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Open Access Publications from the University of California

Scholarly Works (8 results)

  • Thesis
  • Peer Reviewed
UC Riverside Electronic Theses and Dissertations (2018)

Electronic cigarettes (ECs), popular nicotine-delivery devices, have emerged as potential health hazards. ECs contain nicotine, flavor chemicals, and solvents used to generate aerosols. The purpose of my dissertation was to develop bioassays and video bioinformatics tools to characterize effects of disposable-style ECs on cultured lung cells, stem cells, and cancer cells. A screening method was developed to identify toxic EC products and evaluate their modes of action (MOAs). StemCellQC software can assess the health of pluripotent embryonic stem cell (ESC) colonies and extract data on dynamic processes such as cell proliferation, spreading, migration, and cell death. MitoMo software was developed to assess mitochondrial (important and sensitive organelles) health parameters such as mitophagy, morphology, dynamics, membrane potential, oxidative stress, calcium levels, and mtDNA nucleoids.

A two-tiered screen was performed to identify harmful EC products. Based on tier 1 assays, two brands were identified for further investigation. In tier 2 assays, Greensmoke exposure led to a decrease in growth rate, cytoskeletal depolymerization, adhesion defects, oxidation of mitochondrial proteins, and eventual apoptosis. Vuse exposure produced an epithelial-to-mesenchymal transition (EMT) and increased α-smooth muscle actin, a fibrosis biomarker. It also caused loss of cell-to-cell junctions, migratory behavior, internalization of junctional stabilizers E-cadherin and P120-catenin, and nuclear translocation of β-catenin (dual role as a transcription factor for EMT). EMT is the initial step enabling metastasis of cancer cells, which is a concern for former smokers with a pre-existing lung tumor. Fibrosis, epithelial cell disruption, and oxidative damage can lead to chronic lung diseases.

The effects of ECs were studied on neural stem cells (NSCs) as an in vitro model for early development, since ECs are often targeted to youth and pregnant mothers, raising developmental risks. The high nicotine content in Vuse caused oxidative stress, autophagy defects, and a stress-induced mitochondrial hyperfusion (SIMH). Exposure to Vuse aerosols also led to upregulation and desensitization of nicotinic acetylcholine receptors (nAChRs). These findings are critical considering that nicotine is now widely available in EC products. Mitochondrial damage, oxidative stress and autophagy dysfunction can cause faulty stem cell populations, which may accelerate aging and lead to cancer, diabetes, neurodegenerative disorders.

    Cover page: Decoding the Molecular Mechanisms Underlying Electronic Cigarette Toxicity in Lung, Cancer and Stem Cells
    • Article
    • Peer Reviewed
    UC Riverside Previously Published Works (2017)
    Cofilin and other Actin-regulating proteins are essential in regulating the shape of dendritic spines, which are sites of neuronal communications in the brain, and their malfunctions are implicated in neurodegeneration related to aging. The analysis of cofilin motility in dendritic spines using fluorescence video-microscopy may allow for the discovery of its effects on synaptic functions. To date, the flow of cofilin has not been analyzed by automatic means. This paper presents Dendrite Protein Analysis (DendritePA), a novel automated pattern recognition software to analyze protein trafficking in neurons. Using spatiotemporal information present in multichannel fluorescence videos, the DendritePA generates a temporal maximum intensity projection that enhances the signal-to-noise ratio of important biological structures, segments and tracks dendritic spines, estimates the density of proteins in spines, and analyzes the flux of proteins through the dendrite/spine boundary. The motion of a dendritic spine is used to generate spine energy images, which are used to automatically classify the shape of common dendritic spines such as stubby, mushroom, or thin. By tracking dendritic spines over time and using their intensity profiles, the system can analyze the flux patterns of cofilin and other fluorescently stained proteins. The cofilin flux patterns are found to correlate with the dynamic changes in dendritic spine shapes. Our results also have shown that the activation of cofilin using genetic manipulations leads to immature spines while its inhibition results in an increase in mature spines.
      Cover page: Automated spatio-temporal analysis of dendritic spines and related protein dynamics
      • Article
      • Peer Reviewed
      UC Riverside Previously Published Works (2018)

      Objectives

      Epithelial-to-mesenchymal transition (EMT) is the initial step enabling the metastasis of cancer cells, which often leads to death. Although smoking is a major risk factor for lung cancer, there is still widespread use of conventional cigarettes. Recently, the tobacco industry has been transformed by the introduction of electronic cigarettes (ECs), which have lower levels of carcinogens and may provide a safer alternative. Here, we investigate the ability of EC liquids and aerosols to induce an EMT in A549 lung cancer cells.

      Materials and methods

      Human adenocarcinoma alveolar basal epithelial cells (A549) were exposed to EC liquids and aerosols from a popular product for 3-8 days. Live cell imaging, EMT biomarker analysis, and machine learning/image processing algorithms were used to characterize changes associated with EMT.

      Results

      Long-term exposure of A549 cells to menthol or tobacco-flavored EC liquids or aerosols induced an EMT that was characterized by acquisition of a fibroblast-like morphology, loss of cell-to-cell junctions, internalization of E-cadherin, increased motility, and upregulation of other EMT markers. The EMT was concurrent with plasma membrane to nuclear translocation of active β-catenin.

      Conclusion

      This is the first known study to show an EMT of lung cancer cells during exposure to EC products. Because an EMT is an initial step leading to metastasis, an intractable problem that often leads to patient death, this critical finding has significant implications for former or heavy cigarette smokers who are using EC and may be at risk for lung cancer or who may already have a lung tumor.
        Cover page: Epithelial-to-mesenchymal transition of A549 lung cancer cells exposed to electronic cigarettes
        • Article
        • Peer Reviewed
        UC Riverside Previously Published Works (2018)
        There is a critical need for better analytical methods to study mitochondria in normal and diseased states. Mitochondrial image analysis is typically done on still images using slow manual methods or automated methods of limited types of features. MitoMo integrated software overcomes these bottlenecks by automating rapid unbiased quantitative analysis of mitochondrial morphology, texture, motion, and morphogenesis and advances machine-learning classification to predict cell health by combining features. Our pixel-based approach for motion analysis evaluates the magnitude and direction of motion of: (1) molecules within mitochondria, (2) individual mitochondria, and (3) distinct morphological classes of mitochondria. MitoMo allows analysis of mitochondrial morphogenesis in time-lapse videos to study early progression of cellular stress. Biological applications are presented including: (1) establishing normal phenotypes of mitochondria in different cell types; (2) quantifying stress-induced mitochondrial hyperfusion in cells treated with an environmental toxicant, (3) tracking morphogenesis in mitochondria undergoing swelling, and (4) evaluating early changes in cell health when morphological abnormalities are not apparent. MitoMo unlocks new information on mitochondrial phenotypes and dynamics by enabling deep analysis of mitochondrial features in any cell type and can be applied to a broad spectrum of research problems in cell biology, drug testing, toxicology, and medicine.
          Cover page: Deep Analysis of Mitochondria and Cell Health Using Machine Learning
          • Article
          • Peer Reviewed
          UC Riverside Previously Published Works (2016)
          Thirdhand cigarette smoke (THS) was recently recognized as an environmental health hazard; however, little is known about it effects on cells. Mitochondria are sensitive monitors of cell health and report on environmentally induced stress. We tested the effects of low levels of THS extracted from terry cloth on mitochondrial morphology and function using stem cells with well-defined mitochondria. Concentrations of THS that did not kill cells caused stress-induced mitochondrial hyperfusion (SIMH), which was characterized by changes in mitochondrial morphology indicative of fusion, increased mitochondrial membrane potential (MMP), increased ATP levels, increased superoxide production, and increased oxidation of mitochondrial proteins. SIMH was accompanied by a decrease in Fis1 expression, a gene responsible for mitochondrial fission, and a decrease in apoptosis-related genes, including Aifm2, Bbc3, and Bid There was also down regulation of Ucp2, Ucp4, and Ucp5, genes that decrease MMP thereby reducing oxidative phosphorylation, while promoting glycolysis. These effects, which collectively accompany SIMH, are a prosurvival mechanism to rescue damaged mitochondria and protect cells from apoptosis. Prolonged exposure to THS caused a reduction in MMP and decreased cell proliferation, which likely leads to apoptosis.
            Cover page: From the Cover: Thirdhand Cigarette Smoke Causes Stress-Induced Mitochondrial Hyperfusion and Alters the Transcriptional Profile of Stem Cells
            • Article
            • Peer Reviewed
            UC Riverside Previously Published Works (2019)
            Stem cells provide a sensitive model to study exposure to toxicants, such as cigarette smoke. Electronic cigarettes (ECs) are popular nicotine delivery devices, often targeted to youth and pregnant mothers. However, little is known about how chemicals in ECs might affect neural stem cells, and in particular their mitochondria, organelles that maintain cell functionality and health. Here we show that the mechanism underlying EC-induced stem cell toxicity is stress-induced mitochondrial hyperfusion (SIMH), a transient survival response accompanied by increased mitochondrial oxidative stress. We identify SIMH as a survival response to nicotine, now widely available in EC refill fluids and in pure form for do-it-yourself EC products. These observed mitochondrial alterations combined with autophagy dysfunction to clear damaged mitochondria could lead to faulty stem cell populations, accelerate cellular aging, and lead to acquired mitochondriopathies. Any nicotine-containing product may likewise stress stem cells with long-term repercussions for users and passively exposed individuals. VIDEO ABSTRACT.
              Cover page: Mitochondrial Stress Response in Neural Stem Cells Exposed to Electronic Cigarettes
              • Article
              • Peer Reviewed
              UC Riverside Previously Published Works (2016)
              There is a foundational need for quality control tools in stem cell laboratories engaged in basic research, regenerative therapies, and toxicological studies. These tools require automated methods for evaluating cell processes and quality during in vitro passaging, expansion, maintenance, and differentiation. In this paper, an unbiased, automated high-content profiling toolkit, StemCellQC, is presented that non-invasively extracts information on cell quality and cellular processes from time-lapse phase-contrast videos. Twenty four (24) morphological and dynamic features were analyzed in healthy, unhealthy, and dying human embryonic stem cell (hESC) colonies to identify those features that were affected in each group. Multiple features differed in the healthy versus unhealthy/dying groups, and these features were linked to growth, motility, and death. Biomarkers were discovered that predicted cell processes before they were detectable by manual observation. StemCellQC distinguished healthy and unhealthy/dying hESC colonies with 96% accuracy by non-invasively measuring and tracking dynamic and morphological features over 48 hours. Changes in cellular processes can be monitored by StemCellQC and predictions can be made about the quality of pluripotent stem cell colonies. This toolkit reduced the time and resources required to track multiple pluripotent stem cell colonies and eliminated handling errors and false classifications due to human bias. StemCellQC provided both user-specified and classifier-determined analysis in cases where the affected features are not intuitive or anticipated. Video analysis algorithms allowed assessment of biological phenomena using automatic detection analysis, which can aid facilities where maintaining stem cell quality and/or monitoring changes in cellular processes are essential. In the future StemCellQC can be expanded to include other features, cell types, treatments, and differentiating cells.
                Cover page: Evaluating Cell Processes, Quality, and Biomarkers in Pluripotent Stem Cells Using Video Bioinformatics
                • Article
                • Peer Reviewed
                UC Irvine Previously Published Works (2024)
                Regeneration in the injured spinal cord is limited by physical and chemical barriers. Acute implantation of a multichannel poly(lactide-co-glycolide) (PLG) bridge mechanically stabilizes the injury, modulates inflammation, and provides a permissive environment for rapid cellularization and robust axonal regrowth through this otherwise inhibitory milieu. However, without additional intervention, regenerated axons remain largely unmyelinated (<10%), limiting functional repair. While transplanted human neural stem cells (hNSC) myelinate axons after spinal cord injury (SCI), hNSC fate is highly influenced by the SCI inflammatory microenvironment, also limiting functional repair. Accordingly, we investigated the combination of PLG scaffold bridges with hNSC to improve histological and functional outcome after SCI. In vitro, hNSC culture on a PLG scaffold increased oligodendroglial lineage selection after inflammatory challenge. In vivo, acute PLG bridge implantation followed by chronic hNSC transplantation demonstrated a robust capacity of donor human cells to migrate into PLG bridge channels along regenerating axons and integrate into the host spinal cord as myelinating oligodendrocytes and synaptically integrated neurons. Axons that regenerated through the PLG bridge formed synaptic circuits that connected the ipsilateral forelimb muscle to contralateral motor cortex. hNSC transplantation significantly enhanced the total number of regenerating and myelinated axons identified within the PLG bridge. Finally, the combination of acute bridge implantation and hNSC transplantation exhibited robust improvement in locomotor recovery. These data identify a successful strategy to enhance neurorepair through a temporally layered approach using acute bridge implantation and chronic cell transplantation to spare tissue, promote regeneration, and maximize the function of new axonal connections.
                  Cover page: Multichannel bridges and NSC synergize to enhance axon regeneration, myelination, synaptic reconnection, and recovery after SCI.
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