Publications by authors named "Gerhard Gstraunthaler"

27 Publications

  • Page 1 of 1

A Protocol for One-Step Differentiation of Human Induced Pluripotent Stem Cells into Mature Podocytes.

Methods Mol Biol 2019 ;1994:93-99

Division of Molecular and Computational Toxicology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.

Within the glomerulus, podocytes are highly specialized visceral epithelial cells that are part of the glomerular filtration barrier. Human podocyte cell culture is rather challenging for primary or immortalized cells, due to the nonproliferative state of the cells. In addition, rapid dedifferentiation is often observed. Hence, iPSC-derived podocytes offer an exciting alternative to culture podocyte-like cells from different donors over prolonged time. Here we report a simple and rapid one-step protocol that drives iPSC into podocyte-like cells in 10 days.
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http://dx.doi.org/10.1007/978-1-4939-9477-9_8DOI Listing
March 2020

Major changes of cell function and toxicant sensitivity in cultured cells undergoing mild, quasi-natural genetic drift.

Arch Toxicol 2018 12 8;92(12):3487-3503. Epub 2018 Oct 8.

Department for in vitro toxicology and biomedicine (Doerenkamp-Zbinden chair), University of Konstanz, PO Box M657, 78457, Konstanz, Germany.

Genomic drift affects the functional properties of cell lines, and the reproducibility of data from in vitro studies. While chromosomal aberrations and mutations in single pivotal genes are well explored, little is known about effects of minor, possibly pleiotropic, genome changes. We addressed this question for the human dopaminergic neuronal precursor cell line LUHMES by comparing two subpopulations (SP) maintained either at the American-Type-Culture-Collection (ATCC) or by the original provider (UKN). Drastic differences in susceptibility towards the specific dopaminergic toxicant 1-methyl-4-phenylpyridinium (MPP+) were observed. Whole-genome sequencing was performed to identify underlying genetic differences. While both SP had normal chromosome structures, they displayed about 70 differences on the level of amino acid changing events. Some of these differences were confirmed biochemically, but none offered a direct explanation for the altered toxicant sensitivity pattern. As second approach, markers known to be relevant for the intended use of the cells were specifically tested. The "ATCC" cells rapidly down-regulated the dopamine-transporter and tyrosine-hydroxylase after differentiation, while "UKN" cells maintained functional levels. As the respective genes were not altered themselves, we conclude that polygenic complex upstream changes can have drastic effects on biochemical features and toxicological responses of relatively similar SP of cells.
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http://dx.doi.org/10.1007/s00204-018-2326-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6290691PMC
December 2018

Differentiation of human iPSCs into functional podocytes.

PLoS One 2018 17;13(9):e0203869. Epub 2018 Sep 17.

Division of Physiology, Medical University Innsbruck, Innsbruck Austria.

Podocytes play a critical role in glomerular barrier function, both in health and disease. However, in vivo terminally differentiated podocytes are difficult to be maintained in in vitro culture. Induced pluripotent stem cells (iPSCs) offer the unique possibility for directed differentiation into mature podocytes. The current differentiation protocol to generate iPSC-derived podocyte-like cells provides a robust and reproducible method to obtain podocyte-like cells after 10 days that can be employed in in vitro research and biomedical engineering. Previous published protocols were improved by testing varying differentiation media, growth factors, seeding densities, and time course conditions. Modifications were made to optimize and simplify the one-step differentiation procedure. In contrast to earlier protocols, adherent cells for differentiation were used, the use of fetal bovine serum (FBS) was reduced to a minimum, and thus ß-mercaptoethanol could be omitted. The plating densities of iPSC stocks as well as the seeding densities for differentiation cultures turned out to be a crucial parameter for differentiation results. Conditionally immortalized human podocytes served as reference controls. iPSC-derived podocyte-like cells showed a typical podocyte-specific morphology and distinct expression of podocyte markers synaptopodin, podocin, nephrin and WT-1 after 10 days of differentiation as assessed by immunofluorescence staining or Western blot analysis. qPCR results showed a downregulation of pluripotency markers Oct4 and Sox-2 and a 9-fold upregulation of the podocyte marker synaptopodin during the time course of differentiation. Cultured podocytes exhibited endocytotic uptake of albumin. In toxicological assays, matured podocytes clearly responded to doxorubicin (Adriamycin™) with morphological alterations and a reduction in cell viability after 48 h of incubation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0203869PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6141081PMC
March 2019

Advanced Good Cell Culture Practice for human primary, stem cell-derived and organoid models as well as microphysiological systems.

ALTEX 2018 13;35(3):353-378. Epub 2018 Apr 13.

CAAT-Europe, University of Konstanz, Konstanz, Germany.

A major reason for the current reproducibility crisis in the life sciences is the poor implementation of quality control measures and reporting standards. Improvement is needed, especially regarding increasingly complex in vitro methods. Good Cell Culture Practice (GCCP) was an effort from 1996 to 2005 to develop such minimum quality standards also applicable in academia. This paper summarizes recent key developments in in vitro cell culture and addresses the issues resulting for GCCP, e.g. the development of induced pluripotent stem cells (iPSCs) and gene-edited cells. It further deals with human stem-cell-derived models and bioengineering of organo-typic cell cultures, including organoids, organ-on-chip and human-on-chip approaches. Commercial vendors and cell banks have made human primary cells more widely available over the last decade, increasing their use, but also requiring specific guidance as to GCCP. The characterization of cell culture systems including high-content imaging and high-throughput measurement technologies increasingly combined with more complex cell and tissue cultures represent a further challenge for GCCP. The increasing use of gene editing techniques to generate and modify in vitro culture models also requires discussion of its impact on GCCP. International (often varying) legislations and market forces originating from the commercialization of cell and tissue products and technologies are further impacting on the need for the use of GCCP. This report summarizes the recommendations of the second of two workshops, held in Germany in December 2015, aiming map the challenge and organize the process or developing a revised GCCP 2.0.
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http://dx.doi.org/10.14573/altex.1710081DOI Listing
November 2018

Fetal Bovine Serum (FBS) - A pain in the dish?

Altern Lab Anim 2017 Dec;45(6):329-332

Division of Physiology, Medical University Innsbruck, Innsbruck, Austria.

The use of Fetal Bovine Serum in replacement alternative methods is associated with serious animal welfare concerns, as well as worrying reproducibility issues.
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http://dx.doi.org/10.1177/026119291704500611DOI Listing
December 2017

Towards optimisation of induced pluripotent cell culture: Extracellular acidification results in growth arrest of iPSC prior to nutrient exhaustion.

Toxicol In Vitro 2017 Dec 15;45(Pt 3):445-454. Epub 2017 Aug 15.

Division of Molecular and Computational toxicology, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands. Electronic address:

Human induced pluripotent stem cells (iPSC) have the potential to radically reduce the number of animals used in both toxicological science and disease elucidation. One initial obstacle culturing iPSC is that they require daily medium exchange. This study attempts to clarify why and propose some practical solutions. Two iPSC lineages were fed at different intervals in a full growth area (FGA) or a restricted growth area (RGA). The FGA consisted of a well coated with Matrigel™ and the RGA consisted of a coated coverslip placed in a well. Glucose, lactate, extracellular pH and cell cycle phases were quantified. Without daily feeding, FGA cultured iPSC had significantly reduced growth rates by day 2 and began to die by day 3. In contrast, RGA cultured cells grew to confluence over 3days. Surprisingly, glucose was not exhausted under any condition. However, extracellular pH reached 6.8 after 72h in FGA cultures. Artificially reducing medium pH to 6.8 also inhibited glycolysis and initiated an increase in G0/G1 phase of the cell cycle, while adding an additional 10mM bicarbonate to the medium increased glycolysis rates. This study demonstrates that iPSC are highly sensitive to extracellular acidification, a likely limiting factor in maintenance of proliferative and pluripotent status. Culturing iPSC in RGA prevents rapid extracellular acidification, while still maintaining pluripotency and allowing longer feeding cycles.
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http://dx.doi.org/10.1016/j.tiv.2017.07.023DOI Listing
December 2017

Fetal Bovine Serum (FBS): Past - Present - Future.

ALTEX 2018 9;35(1):99-118. Epub 2017 Aug 9.

Division of Physiology, Medical University Innsbruck, Innsbruck, Austria.

The supplementation of culture medium with fetal bovine serum (FBS, also referred to as "fetal calf serum") is still common practice in cell culture applications. Due to a number of disadvantages in terms of quality and reproducibility of in vitro data, animal welfare concerns, and in light of recent cases of fraudulent marketing, the search for alternatives and the development of serum-free medium formulations has gained global attention. Here, we report on the 3rd Workshop on FBS, Serum Alternatives and Serum-free Media, where regulatory aspects, the serum dilemma, alternatives to FBS, case-studies of serum-free in vitro applications, and the establishment of serum-free databases were discussed. The whole process of obtaining blood from a living calf fetus to using the FBS produced from it for scientific purposes is de facto not yet legally regulated despite the existing EU-Directive 2010/63/EU on the use of animals for scientific purposes. Together with the above-mentioned challenges, several strategies have been developed to reduce or replace FBS in cell culture media in terms of the 3Rs (Refinement, Reduction, Replacement). Most recently, releasates of activated human donor thrombocytes (human platelet lysates) have been shown to be one of the most promising serum alternatives when chemically-defined media are not yet an option. Additionally, new developments in cell-based assay techniques, advanced organ-on-chip and microphysiological systems are covered in this report. Chemically-defined serum-free media are shown to be the ultimate goal for the majority of culture systems, and examples are discussed.
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http://dx.doi.org/10.14573/altex.1705101DOI Listing
August 2018

Impairment of human neural crest cell migration by prolonged exposure to interferon-beta.

Arch Toxicol 2017 Oct 1;91(10):3385-3402. Epub 2017 Apr 1.

Department of In Vitro Toxicology and Biomedicine, University of Konstanz, Box 657, 78457, Konstanz, Germany.

Human cell-based toxicological assays have been used successfully to detect known toxicants, and to distinguish them from negative controls. However, there is at present little experience on how to deal with hits from screens of compounds with yet unknown hazard. As a case study to this issue, we characterized human interferon-beta (IFNβ) as potential developmental toxicant affecting neural crest cells (NCC). The protein was identified as a hit during a screen of clinically used drugs in the 'migration inhibition of neural crest' (MINC) assay. Concentration-response studies in the MINC combined with immunocytochemistry and mRNA quantification of cellular markers showed that IFNβ inhibited NCC migration at concentrations as low as 20 pM. The effective concentrations found here correspond to levels found in human plasma, and they were neither cytostatic nor cytotoxic nor did they did they affect the differentiation state and overall phenotype of NCC. Data from two other migration assays confirmed that picomolar concentration of IFNβ reduced the motility of NCC, while other interferons were less potent. The activation of JAK kinase by IFNβ, as suggested by bioinformatics analysis of the transcriptome changes, was confirmed by biochemical methods. The degree and duration of pathway activation correlated with the extent of migration inhibition, and pharmacological block of this signaling pathway before, or up to 6 h after exposure to the cytokine prevented the effects of IFNβ on migration. Thus, the reduction of vital functions of human NCC is a hitherto unknown potential hazard of endogenous or pharmacologically applied interferons.
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http://dx.doi.org/10.1007/s00204-017-1966-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608792PMC
October 2017

Serotonin improves glucose metabolism by Serotonylation of the small GTPase Rab4 in L6 skeletal muscle cells.

Diabetol Metab Syndr 2017 3;9. Epub 2017 Jan 3.

Department of Internal Medicine I, Medical University of Innsbruck, Innsbruck, Austria.

Background: Serotonin (5-HT) improves insulin sensitivity and glucose metabolism, however, the underlying molecular mechanism has remained elusive. Previous studies suggest that 5-HT can activate intracellular small GTPases directly by covalent binding, a process termed serotonylation. Activated small GTPases have been associated with increased GLUT4 translocation to the cell membrane. Therefore, we investigated whether serotonylation of small GTPases may be involved in improving Insulin sensitivity and glucose metabolism.

Methods: Using fully differentiated L6 rat skeletal muscle cells, we studied the effect of 5-HT in the absence or presence of insulin on glycogen synthesis, glucose uptake and GLUT4 translocation. To prove our L6 model we additionally performed preliminary experiments in C2C12 murine skeletal muscle cells.

Results: Incubation with 5-HT led to an increase in deoxyglucose uptake in a concentration-dependent fashion. Accordingly, GLUT4 translocation to the cell membrane and glycogen content were increased. These effects of 5-HT on Glucose metabolism could be augmented by co-incubation with insulin and blunted by co incubation of 5-HT with monodansylcadaverine, an inhibitor of protein serotonylation. In accordance with this observation, incubation with 5-HT resulted in serotonylation of a protein with a molecular weight of approximately 25 kDa. We identified this protein as the small GTPase Rab4, the activity of which has been shown to be stimulated by both insulin signalling and serotonylation.

Conclusion: Our data suggest that 5-HT elicits its beneficial effects on Glucose metabolism through serotonylation of Rab4, which likely represents the converging point between the insulin and the 5-HT signalling cascades.
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http://dx.doi.org/10.1186/s13098-016-0201-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5209910PMC
January 2017

Sex Differences in Renal Proximal Tubular Cell Homeostasis.

J Am Soc Nephrol 2016 Oct 28;27(10):3051-3062. Epub 2016 Apr 28.

Division of Physiology, Medical University of Innsbruck, Innsbruck, Austria

Studies in human patients and animals have revealed sex-specific differences in susceptibility to renal diseases. Because actions of female sex hormones on normal renal tissue might protect against damage, we searched for potential influences of the female hormone cycle on basic renal functions by studying excretion of urinary marker proteins in healthy human probands. We collected second morning spot urine samples of unmedicated naturally ovulating women, postmenopausal women, and men daily and determined urinary excretion of the renal tubular enzymes fructose-1,6-bisphosphatase and glutathione-S-transferase-α Additionally, we quantified urinary excretion of blood plasma proteins α1-microglobulin, albumin, and IgG. Naturally cycling women showed prominent peaks in the temporal pattern of urinary fructose-1,6-bisphosphatase and glutathione-S-transferase-α release exclusively within 7 days after ovulation or onset of menses. In contrast, postmenopausal women and men showed consistently low levels of urinary fructose-1,6-bisphosphatase excretion over comparable periods. We did not detect changes in urinary α1-microglobulin, albumin, or IgG excretion. Results of this study indicate that proximal tubular tissue architecture, representing a nonreproductive organ-derived epithelium, undergoes periodical adaptations phased by the female reproductive hormone cycle. The temporally delimited higher rate of enzymuria in ovulating women might be a sign of recurring increases of tubular cell turnover that potentially provide enhanced repair capacity and thus, higher resistance to renal damage.
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http://dx.doi.org/10.1681/ASN.2015080886DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042665PMC
October 2016

Activated platelets release sphingosine 1-phosphate and induce hypersensitivity to noxious heat stimuli in vivo.

Front Neurosci 2015 22;9:140. Epub 2015 Apr 22.

Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck Innsbruck, Austria.

At the site of injury activated platelets release various mediators, one of which is sphingosine 1-phosphate (S1P). It was the aim of this study to explore whether activated human platelets had a pronociceptive effect in an in vivo mouse model and whether this effect was based on the release of S1P and subsequent activation of neuronal S1P receptors 1 or 3. Human platelets were prepared in different concentrations (10(5)/μl, 10(6)/μl, 10(7)/μl) and assessed in mice with different genetic backgrounds (WT, S1P1 (fl/fl), SNS-S1P1 (-/-), S1P3 (-/-)). Intracutaneous injections of activated human platelets induced a significant, dose-dependent hypersensitivity to noxious thermal stimulation. The degree of heat hypersensitivity correlated with the platelet concentration as well as the platelet S1P content and the amount of S1P released upon platelet activation as measured with LC MS/MS. Despite the significant correlations between S1P and platelet count, no difference in paw withdrawal latency (PWL) was observed in mice with a global null mutation of the S1P3 receptor or a conditional deletion of the S1P1 receptor in nociceptive primary afferents. Furthermore, neutralization of S1P with a selective anti-S1P antibody did not abolish platelet induced heat hypersensitivity. Our results suggest that activated platelets release S1P and induce heat hypersensitivity in vivo. However, the platelet induced heat hypersensitivity was caused by mediators other than S1P.
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http://dx.doi.org/10.3389/fnins.2015.00140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4406086PMC
May 2015

A severe case of fraudulent blending of fetal bovine serum strengthens the case for serum-free cell and tissue culture applications.

Altern Lab Anim 2014 Jun;42(3):207-9

3Rs-Centre Utrecht Life Sciences, Utrecht University, Utrecht, The Netherlands.

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http://dx.doi.org/10.1177/026119291404200308DOI Listing
June 2014

pH-responsive, gluconeogenic renal epithelial LLC-PK1-FBPase+cells: a versatile in vitro model to study renal proximal tubule metabolism and function.

Am J Physiol Renal Physiol 2014 Jul 7;307(1):F1-F11. Epub 2014 May 7.

Division of Physiology, Innsbruck Medical University, Innsbruck, Austria

Ammoniagenesis and gluconeogenesis are prominent metabolic features of the renal proximal convoluted tubule that contribute to maintenance of systemic acid-base homeostasis. Molecular analysis of the mechanisms that mediate the coordinate regulation of the two pathways required development of a cell line that recapitulates these features in vitro. By adapting porcine renal epithelial LLC-PK1 cells to essentially glucose-free medium, a gluconeogenic subline, termed LLC-PK1-FBPase(+) cells, was isolated. LLC-PK1-FBPase(+) cells grow in the absence of hexoses and pentoses and exhibit enhanced oxidative metabolism and increased levels of phosphate-dependent glutaminase. The cells also express significant levels of the key gluconeogenic enzymes, fructose-1,6-bisphosphatase (FBPase) and phosphoenolpyruvate carboxykinase (PEPCK). Thus the altered phenotype of LLC-PK1-FBPase(+) cells is pleiotropic. Most importantly, when transferred to medium that mimics a pronounced metabolic acidosis (9 mM HCO3 (-), pH 6.9), the LLC-PK1-FBPase(+) cells exhibit a gradual increase in NH4 (+) ion production, accompanied by increases in glutaminase and cytosolic PEPCK mRNA levels and proteins. Therefore, the LLC-PK1-FBPase(+) cells retained in culture many of the metabolic pathways and pH-responsive adaptations characteristic of renal proximal tubules. The molecular mechanisms that mediate enhanced expression of the glutaminase and PEPCK in LLC-PK1-FBPase(+) cells have been extensively reviewed. The present review describes novel properties of this unique cell line and summarizes the molecular mechanisms that have been defined more recently using LLC-PK1-FBPase(+) cells to model the renal proximal tubule. It also identifies future studies that could be performed using these cells.
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http://dx.doi.org/10.1152/ajprenal.00067.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4080158PMC
July 2014

A plea to reduce or replace fetal bovine serum in cell culture media.

Cytotechnology 2013 Oct 22;65(5):791-3. Epub 2013 Aug 22.

Division of Physiology, Innsbruck Medical University, Innsbruck, Austria,

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http://dx.doi.org/10.1007/s10616-013-9633-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3967615PMC
October 2013

Delineation of the key aspects in the regulation of epithelial monolayer formation.

Mol Cell Biol 2013 Jul 22;33(13):2535-50. Epub 2013 Apr 22.

Division of Physiology, Department of Physiology and Medical Physics, Innsbruck Medical University, Innsbruck, Austria.

The formation, maintenance, and repair of epithelial barriers are of critical importance for whole-body homeostasis. However, the molecular events involved in epithelial tissue maturation are not fully established. To this end, we investigated the molecular processes involved in renal epithelial proximal-tubule monolayer maturation utilizing transcriptomic, metabolomic, and functional parameters. We uncovered profound dynamic alterations in transcriptional regulation, energy metabolism, and nutrient utilization over the maturation process. Proliferating cells exhibited high glycolytic rates and high transcript levels for fatty acid synthesis genes (FASN), whereas matured cells had low glycolytic rates, increased oxidative capacity, and preferentially expressed genes for beta oxidation. There were dynamic alterations in the expression and localization of several adherens (CDH1, -4, and -16) and tight junction (TJP3 and CLDN2 and -10) proteins. Genes involved in differentiated proximal-tubule function, cilium biogenesis (BBS1), and transport (ATP1A1 and ATP1B1) exhibited increased expression during epithelial maturation. Using TransAM transcription factor activity assays, we could demonstrate that p53 and FOXO1 were highly active in matured cells, whereas HIF1A and c-MYC were highly active in proliferating cells. The data presented here will be invaluable in the further delineation of the complex dynamic cellular processes involved in epithelial cell regulation.
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http://dx.doi.org/10.1128/MCB.01435-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3700122PMC
July 2013

Optimizing high-throughput metabolomic biomarker screening: a study of quenching solutions to freeze intracellular metabolism in CHO cells.

OMICS 2012 Mar;16(3):90-7

University of Innsbruck, Innsbruck, Austria.

Metabolomics is a rapidly emerging tool for studying and optimizing both media and bioprocess development for culturing recombinant mammalian cells that are used in protein production processes. Quenching of the cells is crucial to fix their metabolic status at the time of sampling. Three precooled quenching solutions were tested for their ability to fix the metabolic activity of CHO cells: phosphate-buffered saline (PBS) (pH 7.4; 0.5°C), 60% methanol with 70 mM HEPES (pH 7.4; -20°C), and 60% methanol with 0.85% (w/v) ammonium bicarbonate (AMBIC) (pH 7.4; -20°C). The metabolic activity of the sampled CHO cells was assessed by determining the intracellular levels of ATP using a bioluminescence assay and selected metabolites with LC-MS/MS. We found the precooled PBS (pH 7.4; 0.5°C) to be the optimal quenching reagent for fixing intracellular metabolism. Importantly, the structural integrity of the cell membrane was maintained and highest yields were obtained for intracellular levels of ATP as well as for 18 out of 28 intracellular metabolites. In contrast to the previously reported studies, buffered methanol quenching was not applicable for suspension cultured CHO cells as cellular membrane integrity was affected. We recommend that the cells are quenched and washed simultaneously to keep the sampling time to a minimum and to prevent any further metabolic activity in the cells. We observed that additional washing steps are not required. Our analyses suggest that methanol as quenching solution, even in combination with a buffer substance, appears not suitable for quenching sensitive mammalian cells. The protocol we report herein is a simple cell sampling method that enables high-throughput metabolomic analyses and is suitable for a large number of samples.
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http://dx.doi.org/10.1089/omi.2011.0048DOI Listing
March 2012

Alternatives to the use of fetal bovine serum: human platelet lysates as a serum substitute in cell culture media.

ALTEX 2011 ;28(4):305-16

Division of Physiology, Innsbruck Medical University, Austria.

The search for alternatives to the use of fetal bovine serum (FBS) in cell and tissue culture media has become a major goal in terms of the 3R principles in order to reduce or to avoid harvesting of FBS from bovine fetuses, and, in terms of Good Manufacturing Practice (GMP), to ensure safe and animal product-free conditions for biomedical tissue engineering and (adult) stem cell therapy, respectively. In the present study, we investigated the feasibility of using platelet lysates (PL) as a substitute for FBS, based on the fact that most of the potent mitogenic factors present in serum are derived from activated thrombocytes. Platelet lysates were obtained from outdated human donor platelet concentrates. Methods were established to activate human donor platelets in order to achieve a maximum yield of platelet a-granule growth factors. Platelet lysates were successfully introduced to grow and maintain anchorage-dependent and -independent human and animal cell lines. For cell culture experiments, cells were either grown in culture media supplemented with 10% FBS, 5% PL, or under serum-free conditions. Growth experiments, viability assays, and platelet lysate-induced activation of ERK1/2 mitogen-activated protein kinase revealed platelet lysates as a valuable alternative to FBS in cell culture media.
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http://dx.doi.org/10.14573/altex.2011.4.305DOI Listing
April 2012

Serum-free cell culture: the serum-free media interactive online database.

ALTEX 2010 ;27(1):53-62

zet - Centre for Alternative and Complementary Methods to Animal Testing, Linz, Austria.

Fetal bovine serum (FBS) is a ubiquitously used essential supplement in cell culture media. However, there are serious scientific and ethical concerns about the use of FBS regarding its harvest and production. During the last three decades, FBS could be substituted by other supplements or by the use of defined chemical components in serum-free cell culture. A number of serum-free medium formulations have been described for mammalian and insect cell lines as well as for primary cultures. However, the switch to serum-free media still demands a time-consuming literature survey and a manufacturer search for appropriate medium formulations, respectively. Here we present the second collection of commercially available serum-free media in an updated, freely accessible interactive online database. Searches for serum-free media and continuous cell lines already adapted to serum-free culture can be performed according to various criteria. These include the degree of chemical definition, e.g. serum-free (SF), animal-derived component free (ADCF) or chemically defined (CD), and the type of medium, e.g. basal media, medium supplements, or full replacement media. In order to specify the cell lines that are adapted to serum-free media, search terms like species, organ, tissue, cell type and disease can be used. All commercially available serum-free media and adapted cell lines currently available from major distributors (e.g. ATCC, ECACC and DMSZ) are included in the database. Despite an extensive search for serum-free media and adapted cell lines, detailed information from certain companies and suppliers is still lacking and is specifically highlighted. It is intended to create a platform for the interactive exchange of information and experience by experts in the field in order to continuously improve and extend the serum-free online database. The database is accessible at http://www.goodcellculture.com/
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http://dx.doi.org/10.14573/altex.2010.1.53DOI Listing
July 2010

Oncostatin M-induced effects on EMT in human proximal tubular cells: differential role of ERK signaling.

Am J Physiol Renal Physiol 2007 Nov 19;293(5):F1714-26. Epub 2007 Sep 19.

Division of Nephrology, Department of Internal Medicine, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.

Growing evidence suggests that a proportion of interstitial myofibroblasts detected during renal tubulointerstitial fibrosis originates from tubular epithelial cells by a process called epithelial-mesenchymal transition (EMT). The IL-6-type cytokine oncostatin M (OSM) has been recently implicated in the induction of EMT. We investigated OSM effects on the expression of both cell-cell contact proteins and mesenchymal markers and studied OSM-induced intracellular signaling mechanisms associated with these events in human proximal tubular cells. Human recombinant OSM attenuated the expression of N-cadherin, E-cadherin, and claudin-2 in human kidney-2 (HK-2) cells associated with the induction of HK-2 cell scattering in 3D collagen matrices. Conversely, expression of collagen type I, vimentin, and S100A4 was induced by OSM. OSM-stimulated cell scattering was inhibited by antibodies against gp130. Besides inducing phosphorylation of Stat1 and Stat3, OSM led to a strong concentration- and time-dependent phosphorylation of the mitogen-activated protein kinases ERK1, ERK2, and ERK5. MEK1/2 inhibitor U0126 (10 muM) blocked basal and OSM-induced ERK1/2 phosphorylation but not phosphorylation of either ERK5 or Stat1/3. Both synthetic MEK1/2 inhibitors U0126 and Cl-1040, when used at concentrations which inhibit ERK1/2 phosphorylation but not ERK5 phosphorylation, restored N-cadherin expression in the presence of OSM, inhibited basal claudin-2 expression, but did not affect either basal or OSM-inhibited E-cadherin expression or OSM-induced expression of collagen type I and vimentin. These results suggest that in human proximal tubular cells ERK1/2 signaling represents an important component of OSM's inhibitory effect on N-cadherin expression. Furthermore, functional ERK1/2 signaling is necessary for basal claudin-2 expression.
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http://dx.doi.org/10.1152/ajprenal.00130.2007DOI Listing
November 2007

TGF-beta signaling and its effect on glutaminase expression in LLC-PK1-FBPase+ cells.

Am J Physiol Renal Physiol 2007 Sep 27;293(3):F846-53. Epub 2007 Jun 27.

Department of Physiology and Medical Physics, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria.

During systemic acidosis, renal proximal tubular cells exhibit enhanced rates of bicarbonate and ammonium ion synthesis and undergo extensive hypertrophy. The former adaptations are accomplished, in part, by increased expression of glutaminase (GA). LLC-PK(1)-FBPase+ cells, a gluconeogenic line of porcine kidney cells, exhibit a rapid activation of the ERK1/2 and p38 MAPK pathways and a two- to threefold increase in GA mRNA when transferred to acidic medium (pH 6.9). Transforming growth factor-beta (TGF-beta), a potent activator of MAPK and Smad signaling cascades, also causes extensive renal hypertrophy. Thus the potential role of TGF-beta in the renal response to metabolic acidosis was investigated. Western blot analyses established that in LLC-PK(1)-FBPase+ cells, TGF-beta activated the ERK1/2, p38 MAPK, and Smad1/5/8 pathways, but not the JNK and Smad2/3 pathways. Addition of TGF-beta to cells cultured in normal medium (pH 7.4) produced a steady increase in GA mRNA, resulting in a twofold induction after 18 h. Western blot analysis indicated that treatment with either TGF-beta or acidic medium resulted in an increased level of fibronectin. However, the effects of the two treatments on both GA mRNA and fibronectin levels occurred with different time courses and were additive. In addition, the rates of ammonia production were decreased slightly by addition of TGF-beta. Finally, a GA-luciferase reporter construct, which is activated 3.5-fold by treatment with acidic medium, is not affected by TGF-beta. Therefore, TGF-beta and metabolic acidosis activate some of the same signaling pathways in LLC-PK(1)-FBPase+ cells, but produce separate effects on GA expression.
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http://dx.doi.org/10.1152/ajprenal.00139.2007DOI Listing
September 2007

Effects of constitutively active and dominant negative MAPK kinase (MKK) 3 and MKK6 on the pH-responsive increase in phosphoenolpyruvate carboxykinase mRNA.

J Biol Chem 2006 Feb 30;281(5):2982-8. Epub 2005 Nov 30.

Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, 80523-1870, USA.

Metabolic acidosis is partially compensated by a pronounced increase in renal catabolism of glutamine. This adaptive response is sustained, in part, through increased expression of phosphoenolpyruvate carboxykinase (PEPCK). Previous inhibitor studies suggested that the pH-responsive increase in PEPCK mRNA in LLC-PK1-FBPase+ cells is mediated by a p38 mitogen-activated protein kinase (MAPK). These cells express high levels of the upstream kinase MAPK kinase (MKK) 3 but relatively low levels of the alternative upstream kinase MKK6. To firmly establish the role of the p38 MAPK signaling pathway, clonal lines of LLC-PK1-FBPase+ cells that express constitutively active (ca) and dominant negative (dn) forms of MKK3 and MKK6 from a tetracycline-responsive promoter were developed. Western blot analyses confirmed that 0.5 microg/ml doxycycline was sufficient to block transcription and that removal of doxycycline led to pronounced and sustained expression of the caMKKs and dnMKKs. Expression of caMKK6 (but not caMKK3) caused an increase in phosphorylation of p38 MAPK and an increase in the level of PEPCK mRNA that closely mimicked the effect of treatment with acidic medium (pH 6.9, 10 mm HCO3-). Only caMKK6 activated transcription of a PEPCK-luciferase reporter construct. Co-expression of both dnMKKs blocked the increases in phosphorylation of p38 MAPK and PEPCK mRNA. The latter effect closely mimicked that of the p38 MAPK inhibitor SB203580. The expression of either dnMKK3 or dnMKK6 was less effective than co-expression of both dnMKKs. Thus, the pH-responsive increase in PEPCK mRNA in the kidney is mediated by the p38 MAPK signaling pathway and involves activation of MKK3 and/or MKK6.
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http://dx.doi.org/10.1074/jbc.M510084200DOI Listing
February 2006

Alternatives to the use of fetal bovine serum: serum-free cell culture.

ALTEX 2003 ;20(4):275-81

Department of Physiology, University of Innsbruck, Innsbruck, Austria.

Serum is commonly used as a supplement to cell culture media. It provides a broad spectrum of macromolecules, carrier proteins for lipoid substances and trace elements, attachment and spreading factors, low molecular weight nutrients, and hormones and growth factors. The most widely used animal serum supplement is fetal bovine serum, FBS. Since serum in general is an ill-defined component in cell culture media, a number of chemically defined serum-free media formulations have been developed in the last two decades. Besides modern cell biological advances in cell and tissue culture and efforts towards a standardisation of cell culture protocols in Good Cell Culture Practice, in addition, considerable ethical concerns were raised recently about the harvest and collection of fetal bovine serum. Thus, in order to decrease the annual need for bovine fetuses in terms of the 3Rs through any reduction in the use or partial replacement of serum, as well as in terms of an improvement of cell and tissue culture methodology, serum-free cell culture represents a modern, valuable and scientifically well accepted alternative to the use of FBS in cell and tissue culture.
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February 2004

Loss of active MEK1-ERK1/2 restores epithelial phenotype and morphogenesis in transdifferentiated MDCK cells.

Am J Physiol Cell Physiol 2003 Sep;285(3):C652-61

Department of Physiology, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6010 Innsbruck, Austria.

Constitutive activation of the MAPK/ERK kinase (MEK)1-ERK2 signaling module in Madin-Darby canine kidney (MDCK)-C7 cells disrupts their ability to form cyst-like structures in collagen gels and induces an invasive, myofibroblast-like phenotype. However, the reversibility of these cellular events, as well as the relative role of both MEK isoforms (MEK1 and MEK2) and both ERK isoforms (ERK1 and ERK2) during these processes, has not yet been investigated. We now report that loss of constitutively active MEK1 (caMEK1) and, thus, loss of active ERK1/2 in C7caMEK1 cells is associated with increased MEK2 protein expression, reexpression of ERK1 protein, and epithelial redifferentiation of these cells. The morphological changes toward an epithelial phenotype in these revertant cell lines (C7rev4, C7rev5, C7rev7) are reflected by the upregulation of epithelial marker proteins, such as E-cadherin, beta-catenin, and cytokeratin, by the loss of alpha-smooth muscle actin expression, and by the ability of these epithelial revertants to form well-organized spherical cysts when grown in three-dimensional collagen gels. Further evidence for a role of the MEK1-ERK1/2 module in epithelial-mesenchymal transition was obtained from the analysis of two novel, spontaneously transdifferentiated MDCK-C7 cell clones (C7e1 and C7e2 cells). In these clones, increased MEK1/2-ERK1/2 phosphorylation, reduced MEK2 protein expression, and loss of ERK1 protein expression is associated with phenotypic alterations similar to those observed in transdifferentiated C7caMEK1 cells. C7e1 cells at least partially regained some of their epithelial characteristics at higher passages. In contrast, C7e2 cells maintained a transdifferentiated phenotype at high passage, were unable to generate cyst-like epithelial structures, and retained invasive properties when grown on a three-dimensional collagen matrix. We conclude that in renal epithelial MDCK-C7 cells, stable epithelial-to-mesenchymal transition (EMT) is associated with loss of ERK1 protein expression, reduced MEK2 protein expression, and increased basal ERK2 phosphorylation. In contrast, loss of active MEK1-ERK1/2 results in increased MEK2 protein expression and reexpression of ERK1 protein, concomitant with the restoration of epithelial phenotype and the ability to form cystic structures.
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http://dx.doi.org/10.1152/ajpcell.00463.2002DOI Listing
September 2003

Good Cell Culture Practice. ECVAM Good Cell Culture Practice Task Force Report 1.

Altern Lab Anim 2002 Jul-Aug;30(4):407-14

Biochemical Pharmacology, University of Konstanz, 78457 Konstanz, Germany.

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http://dx.doi.org/10.1177/026119290203000404DOI Listing
November 2002

p38 MAPK mediates acid-induced transcription of PEPCK in LLC-PK(1)-FBPase(+) cells.

Am J Physiol Renal Physiol 2002 Oct;283(4):F678-88

Department of Physiology, University of Innsbruck, Austria.

LLC-PK(1)-FBPase(+) cells are a gluconeogenic and pH-responsive renal proximal tubule-like cell line. On incubation with acidic medium (pH 6.9), LLC-PK(1)-FBPase(+) cells exhibit an increased rate of ammonia production as well as increases in glutaminase and phosphoenolpyruvate carboxykinase (PEPCK) mRNA levels and enzyme activities. The increase in PEPCK mRNA is due to an enhanced rate of transcription that is initiated in response to intracellular acidosis. The involvement of known MAPK activities (ERK1/2, SAPK/JNK, p38) in the associated signal transduction pathway was examined by determining the effects of specific MAPK activators and inhibitors on basal and acid-induced PEPCK mRNA levels. Transfer of LLC-PK(1)-FBPase(+) cultures to acidic medium resulted in specific phosphorylation, and thus activation, of p38 and of activating transcription factor-2 (ATF-2), respectively. Anisomycin (AI), a strong p38 activator, increased PEPCK mRNA to levels comparable to those observed with acid stimulation. AI also induced a time-dependent phosphorylation of p38 and ATF-2. SB-203580, a specific p38 inhibitor, blocked both acid- and AI-induced PEPCK mRNA levels. Western blot analyses revealed that the SB-203580-sensitive p38alpha isoform is strongly expressed. The octanucleotide sequence of the cAMP-response element-1 site of the PEPCK promotor is a perfect match to the consensus element for binding ATF-2. The specificity of ATF-2 binding was proven by ELISA. We conclude that the SB-203580-sensitive p38alpha-ATF-2 signaling pathway is a likely mediator of the pH-responsive induction of PEPCK mRNA levels in renal LLC-PK(1)-FBPase(+) cells.
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http://dx.doi.org/10.1152/ajprenal.00097.2002DOI Listing
October 2002