Dose-dependent effects of nicotine on proliferation and differentiation of human bone marrow stromal cells and the antagonistic action of vitamin C

The impact of diabetic glucose concentration on viability and cardiac differentiation of mesenchymal stem cells

INTRODUCTION

Hyperglycemia may be a stumbling block for delivery of regenerative benefits of mesenchymal stem cells (MSCs) to diabetic patients with cardiovascular diseases. Our study aims to assess the viability and cardiac differentiation potential of MSCs after being exposed to diabetic glucose concentration.

METHODS

MSCs were extracted from rat bone marrow. Cells were characterized based on morphology, differentiation potential, and expression of mesenchymal specific markers. MTT assay was done to evaluate the viability of MSCs after treatment with different glucose concentrations. Case group was MSCs treated with diabetic concentration of glucose versus cells treated with PBS as the control group. Growth curve and population doubling time were calculated in both groups. Expression of GATA4 and troponin, as the early and late markers during cardiac differentiation, were measured following 5-azacytidine exposure.

RESULTS

Proliferated cells at passage three had fibroblastic-shape, was able to differentiate into adipocytes or osteocytes, and expressed CD73 and CD90. MSCs viability was gradually decreased by increasing glucose concentration. Irrespective of nicotine concentration, three-day exposure imposed more severe detrimental effects on viability compared with one-day treatment. Proliferation rate of the MSCs was lower in the case group, and they need more time for population doubling. Expression of both cardiac markers were downregulated in the case group at day three. However, their expression became higher at day seven.

CONCLUSION

Diabetic glucose concentration inhibits normal proliferation and cardiac differentiation of MSCs. This effect should be considered in stem cell therapy of cardiovascular patients who are concurrently affected by hyperglycemia, a common comorbidity in such individuals. Why carry out this study? What was learned from the study?

FINDINGS

The impact of high nicotine concentrations on the viability and cardiac differentiation of mesenchymal stromal cells: a barrier to regenerative therapy for smokers

Background: Current treatment methods are not successful in restoring the lost cardiomyocytes after injury. Stem cell-based strategies have attracted much attention in this regard. Smoking, as a strong cardiovascular risk factor, not only affects the cardiac cells adversely but also deteriorates the function of stem cells. Since mesenchymal stem cells (MSCs) are one of the popular candidates in cardiovascular disease (CVD) clinical trials, we investigated the impact of nicotine on the regenerative properties (viability and cardiac differentiation) of these cells. Methods: MSCs were isolated from rat bone marrow and characterized based on morphology, differentiation capability, and the expression of specific mesenchymal markers. The MTT assay was used to assess the viability of MSCs after being exposed to different concentrations of nicotine. Based on MTT findings and according to the concentration of nicotine in smokers' blood, the growth curve and population doubling time were investigated for eight consecutive days. Cells were treated with 5-azacytidine (an inducer of cardiac differentiation), and then the expressions of cardiac-specific markers were calculated by qPCR. Results: MSCs were spindle-shaped, capable of differentiating into adipocyte and osteocyte, and expressed CD73 and CD90. The viability of MSCs was reduced upon exposure to nicotine in a concentration- and time-dependent manner. The growth curve showed that nicotine reduced the proliferation of MSCs, and treated cells needed more time to double. In addition, the expressions of GATA4 and troponin were downregulated in nicotine-treated cells on day 3. However, these two cardiac markers were overexpressed on day 7. Conclusion: Nicotine decreased normal growth and reduced the expression of cardiac markers in MSCs. This aspect is of eminent importance to smokers with cardiovascular disease who are candidates for stem cell therapy.

Nicotine reduces ROS and enhances cell proliferation via the α4 nicotinic acetylcholine receptor subunit in human induced pluripotent stem cells

The effects of smoking on fetal development and stem cell differentiation are not fully understood. Although nicotinic acetylcholine receptors (nAChRs) are expressed in many organs of the human body, their significance in human induced pluripotent stem cells (hiPSCs) remains unclear. After expression levels of nAChR subunits in hiPSCs were determined, the effects of the nAChR agonist, nicotine, on undifferentiated hiPSCs were evaluated using a Clariom S Array. We also determined the effect of nicotine alone and with a nAChR subunit antagonist on hiPSC cells. NAChR α4, α7, and β4 subunits were strongly expressed in hiPSCs. cDNA microarray, gene ontology, and enrichment analyses showed that exposing hiPSCs to nicotine altered expression of genes associated with immune responses, neurological system, carcinogenesis, cell differentiation, and cell proliferation. Particularly affected was metallothionein, which acts to decrease reactive oxygen species (ROS). The nicotine-induced reduction of ROS in hiPSCs was canceled by an α4 subunit or nonselective nAChR antagonist. HiPSC proliferation was increased by nicotine, and this effect, too, was canceled by an α4 antagonist. In conclusion, nicotine reduces ROS and enhances cell proliferation via the α4 nAChR subunit in hiPSCs. These findings provide new insight into the significance of nAChRs on human stem cells and fertilized human ova.

Effects of smoking on the tissue regeneration-associated functions of human endometrial stem cells via a novel target gene SERPINB2

BACKGROUND

Smokers directly inhale mainstream cigarette smoke, which contains numerous known and potential toxic substances, and thus, smoking is expected to have broad harmful effects that cause tissue injury and dysfunction. Interestingly, many studies have suggested that the recent decline in female fertility and increased rate of spontaneous abortion could be associated with increased smoking rates. Indeed, women that smoked for 10 years or more were reported to have a ~ 20% higher infertility rate than women that had never smoked. However, the reasons for the underlying harmful aspects of smoking on female fertility remain a matter of debate. Importantly, a previous study revealed that resident endometrial stem cell deficiency significantly limits the cyclic regeneration potential of endometrium, which, in turn, decreases successful pregnancy outcomes. In this context, we postulated that exposure to mainstream cigarette smoke extracts might decrease female fertility by inhibiting the functions of resident endometrial stem cells.

METHODS

We investigated whether cigarette mainstream smoke exposure directly inhibits various tissue regeneration-associated functions of endometrial stem cells, such as self-renewal, migration, pluripotency, and differentiation capacity in vitro. Next, we determined whether SERPINB2 mediates cigarette smoke-induced suppressive effects on various tissue regeneration-associated functions by depleting SERPINB2 expression with specific shRNA targeting SERPINB2. Mice were injected intraperitoneally with low (0.5 mg/kg) or high (1 mg/kg) doses of cigarette smoke extract (10 times for two weeks), and endometrial stem cells were then isolated from mice uterine tissues.

RESULTS

We found that exposure to cigarette smoke extracts remarkably suppressed various tissue regeneration-associated functions of endometrial stem cells, such as self-renewal, migration, multilineage differentiation ability, and pluripotency in vitro and in vivo by activating the SERPINB2 gene. Indeed, cigarette smoke-induced inhibitory effects on various endometrial stem cell functions were significantly abolished by SERPINB2 knockdown.

CONCLUSIONS

These findings provide valuable information on the harmful effects of cigarette smoking on resident endometrial stem cells and hopefully will facilitate the developments of promising therapeutic strategies for subfertile or infertile women that smoke cigarettes.

Hormesis and bone marrow stem cells: Enhancing cell proliferation, differentiation and resilience to inflammatory stress

This paper identifies and provides the first detailed assessment of hormetic dose responses by bone marrow stem cells (BMSCs) from a broad range of animal models and humans with particular emphasis on cell renewal (proliferation), cell differentiation and enhancing resilience to inflammatory stress. Such hormetic dose responses are commonly reported, being induced by a broad range of chemicals, including pharmaceuticals (e.g., caffeine, dexamethasone, nicotine), dietary supplements (e.g., curcumin, Ginkgo biloba, green tea extracts. resveratrol, sulforaphane), endogenous agents (e.g., hydrogen sulfide, interleukin 10), environmental contaminants (e.g., arsenic, PFOS) and physical stressor agents (e.g., EMF, shockwaves). Hormetic dose responses reported here for BMSCs are similar to those induced with other stem cell types [e.g., adipose-derived stem cells (ADSCs), dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), neuro stem cells (NSCs), embryonic stem cells (ESCs)], indicating a substantial degree of generality for hormetic responses in stem cells. The paper assesses both the underlying mechanistic foundations of BMSC hormetic responses and their potential therapeutic implications.

Ascorbic acid mitigates the deleterious effects of nicotine on tendon stem cells

Purpose: Nicotine causes tendon degeneration, whereas ascorbic acid imparts beneficial effects on tendon cells. Tendon stem cells (TSCs) play a vital role in maintaining tissue integrity and promoting restoration of structure and function after tendon injury. In the present study, cell culture experiments were performed to determine the effects of nicotine on TSCs and whether ascorbic acid supplementation could antagonize the action of high concentration nicotine. Methods: After treatment with nicotine and ascorbic acid, TSC proliferation, migration, stemness, apoptosis, and differentiation were analyzed. Results: TSC proliferation and expression of stem cell markers were significantly impaired by a high concentration of nicotine (1000 ng/mL), but a lower concentration (100 ng/mL) induced proliferative effects in TSCs. Moreover, the highest concentration of nicotine tested (1000 ng/mL) significantly inhibited the migratory ability of TSCs, while relatively high concentrations (100 and 1000 ng/mL) significantly (p < 0.05) up-regulated non-tenocyte genes. When ascorbic acid was added, the inhibitory effects of nicotine on the proliferation, migration, and stemness of TSCs were reversed. In addition, flow cytometry analysis showed that these nicotine concentrations could induce cell apoptosis, while the addition of ascorbic acid inhibited apoptosis. Conclusion: Addition of ascorbic acid partially reversed the inhibitory effect of a high concentration of nicotine. These findings indicate that while nicotine impairs the biological characteristics of TSCs, ascorbic acid can mitigate these deleterious effects and, therefore, may be useful for decreasing nicotine-induced tendon degeneration.

Histopathologic and Immunohistochemical Investigation of the Effects of Vitamin C on Bone Healing in Rats Exposed to Nicotine

PURPOSE

The aim of the present study was to perform a histopathologic and immunohistochemical investigation of the effects of vitamin C on bone healing in rats exposed to nicotine.

MATERIALS AND METHODS

A total of 52 male Sprague-Dawley rats were assigned to 4 main groups: control, vitamin C, nicotine, and nicotine plus vitamin C. The rats in the nicotine groups were injected with nicotine at 12-hour intervals for 4 weeks. At the end of 4 weeks, a tibial defect was created in all the rats. Subcutaneous injections were administered at the same intervals postoperatively, and the vitamin C groups received intraperitoneal vitamin C injections every day for the first 3 days and then every other day postoperatively. The rats were sacrificed on postoperative days 7 and 21. The blood samples collected during sacrifice were tested to determine the blood cotinine levels, and histopathological and immunohistochemical analyses were performed on tibia samples.

RESULTS

The histopathologic evaluation revealed that nicotine significantly increased the amount of necrosis and significantly decreased new bone formation and the bone healing score. The presence of necrosis in the nicotine plus vitamin C group was significantly lower on day 21 (P = .005). A statistically significant difference was observed among the new bone formation of the control, nicotine, vitamin C, and nicotine plus vitamin C groups on day 21 (P = .001). The new bone healing score of the nicotine group was significantly lower than that of the control, vitamin C, and nicotine plus vitamin C groups (P = .003, P = .001, and P = .001). The immunohistochemical evaluation showed that nicotine increased the hypoxia-inducible factor-1α and vascular endothelial growth factor levels and decreased the bone morphogenetic protein-2 levels, especially in the groups sacrificed on day 21.

CONCLUSIONS

Vitamin C did not have a significant effect on bone healing. However, vitamin C administered with nicotine decreased the metabolism of nicotine and, thus, increased nicotine excretion.

Apoptotic effects of cigarette smoke extracts on mouse embryonic stem cells via oxidative stress

Previous studies have reported that cigarette smoke and cigarette smoke extract (CSE) have negative effects on embryonic development. However, no studies have investigated the mechanism through which CSE affects the cellular signaling pathway leading to apoptosis and oxidative stress in embryonic cells, or how the two pathways are cross-linked. Thus, we studied the effects of CSE on apoptosis and oxidative stress in mouse embryonic stem cells (mESCs). Specifically, we measured changes in cell viability in response to CSEs (3R4F and two domestic cigarettes CSE 1 and 2) using a water soluble tetrazolium (WST) assay and a neutral red uptake (NRU) assay, which revealed that cell viability decreased in a concentration-dependent manner. Western blot analysis revealed that the expression of cyclin D1 and cyclin E1 was decreased and that of p21 and p27 was increased by CSE. Additionally, the number of terminal deoxynucleotidyl transferase (TUNEL)-stained cells was increased by CSE, while the levels of Bax and Caspase-3 increased and Bcl-2 decreased. Moreover, a 2',7'-dichlorofluorescin diacetate (DCF-DA) assay and reactive oxygen species (ROS)-Glo H2 O2 assay confirmed that ROS were generated in response to CSE and that they were associated with up-regulated Keaf-1 and CHOP. Overall, the results revealed that cigarette smoke extract (CSE) inhibited cell proliferation by regulating cell cycle-related protein expression and increased oxidative stress by regulating the expression of Kelch-like ECH-associated protein 1 (Keap-1) and CCAAT/enhancer-binding protein homologous protein (CHOP), resulting in apoptosis in mESCs.

Effects of cigarette smoke condensate on proliferation and pluripotency gene expression in mouse embryonic stem cells

BACKGROUND

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of blastocysts. They can be used as valuable experimental models to test the effects of drugs, chemicals, and environmental contaminants such as cigarette smoke condensate (CSC) on preimplantation embryo development. The aim of this study was to evaluate the effect of CSC on ESCs derived from mice with different genetic backgrounds and maternal ages.

METHODS

The study groups consisted of mouse ESCs (mESCs) obtained from three sources: blastocysts developed from fertilized oocytes of two-month-old (2-C57) and six-month-old (6-C57) C57BL/6 inbred mice and those developed from fertilized oocytes of two-month-old (2-NMRI) NMRI outbred mice. The groups of mESCs were exposed to 0.04, 4, and 40 μg/mL CSC. After exposure, we measured cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and real-time polymerase chain reaction for changes in expressions of Oct4, Sox2, Nanog, Ahr, Bax, Bcl2, TFAM, and POLG. The cell doubling time (DT) of these populations was also determined.

RESULTS

We observed that CSC changed proliferation and DT in the 2-C57 and 6-C57 cells. There was no change in 2-NMRI cells. Exposure to CSC caused changes in the gene expressions and induced apoptosis in all three cell lines.

CONCLUSION

Based on the results of the study, it can be concluded that CSC has an effect on the viability, DT and gene expression patterns in mouse ESCs and its effects vary based on the genetic background and maternal age of isolated mouse ESCs.

Effects of new beta-type Ti-40Nb implant materials, brain-derived neurotrophic factor, acetylcholine and nicotine on human mesenchymal stem cells of osteoporotic and non osteoporotic donors

Introduction

Treatment of osteoporotic fractures is still challenging and an urgent need exists for new materials, better adapted to osteoporotic bone by adjusted Young’s modulus, appropriate surface modification and pharmaceuticals.

Materials and methods

Titanium-40-niobium alloys, mechanically ground or additionally etched and titanium-6-aluminium-4-vanadium were analyzed in combination with brain-derived neurotrophic factor, acetylcholine and nicotine to determine their effects on human mesenchymal stem cells in vitro over 21 days using lactate dehydrogenase and alkaline phosphatase assays, live cell imaging and immunofluorescence microscopy.

Results

Cell number of human mesenchymal stem cells of osteoporotic donors was increased after 14 d in presence of ground titanium-40-niobium or titanium-6-aluminium-4-vanadium, together with brain-derived neurotrophic factor. Cell number of human mesenchymal stem cells of non osteoporotic donors increased after 21 d in presence of titanium-6-aluminium-4-vanadium without pharmaceuticals. No significant increase was measured for ground or etched titanium-40-niobium after 21 d. Osteoblast differentiation of osteoporotic donors was significantly higher than in non osteoporotic donors after 21 d in presence of etched, ground titanium-40-niobium or titanium-6-aluminium-4-vanadium accompanied by all pharmaceuticals tested. In presence of all alloys tested brain-derived neurotrophic factor, acetylcholine and nicotine increased differentiation of cells of osteoporotic donors and accelerated it in non osteoporotic donors.

Conclusion

We conclude that ground titanium-40-niobium and brain-derived neurotrophic factor might be most suitable for subsequent in vivo testing.

Clinical, radiological, and gene expression analyses in smokers and non-smokers, Part 2: RCT on the late healing phase of osseointegration

BACKGROUND

The mechanisms behind the impact of smoking on osseointegration are not fully understood.

PURPOSE

To investigate the initial clinical and molecular course of osseointegration of different implants in smokers and non-smokers in a randomized controlled trial (RCT).

MATERIALS AND METHODS

Smoking (n = 16) and non-smoking (n = 16) patients received 3 implant types: machined, oxidized, and laser-modified surfaces. Baseline bone biopsies were retrieved from the implant sites. After 60 and 90 days, the pain score, implant stability quotient (ISQ), and peri-implant crevicular fluid (PICF) gene expression were analyzed. Furthermore, radiological and clinical assessments were made at 90 days.

RESULTS

At 90 days, no pain was reported, irrespective of smoking habit. A higher ISQ was found in smokers compared with non-smokers. Marginal bone loss (MBL) was greater in smokers than in non-smokers. The comparison of implant surfaces revealed greater MBL exclusively at the machined implants in smokers. At 90 days in smokers, the PICF around machined implants revealed a higher expression of the proinflammatory cytokine, interleukin-6 (IL-6), and a lower expression of the osteogenic gene, osteocalcin (OC), compared with the PICF around modified implants. Furthermore, OC expression was lower at machined implants in smokers compared with machined implants in non-smokers. After adjustment for age and implant location (maxilla/mandible), multivariate regression revealed the following predictors of MBL: smoking, bleeding on probing at 90 days, hypoxia-inducible factor 1 alpha (HIF-1α) expression at baseline and IL-6 expression in PICF at 90 days.

CONCLUSIONS

During the early phase of osseointegration, non-smokers and smokers present a similar, high implant survival. In contrast, smokers present a greater MBL, particularly at machined implants. HIF-1α baseline expression in the recipient bone and IL-6 expression in PICF cells are important molecular determinants for MBL after 90 days. It is concluded that smoking has an early effect on osseointegration, which is dependent on the implant surface properties and the local host response.

Concise Review: The Deleterious Effects of Cigarette Smoking and Nicotine Usage and Mesenchymal Stem Cell Function and Implications for Cell-Based Therapies

Stem cell sources for cell‐based therapeutics are often screened for infectious agents and genetic diseases prior to implantation; however, there are other risk factors that are often overlooked, which may ultimately lead to less efficacious clinical outcomes. One such risk factor is exposure of mesenchymal stem cells (MSCs) to cigarette smoke or nicotine. Recent data have shown that exposure to cigarette smoke or nicotine leads to decreased regenerative potential, namely decreased proliferation, decreased migration, and decreased differentiation potential of exposed MSCs. This review provides a brief introduction into MSCs and their respective niches and a summary regarding the interactions of cigarettes and nicotine with MSCs populations. Specifically, the effects of cigarette smoke and nicotine on the regenerative potential of MSCs (i.e., proliferation, migration, and differentiation) will be covered with an emphasis on considerations for the development of future cell‐based clinical trials and therapies. stemcellstranslationalmedicine2017;6:1815–1821

Effects of nicotine in the presence and absence of vitamin E on morphology, viability and osteogenic gene expression in MG-63 osteoblast-like cells

BACKGROUND

Evidence shows that oxidative stress induced by nicotine plays an important role in bone loss. Vitamin E with its antioxidative properties may be able to reverse the effects of nicotine on bone. This study aimed to assess the effects of nicotine in the presence and absence of vitamin E on morphology, viability and osteogenic gene expression in MG-63 (osteosarcoma) human osteoblast-like cells.

METHODS

We treated the cells with 5 mM nicotine. The viability and morphology of cells were evaluated respectively using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) and crystal violet assays. The effect of nicotine on osteogenic gene expression in MG-63 cells was assessed by real-time reverse-transcription polymerase chain reaction of osteoblast markers, namely, alkaline phosphatase, osteocalcin and bone sialoprotein.

RESULTS

The results revealed that survival and proliferation of MG-63 cells were suppressed following exposure to nicotine, and cytoplasm vacuolization occurred in the cells. Nicotine significantly down-regulated the expression of osteogenic marker genes. Such adverse effects on morphology, viability and osteogenic gene expression of MG-63 cells were reversed by vitamin E therapy.

CONCLUSIONS

In conclusion, vitamin E supplementation may play a role in proliferation and differentiation of osteoblasts, and vitamin E can be considered as an anabolic agent to treat nicotine-induced bone loss.

Biomimetic approaches in bone tissue engineering: Integrating biological and physicomechanical strategies

The development of responsive biomaterials capable of demonstrating modulated function in response to dynamic physiological and mechanical changes in vivo remains an important challenge in bone tissue engineering. To achieve long-term repair and good clinical outcomes, biologically responsive approaches that focus on repair and reconstitution of tissue structure and function through drug release, receptor recognition, environmental responsiveness and tuned biodegradability are required. Traditional orthopedic materials lack biomimicry, and mismatches in tissue morphology, or chemical and mechanical properties ultimately accelerate device failure. Multiple stimuli have been proposed as principal contributors or mediators of cell activity and bone tissue formation, including physical (substrate topography, stiffness, shear stress and electrical forces) and biochemical factors (growth factors, genes or proteins). However, optimal solutions to bone regeneration remain elusive. This review will focus on biological and physicomechanical considerations currently being explored in bone tissue engineering.

The convergence of fracture repair and stem cells: interplay of genes, aging, environmental factors and disease

The complexity of fracture repair makes it an ideal process for studying the interplay between the molecular, cellular, tissue, and organ level events involved in tissue regeneration. Additionally, as fracture repair recapitulates many of the processes that occur during embryonic development, investigations of fracture repair provide insights regarding skeletal embryogenesis. Specifically, inflammation, signaling, gene expression, cellular proliferation and differentiation, osteogenesis, chondrogenesis, angiogenesis, and remodeling represent the complex array of interdependent biological events that occur during fracture repair. Here we review studies of bone regeneration in genetically modified mouse models, during aging, following environmental exposure, and in the setting of disease that provide insights regarding the role of multipotent cells and their regulation during fracture repair. Complementary animal models and ongoing scientific discoveries define an increasing number of molecular and cellular targets to reduce the morbidity and complications associated with fracture repair. Last, some new and exciting areas of stem cell research such as the contribution of mitochondria function, limb regeneration signaling, and microRNA (miRNA) posttranscriptional regulation are all likely to further contribute to our understanding of fracture repair as an active branch of regenerative medicine.