Publications by authors named "Shannon L J Sproul"

3 Publications

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Physioxic human cell culture improves viability, metabolism, and mitochondrial morphology while reducing DNA damage.

FASEB J 2019 04 16;33(4):5716-5728. Epub 2019 Jan 16.

Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.

Multicellular organisms balance oxygen delivery and toxicity by having oxygen pass through several barriers before cellular delivery. In human cell culture, these physiologic barriers are removed, exposing cells to higher oxygen levels. Human cells cultured in ambient air may appear normal, but this is difficult to assess without a comparison at physiologic oxygen. Here, we examined the effects of culturing human cells throughout the spectrum of oxygen availability on oxidative damage to macromolecules, viability, proliferation, the antioxidant and DNA damage responses, metabolism, and mitochondrial fusion and morphology. We surveyed 4 human cell lines cultured for 3 d at 7 oxygen conditions between 1 and 21% O. We show that oxygen levels and cellular benefit are not inversely proportional, but the benefit peaks within the physioxic range. Normoxic cells are in a perpetual state of responding to damaged macromolecules and mitochondrial networks relative to physioxic cells, which could compromise an investigation. These data contribute to the concept of an optimal oxygen availability for cell culture in the physioxic range where the oxygen is not too high to reduce oxidative damage, and not too low for efficient oxidative metabolism, but just right: the Goldiloxygen zone.-Timpano, S., Guild, B. D., Specker, E. J., Melanson, G., Medeiros, P. J., Sproul, S. L. J., Uniacke, J. Physioxic human cell culture improves viability, metabolism, and mitochondrial morphology while reducing DNA damage.
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http://dx.doi.org/10.1096/fj.201802279RDOI Listing
April 2019

Single-Cell Transcriptome Profiling of Mouse and hESC-Derived Pancreatic Progenitors.

Stem Cell Reports 2018 12;11(6):1551-1564

Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, BC V5Z 4H4, Canada; Departments of Surgery and Cellular and Physiological Sciences, University of British Columbia, 950 28(th) Avenue West, Vancouver, BC V5Z4H4, Canada. Electronic address:

Human embryonic stem cells (hESCs) are a potential unlimited source of insulin-producing β cells for diabetes treatment. A greater understanding of how β cells form during embryonic development will improve current hESC differentiation protocols. All pancreatic endocrine cells, including β cells, are derived from Neurog3-expressing endocrine progenitors. This study characterizes the single-cell transcriptomes of 6,905 mouse embryonic day (E) 15.5 and 6,626 E18.5 pancreatic cells isolated from Neurog3-Cre; Rosa26 embryos, allowing for enrichment of endocrine progenitors (yellow; tdTomato + EGFP) and endocrine cells (green; EGFP). Using a NEUROG3-2A-eGFP CyT49 hESC reporter line (N5-5), 4,462 hESC-derived GFP+ cells were sequenced. Differential expression analysis revealed enrichment of markers that are consistent with progenitor, endocrine, or previously undescribed cell-state populations. This study characterizes the single-cell transcriptomes of mouse and hESC-derived endocrine progenitors and serves as a resource (https://lynnlab.shinyapps.io/embryonic_pancreas) for improving the formation of functional β-like cells from hESCs.
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http://dx.doi.org/10.1016/j.stemcr.2018.11.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6294286PMC
December 2018

Potential role of ferric hemoglobin in MS pathogenesis: Effects of oxidative stress and extracellular methemoglobin or its degradation products on myelin components.

Free Radic Biol Med 2017 11 31;112:494-503. Epub 2017 Aug 31.

Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1. Electronic address:

There is a well-documented relationship between cerebral vasculature and multiple sclerosis (MS) lesions: abnormal accumulations of iron have been found in the walls of the dilated veins in cerebral MS plaques. The source of this iron is unknown, but could be related to the recognized phenomenon of capillary and venous hemorrhages leading to blood extravasation. In turn, hemorrhaging leading to hemolysis results in extracellular release of hemoglobin, a reactive molecule that could induce local oxidative stress, inflammation, and tissue damage. Our previous studies with a reduced form of hemoglobin (oxyHb) have demonstrated its ability to cause extensive lipid and protein oxidation in vitro, which would result in membrane destabilization. Here, we investigated in further detail the mechanism by which the more abundant oxidized form of extracellular hemoglobin (metHb), and dissociated hemin, cause direct oxidative damage to myelin components, specifically membrane-mimetic lipid vesicles and myelin basic protein (MBP), a highly-abundant protein in the CNS. Oxidation of lipids was assessed by the formation of conjugated diene/triene and malondialdehyde, and oxidation of MBP was demonstrated by the bityrosine formation and by the change in protein mass. Our results show that metHb causes oxidative damage to MBP and myelin lipids, partly by transferring its hemin moiety to protein and lipid, but mostly as an intact protein possibly via formation of a ferryl radical. These results elucidating the mechanism of extracellular hemoglobin-induced oxidative damage to myelin components support the need for further research into vascular pathology in MS pathogenesis, to gain insight into the role of iron deposits and/or in stimulation of different comorbidities associated with the disease.
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http://dx.doi.org/10.1016/j.freeradbiomed.2017.08.022DOI Listing
November 2017
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