Functional nicotinic and muscarinic receptors on mesenchymal stem cells

Weight Gain With Advancing Age Is Controlled by the Muscarinic Acetylcholine Receptor M4 in Male Mice

Obesity is characterized by the excessive accumulation of adipose tissue, and it is a serious global health issue. Understanding the pathology of obesity is crucial for developing effective interventions. In this study, we investigated the role of muscarinic acetylcholine receptor M4 (mAChR-M4) in the regulation of obesity in Chrm4-knockout (M4-KO) mice. Male M4-KO mice showed higher weight gain and accumulation of white adipose tissue (WAT) with advancing age than the wild-type mice. The M4-KO mice also showed increased leptin expression at both the transcription and the translation levels. RNA sequencing and quantitative reverse transcription polymerase chain reaction analyses of subcutaneous adipose tissues revealed that the expression of WAT marker genes was significantly enhanced in the M4-KO mice. In contrast, the expression levels of brown adipose tissue/beige adipose tissue markers were strongly decreased in the M4-KO mice. To identify the Chrm4-expressing cell types, we generated Chrm4-mScarlet reporter mice and examined the localization of the mScarlet fluorescent signals in subcutaneous tissues. Fluorescent signals were prominently detected in WAT and mesenchymal stem cells. Additionally, we also found that choline acetyltransferase was expressed in macrophages, suggesting their involvement in acetylcholine (ACh) secretion. Corroborating this notion, we were able to quantitatively measure the ACh in subcutaneous tissues by liquid chromatography tandem mass spectrometry. Collectively, our findings suggest that endogenous ACh released from macrophages maintains the homeostasis of adipose cell growth and differentiation via mAChR-M4 in male mice. This study provides new insights into the molecular mechanisms underlying obesity and potential targets for therapeutic interventions.

A non-adaptationist hypothesis of play behaviour

Play is a suite of apparently non-functional, pleasurable behaviours observed in human and non-human animals. Although the phenomenon has been studied extensively, no adaptationist behavioural theory of how play evolved can be supported by the available evidence. However, the advancement of the extended evolutionary synthesis and developments in systems biology offer alternative avenues for non-adaptationist physiological hypotheses. I therefore propose a hypothesis of play, based upon a complex ACh activity that is under agential control of the organism, whereby play initiates ACh-mediated feedforward and feedback processes which act to: (i) regulate metabolic processes; (ii) form new ACh receptors via ACh mRNA activity; (iii) mediate attention, memory consolidation and learning; and (iv) mediate social behaviours, reproduction and embryonic development. However, play occurs across taxa, but does not occur across all taxonomic groups or within all species of a taxonomic group. Thus, to support the validity of the proposed hypothesis, I further propose potential explanations for this anomaly, which include sampling and observer biases, altricial versus precocial juvenile development, and the influence of habitat niche and environmental conditions on behaviour. The proposed hypothesis thus offers new avenues for study in both the biological and social sciences, in addition to having potential applications in applied sciences, such as animal welfare and biomedical research. Crucially, it is hoped that this hypothesis will promote further study of a valid and behaviourally significant, yet currently enigmatic, biological phenomenon.

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.

The C-terminus of the prototypical M2 muscarinic receptor localizes to the mitochondria and regulates cell respiration under stress conditions

Muscarinic acetylcholine receptors are prototypical G protein-coupled receptors (GPCRs), members of a large family of 7 transmembrane receptors mediating a wide variety of extracellular signals. We show here, in cultured cells and in a murine model, that the carboxyl terminal fragment of the muscarinic M2 receptor, comprising the transmembrane regions 6 and 7 (M2tail), is expressed by virtue of an internal ribosome entry site localized in the third intracellular loop. Single-cell imaging and import in isolated yeast mitochondria reveals that M2tail, whose expression is up-regulated in cells undergoing integrated stress response, does not follow the normal route to the plasma membrane, but is almost exclusively sorted to the mitochondria inner membrane: here, it controls oxygen consumption, cell proliferation, and the formation of reactive oxygen species (ROS) by reducing oxidative phosphorylation. Crispr/Cas9 editing of the key methionine where cap-independent translation begins in human-induced pluripotent stem cells (hiPSCs), reveals the physiological role of this process in influencing cell proliferation and oxygen consumption at the endogenous level. The expression of the C-terminal domain of a GPCR, capable of regulating mitochondrial function, constitutes a hitherto unknown mechanism notably unrelated to its canonical signaling function as a GPCR at the plasma membrane. This work thus highlights a potential novel mechanism that cells may use for controlling their metabolism under variable environmental conditions, notably as a negative regulator of cell respiration.

Activation of a non-neuronal cholinergic system in visceral white adipose tissue of obese mice and humans

BACKGROUND AND OBJECTIVES

Since white adipose tissue (WAT) lacks parasympathetic cholinergic innervation, the source of the acetylcholine (ACh) acting on white adipocyte cholinergic receptors is unknown. This study was designed to identify ACh-producing cells in mouse and human visceral WAT and to determine whether a non-neuronal cholinergic system becomes activated in obese inflamed WAT.

METHODS

Mouse epididymal WAT (eWAT) and human omental fat were studied in normal and obese subjects. The expression of the key molecules involved in cholinergic signaling was evaluated by qRT-PCR and western blotting whereas their tissue distribution and cellular localization were investigated by immunohistochemistry, confocal microscopy and in situ hybridization. ACh levels were measured by liquid chromatography/tandem mass spectrometry. The cellular effects of ACh were assessed in cultured human multipotent adipose-derived stem cell (hMADS) adipocytes.

RESULTS

In mouse eWAT, diet-induced obesity modulated the expression of key cholinergic molecular components and, especially, raised the expression of choline acetyltransferase (ChAT), the ACh-synthesizing enzyme, which was chiefly detected in interstitial macrophages, in macrophages forming crown-like structures (CLSs), and in multinucleated giant cells (MGCs). The stromal vascular fraction of obese mouse eWAT contained significantly higher ACh and choline levels than that of control mice. ChAT was undetectable in omental fat from healthy subjects, whereas it was expressed in a number of interstitial macrophages, CLSs, and MGCs from some obese individuals. In hMADS adipocytes stressed with tumor necrosis factor α, ACh, alone or combined with rivastigmine, significantly blunted monocyte chemoattractant protein 1 and interleukin 6 expression, it partially but significantly, restored adiponectin and GLUT4 expression, and promoted glucose uptake.

CONCLUSIONS

In mouse and human visceral WAT, obesity induces activation of a macrophage-dependent non-neuronal cholinergic system that is capable of exerting anti-inflammatory and insulin-sensitizing effects on white adipocytes.

Varenicline Mitigates the Increased Risk of Pseudoarthrosis Associated with Nicotine

BACKGROUND CONTEXT

High serum nicotine levels increase the risk of non-union after spinal fusion. Varenicline, a pharmaceutical adjunct for smoking cessation, is a partial agonist designed to displace and outcompete nicotine at its receptor binding site, thereby limiting downstream activation. Given its mechanism, varenicline may have therapeutic benefits in mitigating non-union for active smokers undergoing spinal fusion.

PURPOSE

To compare fusion rate and fusion mass characteristics between cohorts receiving nicotine, varenicline, or concurrent nicotine and varenicline after lumbar fusion.

STUDY DESIGN

Rodent non-instrumented spinal fusion model.

METHODS

Sixty eight-week-old male Sprague-Dawley rats weighing approximately 300 grams underwent L4-5 posterolateral fusion (PLF) surgery. Four experimental groups (control: C, nicotine: N, varenicline: V, and combined: NV [nicotine and varenicline]) were included for analysis. Treatment groups received nicotine, varenicline, or a combination of nicotine and varenicline delivered through subcutaneous osmotic pumps beginning two weeks before surgery until the time of sacrifice at age 14 weeks. Manual palpation testing, microCT imaging, bone histomorphometry, and biomechanical testing were performed on harvested spinal fusion segments.

RESULTS

Control (p=0.016) and combined (p=0.032) groups, when compared directly to the nicotine group, demonstrated significantly greater manual palpation scores. The fusion rate in the control (93.3%) and combined (93.3%) groups were significantly greater than that of the nicotine group (33.3%) (p=0.007, both). Biomechanical testing demonstrated greater Young's modulus of the fusion segment in the control (17.1 MPa) and combined groups (34.5 MPa) compared to the nicotine group (8.07 MPa) (p<0.001, both). MicroCT analysis demonstrated greater bone volume fraction (C:0.35 vs N:0.26 vs NV:0.33) (p<0.001, all) and bone mineral density (C:335 vs N:262 vs NV:328 mg Ha/cm³) (p<0.001, all) in the control and combined groups compared to the nicotine group. Histomorphometry demonstrated a greater mineral apposition rate in the combined group compared to the nicotine group (0.34 vs 0.24 μm/day, p=0.025).

CONCLUSION

In a rodent spinal fusion model, varenicline mitigates the adverse effects of high nicotine serum levels on the rate and quality of spinal fusion.

CLINICAL SIGNIFICANCE

These findings have the potential to significantly impact clinical practice guidelines and the use of pharmacotherapy for active nicotine users undergoing fusion surgery.

Acetylcholine Receptors in Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are well known for their regenerative potential. Even though the ability of MSCs to proliferate and differentiate has been studied extensively, there remains much to learn about the signaling mechanisms and pathways that control proliferation and influence the differentiation phenotype. In recent years, there has been growing evidence for the utility of non-neuronal cholinergic signaling systems and that acetylcholine (ACh) plays an important ubiquitous role in cell-to-cell communication. Indeed, cholinergic signaling is hypothesized to occur in stem cells and ACh synthesis, as well as in ACh receptor (AChR) expression, has been identified in several stem cell populations, including MSCs. Furthermore, AChRs have been found to influence MSC regenerative potential. In humans, there are two major classes of AChRs, muscarinic AChRs and nicotinic AChRs, with each class possessing several subtypes or subunits. In this review, the expression and function of AChRs in different types of MSC are summarized with the aim of highlighting how AChRs play a pivotal role in regulating MSC regenerative function.

Emerging Roles of Cholinergic Receptors in Schwann Cell Development and Plasticity

The cross talk between neurons and glial cells during development, adulthood, and disease, has been extensively documented. Among the molecules mediating these interactions, neurotransmitters play a relevant role both in myelinating and non-myelinating glial cells, thus resulting as additional candidates regulating the development and physiology of the glial cells. In this review, we summarise the contribution of the main neurotransmitter receptors in the regulation of the morphogenetic events of glial cells, with particular attention paid to the role of acetylcholine receptors in Schwann cell physiology. In particular, the M2 muscarinic receptor influences Schwann cell phenotype and the α7 nicotinic receptor is emerging as influential in the modulation of peripheral nerve regeneration and inflammation. This new evidence significantly improves our knowledge of Schwann cell development and function and may contribute to identifying interesting new targets to support the activity of these cells in pathological conditions.

Clinical significance of acetylcholinesterase activity in brain tumors

It has been established that the non-neuronal cholinergic system is related to the oncogenesis which increases the attractiveness of its components as the promising markers of oncologic diseases. The purpose of this work is to evaluate the clinical significance of the analysis of the activity of acetyl cholinesterase as a new marker of gliomas. The activity of acetyl cholinesterase was assessed by photo colorimetric analysis according to the Hestrin method recalculating the activity of the enzyme in the tumor tissue per 1 g of protein, and in the blood - by 0.1 g of hemoglobin. The data obtained in the primary tumors of the brain (28) in the tissue of the brain of persons who died as a result of injury (6) and in whole blood of patients with gliomas (28) and practically healthy people (10) were compared with the use of a number of statistical programs. A significant decrease in the activity of acetyl cholinesterase in tumor tissue and in whole blood is revealed as the degree of anaplasia of tumors increases, starting with Grade II. It is for the first time that a significant direct correlation was noted showing the consistency between the decrease in the activity of acetyl cholinesterase in the tumor tissue of the brain and blood. Bioinformatic analysis showed the connection of the enzyme of acetyl cholinesterase with proteins of the PI3K-AKT and Notch signaling pathways providing antiapoptotic and proliferative effects. The found dependences provide new insights into understanding of the mechanisms of gliomas genesis and can be used for selection of new diagnostic markers of brain tumors.

Latent Tri-lineage Potential of Human Menstrual Blood-Derived Mesenchymal Stromal Cells Revealed by Specific In Vitro Culture Conditions

Human menstrual blood-derived mesenchymal stromal cells (MenSCs) have become not only an important source of stromal cells for cell therapy but also a cellular source for neurologic disorders in vitro modeling. By using culture protocols originally developed in our laboratory, we show that MenSCs can be converted into floating neurospheres (NSs) using the Fast-N-Spheres medium for 24-72 h and can be transdifferentiated into functional dopaminergic-like (DALNs, ~ 26% TH + /DAT + flow cytometry) and cholinergic-like neurons (ChLNs, ~ 46% ChAT + /VAChT flow cytometry) which responded to dopamine- and acetylcholine-triggered neuronal Ca²⁺ inward stimuli when cultured with the NeuroForsk and the Cholinergic-N-Run medium, respectively in a timely fashion (i.e., 4-7 days). Here, we also report a direct transdifferentiation method to induce MenSCs into functional astrocyte-like cells (ALCs) by incubation of MenSCs in commercial Gibco® Astrocyte medium in 7 days. The MSC-derived ALCs (~ 59% GFAP + /S100β +) were found to respond to glutamate-induced Ca²⁺ inward stimuli. Altogether, these results show that MenSCs are a reliable source to obtain functional neurogenic cells to further investigate the neurobiology of neurologic disorders.

Snail/HDAC1/2 mediate skeletal growth retardation in fetuses caused by prenatal nicotine exposure

Previous findings have confirmed that prenatal nicotine exposure (PNE) leads to retarded cartilage development in the fetal growth plate. It is characterized by insufficient matrix synthesis and decreased expression of matrix phenotype genes aggrecan (ACAN) and Col2A1 in the fetal growth plate chondrocytes; however, the specific molecular mechanism is yet unclear. This study intends to clarify the specific molecular mechanism of fetal osteochondral retardation caused by PNE through animal and cellular experiments. The present study demonstrated that in male offspring of the PNE group (the pregnant rats were subcutaneously administered nicotine 1.0 mg/kg twice per day (2.0 mg/kg.d) at GD11-20), the cartilage matrix of the fetal growth plate was lightly stained, the collagen was reduced, and expression of the matrix phenotype genes, ACAN and Col2A1, was significantly decreased. It was further found that PNE decreased histone acetylation (H3K9/H3K14) levels in the ACAN and Col2A1 promoter regions. Moreover, the expression of Snail and HDAC1/2 was increased in the PNE group. in vitro, the nicotine treatment at different concentrations elevated the expression of Snail/HDAC1/2 while decreasing the H3K9/H3K14 levels in the ACAN and Col2A1 promoter regions. Snail-siRNA transfection partially abolished the nicotine-induced increase in HDAC1/2 expression and decreased the histone acetylation levels in the ACAN and Col2A1 promoter regions. Trichostatin A (TSA) treatment partially reversed the nicotine-induced changes in downstream parameters. In summary, PNE-induced decreased cartilage matrix synthesis in the fetal growth plate of male offspring is effectuated by Snail/HDAC1/2-mediated decreased H3K9/H3K14 levels in the ACAN and Col2A1 promoter regions.

The Shift of HbF to HbA under Influence of SKA2 Gene; A Possible Link between Cortisol and Hematopoietic Maturation in Term and Preterm Newborns

BACKGROUND

We hypothesized that the SKA2 gene can convert hemoglobin F to A leading to the maturity of the hematopoietic system by glucocorticoid hormone; so, the present study aimed to investigate the health outcome of newborns by using the effect of SKA2 gene on hematopoietic maturation.

METHODS

At first, 142 samples were divided into term and preterm. After sampling from the umbilical cord blood, the expression of SKA2 genes and HbA and F were evaluated by quantitative RT-PCR. The blood gases were measured by Campact 3 device. Finally, the cortisol level was measured by ELISA method and HbA and F levels were investigated by capillary electrophoresis.

RESULTS

The blood gases and Apgar scores were more favorable in term newborns (P <0.001). Levels of protein/expression of HbF in newborns with Apgar score greater than 7 was lower than that of the newborns with Apgar score below 7 (P <0.001). Cortisol and HbA levels were considerably higher in term newborns compared to the preterm ones (P <0.001). In the preterm and term groups, SKA2 gene expression had a positive and significant relationship with cortisol and HbA levels as well as a negative relationship with the HbF level. In the preterm group, a positive and significant relationship was observed between the expression of SKA2 and HbF genes.

CONCLUSION

The results revealed that the SKA2 gene affected hematopoietic maturation in preterm and term newborns and the health outcome of newborns improved by increasing HbA level.

Effects mediated by the α7 nicotinic acetylcholine receptor on cell proliferation and migration in rat adipose-derived stem cells

Adipose-derived stem cells (ASCs) are an attractive source for regenerative medicine as they can be easily isolated, rapidly expandable in culture and show excellent in vitro differentiation potential. Acetylcholine (ACh), one of the main neurotransmitters in central and peripheral nervous systems, plays key roles in the control of several physiological processes also in non-neural tissues. As demonstrated in our previous studies, ACh can contribute to the rat ASCs physiology, negatively modulating ASCs proliferation and migration via M2 muscarinic receptor (mAChR) activation. In the present work we show that rat ASCs also express α7 nicotinic receptors (nAChRs). In particular, we have investigated the effects mediated by the selective activation of α7 nAChRs, which causes a reduction of ASC proliferation without affecting cell survival and morphology, and significantly promotes cell migration via upregulation of the CXCR4 expression. Interestingly, the activation of the α7 nAChR also upregulates the expression of M2 mAChR protein, indicating a cooperation between muscarinic and nicotinic receptors in the inhibition of ASC proliferation.

Vagal α7nAChR signaling regulates α7nAChR+Sca1+ cells during lung injury repair

Background

The distal airways of the lung and bone marrow are innervated by the vagus nerve. Vagal α7nAChR signaling plays a key role in regulating lung infection and inflammation; however, whether this pathway regulates α7nAChR⁺Sca1⁺ cells during lung injury repair remains unknown. We hypothesized that vagal α7nAChR signaling controls α7nAChR⁺Sca1⁺ cells, which contribute to the resolution of lung injury.

Methods

Pneumonia was induced by intratracheal challenge with E. coli. The bone marrow mononuclear cells (BM-MNCs) were isolated from the bone marrow of pneumonia mice for immunofluorescence. The bone marrow, blood, BAL, and lung cells were isolated for flow cytometric analysis by labeling with anti-Sca1, VE-cadherin, p-Akt1, or Flk1 antibodies. Immunofluorescence was also used to examine the coexpression of α7nAChR, VE-cadherin, and p-Akt1. Sham, vagotomized, α7nAChR knockout, and Akt1 knockout mice were infected with E. coli to study the regulatory role of vagal α7nAChR signaling and Akt1 in Sca1⁺ cells.

Results

During pneumonia, BM-MNCs were enriched with α7nAChR⁺Sca1⁺ cells, and this cell population proliferated. Transplantation of pneumonia BM-MNCs could mitigate lung injury and increase engraftment in recipient pneumonia lungs. Activation of α7nAChR by its agonist could boost α7nAChR⁺Sca1⁺ cells in the bone marrow, peripheral blood, and bronchoalveolar lavage (BAL) in pneumonia. Immunofluorescence revealed that α7nAChR, VE-cadherin, and p-Akt1 were coexpressed in the bone marrow cells. Vagotomy could reduce α7nAChR⁺VE-cadherin⁺ and VE-cadherin⁺p-Akt1⁺ cells in the bone marrow in pneumonia. Knockout of α7nAChR reduced VE-cadherin⁺ cells and p-Akt1⁺ cells in the bone marrow. Deletion of Akt1 reduced Sca1⁺ cells in the bone marrow and BAL. More importantly, 91.3 ± 4.9% bone marrow and 77.8 ± 4.9% lung α7nAChR⁺Sca1⁺VE-cadherin⁺ cells expressed Flk1, which is a key marker of endothelial progenitor cells (EPCs). Vagotomy reduced α7nAChR⁺Sca1⁺VE-cadherin⁺p-Akt1⁺ cells in the bone marrow and lung from pneumonia mice. Treatment with cultured EPCs reduced ELW compared to PBS treatment in E. coli pneumonia mice at 48 h. The ELW was further reduced by treatment with EPCs combining with α7nAChR agonist-PHA568487 compared to EPC treatments only.

Conclusions

Vagal α7nAChR signaling regulates α7nAChR⁺Sca1⁺VE-cadherin⁺ EPCs via phosphorylation of Akt1 during lung injury repair in pneumonia.

Brain-Derived Acetylcholine Maintains Peak Bone Mass in Adult Female Mice

Preclinical and clinical data support a role of the sympathetic nervous system in the regulation of bone remodeling, but the contribution of parasympathetic arm of the autonomic nervous system to bone homeostasis remains less studied. In this study, we sought to determine whether acetylcholine (ACh) contributes to the regulation of bone remodeling after peak bone mass acquisition. We show that reduced central ACh synthesis in mice heterozygous for the choline transporter (ChT) leads to a decrease in bone mass in young female mice, thus independently confirming the previously reported beneficial effect of ACh signaling on bone mass accrual. Increasing brain ACh levels through the use of the blood brain barrier (BBB)-permeable acetylcholinesterase inhibitor (AChEI) galantamine increased trabecular bone mass in adult female mice, whereas a peripheral increase in ACh levels induced by the BBB-impermeable AChEI pyridostigmine caused trabecular bone loss. AChEIs did not alter skeletal norepinephrine level, and induced an overall increase in osteoblast and osteoclast densities, two findings that do not support a reduction in sympathetic outflow as the mechanism involved in the pro-anabolic effect of galantamine on the skeleton. In addition, we did not detect changes in the commitment of skeletal progenitor cells to the osteoblast lineage in vivo in AChEI-treated mice, nor a direct impact of these drugs in vitro on the survival and differentiation of osteoblast and osteoclast progenitors. Last, ChT heterozygosity and galantamine treatment triggered bone changes in female mice only, thus revealing the existence of a gender-specific skeletal response to brain ACh level. In conclusion, this study supports the stimulatory effect of central ACh on bone mass accrual, shows that it also promotes peak bone mass maintenance in adult mice, and suggests that central ACh regulates bone mass via different mechanisms in growing versus sexually mature mice. © 2020 American Society for Bone and Mineral Research.

Functional Heterogeneity of Protein Kinase A Activation in Multipotent Stromal Cells

Multipotent stromal cells (MSC) demonstrate remarkable functional heterogeneity; however, its molecular mechanisms remain largely obscure. In this study, we explored MSC response to hormones, which activate Gs-protein / cyclic AMP (cAMP) / protein kinase A (PKA) dependent signaling, at the single cell level using genetically encoded biosensor PKA-Spark. For the first time, we demonstrated that about half of cultured MSCs are not able to activate the cAMP/PKA pathway, possibly due to the limited availability of adenylyl cyclases. Using this approach, we showed that MSC subpopulations responding to various hormones largely overlapped, and the share of responding cells did not exceed 40%. Using clonal analysis, we showed that signaling heterogeneity of MSC could be formed de novo within 2 weeks.

Novel Potent Muscarinic Receptor Antagonists: Investigation on the Nature of Lipophilic Substituents in the 5- and/or 6-Positions of the 1,4-Dioxane Nucleus

A series of novel 1,4-dioxane analogues of the muscarinic acetylcholine receptor (mAChR) antagonist 2 was synthesized and studied for their affinity at M₁–M₅ mAChRs. The 6-cyclohexyl-6-phenyl derivative 3b, with a cis configuration between the CH₂N⁺(CH₃)₃ chain in the 2-position and the cyclohexyl moiety in the 6-position, showed pK_i values for mAChRs higher than those of 2 and a selectivity profile analogous to that of the clinically approved drug oxybutynin. The study of the enantiomers of 3b and the corresponding tertiary amine 33b revealed that the eutomers are (2S,6S)-(−)-3b and (2S,6S)-(−)-33b, respectively. Docking simulations on the M₃ mAChR-resolved structure rationalized the experimental observations. The quaternary ammonium function, which should prevent the crossing of the blood–brain barrier, and the high M₃/M₂ selectivity, which might limit cardiovascular side effects, make 3b a valuable starting point for the design of novel antagonists potentially useful in peripheral diseases in which M₃ receptors are involved.

Smoking is an important factor that affects peripheral blood progenitor cells yield in healthy male donors

BACKGROUND

Smoking could reduce the CD34+ cells in peripheral blood of healthy individual. This study aimed to investigate the correlation between smoking load and the effect of peripheral blood hematopoietic progenitor cells (PBPCs) mobilization by granulocyte colony-stimulating factor (G-CSF) alone in healthy donors.

METHODS

Retrospective analysis was performed on 145 healthy adult PBPCs donors who underwent PBPCs mobilization and collection. Smoking factors were evaluated and correlated with mobilization responses, as indicated by the collected CD34+ cells concentration.

RESULTS

The collected CD34+ cells concentration was closely related to pre-CD34 (P < .001) and CD34+ cells collected per volume blood processed (P < .001) which suggested that collected CD34+ cells concentration was a reliable indicator of PBPCs mobilization efficiency. The heavy smoking donors revealed significantly lower collected CD34+ cells concentration, compared to that of the nonsmoking (P < .001) and light smoking donors (P < .05). The levels of collected CD34+ cells in light smoking were also obviously lower than that in nonsmoking donors (P < .05).There were no obvious differences in the collected CD34+ cells concentration, overall processed blood volume and total collected CD34+ cells between nonsmoking and smoking cessation groups (P = .490; P = .464; P = .819).

CONCLUSION

Cigarette smoking is an important factor that affects the yield of PBPCs in male donors, especially when the smoking load is more than five pack-years. Mobilization of PBMCs could be restored by smoking cessation in chronic smokers.

A Novel Immunomodulatory Mechanism Dependent on Acetylcholine Secreted by Human Bone Marrow-derived Mesenchymal Stem Cells

Background and Objectives

Mesenchymal stem cells (MSCs) are used to treat autoimmune or inflammatory diseases. Our aim was to determine the immunomodulatory mechanisms elicited by MSCs during inflammation.

Methods and Results

We cocultured MSCs with peripheral blood mononuclear cells for a mixed lymphocyte reaction or stimulated them by phytohemagglutinin. Morphological changes of MSCs and secretion of acetylcholine (ACh) from MSCs were measured. The effects of an ACh antagonist and ACh agonist on lymphocyte proliferation and proinflammatory-cytokine production were determined. The inflammatory milieu created by immune-cell activation caused MSCs to adopt a neuronlike phenotype and induced them to release ACh. Additionally, nicotinic acetylcholine receptors (nAChRs) were upregulated in activated peripheral blood mononuclear cells. We observed that ACh bound to nAChR on activated immune cells and led to the inhibition of lymphocyte proliferation and of proinflammatory-cytokine production. MSC-mediated immunosuppression through ACh activity was reversed by an ACh antagonist called α-bungarotoxin, and lymphocyte proliferation was inhibited by an ACh agonist, ACh chloride.

Conclusions

Our findings point to a novel immunomodulatory mechanism in which ACh secreted by MSCs under inflammatory conditions might modulate immune cells. This study may provide a novel method for the treatment of autoimmune diseases by means of MSCs.

Human umbilical cord perivascular cells: A novel source of the organophosphate antidote butyrylcholinesterase

Human butyrylcholinesterase (BChE) is a well-characterized bioscavenger with significant potential as a prophylactic or post-exposure treatment for organophosphate poisoning. Despite substantial efforts, BChE has proven technically challenging to produce in recombinant systems. Recombinant BChE tends to be insufficiently or incorrectly glycosylated, and consequently exhibits a truncated half-life, compromised activity, or is immunogenic. Thus, expired human plasma remains the only reliable source of the benchmark BChE tetramer, but production is costly and time intensive and presents possible blood-borne disease hazards. Here we report a human BChE production platform that produces functionally active, tetrameric BChE enzyme, without the addition of external factors such as polyproline peptides or chemical or gene modification required by other systems. Human umbilical cord perivascular cells (HUCPVCs) are a rich population of mesenchymal stromal cells (MSCs) derived from Wharton's jelly. We show that HUCPVCs naturally and stably secrete BChE during culture in xeno- and serum-free media, and can be gene-modified to increase BChE output. However, BChE secretion from HUCPVCs is limited by innate feedback mechanisms that can be interrupted by addition of miR 186 oligonucleotide mimics or by competitive inhibition of muscarinic cholinergic signalling receptors by addition of atropine. By contrast, adult bone marrow-derived mesenchymal stromal cells neither secrete measurable levels of BChE naturally, nor after gene modification. Further work is required to fully characterize and disable the intrinsic ceiling of HUCPVC-mediated BChE secretion to achieve commercially relevant enzyme output. However, HUCPVCs present a unique opportunity to produce both native and strategically engineered recombinant BChE enzyme in a human platform with the innate capacity to secrete the benchmark human plasma form.

Direct transdifferentiation of human Wharton's jelly mesenchymal stromal cells into cholinergic-like neurons

Barckground Alzheimer's disease (AD) is mainly caused by cellular loss and dysfunction of the basal forebrain cholinergic neurons and cholinergic axons in the cortex leading to slowly progressive decline in learning and memory performance. Unfortunately, no definitive treatment to halt neural cell loss exists to date. Therefore, it is necessary to obtain an unlimited source of cholinergic neurons for future pharmacological applications in AD. Human mesenchymal stromal cells (hMSCs) represent a unique source of cholinergic-like neurons (ChLNs). New method hWJ-MSCs were incubated with Cholinergic-N-Run medium for 4 and 7 days. Results hWJ-MSCs cultured with Cholinergic-N-Run medium differentiated into ChLNs in 4 days as evidenced by high levels of protein expression of the neuronal markers ChAT, VAChT, AChE, MAP2, β-Tubulin III, NeuN, TUC-4, NF-L and no expression of the immature marker SOX2, the dopaminergic marker TH, GABAergic marker GAD67 and glial marker GFAP. Comparison with existing method(s) The hWJ-MSCs form ChLNs (e.g., ∼26% IF+) within 20 days by using complex conditioned mediums that are expensive and time-consuming. We report for the first time, to our best knowledge, a direct method of hWJ-MSCs transdifferentiation into ChLNs (∼76% ChAT /VAChT assessed by immunofluorescence microscopy and flow cytometry) in an economic, efficient and timely fashion. Conclusions The fastest method to obtain ChLNs from hWJ-MSCs takes only four days using the one-step incubation medium Cholinergic-N-Run.

Maternal Nicotine Exposure Leads to Augmented Expression of the Antioxidant Adipose Tissue Triglyceride Lipase Long-Term in the White Adipose of Female Rat Offspring

Globally, approximately 10%-25% of women smoke during pregnancy. Since nicotine is highly addictive, women may use nicotine-containing products like nicotine replacement therapies for smoking cessation, but the long-term consequences of early life exposure to nicotine remain poorly defined. Our laboratory has previously demonstrated that maternal nicotine exposed (MNE) rat offspring exhibit hypertriglyceridemia due to increased hepatic de novo lipogenesis. Hypertriglyceridemia may also be attributed to impaired white adipose tissue (WAT) lipid storage; however, the effects of MNE on WAT are not completely understood. We hypothesize that nicotine-induced alterations in adipose function (eg, lipid storage) underlie dyslipidemia in MNE adults. Female 6-month-old rats exposed to nicotine during gestation and lactation exhibited significantly decreased visceral adipocyte cell area by 40%, attributed, in part, to a 3-fold increase in adipose triglyceride lipase (ATGL) protein expression compared with vehicle. Given ATGL has antioxidant properties and in utero nicotine exposure promotes oxidative stress in various tissues, we next investigated if there was evidence of increased oxidative stress in MNE WAT. At both 3 weeks and 6 months, MNE offspring expressed 37%-48% higher protein levels of superoxide dismutase-1 and -2 in WAT. Since oxidative stress can induce inflammation, we examined the inflammatory profile of WAT and found increased expression of cytokines (interleukin-1β, tumor necrosis factor α, and interleukin-6) by 44%-61% at 6 months. Collectively, this suggests that the expression of WAT ATGL may be induced to counter MNE-induced oxidative stress and inflammation. However, higher levels of ATGL would further promote lipolysis in WAT, culminating in impaired lipid storage and long-term dyslipidemia.

Histone hypo-acetylation of Sox9 mediates nicotine-induced weak cartilage repair by suppressing BMSC chondrogenic differentiation

BACKGROUND

Nicotine has negative effects on tissue repair, little research concerns its effect on the cartilage repair of tissue engineering stem cells. The present study aimed to investigate the effects of nicotine on the bone marrow-derived mesenchymal stem cells' (BMSCs) chondrogenic repair function of cartilage defects and explored the molecular mechanism.

METHODS

A cartilage defect model of rat was repaired by BMSC transplantation, and treated with nicotine or saline at 2.0 mg/kg/d in 12 weeks. Nicotine's effect on chondrogenic differentiation was studied by exposing BMSCs to nicotine at 0.1, 1, 10, and 100 μM, and methyllycaconitine (MLA), which is a selective α7-nicotinic acetylcholine receptor (nAChR) inhibitor and si-RNA of nuclear factor of activated T cells 2 (NFATc2), were used to verify the molecular mechanism of nicotine's effect.

RESULTS

Data showed that nicotine inhibited cartilage repair function by suppressing SRY-type high-mobility group box 9 (Sox9) in regenerated tissues. Further in vitro study demonstrated that nicotine enhanced intracellular Ca²⁺ and activity of calcineurin (CaN) through α7-nAChR, increased the nucleic expressions of NFATc2 and the bindings to SOX9 promoter, and thus reduced the acetylation of H3K9 and H3K14 in SOX9 promoter.

CONCLUSIONS

Findings from this study demonstrated that nicotine suppressed the chondrogenic differentiation of BMSCs in vivo and in vitro, which offers insight into the risk assessment of cartilage defect repair in a nicotine exposure population and its therapeutic target.

Differential Expression of Cholinergic System Components in Human Induced Pluripotent Stem Cells, Bone Marrow-Derived Multipotent Stromal Cells, and Induced Pluripotent Stem Cell-Derived Multipotent Stromal Cells

The components of the cholinergic system are evolutionary very old and conserved molecules that are expressed in typical spatiotemporal patterns. They are involved in signaling in the nervous system, whereas their functions in nonneuronal tissues are hardly understood. Stem cells present an attractive cellular system to address functional issues. This study therefore compared human induced pluripotent stem cells (iPSCs; from cord blood endothelial cells), mesenchymal stromal cells derived from iPSCs (iPSC-MSCs), and bone marrow-derived MSCs (BM-MSCs) from up to 33 different human donors with respect to gene expressions of components of the cholinergic system. The status of cells was identified and characterized by the detection of cell surface antigens using flow cytometry. Acetylcholinesterase expression in iPSCs declined during their differentiation into MSCs and was comparably low in BM-MSCs. Butyrylcholinesterase was present in iPSCs, increased upon transition from the three-dimensional embryoid body phase into monolayer culture, and declined upon further differentiation into iPSC-MSCs. In BM-MSCs a notable butyrylcholinesterase expression could be detected in only four donors, but was elusive in other patient-derived samples. Different nicotinic acetylcholine receptor subunits were preferentially expressed in iPSCs and during early differentiation into iPSC-MSCs, low expression was detected in iPS-MSCs and in BM-MSCs. The m2 and m3 variants of muscarinic acetylcholine receptors were detected in all stem cell populations. In BM-MSCs, these gene expressions varied between donors. Together, these data reveal the differential expression of cholinergic signaling system components in stem cells from specific sources and suggest the utility of our approach to establish informative biomarkers.

M2 muscarinic receptor activation inhibits cell proliferation and migration of rat adipose-mesenchymal stem cells

Mesenchymal stem cells (MSCs), also known as stromal mesenchymal stem cells, are multipotent cells, which can be found in many tissues and organs as bone marrow, adipose tissue and other tissues. In particular MSCs derived from Adipose tissue (ADSCs) are the most frequently used in regenerative medicine because they are easy to source, rapidly expandable in culture and excellent differentiation potential into adipocytes, chondrocytes, and other cell types. Acetylcholine (ACh), the most important neurotransmitter in Central nervous system (CNS) and peripheral nervous system (PNS), plays important roles also in non-neural tissue, but its functions in MSCs are still not investigated. Although MSCs express muscarinic receptor subtypes, their role is completely unknown. In the present work muscarinic cholinergic effects were characterized in rat ADSCs. Analysis by RT-PCR demonstrates that ADSCs express M1-M4 muscarinic receptor subtypes, whereas M2 is one of the most expressed subtype. For this reason, our attention was focused on M2 subtype. By using the selective M2 against Arecaidine Propargyl Ester (APE) we performed cell proliferation and migration assays demonstrating that APE causes cell growth and migration inhibition without affecting cell survival. Our results indicate that ACh via M2 receptors, may contribute to the maintaining of the ADSCs quiescent status. These data are the first evidence that ACh, via muscarinic receptors, might contribute to control ADSCs physiology.

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

Distribution and immunohistochemical characteristics of cocaine- and amphetamineregulated transcript-positive nerve elements in the pelvic ganglia of the female pig

Cocaine- and amphetamine-regulated transcript (CART) peptides are widely expressed not only in the brain but also in numerous endocrine/neuroendocrine cells as well as in neurons of the peripheral nervous system. The present study investigated the distribution patterns of CART-like immunoreactivity in the pelvic plexus (PP) of the female pig. The co-expression of CART with principal neurotransmitter markers: choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), serotonin (5-HT) or biologically active neuropeptides: pituitary adenylate cyclase-activating polypeptide (PACAP), substance P (SP), calbindin was analyzed using double immunohistochemical stainings. Amongst neurons immunopositive to Hu C/D panneuronal marker as many as 4.1 ± 1.2% in right and 4.4 ± 1.6% in left pelvic ganglia were found to express CART. The vast majority of CART-IR ganglionic neurons were predominantly small in size and were evenly scattered throughout particular ganglia. Immunoreactivity to CART was also detected in numerous nerve terminals (which frequently formed pericellular formations around CART-negative perikarya) as well as in numerous nerve fibres within nerve branches interconnecting the unilateral pelvic ganglia. Immunohistochemistry revealed that virtually all CART-IR neurons were cholinergic in nature and CART-IR basket-like formations frequently encircled TH-positive/CART-negative perikarya. None of CART-IR ganglionic neurons showed immunoreactivity to SP, PACAP, 5-HT or calbindin. CART-IR nerve fibres ran in a close vicinity to serotonin-containing cells or faintly labelled SP-expressing neurons. On the other hand, PACAP-IR, SP-IR (but not 5-HT-positive) nerve terminals were found to run in close proximity to CART-IR neurons. Our results indicate that: 1) CART present in PP may influence the activity of pelvic ganglionic neurons/SIF cells, 2) PP should be considered as a potential source of CART-like supply to pelvic viscera and 3) functional interactions between CART and SP or PACAP are possible at the periphery.

Cigarette smoke challenges bone marrow mesenchymal stem cell capacities in guinea pig

Background

Cigarette smoke (CS) is associated with lower numbers of circulating stem cells and might severely affect their mobilization, trafficking and homing. Our study was designed to demonstrate in an animal model of CS exposure whether CS affects the homing and functional capabilities of bone marrow-derived mesenchymal stem cells (BM-MSCs).

Methods

Guinea pigs (GP), exposed or sham-exposed to CS, were administered via tracheal instillation or by vascular administration with 2.5 × 10⁶ BM-MSCs obtained from CS-exposed or sham-exposed animal donors. Twenty-four hours after cell administration, animals were sacrificed and cells were visualised into lung structures by optical microscopy. BM-MSCs from 8 healthy GP and from 8 GP exposed to CS for 1 month were isolated from the femur, cultured in vitro and assessed for their proliferation, migration, senescence, differentiation potential and chemokine gene expression profile.

Results

CS-exposed animals showed greater BM-MSCs lung infiltration than sham-exposed animals regardless of route of administration. The majority of BM-MSCs localized in the alveolar septa. BM-MSCs obtained from CS-exposed animals showed lower ability to engraft and lower proliferation and migration. In vitro, BM-MSCs exposed to CS extract showed a significant reduction of proliferative, cellular differentiation and migratory potential and an increase in cellular senescence in a dose dependent manner.

Conclusion

Short-term CS exposure induces BM-MSCs dysfunction. Such dysfunction was observed in vivo, affecting the cell homing and proliferation capabilities of BM-MSCs in lungs exposed to CS and in vitro altering the rate of proliferation, senescence, differentiation and migration capacity. Additionally, CS induced a reduction in CXCL9 gene expression in the BM from CS-exposed animals underpinning a potential mechanistic action of bone marrow dysfunction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0530-0) contains supplementary material, which is available to authorized users.

Retinoic acid exacerbates chlorpyrifos action in ensuing adipogenic differentiation of C3H10T½ cells in a GSK3β dependent pathway

The cell differentiation can be exploited as a paradigm to evaluate the effects of noxious chemicals, on human health, either alone or in combinations. In this regard, the effect of a known cell differentiation agent, retinoic acid (RA) was analyzed in the presence of a noxious chemical chlorpyrifos (CPF), an organophosphate (OP), the receptors of which have recently been localized to mesenchymal stem cells (MSCs). The observed imbalance of adipogenic to skeletal differentiation by CPF together with conundrum about adipogenic potential of RA prompted us to delineate their combinatorial effects on C₃H₁₀T½MSC-like undifferentiated cells. Based on MTT assay, the cellular viability was retained by CPF at concentrations ranging from 0.01–50μM, beyond which it caused cytotoxicity. These non-toxic concentrations also mildly interfered with adipogenesis of C₃H₁₀T½ cells following exposure to adipogenic cocktail. However, upon exposure to RA alone, these MSCs adopted elongated morphology and accumulated lipid vesicles, by day 20, as discerned by phase-contrast and transmission electron microscopy (TEM), in concert with enhanced Oil Red O stained cells. This effect got strongly augmented upon exposure to combination of CPF and RA in a dose-dependent manner. Simultaneous up-regulation in perilipin-1 (PLIN1) and adipsin (ADN) genes, additionally reiterated the adipogenic differentiation. Mechanistically, GSK3β pathway was found to be a major player, whereby inhibiting it with lithium chloride (LiCl) resulted in complete blockage of lipid accumulation, accompanied by complete down regulation of PLIN1 and ADN gene expression. In conclusion, these observations for the first time, lend evidence that exposure of CPF accompanied by RA directs commitment of C₃H₁₀T½ cells to adipogenic differentiation through a process involving a crosstalk at GSK3β signaling.

Nicotine can modulate the effects of the mesenchymal stem cells on neutrophils

PURPOSE

It has been revealed that mesenchymal stem cells (MSCs) express some of the nicotinic receptor subunits. Moreover, the crosstalk between MSCs and neutrophils is not far-fetched. Therefore, the aim of the present study is to determine the role of nicotine on the effects of MSCs on neutrophils.

METHODS

After the isolation of mesenchymal stem cells from the bone marrow of rats, these cells were pulsed with different concentrations of nicotine (0, 0.1, 0.5, and 1μM) for different periods (24, 48, and 72h). Then, the neutrophils were co-cultured with MSCs for 4h and the functions of neutrophils were evaluated.

RESULTS

The obtained findings showed that MSCs pulsed with nicotine significantly enhanced the viability and the phagocytic activity of co-cultured neutrophils and simultaneously, decreased the production of reactive oxygen substances (ROS), induced by f-MLP in neutrophils, more profound than MSCs without treatment. Moreover, MSCs, pulsed with nicotine at low to moderate concentrations, preserved the respiratory burst, triggered by opsonized yeast in neutrophils. Nevertheless, a high concentration of nicotine can interfere with the latter aspect of the crosstalk between MSCs and neutrophils.

CONCLUSION

The obtained data can offer a new insight into the potential mechanisms, underlying the immunomodulatory effects of nicotine.

Involvement of the Nonneuronal Cholinergic System in Bone Remodeling in Rat Midpalatal Suture after Rapid Maxillary Expansion

Few studies sought to analyze the expression and function of the nonneuronal acetylcholine system in bone remodeling in vivo due to the lack of suitable models. We established a rat maxilla expansion model in which the midline palatine suture of the rat was rapidly expanded under mechanical force application, inducing tissue remodeling and new bone formation, which could be a suitable model to investigate the role of the nonneuronal acetylcholine system in bone remodeling in vivo. During the expansion, the expression pattern changes of the nonneuronal cholinergic system components and the mRNA levels of OPG/RANKL were detected by immunohistochemistry or real-time PCR. The value of the RANKL/OPG ratio significantly increased after 1 day of expansion, indicating dominant bone resorption induced by the mechanical stimulation; however after 3 days of expansion, the value of the RANKL/OPG ratio significantly decreased, suggesting a dominant role of the subsequent bone formation process. Increasing expression of Ach was detected after 3 days of expansion which indicated that ACh might play a role in bone formation. The mRNA expression levels of other components also showed observable changes during the expansion which confirmed the involvement of the nonneuronal cholinergic system in the process of bone remodeling in vivo. Further researches are still needed to figure out the detailed functions of the nonneuronal cholinergic system and its components.

Expression and Functional Role of α7 Nicotinic Receptor in Human Cytokine-stimulated Natural Killer (NK) Cells

The homomeric α7 nicotinic receptor (nAChR) is one of the most abundant nAChRs in the central nervous system where it contributes to cognition, attention, and working memory. α7 nAChR is also present in lymphocytes, dendritic cells (DCs), and macrophages and it is emerging as an important drug target for intervention in inflammation and sepsis. Natural killer (NK) cells display cytotoxic activity against susceptible target cells and modulate innate and adaptive immune responses through their interaction with DCs. We here show that human NK cells also express α7 nAChR. α7 nAChR mRNA is detected by RT-PCR and cell surface expression of α7 nAChR is detected by confocal microscopy and flow cytometry using α-bungarotoxin, a specific antagonist. Both mRNA and protein levels increase during NK stimulation with cytokines (IL-12, IL-18, and IL-15). Exposure of cytokine-stimulated NK cells to PNU-282987, a specific α7 nAChR agonist, increases intracellular calcium concentration ([Ca(2+)]i) mainly released from intracellular stores, indicating that α7 nAChR is functional. Moreover, its activation by PNU-282987 plus a specific positive allosteric modulator greatly enhances the Ca(2+) responses in NK cells. Stimulation of NK cells with cytokines and PNU-282987 decreases NF-κB levels and nuclear mobilization, down-regulates NKG2D receptors, and decreases NKG2D-dependent cell-mediated cytotoxicity and IFN-γ production. Also, such NK cells are less efficient to trigger DC maturation. Thus, our results demonstrate the anti-inflammatory role of α7 nAChR in NK cells and suggest that modulation of its activity in these cells may constitute a novel target for regulation of the immune response.

Linking Pesticide Exposure with Pediatric Leukemia: Potential Underlying Mechanisms

Leukemia is the most common cancer in children, representing 30% of all childhood cancers. The disease arises from recurrent genetic insults that block differentiation of hematopoietic stem and/or progenitor cells (HSPCs) and drives uncontrolled proliferation and survival of the differentiation-blocked clone. Pediatric leukemia is phenotypically and genetically heterogeneous with an obscure etiology. The interaction between genetic factors and environmental agents represents a potential etiological driver. Although information is limited, the principal toxic mechanisms of potential leukemogenic agents (e.g., etoposide, benzene metabolites, bioflavonoids and some pesticides) include topoisomerase II inhibition and/or excessive generation of free radicals, which may induce DNA single- and double-strand breaks (DNA-DSBs) in early HSPCs. Chromosomal rearrangements (duplications, deletions and translocations) may occur if these lesions are not properly repaired. The initiating hit usually occurs in utero and commonly leads to the expression of oncogenic fusion proteins. Subsequent cooperating hits define the disease latency and occur after birth and may be of a genetic, epigenetic or immune nature (i.e., delayed infection-mediated immune deregulation). Here, we review the available experimental and epidemiological evidence linking pesticide exposure to infant and childhood leukemia and provide a mechanistic basis to support the association, focusing on early initiating molecular events.

Intrauterine low-functional programming of IGF1 by prenatal nicotine exposure mediates the susceptibility to osteoarthritis in female adult rat offspring

This study aimed to evaluate whether female adult offspring born with intrauterine growth retardation induced by prenatal nicotine exposure (PNE) are susceptible to osteoarthritis (OA) and to explore the underlying programming mechanisms. Pregnant rats were treated with nicotine or saline at 2.0 mg/kg/d from gestational d 11 to 20. The female adult offspring with or without PNE were forced with a strenuous treadmill running for 6 wk to induce OA. Nicotine's effects on fetal articular chondrocytes were studied by exposing chondrocytes to nicotine for 10 d, and dihydro-β-erythroidine, a selective α4β2-nicotinic acetylcholine receptor (nAChR) inhibitor, was used to identify the change of nicotine's effect. For adult offspring, increased cartilage destruction and accelerated OA progression were observed in the PNE group with running; the expression of α1 chain of type II collagen (Col2A1), aggrecan, SRY-type high mobility group box 9 (Sox9), and IGF1 signaling molecules in the cartilage of PNE offspring were decreased. For fetuses, elevated serum corticosteroid and nicotine levels and suppressed IGF1 levels were observed; expression of Col2A1, aggrecan, Sox9, and IGF1 were reduced. The result of chondrocytes revealed that nicotine impeded the expression of Col2A1, aggrecan, and IGF1; blocking α4β2-nAChR rescued nicotine's suppression. In conclusion, PNE increases the susceptibility of adult offspring to OA; the potential mechanism involves IGF1 low-functional programming in articular cartilage caused directly by the action of nicotine on α4β2-nAChR.

Effective gene delivery into human stem cells with a cell-targeting Peptide-modified bioreducible polymer

Stem cells are poorly permissive to non-viral gene transfection reagents. In this study, we explored the possibility of improving gene delivery into human embryonic (hESC) and mesenchymal (hMSC) stem cells by synergizing the activity of a cell-binding ligand with a polymer that releases nucleic acids in a cytoplasm-responsive manner. A 29 amino acid long peptide, RVG, targeting the nicotinic acetylcholine receptor (nAchR) was identified to bind both hMSC and H9-derived hESC. Conjugating RVG to a redox-sensitive biodegradable dendrimer-type arginine-grafted polymer (PAM-ABP) enabled nanoparticle formation with plasmid DNA without altering the environment-sensitive DNA release property and favorable toxicity profile of the parent polymer. Importantly, RVG-PAM-ABP quantitatively enhanced transfection into both hMSC and hESC compared to commercial transfection reagents like Lipofectamine 2000 and Fugene. ∼60% and 50% of hMSC and hESC were respectively transfected, and at increased levels on a per cell basis, without affecting pluripotency marker expression. RVG-PAM-ABP is thus a novel bioreducible, biocompatible, non-toxic, synthetic gene delivery system for nAchR-expressing stem cells. Our data also demonstrates that a cell-binding ligand like RVG can cooperate with a gene delivery system like PAM-ABP to enable transfection of poorly-permissive cells.

Vagus nerve through α7 nAChR modulates lung infection and inflammation: models, cells, and signals

Cholinergic anti-inflammatory pathway (CAP) bridges immune and nervous systems and plays pleiotropic roles in modulating inflammation in animal models by targeting different immune, proinflammatory, epithelial, endothelial, stem, and progenitor cells and signaling pathways. Acute lung injury (ALI) is a devastating inflammatory disease. It is pathogenically heterogeneous and involves many cells and signaling pathways. Here, we emphasized the research regarding the modulatory effects of CAP on animal models, cell population, and signaling pathways that involved in the pathogenesis of ALI. By comparing the differential effects of CAP on systemic and pulmonary inflammation, we postulated that a pulmonary parasympathetic inflammatory reflex is formed to sense and respond to pathogens in the lung. Work targeting the formation and function of pulmonary parasympathetic inflammatory reflex would extend our understanding of how vagus nerve senses, recognizes, and fights with pathogens and inflammatory responses.

Acetylcholine affects osteocytic MLO-Y4 cells via acetylcholine receptors

The identification of the neuronal control of bone remodeling has become one of the many significant recent advances in bone biology. Cholinergic activity has recently been shown to favor bone mass accrual by complex cellular regulatory networks. Here, we identified the gene expression of the muscarinic and nicotinic acetylcholine receptors (m- and nAChRs) in mice tibia tissue and in osteocytic MLO-Y4 cells. Acetylcholine, which is a classical neurotransmitter and an osteo-neuromediator, not only influences the mRNA expression of the AChR subunits but also significantly induces the proliferation and viability of osteocytes. Moreover, acetylcholine treatment caused the reciprocal regulation of RANKL and OPG mRNA expression, which resulted in a significant increase in the mRNA ratio of RANKL:OPG in osteocytes via acetylcholine receptors. The expression of neuropeptide Y and reelin, which are two neurogenic markers, was also modulated by acetylcholine via m- and nAChRs in MLO-Y4 cells. These results indicated that osteocytic acetylcholine receptors might be a new valuable mediator for cell functions and even for bone remodeling.

Cell therapy with autologous mesenchymal stem cells-how the disease process impacts clinical considerations

The prospective clinical use of multipotent mesenchymal stromal cells (MSCs) holds enormous promise for the treatment of a large number of degenerative and age-related diseases. In particular, autologous MSCs isolated from bone marrow (BM) are considered safe and have been extensively evaluated in clinical trials. Nevertheless, different efficacies have been reported, depending on the health status and age of the donor. In addition, the biological functions of BM-MSCs from patients with various diseases may be impaired. Furthermore, medical treatments such as long-term chemotherapy and immunomodulatory therapy may damage the BM microenvironment and affect the therapeutic potential of MSCs. Therefore, a number of practical problems must be addressed before autologous BM-MSCs can be widely applied with higher efficiency in patients. As such, this review focuses on various factors that directly influence the biological properties of BM-MSCs, and we discuss the possible mechanisms of these alterations.

Bone marrow stromal and vascular smooth muscle cells have chemosensory capacity via bitter taste receptor expression

The ability of cells to detect changes in the microenvironment is important in cell signaling and responsiveness to environmental fluctuations. Our interest is in understanding how human bone marrow stromal-derived cells (MSC) and their relatives, vascular smooth muscle cells (VSMC), interact with their environment through novel receptors. We found, through a proteomics screen, that MSC express the bitter taste receptor, TAS2R46, a protein more typically localized to the taste bud. Expression was also confirmed in VSMCs. A prototypical bitter compound that binds to the bitter taste receptor class, denatonium, increased intracellular calcium release and decreased cAMP levels as well as increased the extracellular release of ATP in human MSC. Denatonium also bound and activated rodent VSMC with a change in morphology upon compound exposure. Finally, rodents given denatonium in vivo had a significant drop in blood pressure indicating a vasodilator response. This is the first description of chemosensory detection by MSC and VSMCs via a taste receptor. These data open a new avenue of research into discovering novel compounds that operate through taste receptors expressed by cells in the marrow and vascular microenvironments.

Cotransplantation with specific populations of spina bifida bone marrow stem/progenitor cells enhances urinary bladder regeneration

Spina bifida (SB) patients afflicted with myelomeningocele typically possess a neurogenic urinary bladder and exhibit varying degrees of bladder dysfunction. Although surgical intervention in the form of enterocystoplasty is the current standard of care in which to remedy the neurogenic bladder, it is still a stop-gap measure and is associated with many complications due to the use of bowel as a source of replacement tissue. Contemporary bladder tissue engineering strategies lack the ability to reform bladder smooth muscle, vasculature, and promote peripheral nerve tissue growth when using autologous populations of cells. Within the context of this study, we demonstrate the role of two specific populations of bone marrow (BM) stem/progenitor cells used in combination with a synthetic elastomeric scaffold that provides a unique and alternative means to current bladder regeneration approaches. In vitro differentiation, gene expression, and proliferation are similar among donor mesenchymal stem cells (MSCs), whereas poly(1,8-octanediol-cocitrate) scaffolds seeded with SB BM MSCs perform analogously to control counterparts with regard to bladder smooth muscle wall formation in vivo. SB CD34(+) hematopoietic stem/progenitor cells cotransplanted with donor-matched MSCs cause a dramatic increase in tissue vascularization as well as an induction of peripheral nerve growth in grafted areas compared with samples not seeded with hematopoietic stem/progenitor cells. Finally, MSC/CD34(+) grafts provided the impetus for rapid urothelium regeneration. Data suggest that autologous BM stem/progenitor cells may be used as alternate, nonpathogenic cell sources for SB patient-specific bladder tissue regeneration in lieu of current enterocystoplasty procedures and have implications for other bladder regenerative therapies.

Nicotine alters MicroRNA expression and hinders human adult stem cell regenerative potential

Adult stem cells are critical for the healing process in regenerative medicine. However, cigarette smoking inhibits stem cell recruitment to tissues and delays the wound-healing process. This study investigated the effect of nicotine, a major constituent in the cigarette smoke, on the regenerative potentials of human mesenchymal stem cells (MSC) and periodontal ligament-derived stem cells (PDLSC). The cell proliferation of 1.0 μM nicotine-treated MSC and PDLSC was significantly reduced when compared to the untreated control. Moreover, nicotine also retarded the locomotion of these adult stem cells. Furthermore, their osteogenic differentiation capabilities were reduced in the presence of nicotine as evidenced by gene expression (RUNX2, ALPL, BGLAP, COL1A1, and COL1A2), calcium deposition, and alkaline phosphatase activity analyses. In addition, the microRNA (miRNA) profile of nicotine-treated PDLSC was altered; suggesting miRNAs might play an important role in the nicotine effects on stem cells. This study provided the possible mechanistic explanations on stem cell-associated healing delay in cigarette smoking.

Nicotine-induced chondrogenic differentiation of human bone marrow stromal cells in vitro

PURPOSE

Nicotine has been reported that it has a dose-dependent effect on matrix mineralization by human bone marrow cells. However, there is no relevant research concerning on chondrogenic differentiation potential of bone marrow stromal stem cells (BMSCs) treated with nicotine in vitro. The aims of the study were to examine the effects of nicotine (0, 10(-7), 10(-6) and 10(-5) M) on the proliferation and chondrogenic differentiation of BMSCs from three healthy donors in vitro.

METHODS

BMSCs proliferation was analyzed by CCK8 assay and real-time polymerase chain reaction was used to assay the expression of type II collagen, aggrecan, type I collagen and type X collagen. The proteoglycan content was stained by Alcian blue, and the sulfated glycosaminoglycan (sGAG) content of BMSCs was quantified spectrofluorometrically using dimethylmethylene blue.

RESULTS

The cell viability was not significantly impaired until up to a concentration of 10(-5) M nicotine. Nicotine promoted the proliferation and enhanced the expression of type II collagen at the level up to 10(-6) M (P < 0.05). The expression of aggrecan was reduced at the concentration of 10(-5) M nicotine at day 14 (P < 0.05), and there was no significant difference in aggrecan gene expression at 10(-7) and 10(-6) M nicotine levels compared to control group (n.s.). Also the fibroblastic and hypertrophic gene expressions were down-regulated in the chondrogenic medium with 10(-7)-10(-5) M nicotine (P < 0.05).

CONCLUSION

It was implied that local application of nicotine at an appropriate concentration may be a promising approach for enhancing chondrogenic differentiation capacity of BMSCs in cell-based cartilage tissue engineering. Also these results indicate that nicotine maybe a potentially useful drug for the treatment of Osteoarthritis.

Acetylcholine induces mesenchymal stem cell migration via Ca2+ /PKC/ERK1/2 signal pathway

Acetylcholine (ACh) plays an important role in neural and non-neural function, but its role in mesenchymal stem cell (MSC) migration remains to be determined. In the present study, we have found that ACh induces MSC migration via muscarinic acetylcholine receptors (mAChRs). Among several mAChRs, MSCs express mAChR subtype 1 (m1AChR). ACh induces MSC migration via interaction with mAChR1. MEK1/2 inhibitor PD98059 blocks ERK1/2 phosphorylation while partially inhibiting the ACh-induced MSC migration. InsP3Rs inhibitor 2-APB that inhibits MAPK/ERK phosphorylation completely blocks ACh-mediated MSC migration. Interestingly, intracellular Ca(2+) ATPase-specific inhibitor thapsigargin also completely blocks ACh-induced MSC migration through the depletion of intracellular Ca(2+) storage. PKCα or PKCβ inhibitor or their siRNAs only partially inhibit ACh-induced MSC migration, but PKC-ζ siRNA completely inhibits ACh-induced MSC migration via blocking ERK1/2 phosphorylation. These results indicate that ACh induces MSC migration via Ca(2+), PKC, and ERK1/2 signal pathways.

Ion channels in hematopoietic and mesenchymal stem cells

Hematopoietic stem cells (HSCs) reside in bone marrow niches and give rise to hematopoietic precursor cells (HPCs). These have more restricted lineage potential and eventually differentiate into specific blood cell types. Bone marrow also contains mesenchymal stromal cells (MSCs), which present multilineage differentiation potential toward mesodermal cell types. In bone marrow niches, stem cell interaction with the extracellular matrix is mediated by integrin receptors. Ion channels regulate cell proliferation and differentiation by controlling intracellular Ca(2+), cell volume, release of growth factors, and so forth. Although little evidence is available about the ion channel roles in true HSCs, increasing information is available about HPCs and MSCs, which present a complex pattern of K(+) channel expression. K(+) channels cooperate with Ca(2+) and Cl(-) channels in regulating calcium entry and cell volume during mitosis. Other K(+) channels modulate the integrin-dependent interaction between leukemic progenitor cells and the niche stroma. These channels can also regulate leukemia cell interaction with MSCs, which also involves integrin receptors and affects the MSC-mediated protection from chemotherapy. Ligand-gated channels are also implicated in these processes. Nicotinic acetylcholine receptors regulate cell proliferation and migration in HSCs and MSCs and may be implicated in the harmful effects of smoking.