Long-term nicotine exposure induces dysfunction of mouse endothelial progenitor cells

Chronic nicotine impairs the angiogenic capacity of human induced pluripotent stem cell-derived endothelial cells in a murine model of peripheral arterial disease

Objective

Lifestyle choices such as tobacco and e-cigarette use are a risk factor for peripheral arterial disease (PAD) and may influence therapeutic outcomes. The effect of chronic nicotine exposure on the angiogenic capacity of human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) was assessed in a murine model of PAD.

Methods

Mice were exposed to nicotine or phosphate-buffered saline (PBS) for 28 days, followed by induction of limb ischemia and iPSC-EC transplantation. Cells were injected into the ischemic limb immediately after induction of hindlimb ischemia and again 7 days later. Limb perfusion was assessed by laser Doppler spectroscopy, and transplant cell survival was monitored for 14 days afterward using bioluminescence imaging, followed by histological analysis of angiogenesis.

Results

Transplant cell retention progressively decreased over time after implantation based on bioluminescence imaging, and there were no significant differences in cell survival between mice with chronic exposure to nicotine or PBS. However, compared with mice without nicotine exposure, mice with prior nicotine exposure had had an impaired therapeutic response to iPSC-EC therapy based on decreased vascular perfusion recovery. Mice with nicotine exposure, followed by cell transplantation, had significantly lower mean perfusion ratio after 14 days (0.47 ± 0.07) compared with mice undergoing cell transplantation without prior nicotine exposure (0.79 ± 0.11). This finding was further supported by histological analysis of capillary density, in which animals with prior nicotine exposure had a lower capillary density (45.9 ± 4.7 per mm2) compared with mice without nicotine exposure (66.5 ± 8.1 per mm2). Importantly, the ischemic limbs mice exposed to nicotine without cell therapy also showed significant impairment in perfusion recovery after 14 days, compared with mice that received PBS + iPSC-EC treatment. This result suggested that mice without chronic nicotine exposure could respond to iPSC-EC implantation into the ischemic limb by inducing perfusion recovery, whereas mice with chronic nicotine exposure did not respond to iPSC-EC therapy.

Conclusions

Together, these findings show that chronic nicotine exposure adversely affects the ability of iPSC-EC therapy to promote vascular perfusion recovery and angiogenesis in a murine PAD model.

Piper sarmentosum Roxb. Attenuates Vascular Endothelial Dysfunction in Nicotine-Induced Rats

Exposure to cigarette smoke is an important risk factor for cardiovascular diseases. Nicotine is an addictive compound in cigarette smoke that triggers oxidative stress, which leads to vascular dysfunction. Piper sarmentosum Roxb. is a herb with antioxidant and vascular protective effects. This study evaluated the potential protective effect of the aqueous extract of P. sarmentosum leaf (AEPS) on vascular dysfunction in rats induced with prolonged nicotine administration. A total of 22 male Sprague-Dawley rats were divided into control (normal saline, oral gavage [p.o.]), nicotine (0.8 mg/kg/day nicotine, intraperitoneally [i.p.]), and nicotine + AEPS groups (250 mg/kg/day AEPS, p.o. + 0.8 mg/kg/day nicotine, i.p.). Treatment was given for 21 days. Thoracic aortae were harvested from the rats for the measurement of vasorelaxation, vascular nitric oxide (NO) level, and antioxidant level and the assessment of vascular remodeling. Rats treated with AEPS had improved vasorelaxation to endothelium-dependent vasodilator, acetylcholine (ACh), compared with the nicotine-induced rats (p < 0.05). The presence of endothelium increased the maximum relaxation of aortic rings in response to ACh. Compared with the nicotine group, AEPS enhanced vascular NO level (p < 0.001) and increased antioxidant levels as measured by superoxide dismutase activity (p < 0.05), catalase activity (p < 0.01), and reduced glutathione level (p < 0.05). No remarkable changes in aortic histomorphometry were detected. In conclusion, P. sarmentosum attenuates vascular endothelial dysfunction in nicotine-induced rats by improving vasorelaxation and enhancing vascular NO and antioxidant levels.

Stem Cell Therapy for Thromboangiitis Obliterans (Buerger’s Disease)

Buerger’s disease or Thromboangiitis Obliterans (TAO) is a nonatherosclerotic segmental vascular disease which affects small and medium arteries and veins in the upper and lower extremities. Based on pathological findings, TAO can be considered as a distinct form of vasculitis that is most prevalent in young male smokers. There is no definitive cure for this disease as therapeutic modalities are limited in number and efficacy. Surgical bypass has limited utility and 24% of patients will ultimately require amputation. Recently, studies have shown that therapeutic angiogenesis and immunomodulatory approaches through the delivery of stem cells to target tissues are potential options for ischemic lesion treatment. In this review, we summarize the current knowledge of TAO treatment and provide an overview of stem cell-based treatment modalities.

Rejuvenation of Senescent Endothelial Progenitor Cells by Extracellular Vesicles Derived From Mesenchymal Stromal Cells

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EVs derived from young, but not aged, MSCs rejuvenate senescent EPCs in vitro, recapitulating the effect of MSC transplantation.

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Aged MSCs can be genetically modified to produce tailored EVs with increased EPC rejuvenation capacity in vitro and increased angiogenesis capacity following ischemic event in vivo.

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EVs represent a promising platform to develop an acellular therapeutic approach in regenerative medicine for cardiovascular diseases.

Mesenchymal stromal cell (MSC) transplantation is a form of the stem-cell therapy that has shown beneficial effects for many diseases. The use of stem-cell therapy, including MSC transplantation, however, has limitations such as the tumorigenic potential of stem cells and the lack of efficacy of aged autologous cells. An ideal therapeutic approach would keep the beneficial effects of MSC transplantation while circumventing the limitations associated with the use of intact stem cells. This study provides proof-of-concept evidence that MSC-derived extracellular vesicles represent a promising platform to develop an acellular therapeutic approach that would just do that. Extracellular vesicles are membranous vesicles secreted by MSCs and contain bioactive molecules to mediate communication between different cells. Extracellular vesicles can be taken up by recipient cells, and once inside the recipient cells, the bioactive molecules are released to exert the beneficial effects on the recipient cells. This study, for the first time to our knowledge, shows that extracellular vesicles secreted by MSCs recapitulate the beneficial effects of MSCs on vascular repair and promote blood vessel regeneration after ischemic events. Furthermore, MSCs from aged donors can be engineered to produce extracellular vesicles with improved regenerative potential, comparable to MSCs from young donors, thus eliminating the need for allogenic young donors for elderly patients.

Effects of nicotine on the translation of stem cell therapy

Although stem cell therapy has tremendous therapeutic potential, clinical translation of stem cell therapy has yet to be fully realized. Recently, patient comorbidities and lifestyle choices have emerged to be important factors in the efficacy of stem cell therapy. Tobacco usage is an important risk factor for numerous diseases, and nicotine exposure specifically has become increasing more prevalent with the rising use of electronic cigarettes. This review describes the effects of nicotine exposure on the function of various stem cells. We place emphasis on the differential effects of nicotine exposure in vitro and as well as in preclinical models. Further research on the effects of nicotine on stem cells will deepen our understanding of how lifestyle choices can impact the outcome of stem cell therapies.

Age-Related Dysfunctions: Evidence and Relationship with Some Risk Factors and Protective Drugs

The theories interpreting senescence as a phenomenon favored by natural selection require the existence of specific, genetically determined and regulated mechanisms that cause a progressive age-related increase in mortality. The mechanisms defined in the subtelomere-telomere theory suggest that progressive slackening of cell turnover and decline in cellular functions are determined by the subtelomere-telomere-telomerase system, which causes a progressive "atrophic syndrome" in all organs and tissues. If the mechanisms underlying aging-related dysfunctions are similar and having the same origin, it could be hypothesized that equal interventions could produce similar effects. This article reviews the consequences of some factors (diabetes, obesity/dyslipidemia, hypertension, smoking, moderate use and abuse of alcohol) and classes of drugs [statins, angiotensin-converting enzyme (ACE) inhibitors, sartans] in accelerating and anticipating or in counteracting the process of aging. The evidence is compatible with the programmed aging paradigm and the mechanisms defined by the subtelomere-telomere theory but it has no obvious discriminating value against the theories of non-programmed aging paradigm. However, the existence of mechanisms, determined by the subtelomere-telomere-telomerase system and causing a progressive age-related decline in fitness through gradual cell senescence and cell senescence, is not justifiable without an evolutionary motivation. Their existence is expected by the programmed aging paradigm, while is incompatible with the opposite paradigm.

Inhibition of Galectin-3 Alleviates Cigarette Smoke Extract-Induced Autophagy and Dysfunction in Endothelial Progenitor Cells

Endothelial progenitor cells (EPCs) have the potential to repair damaged blood vessels and promote angiogenesis. Smoking, an important risk factor for cardiovascular diseases, is associated with impaired functions of EPCs. However, the underlying mechanisms remain unclear. The aim of the study was to investigate the effects of cigarette smoke extract (CSE) on autophagy and dysfunction of EPCs and the involvement of galectin-3 in its effects. EPCs were treated with 8% CSE for 24 h (without affecting cell viability). EPC functions were assessed by tube formation and migration capacity and intracellular ROS and eNOS expression. Autophagy was assessed by autophagic protein expression by Western blotting and immunofluorescence microscopy and autophagosome accumulation by transmission electron microscopy. Galectin-3 expression was measured by real-time PCR, Western blotting, and immunofluorescence microscopy, while phospho-AMPK and phospho-mTOR were measured by Western blotting. EPCs were transfected by shRNA-Gal-3 or shRNA-NC before treatment with CSE to examine the effects of galectin-3 on CSE-induced autophagy and dysfunction of EPCs. CSE-treated EPCs showed decreased tube formation and migration ability and eNOS expression but increased oxidative stress. CSE also induced autophagy which was characterized by a decrease in p62 protein, an increase in LC3B-II/I ratio, and accumulation of autophagosomes. CSE upregulated galectin-3 expression on EPCs. Inhibition of galectin-3 abrogated CSE-induced autophagy and dysfunction of EPCs. CSE activated phospho-AMPK and inhibited phospho-mTOR, and inhibition of galectin-3 abolished CSE's effect on activating phospho-AMPK and inhibiting phospho-mTOR. In conclusion, our results suggest that galectin-3 mediates CSE-induced EPC autophagy and dysfunction, likely via the AMPK/mTOR signaling pathway.

Biological effects of nicotine exposure: A narrative review of the scientific literature

The emergence of new tobacco heating products and electronic nicotine delivery systems (ENDS) is changing the way humans are exposed to nicotine. The purpose of this narrative review is to provide a broad overview of published scientific literature with respect to the effects of nicotine on three key health-related areas: 1) cardiovascular risk, 2) carcinogenesis and 3) reproductive outcomes. These areas are known to be particularly vulnerable to the effects of cigarette smoke, and in addition, nicotine has been hypothesized to play a role in disease pathogenesis. Acute toxicity will also be discussed. The literature to February 2019 suggests that there is no increased cardiovascular risk of nicotine exposure in consumers who have no underlying cardiovascular pathology. There is scientific consensus that nicotine is not a direct or complete carcinogen, however, it remains to be established whether it plays some role in human cancer propagation and metastasis. These cancer progression pathways have been proposed in models in vitro and in transgenic rodent lines in vivo but have not been demonstrated in cases of human cancer. Further studies are needed to determine whether nicotine is linked to decreased fertility in humans. The results from animal studies indicate that nicotine has the potential to act across many mechanisms during fetal development. More studies are needed to address questions regarding nicotine exposure in humans, and this may lead to additional guidance concerning new ENDS entering the market.

Cardiovascular, carcinogenic and reproductive effects of nicotine exposure: A narrative review of the scientific literature

The emergence of new tobacco heating products and electronic nicotine delivery systems (ENDS) is changing the way humans are exposed to nicotine. The purpose of this narrative review is to provide a broad overview of published scientific literature with respect to the effects of nicotine on three key health-related areas: 1) cardiovascular risk, 2) carcinogenesis and 3) reproductive outcomes. These areas are known to be particularly vulnerable to the effects of cigarette smoke, and in addition, nicotine has been hypothesized to play a role in disease pathogenesis. Acute toxicity will also be discussed. The literature to February 2019 suggests that there is no increased cardiovascular risk of nicotine exposure in consumers who have no underlying cardiovascular pathology. There is scientific consensus that nicotine is not a direct or complete carcinogen, however, it remains to be established whether it plays some role in human cancer propagation and metastasis. These cancer progression pathways have been proposed in models in vitro and in transgenic rodent lines in vivo but have not been demonstrated in cases of human cancer. Further studies are needed to determine whether nicotine is linked to decreased fertility in humans. The results from animal studies indicate that nicotine has the potential to act across many mechanisms during fetal development. More studies are needed to address questions regarding nicotine exposure in humans, and this may lead to additional guidance concerning new ENDS entering the market.

Humoral and Cellular Patterns of Early Endothelial Progenitor Cells in Relation to the Cardiovascular Risk in Axial Spondylarthritis

Background

Spondylarthritis (SpA) significantly affects sacroiliac, intervertebral and peripheral joints. Patients with SpA suffer from increased cardiovascular risk (CVR). The endothelial progenitor cell (EPC) system critically perpetuates vascular repair. The aim of the study was to evaluate circulating EPCs in axial (ax)SpA with special attention on parameters of disease activity and CVR.

Methods

Disease activity and functional impairment were quantified in 50 axSpA patients by using standardized parameters (Bath ankylosing spondylitis disease activity index (BASDAI), C-reactive protein (CRP), finger-floor distance (FFD) and Ott’ sign). Circulating EPCs and EPC regeneration were analyzed (fluorescence-activated cell sorting (FACS) and colony-forming unit (CFU) assay). Serum vasomodulatory mediators were quantified by enzyme-linked immunosorbent assay (ELISA).

Results

EPC colony numbers were lower in axSpA as compared to controls. Females displayed more colonies than males. In addition, fewer colonies were observed in smokers, in patients with a BASDAI of below 4 and in hypertension. Circulating CD133⁺/KDR⁺ cells did not differ between the groups. Follow-up analysis (33 months later) did not show any differences in gender, colony formation, CD133⁺/KDR⁺ cells or serum levels of vasomodulatory mediators if related to the categories of BASDAI, Ott’ sign or FFD.

Conclusions

EPC colony formation is significantly affected in axSpA with particularly low levels in males. EPC-related parameters do not allow predicting disease activity-related or functional parameters nor are they useful for CVR assessment in SpA.

Insights into Endothelial Progenitor Cells: Origin, Classification, Potentials, and Prospects

With the discovery of endothelial progenitor cells (EPCs) in the late 1990s, a paradigm shift in the concept of neoangiogenesis occurred. The identification of circulating EPCs in peripheral blood marked the beginning of a new era with enormous potential in the rapidly transforming regenerative field. Overwhelmed with the revelation, researchers across the globe focused on isolating, defining, and interpreting the role of EPCs in various physiological and pathological conditions. Consequently, controversies emerged regarding the isolation techniques and classification of EPCs. Nevertheless, the potential of using EPCs in tissue engineering as an angiogenic source has been extensively explored. Concomitantly, the impact of EPCs on various diseases, such as diabetes, cancer, and cardiovascular diseases, has been studied. Within the limitations of the current knowledge, this review attempts to delineate the concept of EPCs in a sequential manner from the speculative history to a definitive presence (origin, sources of EPCs, isolation, and identification) and significance of these EPCs. Additionally, this review is aimed at serving as a guide for investigators, identifying potential research gaps, and summarizing our current and future prospects regarding EPCs.

Peripheral blood SIRT1 mRNA levels in depression and treatment with electroconvulsive therapy

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD+) dependent enzymes that regulate cellular functions through deacetylation of protein targets. They have roles in both the periphery and central nervous system and have been implicated in depression biology. A recent genome-wide association study has identified a locus for major depression in the Sirtuin1 gene (SIRT1) and lower blood levels of SIRT1 mRNA in patients with depression have also been observed in two studies. To our knowledge, no studies have examined the effect of treatment on SIRT1 levels in patients with depression. We therefore examined SIRT1 mRNA levels in a well characterised group of patients with depression, compared to healthy controls, and characterised the effects of a course of electroconvulsive therapy (ECT) on peripheral blood SIRT1 mRNA. Depressed patients (n = 91) were matched to healthy controls (n = 85) on the basis of age and sex. In line with previous studies, blood SIRT1 mRNA levels were lower in depressed patients in comparison to controls (p = 0.005). However, ECT had no effect on SIRT1 levels (p = 0.67). There was no relationship between baseline pre-ECT SIRT1 levels and depression severity, change in mood scores, suicidality, depression polarity, presence of psychosis, or response to treatment. There was a trend for a negative association between an increase in SIRT1 mRNA and a decrease in HAM-D24 scores in ECT responders and remitters. These results indicate that reduced peripheral blood SIRT1 mRNA could be a trait feature of depression.