (3) Results: DPSCs obtained from human teeth demonstrated surface characteristics of mesenchymal stem cells, as shown by the positive expression of CD105, CD90, and CD73 markers. An MTT cytotoxicity assay revealed that melatonin was well tolerated by the cells at low (1 µM) and high (25 µM) concentrations. Assessment of DPSC cell differentiation elucidated that melatonin at 1 µM and 25 µM concentrations with the induction media stimulated DPSCs to differentiate into osteocytes, but did not have much influence on adipogenic and chondrogenic differentiation. (4) Conclusions: Melatonin could be used in stem cell and tissue engineering applications for osteogenic differentiation of DPSCs and could protect these cells due to its cytoprotective, immunomodulatory, and antioxidant roles, in addition to being an osteopromoter molecule.

Melatonin-primed ADMSCs elicit an efficacious therapeutic response in improving high-fat diet induced non-alcoholic fatty liver disease in C57BL/6J mice

Background

Stem cells are widely used for therapy including treatment of liver damage. Adipose-derived mesenchymal stem cells (ADMSCs) administered to treat fatty liver are known to improve liver function but their use is restricted due to a poor success rate. This study investigates efficacy of melatonin-primed ADMSCs (Mel. MSCs) in experimentally induced non-alcoholic fatty liver disease (NAFLD).

Results

MSCs treated with LPS showed prominent DCFDA fluorescence as compared to the untreated cells. Also, the JC-1 staining had accounted for higher intensity of green monomer and a weak fluorescence of red dimer indicating weaker mitochondrial membrane potential. But melatonin co-treatment could make necessary corrective changes as evidenced by reverse set of results. The overall cell survival was also found to be improved following melatonin treatment as evidenced by the MTT assay. Also, the antioxidant (Nrf2 and Ho-1) and anti-inflammatory genes (Il-4 and Il-10) showed a decrement in their mRNA levels following LPS treatment whereas the pro-inflammatory genes (Tnf-α, Il-6, Tlr-4, and Lbp) showed a reciprocal increment in the said group. Melatonin co-treatment accounted for an improved status of antioxidant and anti-inflammatory genes as evidenced by their mRNA levels. High-fat high-fructose diet (HFFD) fed C57BL/6J mice recorded higher serum AST and ALT levels and fatty manifestation in histology of liver along with lowered mRNA levels of antioxidant (Nrf2, Catalase, and Gss) genes and Hgf. These set of parameters showed a significant improvement in HFFD + Mel.MSC group.

Conclusion

A significant improvement in viability of MSCs was recorded due to lowered intracellular oxidative stress and improves mitochondrial membrane potential. Further, melatonin-primed MSCs accounted for a significant decrement in fatty manifestations in liver and an improved physiological status of NAFLD in HFFD fed C57BL/6J mice. Taken together, it is hypothesized that melatonin priming to MSCs prior to its use can significantly augment the success of stem cell therapy.

Melatonin Promotes the Therapeutic Effect of Mesenchymal Stem Cells on Type 2 Diabetes Mellitus by Regulating TGF-β Pathway

Abundant evidence proves the therapeutic effect of adipose-derived mesenchymal stem cells (ADMSCs) in the treatment of diabetes mellitus. However, the problems have not been solved that viability of ADMSCs were inconsistent and the cells quickly undergo senescence after in vitro cell culture. In addition, the therapeutic effect of ADMSCs is still not satisfactory. In this study, melatonin (MLT) was added to canine ADMSC culture medium, and the treated cells were used to treat type 2 diabetes mellitus (T2DM). Our research reveals that adding MLT to ADMSC culture medium can promote the viability of ADMSCs. This effect depends on the binding of MLT and MLT receptors, which activates the transforming growth factor β (TGF-β) pathway and then changes the cell cycle of ADMSCs and improves the viability of ADMSCs. Since ADMSCs were found to be used to treat T2DM by anti-inflammatory and anti-endoplasmic reticulum (ER) stress capabilities, our data demonstrate that MLT augment several effects of ADMSCs in remission hyperglycemia, insulin resistance, and liver glycogen metabolism in T2DM patients. This suggest that ADMSCs and MLT-ADMSCs is safe and vabulable for pet clinic.

Dose-Dependent Effects of Zoledronic Acid on Human Periodontal Ligament Stem Cells: An In Vitro Pilot Study

Bisphosphonates (BPs) are widely used to treat several metabolic and oncological diseases affecting the skeletal system. Despite BPs’ well-known therapeutic potential, they also displayed important side effects, among which is BPs-related osteonecrosis of the jaw, by targeting osteoclast activities, osteoblast, and osteocyte behavior. The aim of this study is to evaluate the biological effects of zoledronic acid (ZOL) in an in vitro model of periodontal ligament stem cells (PDLSCs) by using an experimental setting that resembles the in vivo conditions. PDLSCs were treated with different concentrations of ZOL ranging from 0.1 to 5 μM. The effects of ZOL exposure were evaluated on cell viability via 3-[4,5-Dimethylthiaoly]-2,5-diphenyltetrazolium bromide (MTT), cell cycle analysis, apoptosis detection, and immunofluorescence. Quantitative real-time polymerase chain reaction (PCR), colorimetric detection of alkaline phosphatase activity, and Alizarin Red S staining were performed to investigate the osteogenic potential of PDLSCs exposed to ZOL. MTT analysis showed that the viability of PDLSCs exposed to ZOL concentration ≥1.5 μM for 3 and 6 days was significantly lower (P < 0.001) than that of untreated cells. The percentage of apoptotic cells was significantly higher in PDLSCs exposed for 4 days to ZOL at 2 μM (P < 0.01) and 5 μM (P < 0.001) when compared to the control. Moreover, ZOL treatment (3 days) accounted for alterations in cell cycle distribution, with an increase in the proportion of cells in G0/G1 phase and a reduction in the proportion of cells in S phase. Chronic exposure (longer than 7 days) of PDLSCs to ZOL accounted for the downregulation of ALP, RUNX2, and COL1 genes at all tested concentrations, which fit well with the reduced alkaline phosphatase activity reported after 7 and 14 days of treatment. Reduced Col1 deposition in the extracellular matrix was reported after 14 days of treatment. Increased calcium deposits were observed in treated cells when compared to the control cultures. In conclusion, chronic exposure to 1 μM ZOL induced significant reduction of osteogenic differentiation, while ZOL concentrations ≥1.5 μM are required to impair PDLSCs viability and induce apoptosis.

Effect of a Freezing Medium Containing Melatonin on Markers of Pre-meiotic and Post-meiotic Spermatogonial Stem Cells (SSCs) After Transplantation in an Azoospermia Mouse Model Due to Testicular Torsion

Spermatogonial stem cells (SSCs) are essential to the initiation of spermatogenesis. Cryopreservation, long-term maintenance, and auto-transplantation of SSCs could be a new treatment for infertility. The aim of this study was to add melatonin to the basic freezing medium and to evaluate its effect on the efficiency of the thawed SSCs after transplantation into the testicles of azoospermic mice. SSCs were isolated from newborn NMRI mice, and the cells were enriched to assess morphological features. The thawed SSCs were evaluated for survival, apoptosis, and ROS level before transplantation, and the proliferation (MVH and ID4) and differentiation (c-Kit, SCP3, TP1, TP2, and Prm1) markers of SSCs were examined using immunofluorescence, western blot, and quantitative real-time polymerase chain reaction (PCR) after transplantation. It was found that the survival rate of SSCs after thawing was significantly higher in the melatonin group compared with the cryopreservation group containing basic freezing medium, and the rate of apoptosis and level of ROS production also decreased significantly in the cryopreservation group with melatonin (p < 0.05). The expression of proliferation and differentiation markers after transplantation was significantly higher in the cryopreservation group with melatonin compared to the cryopreservation group (p < 0.05). The results suggest that adding melatonin to the basic freezing medium can effectively protect the SSCs by increasing the viability and reducing the ROS production and apoptosis and improve the transplantation efficiency of SSCs after cryopreservation, which will provide a significant suggestion for fertility protection in the clinic.

Melatonin Treatment Alters Biological and Immunomodulatory Properties of Human Dental Pulp Mesenchymal Stem Cells via Augmented Transforming Growth Factor Beta Secretion

INTRODUCTION

Melatonin is an endogenous neurohormone with well-reported anti-inflammatory and antioxidant properties, but the direct biological and immunomodulatory effects of melatonin on human dental pulp stem cells (hDPSCs) has not been fully elucidated. The aim of this study was to evaluate the influence of melatonin on the cytocompatibility, proliferation, cell migration, odontogenic differentiation, mineralized nodule formation, and immunomodulatory properties of hDPSCs.

METHODS

To address the melatonin biological effects on hDPSCs, the cytocompatibility, proliferation, cell migration, odontogenic differentiation, mineralized nodule formation, and immunomodulatory properties of hDPSCs after melatonin treatment were evaluated. The statistical differences were evaluated using 1-way analysis of variance with the Tukey multiple comparison test.

RESULTS

We found that melatonin did not alter hDPSC immunophenotype or cell viability, even at the highest concentrations used. However, using intermediate melatonin concentrations (10-300 μmol/L), a significantly higher proliferation rate (P < .05 and P < .01) and migration of hDPSCs (P < .01) were observed. Importantly, melatonin treatment (100 μmol/L) significantly increased the secretion of the anti-inflammatory cytokine transforming growth factor beta (P < .05 and P < .01) and provoked a more robust antiproliferative effect on mitogen-stimulated T cells (P < .05). Finally, and unlike previous results found with mesenchymal stem cells from other sources, melatonin fails to induce or accelerate the spontaneous osteogenic differentiation of hDPSCs.

CONCLUSIONS

Together, these findings provide key data on the bioactivity of melatonin and its effects on hPDSC biological and immunomodulatory properties.

Melatonin is an effective protector of gingival cells damaged by the cytotoxic effect of glutamate and DL-buthionine sulfoximine

BACKGROUND AND OBJECTIVE

Cellular damage related to oxidative stress (OS) is implicated in periodontal diseases (PD). Melatonin (MEL) has multiple functions, and it has been described as a potential treatment for PD. We aim at evaluating the protective effects of MEL on an in vitro model of cellular damage triggered by glutamate (GLUT) and DL-buthionine sulfoximine (BSO), on gingival cells (GCs) in culture.

MATERIAL AND METHODS

A primary culture of GCs from Wistar rats was developed in order to test the protective property of MEL; BSO and GLUT were administered alone as well as in combination with MEL. The viability and apoptosis were measured with MTT assay and TUNEL, respectively, and the concentration of superoxide anion ( O 2 - ) was measured with the NBT method.

RESULTS

The combination of BSO and GLUT treatment resulted in a decreased viability of GCs. This was evidenced by the increase in both the production of superoxide anion and apoptosis. After MEL administration, the oxidant and pro-apoptotic effects of BSO and GLUT were totally counteracted.

CONCLUSIONS

These findings demonstrated that MEL has an effective protective role on GCs subjected to cellular damage in a model of OS and cytotoxicity triggered by BSO and GLUT. Consequently, MEL could be used as a therapeutic agent in PD which begin with a significative loss of GCs.

Melatonin and Mesenchymal Stem Cells as a Key for Functional Integrity for Liver Cancer Treatment

Hepatocellular carcinoma (HCC) is the most common hepatobiliary malignancy with limited therapeutic options. On the other hand, melatonin is an indoleamine that modulates a variety of potential therapeutic effects. In addition to its important role in the regulation of sleep–wake rhythms, several previous studies linked the biologic effects of melatonin to various substantial endocrine, neural, immune and antioxidant functions, among others. Furthermore, the effects of melatonin could be influenced through receptor dependent and receptor independent manner. Among the other numerous physiological and therapeutic effects of melatonin, controlling the survival and differentiation of mesenchymal stem cells (MSCs) has been recently discussed. Given its controversial interaction, several previous reports revealed the therapeutic potential of MSCs in controlling the hepatocellular carcinoma (HCC). Taken together, the intention of the present review is to highlight the effects of melatonin and mesenchymal stem cells as a key for functional integrity for liver cancer treatment. We hope to provide solid piece of information that may be helpful in designing novel drug targets to control HCC.

Allogeneic Bone Marrow Mesenchymal Stem Cell Transplantation in Tooth Extractions Sites Ameliorates the Incidence of Osteonecrotic Jaw-Like Lesions in Zoledronic Acid-Treated Rats

Medication-related osteonecrosis of the jaw (MRONJ) is defined as the exposed necrotic bone involving the maxillofacial structures in bisphosphonate treated patients, and the pathophysiology of this disease remains unclear. The aim of this study was to assess the effects of the allogeneic transplantation of bone marrow-derived mesenchymal stem cells (BM-MSCs) in a model of Wistar mice with induced MRONJ disease. BM-MSCs from five male Wistar rats were characterized and cultured on β-tricalcium phosphate (β-TCP) granules. Thirty female Wistar rats were injected intraperitoneally with zoledronic acid and afterwards upper jaw molars were extracted. The animals were randomized to receive: Group 1: 1 × 10⁶ BM-MSCs/β-TCP construct in the alveolar socket; and Group 2: Saline solution/β-TCP construct. A clinical and histological analysis was performed. Nested polymerase chain reaction (PCR) was assessed to verify the presence of transplanted male rat cells in the female recipient jaws. Clinical and histological findings evidenced that none of the animals in Group 1 exhibited uncovered sockets or bone exposure associated to MRONJ, whereas we detected 33% of MRONJ cases in Group 2. In addition, male rat cells were detected in the maxillae site four weeks after transplantation in the BM-MSCs-group. Allogeneic BM-MSCs in extractions sites ameliorates MRONJ incidence in zoledronic acid-treated rats compared to non-MSC treatments.

Melatonin plays critical role in mesenchymal stem cell-based regenerative medicine in vitro and in vivo

Although stem cells have emerged as promising sources for regenerative medicine, there are many potential safety hazards for their clinical application, including tumorigenicity, an availability shortage, senescence, and sensitivity to toxic environments. Mesenchymal stem cells (MSCs) have various advantages compared to other stem cells, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); thus, MSCs have been intensely investigated in recent studies. However, they are placed in a harsh environment after isolation and transplantation, and the adverse microenvironment substantially reduces the viability and therapeutic effects of MSCs. Intriguingly, melatonin (MT), which is primarily secreted by the pineal organ, has been found to influence the fate of MSCs during various physiological and pathological processes. In this review, we will focus on the recent progress made regarding the influence of MT on stem cell biology and its implications for regenerative medicine. In addition, several biomaterials have been proven to significantly improve the protective effects of MT on MSCs by controlling the release of MT. Collectively, MT will be a promising agent for enhancing MSC activities and the regenerative capacity via the regulation of reactive oxygen species (ROS) generation and the release of immune factors in regenerative medicine.

Zoledronic Acid, Bevacizumab and Dexamethasone-Induced Apoptosis, Mitochondrial Oxidative Stress, and Calcium Signaling Are Decreased in Human Osteoblast-Like Cell Line by Selenium Treatment

Increased intracellular free calcium ion (Ca²⁺) concentration induces excessive oxidative stress and apoptosis. Medical procedures such as zoledronic acid (Zol), bevacizumab (Bev), and dexamethasone (Dex) are usually used in the treatment of bone diseases (osteoporosis, Paget's disease, etc.) and to prevent metastasis in the bone although the procedures induce osteonecrosis of the jaw through excessive production of reactive oxygen species (ROS). Recently, we observed regulator roles of selenium (Se) on apoptosis and Ca²⁺ entry through transient receptor potential vanilloid 1 (TRPV1) channels in the cancer cell lines. Therefore, Se may modulate Zol, Bev, and Dex-induced oxidative stress and apoptosis through regulation of TRPV1 channel. In the current study, we investigated the protective effects of Se on apoptosis and oxidative stress through TRPV1 in Zol, Bev, and Dex-induced osteoblast-like cell line. We used human osteoblast-like cell line (Saos-2), and the cells were divided into 12 groups as control, Zol, Bev, Dex, Se, Zol+Se, Bev+Se, Dex+Se, Zol+Dex, Zol+Dex+Se, Zol+Bev, and Zol+Bev+Se which were incubated with drugs (Zol, Bev, Dex, and Se) for 24 h. The cytosolic free Ca²⁺ concentration was increased by Zol, Bev, Dex, Zol+Bev, and Zol+Dex, although it was reduced by Se treatment. However, Zol, Bev, and Dex-induced increase in apoptosis, caspase 3, caspase 9, poly (ADP-ribose) polymerase 1 expression levels, and intracellular ROS production values in the cells were decreased by Se treatments. In conclusion, we observed that Zol, Bev, and Dex-induced apoptosis, mitochondrial oxidative stress, and calcium signaling are decreased in human osteoblast-like cell line by the Se treatment. Our findings may be relevant to the etiology and treatment of Zol, Bev, and Dex-induced osteonecrosis by Se.

Effect of zoledronate, a third-generation bisphosphonate, on proliferation and apoptosis of human dental pulp stem cells

Clinical use of zoledronate is accompanied by osteonecrosis of the jaw but the pathogenesis is not well understood. We assumed that zoledronate may have cytotoxicity against stem cells of the oral cavity and in this way helps to initiate or promote osteonecrosis. Dental pulp stem cells (DPSCs) and gingival fibroblasts (GFs) were isolated from volunteers who were undergoing a third molar extraction. The proliferation of DPSCs and GFs was evaluated using the thiazolyl blue tetrazolium bromide assay. The effect of zoledronate on apoptosis was determined by propidium iodide staining and Western blotting analysis. Incubation with zoledronate for 72 h and 7 days significantly decreased proliferation of DPSCs and GFs at concentrations of more than 0.4 μmol/L (p < 0.001). The IC50 of zoledronate was lower for DPSCs than for GFs (0.92 versus 3.5 μmol/L for 7 days of treatment). After 72 h of treatment with zoledronate, the percentage of apoptotic DPSCs significantly increased, which was accompanied by an increased level of pro-apoptotic proteins caspase-3 and Bax and decreased the level of the anti-apoptotic protein Bcl-2. In conclusion, zoledronate has anti-proliferative and pro-apoptotic effects in DPSCs. These effects may be involved in promoting zoledronate-induced osteonecrosis and suggest an unfavorable impact of this drug on regenerative potentials of the body stem cells.

Nigella sativa oil modulates the therapeutic efficacy of mesenchymal stem cells against liver injury in irradiated rats

Stem cell transplantation is a novel strategy for regenerative medicine in liver disease. This study was conducted to explore the modulatory effect of Nigella sativa oil (NSO) on the therapeutic potential of mesenchymal stem cells (MSCs) against irradiation-induced liver damage in rats. Liver damage was induced by a total body exposure to a single dose of 7Gy. NSO (2mg/kg/day) was then given orally for 4 consecutive weeks starting 24h after irradiation with or without a single intravenous MSCs administration, then rats were sacrificed four weeks after exposure to γ radiation. Data revealed that irradiation elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in serum, increased hepatic malondialdehyde (MDA) content and reduced hepatic superoxide dismutase (SOD) activity. Furthermore, it caused elevation in pro-inflammatory mediators such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) associated with reduction in anti-inflammatory cytokine interleukin-10 (IL-10) and it increased fibrogenic marker transforming growth factor-β (TGF-β) in liver tissues. It was observed that combined NSO/MSCs therapy provided more beneficial tissue repair comparable to MSCs alone as demonstrated by modulating the tested parameters. Finally, these results were confirmed by histopathological examination. In conclusion, dual therapy with NSO and MSCs could serve as a promising approach for alleviating radiation-induced liver injury in patients with radiotherapy.

Cytoprotective effects of melatonin on zoledronic acid-treated human osteoblasts

OBJECTIVE

To evaluate the cytoprotective effects of melatonin (MLT) on zoledronic acid (ZA)-treated human osteoblasts.

METHODS

Human osteoblasts were exposed to ZA (1, 5, 10, 50, 100 and 300 μM) and MLT (1, 10, 50, 100 y 200 μM) for 24, 48 and 72 h of incubation, to evaluate their effects on cell viability.

RESULTS

As ZA concentration increased, greater reductions in cell viability of human osteoblasts were induced whether at 24, 48 or 72 h incubation. At 24 h incubation with MLT, greatest cell viability was obtained when low dose of MLT was applied (without significant differences); 48 and 72 h incubation presented the greatest cell viability with the highest MLT concentrations (100 and 200 μM). MLT at concentrations of 100 and 200 μM would appear to have a certain cytoprotective effect on ZA-treated human osteoblasts with low concentrations of ZA (1 y 5 μM), whether at 24, 48 or 72 h; however, at ZA concentrations ≥10 μM the possible cytoprotective effects of MLT were low at 24 h incubation.

CONCLUSIONS

MLT has a cytoprotective effect on ZA-treated human osteoblasts and could represent a promising preventative alternative for patients at risk of bisphosphonate-related osteonecrosis of the jaw.

Melatonin as a promising agent of regulating stem cell biology and its application in disease therapy

Stem cells have emerged as an important approach to repair and regenerate damaged tissues or organs and show great therapeutic potential in a variety of diseases. However, the low survival of engrafted stem cells still remains a major challenge for stem cell therapy. As a major hormone from the pineal gland, melatonin has been shown to play an important role in regulating the physiological and pathological functions of stem cells, such as promoting proliferation, migration and differentiation. Thus, melatonin combined with stem cell transplantation displayed promising application potential in neurodegenerative diseases, liver cirrhosis, wound healing, myocardial infarction, kidney ischemia injury, osteoporosis, etc. It exerts its physiological and pathological functions through its anti-oxidant, anti-inflammatory, anti-apoptosis and anti-ageing properties. Here, we summarize recent advances on exploring the biological role of melatonin in stem cells, and discuss its potential applications in stem cell-based therapy.

Protective mechanisms of melatonin against hydrogen-peroxide-induced toxicity in human bone-marrow-derived mesenchymal stem cells

Many obstacles compromise the efficacy of bone marrow mesenchymal stem cells (BM-MSCs) by inducing apoptosis in the grafted BM-MSCs. The current study investigates the effect of melatonin on important mediators involved in survival of BM-MSCs in hydrogen peroxide (H₂O₂) apoptosis model. In brief, BM-MSCs were isolated, treated with melatonin, and then exposed to H₂O₂. Their viability was assessed by MTT assay and apoptotic fractions were evaluated through Annexin V, Hoechst staining, and ADP/ATP ratio. Oxidative stress biomarkers including ROS, total antioxidant power (TAP), superoxide dismutase (SOD) and catalase (CAT) activity, glutathione (GSH), thiol molecules, and lipid peroxidation (LPO) levels were determined. Secretion of inflammatory cytokines (TNF-α and IL-6) were measured by ELISA assay. The protein expression of caspase-3, Bax, and Bcl-2, was also evaluated by Western blotting. Melatonin pretreatment significantly increased viability and decreased apoptotic fraction of H₂O₂-exposed BM-MSCs. Melatonin also decreased ROS generation, as well as increasing the activity of SOD and CAT enzymes and GSH content. Secretion of inflammatory cytokines in H₂O₂-exposed cells was also reduced by melatonin. Expression of caspase-3 and Bax proteins in H₂O₂-exposed cells was diminished by melatonin pretreatment. The findings suggest that melatonin may be an effective protective agent against H₂O₂-induced oxidative stress and apoptosis in MSC.

Therapeutic potential of melatonin in oral medicine and periodontology

Melatonin (N-acetyl-5-methoxy tryptamine) is a substance secreted by multiple organs in vertebrates. In addition to playing a part in the circadian cycle of the body, melatonin is known to have antioxidant, antiinflammatory, and antioncotic effects on human tissues. Oral cavity is affected by a number of conditions such as periodontitis, mucositis, cancers, and cytotoxicity from various drugs or biomaterials. Research has suggested that melatonin is effective in treating the aforementioned pathologies. Furthermore, melatonin has been observed to enhance osseointegration and bone regeneration. The aim of this review is to critically analyze and summarize the research focusing on the potential of melatonin in the field of oral medicine. Topical administration of melatonin has a positive effect on periodontal health and osseointegration. Furthermore, melatonin is particularly effective in improving the periodontal parameters of diabetic patients with periodontitis. Melatonin exerts a regenerative effect on periodontal bone and may be incorporated into of periodontal scaffolds. The cytotoxic effect of various drugs and dental materials may be countered by the antioxidant properties of melatonin. Topical administration of melatonin promotes the healing of tooth extraction sockets and may also impede the progression of oral cancer. Although, there are a number of current and potential applications of melatonin, further long term clinical and animal studies are needed to assess its efficacy. Moreover, the role of melatonin supplements in the management of periodontitis should also be assessed.