Contamination Of Cell Cultures Research Articles

Serum-free cryoprotectant reagent: Cell Rev™ HQ-Store, improves cell recovery rate and other intrinsic cell properties including MSC self-renewal and differentiation potentials

Background & Aim Cellular cryopreservation is a linchpin of cell therapy and manufacturing. Without proper cryoprotectant reagents, the quality of cellular properties such as basic cell viability, cell attachment, growth, differentiation, characters or even cell death could be jeopardized. The use of fetal bovine serum (FBS) in cell freezing reagents have grown to be laboratory standard practice. However, the composition of the FBS is not well defined both qualitative and quantitatively and also have batch- to – batch variations and most importantly is a loophole subjected to potential contamination of cell cultures. From the biosafety aspects, sera may contain harmful factors like mycoplasma, endotoxin, viral contaminants or prions which increase the probability of the transmission of potentially fatal diseases to human patients. Methods, Results & Conclusion To minimize the possible risks, we have developed a totally chemically defined cryoprotectant recipe to preserve the important qualities of the cells particularly mesenchymal Stem Cells (MSCs). In this study, Mesenchymal Stem Cells have been cryopreserved as adherent cell populations in widely used cryoprotectant recipe, 20% FBS 10% dimethyl sulfoxide (DMSO) and Cell Rev™ HQ-Store defined serum-free cell freezing reagents. Our serum-free cryopreservation recipe has shown a significantly improved post-thawed recovery rate of cells to 95%. Interestingly, MSCs that have been stored in our defined cryoprotectant showed more than 50% enhanced n self-renewal while retaining differentiation potentials. Most importantly, these high-quality cryopreservation remains consistent with more than 10 freeze-thaw cycles, and longer than 2 yrs extended storage. These data illustrate that cell freezing solutions affect not only cytotoxicity but also critical properties of cellular proliferation and differentiation.

Miramistin effect on BHK-21 and PSGK-30 cell line proliferation and FMD virus reproduction in these cells

At present, Miramistin drug (benzyldimethyl [3-(myristoylamino) propyl] ammonium chloride monohydrate), which has a broad bactericidal effect, is used in veterinary practice. This antiseptic is active against most viruses, mycoplasmas, bacteria, fungi and protozoa. According to toxicometric parameters, Miramistin is classified as a low-hazard substance. Use of cell structures as test systems for assessing the toxicity of pharmacological substances instead of conventional tests on experimental animals allows us to better clarify the possible mechanism of the effect of the investigated substance. Since many types of mycoplasmas affect the genitourinary system organs, to assess the cytotoxicity of Miramistin kidney mammalian cells of various mammals can be used as test systems, in particular, the newborn Syrian hamster (VNK-21), Siberian mountain ibex (PSGK-30), and others. The possibility of using BHK-21 and PSGK-30 cell monolayer as test systems for assessing the baseline cytotoxicity of Miramistin was shown. When studying toxicity of the drug, the effect of its various concentrations on the cell morphology was studied, the number of viable cells and the total protein content were determined as an indicator of the cell mass increase. The results of a cytomorphological study indicate that the Miramistin maximum permissible concentration of for BHK-21 and PSGK-30 cell monolayer is 25 μg/cm3. The use of this antibacterial drug in higher concentrations caused the appearance and increased signs of endogenous intoxication and degeneration. When evaluating the proliferative activity of cells under the influence of the Miramistin antibiotic in different concentrations, it was found that increasing the dose to 50, 75, 100, 125, 150 μg/cm3 leads to decrease in the rate of cell growth compared to the control. The Miramistin content in the growth medium in an amount of up to 25 μg/cm3 did not affect the intensity of protein synthesis. Presence of Miramistin in the culture medium at the maximum permissible concentration causes a slight decrease in the reproduction of foot and mouth disease virus in BHK-21 and PSGK-30 cell cultures by 4.5 and 4.0%, respectively, compared with the control without antibiotic. Since mycoplasmas are the most common contaminants of cell cultures, further studies will be aimed at exploring the possibility of using Miramistin for decontamination of BHK-21 and PSGK-30 cell monolayers.

Endometriotic cell culture contamination and authenticity: a source of bias in in vitro research?

STUDY QUESTIONAre the primary cell cultures and cell lines used in endometriosis research of sufficient quality?SUMMARY ANSWERPrimary cells used in endometriosis research lack purity and phenotypic characterisation, and cell lines are not genotypically authenticated.WHAT IS KNOWN ALREADYThe poor reproducibility of in vitro research and the lack of authenticity of the cell lines used represent reasons of concern in the field of reproductive biology and endometriosis research.STUDY DESIGN, SIZE, DURATIONIn the present study, past in vitro research in the field of endometriosis was systematically reviewed to determine whether the appropriate quality controls were considered. In addition, we explored the performance of Paired Box 2 (Pax2) as an endometrium specific marker in endometrial and endometriotic primary cell cultures; we also characterised the most diffused endometriosis cell lines with respect to important markers including the short tandem repeat (STR) profile.PARTICIPANTS/MATERIALS, SETTING, METHODSLiterature review part: almost 300 published protocols describing the isolation and creation of primary cell cultures from endometriosis were reviewed. Wet-lab part: primary cells isolated from 13 endometriosis patients were analysed by immunohistochemistry, immunofluorescence and FACS for the expression of Pax2. Cell lines Z11 and Z12, the most diffused endometriosis cell lines, were characterised with respect to the expression of Pax2, steroid hormone receptors and STR profile.MAIN RESULTS AND THE ROLE OF CHANCEFrom the literature review work, we underscored the lack of sufficient cell purity and phenotypic characterisation of primary cell cultures, which present high risk of contaminations from surrounding non-endometriotic tissues. Past work based on the use of cell lines was reviewed as well, and it emerged that cell line authentication was never performed.In an effort to address these weaknesses for future research, we present data on the performance of Pax2, a suitable marker to exclude ovarian (and other non-endometrial) cell contaminations from primary cell cultures; STR profiles of cell lines Z11 and Z12 were analysed and indicated that the cells were authentic. These profiles are now available for authentication purposes to researchers wishing to perform experiments with these cells.A quality control pipeline to assure sufficient quality of in vitro research in the field of reproductive biology and endometriosis is proposed. We encourage scientists, research institutes, journal reviewers, editors and funding bodies to raise awareness of the problem and adopt appropriate policies to solve it in the future.LARGE-SCALE DATASTR profiles of cell lines Z11 and Z12 are deposited at the Cellosaurus database—web.expasy.org.LIMITATIONS, REASONS FOR CAUTIONThere may be additional markers suitable to assess cell quality.WIDER IMPLICATIONS OF THE FINDINGSFuture in vitro research in endometriosis and the reliability of outcomes can be improved by using the recommendations presented in this study.STUDY FUNDING/COMPETING INTEREST(S)The study was partly financed by the ‘Stichting Fertility Foundation’ (The Netherlands). The authors declare no existing conflict of interest.TRIAL REGISTRATION NUMBERNon-applicable.

A highly sensitive internally-controlled real-time PCR assay for mycoplasma detection in cell cultures

Mycoplasma contamination of cell lines is a common occurrence and may affect the cell line behaviour in a variety of ways. Contamination with mycoplasma is usually not obvious so cell lines should be frequently tested. Several commercially available kits for mycoplasma detection exist, however the Ph. Eur. culture method which can take several weeks to yield results is still considered to be the ‘gold standard’ method. There is therefore a need for rapid alternative methods with comparable sensitivity, specificity and species range. Here, we describe an internally-controlled Taqman-based real-time PCR assay for cell culture medium without the need for DNA extraction. The assay can detect less than 10 CFU of the most frequently encountered mycoplasma contaminants in mammalian cell cultures. The validated assay has the potential to be used as a routine test in the production of cell culture-based Biologicals.

Molecular genetic techniques and oligonucleotides for mycoplasma identification – a review

Control of distribution of mycoplasmal infections in cattle herds is essential in the majority of countries world-wide. Various PCR procedures are available to detect mycoplasmas in cell cultures and bovine mycoplasma in different types of samples. We reviewed some common PCR techniques and specific primers targeted to different bacterial genetic regions of mycoplasma. Several researchers used the same PCR approach and Mycoplasma spp. as a target but their results could not be compared because different primer pairs were used. These methods and primers were first developed to identify mycoplasma species that contaminate animal cell cultures, and then were used by other researchers to differentiate mycoplasmas as a cow infecting agent. Our analysis of the specificity of these primer pairs to nucleotide sequences of five Mycoplasma spp. showed that oligonucleotides have less specificity to them. Numerous commercially available PCR kits are applicable to find mycoplasma contamination in cell cultures and fewer of them can be used in veterinary diagnostics. Although serological and culture techniques are still used, it is necessary to develop a new multiplex PCR technique with a more specific primer set especially in agrarian countries.

Use of polyvinyl alcohol for chimeric antigen receptor T-cell expansion

Serum albumin has long been an essential supplement for ex vivo hematopoietic and immune cell cultures. However, serum albumin medium supplements represent a major source of biological contamination in cell cultures and often cause loss of cellular function. As serum albumin exhibits significant batch-to-batch variability, it has also been blamed for causing major issues in experimental reproducibility. We recently discovered the synthetic polymer polyvinyl alcohol (PVA) as an inexpensive, Good Manufacturing Practice-compatible, and biologically inert serum albumin replacement for ex vivo hematopoietic stem cell cultures. Importantly, PVA is free of the biological contaminants that have plagued serum albumin-based media. Here, we describe that PVA can replace serum albumin in a range of blood and immune cell cultures including cell lines, primary leukemia samples, and human T lymphocytes. PVA can even replace human serum in the generation and expansion of functional chimeric antigen receptor (CAR) T cells, offering a potentially safer and more cost-efficient approach for this clinical cell therapy. In summary, PVA represents a chemically defined, biologically inert, and inexpensive alternative to serum albumin for a range of cell cultures in hematology and immunology.

Mycoplasma contamination-mediated attenuation of plasmid DNA transfection efficiency is augmented via L-arginine deprivation in HEK-293 cells.

Mycoplasma infection is the most prevalent contamination in cell culture. Analysis of cell culture in laboratories from different countries shows that mycoplasma contamination ranges from 15% to 80% and, in some cases, even reaches 100% (Chernov et al., 2014). Whilst mycoplasma infection is not visible to the naked eye in cell culture, the consequences of mycoplasma contamination have been shown to induce a number of cellular changes, for example, increased resistance to chemotherapeutic drugs. Therefore, any results obtained from tissue culture studies, in the presence of mycoplasma contamination, potentially render the data invalid (Kim et al., 2015; Gedye et al., 2016). As such, mycoplasmas are not harmless bystanders and cannot be ignored in in vitro studies.

A New Sensitive Method for the Detection of Mycoplasmas Using Fluorescence Microscopy.

Contamination of cell cultures by mycoplasmas is a very common phenomenon. As they can substantially alter cell metabolism and potentially spread to all cell cultures in laboratory, their early detection is necessary. One of the fastest and cheapest methods of mycoplasma detection relies on the direct staining of mycoplasmas’ DNA by DAPI or Hoechst dyes. Although this method is easy and fast to perform, it suffers from the low signal provided by these dyes compared to the nuclear DNA. Therefore, the reporter cell lines are used for cultivation of mycoplasmas before DAPI or the Hoechst staining step. In the study presented, we have developed and tested a new immunofluorescence assay for the detection of mycoplasmas. The method is based on the enzymatic labeling using DNA polymerase I and modified nucleotides utilizing nicks in the mycoplasmas’ DNA. Modified nucleotides are incorporated into mycoplasmas’ DNA and subsequently visualized by immunofluorescence microscopy. The developed approach is independent of the mycoplasma strain, does not intensely stain nuclear DNA, does not stain other bacteria, and provides higher sensitivity than the approach based on the direct labeling using DAPI or Hoechst dyes.

Impacts of intentional mycoplasma contamination on CHO cell bioreactor cultures.

Mycoplasma contamination events in biomanufacturing facilities can result in loss of production and costly cleanups. Mycoplasma may survive in mammalian cell cultures with only subtle changes to the culture and may penetrate the 0.2 µm filters often used in the primary clarification of harvested cell culture fluid. Culture cell‐based and indicator cell‐based assays that are used to detect mycoplasma are highly sensitive but can take up to 28 days to complete and cannot be used for real‐time decision making during the biomanufacturing process. To support real‐time measurements of mycoplasma contamination, there is a push to explore nucleic acid testing. However, cell‐based methods measure growth or colony forming units and nucleic acid testing measures genome copy number; this has led to ambiguity regarding how to compare the sensitivity of the methods. In addition, the high risk of conducting experiments wherein one deliberately spikes mycoplasma into bioreactors has dissuaded commercial groups from performing studies to explore the multiple variables associated with the upstream effects of a mycoplasma contamination in a manufacturing setting. Here we studied the ability of Mycoplasma arginini to persist in a single‐use, perfusion rocking bioreactor system containing a Chinese hamster ovary (CHO) DG44 cell line expressing a model monoclonal immunoglobulin G1 (IgG1) antibody. We examined M. arginini growth and detection by culture methods, as well as the effects of M. arginini on mammalian cell health, metabolism, and productivity. We compared process parameters and controls normally measured in bioreactors including dissolved oxygen, gas mix, and base addition to maintain pH, to examine parameter changes as potential indicators of contamination. Our work showed that M. arginini affects CHO cell growth profile, viability, nutrient consumption, oxygen use, and waste production at varying timepoints after M. arginini introduction to the culture. Importantly, how the M. arginini contamination impacts the CHO cells is influenced by the concentration of CHO cells and rate of perfusion at the time of M. arginini spike. Careful evaluation of dissolved oxygen, pH control parameters, ammonia, and arginine over time may be used to indicate mycoplasma contamination in CHO cell cultures in a bioreactor before a read‐out from a traditional method.

Novel Mammalian orthorubulavirus 5 Discovered as Accidental Cell Culture Contaminant.

A distinct Russian Mammalian orthorubulavirus 5 (PIV5) was detected in cell culture exhibiting cytopathic effect and hypothesized to be contaminated by a scientist with respiratory symptoms. The identification of the divergent strain indicated a lack of knowledge on the diversity of PIV5 strains and calls for surveillance of global PIV5 strains.

Highly sulfated hyaluronic acid maintains human induced pluripotent stem cells under feeder-free and bFGF-free conditions

Human induced pluripotent stem (hiPS) cells are attracting attention as a tool for regenerative medicine. However, several problems need to be overcome for their widespread and safe use, for example, the high cost of maintaining hiPS cells and the possibility of xenogeneic cell contamination in hiPS cell cultures. One of the main contributors to the high cost of maintaining hiPS cells is basic fibroblast growth factor (bFGF), which is essential for such cultures. Xenogeneic contamination can occur because of the use of mouse-derived feeder cells to culture hiPS cells. To overcome the problems of cell culture cost and xenogeneic contamination, we have developed a novel culture method in which the undifferentiated state and pluripotency of hiPS cells can be maintained under feeder-free and bFGF-free conditions. Our new approach involves the addition to the culture medium of highly sulfated hyaluronic acid (HA-HS), in which the hydroxyl groups of d-glucuronic acid (GlcA) and N-acetyl-d-glucosamine (GlcNAc) are chemically sulfated. HA-HS promotes bFGF signaling and maintains the undifferentiated state and pluripotency of hiPS cells under feeder-free and bFGF-free conditions. By contrast, non-sulfated hyaluronic acid and low sulfated hyaluronic acid do not maintain the undifferentiated state and pluripotency of hiPS cells. These results indicate that the maintenance of hiPS cells under feeder-free and bFGF-free conditions is an HA-HS specific effect. This study is the first to demonstrate the effects of sulfated hyaluronic acid on mammalian pluripotent stem cells, and provides a novel method for maintaining hiPS cells using HA-HS.

Quantification of a cell culture contaminant using 16S rDNA.

In this study, we identified a "black dot"-like cell culture contaminant as a species belonging to the genus of Pusillimonas using 16S rDNA sequencing. Among all antibiotics tested, a combinatorial treatment of ampicillin and gentamicin both at 100 µg/mL was able to eliminate this contaminant. The contaminant was then visualized by fluorescence microscopy using propidium iodide staining and was found inside the cytosol of contaminated A549 cells. To characterize the efficacy of antibiotics for contaminant removal, we devised a quantitative method to determine the average number of 16S rDNA copies associated with a single A549 cell, which is directly proportional to the average number of contaminant per A549 cell. By using primers specific to the 16S rDNA sequence of the contaminant, we were able to estimate contaminants per single contaminated cell using both qPCR-based relative and absolute quantification.

In situ microscopy as online tool for detecting microbial contaminations in cell culture

Microbial contamination in mammalian cell cultures causing rejected batches is costly and highly unwanted. Most methods for detecting a contamination are time-consuming and require extensive off-line sampling. To circumvent these efforts and provide a more convenient alternative, we used an online in situ microscope to estimate the cell diameter of the cellular species in the culture to distinguish mammalian cells from microbial cells depending on their size. A warning system was set up to alert the operator if microbial cells were present in the culture. Hybridoma cells were cultured and infected with either Candida utilis or Pichia stipitis as contaminant. The warning system could successfully detect the introduced contamination and alert the operator. The results suggest that in situ microscopy could be used as an efficient online tool for early detection of contaminations in cell cultures.

Effectiveness of Plasmocure™ in Elimination of Mycoplasma Species from Contaminated Cell Cultures: A Comparative Study versus other Antibiotics.

Objective Mycoplasmas spp. is among major contaminants of eukaryotic cell cultures. They cause a wide range of problems associated with cell culture in biology research centers or biotechnological companies. Mycoplasmas are also resistant to several antibiotics. Plasmocin™ has been used to treat cell lines but Plasmocin™-resistant strains have been reported. InvivoGen has developed a new anti-Mycoplasma agent called Plasmocure™ in order to eliminate resistant Mycoplasma contamination. The aim of this study was the selection of the best antibiotics for treatment of mycoplasma in cell cultures. Materials and Methods In this experimental study, a total of 100 different mammalian cell lines contaminated with different Mycoplasma species were evaluated by microbiological culture (as the gold standard method), indirect DNA fluorochrome staining, enzymatic (MycoAlert™), and universal or species-specific polymerase chain reaction (PCR) detection methods. In this study, animal and human cell lines available in National Cell Bank of Iran, were treated with Plasmocure™. The treatment efficacy and cytotoxicity of Plasmocure™ were compared with those of commonly used antibiotics such as BM- cyclin, Plasmocin™, MycoRAZOR™, sparfloxacin and enrofloxacin. Results Plasmocure™ is comprised of two antibiotics that act through various mechanisms of action than those in Plasmocin™. Two-week treatment with Plasmocure™ was enough to completely eliminate Mycoplasma spp. A moderate toxicity was observed during Mycoplasma treatment with plasmocure™; But, after elimination of Mycoplasma, cells were fully recovered. Mycoplasma infections were eliminated by Plasmocure™, BM-cyclin, Plasmocin™, MycoRAZOR™, sparfloxacin and enrofloxacin. However, the outcome of the treatment process (i.e. the frequency of complete cure, regrowth or cell death) varied among different antibiotics. ConclusionThe highest number of cured cell lines was achieved by using Plasmocure™ which also had the lowest regrowth rate after a period of four months. As a conclusion; Plasmocure™ might be considered an effective antibiotic to treat Mycoplasma infections in mammalian cell cultures especially for precious or vulnerable cells.

Detection of Mycoplasma Contamination of Cell Culture by A Loop-Mediated Isothermal Amplification Method.

Objective Mycoplasmas are major contaminants of cell culture and affect in vitro biological and diagnostic tests. Mycoplasma detection is conducted using culture and molecular methods. These methods vary in terms of accuracy, reliably and sensitivity. Loop-mediated isothermal amplification (LAMP) is used to amplify target DNA in a highly specific and rapid manner. This study aimed to develop a LAMP method for rapid detection of Mycoplasma in culture samples. Materials and Methods In this descriptive laboratory study, for LAMP detection of Mycoplasma contaminations in cell culture, we used primers specifically designed for targeting the 16S rRNA conserved gene of Mycoplasma spp. For a positive control structure, 16S rRNA amplified based on PCR, was cloned in a plasmid vector and sequenced. The assay specificity was evaluated using Mycoplasma genomic DNA and a panel containing genomes of gram-positive and gram-negative organisms. Results In this study, the method developed for detection of Mycoplasma contamination of cell cultures was a rapid, sensitive and cost-effective LAMP approach. The results demonstrated that this method benefits from high specificity (100%) for amplification of Mycoplasma strains and high speed (multiplication within 60 minutes), while it does not require expensive laboratory equipment compared to those needed for polymerase chain reaction (PCR)-based detection. ConclusionOur study is the first report about application of LAMP assay based on 16S rRNA gene for detection of Mycoplasma strains; this technique could be considered a useful tool for rapid detection of contamination of cell culture.

Rapid detection of low-level HeLa cell contamination in cell culture using nested PCR.

HeLa cells are a commonly used cell line in many biological research areas. They are not picky for culture medium and proliferate rapidly. HeLa cells are a notorious source of cell cross‐contamination and have been found to be able to contaminate a wide range of cell lines in cell culture. In this study, we reported a simple and efficient method for detecting the presence of HeLa cell contamination in cell culture. HPV‐18 was used as a biomarker. The cell culture supernatant was used directly as the template for nested PCR without extracting nucleic acid. By PCR amplification of the cell culture supernatant with the designed primers, we were able to detect the presence of HeLa cells in the culture. The sensitivity of this method can reach 1%, which is 10‐fold higher than Short tandem repeat sequence (STR) profiling. This simple, rapid, and “noninvasive” quality checking method should find applications in routine cell culture practice.

Antimicrobial resistance in mollicutes: known and newly emerging mechanisms.

This review is devoted to the mechanisms of antibiotic resistance in mollicutes (class Bacilli, subclass Mollicutes), the smallest self-replicating bacteria, that can cause diseases in plants, animals and humans, and also contaminate cell cultures and vaccine preparations. Research in this area has been mainly based on the ubiquitous mollicute and the main contaminant of cell cultures, Acholeplasma laidlawii. The omics technologies applied to this and other bacteria have yielded a complex picture of responses to antimicrobials, including their removal from the cell, the acquisition of antibiotic resistance genes and mutations that potentially allow global reprogramming of many cellular processes. This review provides a brief summary of well-known resistance mechanisms that have been demonstrated in several mollicutes species and, in more detail, novel mechanisms revealed in A. laidlawii, including the least explored vesicle-mediated transfer of short RNAs with a regulatory potency. We hope that this review highlights new avenues for further studies on antimicrobial resistance in these bacteria for both a basic science and an application perspective of infection control and management in clinical and research/production settings.

A new Aura virus isolate in Brazil shows segment duplication in the variable region of the nsP3 gene

BackgroundA new isolate of Aura virus serendipitously discovered as a cell culture contaminant is reported in this manuscript. Aura virus belongs to the family Togaviridae and is classified in the genus Alphavirus. There are only two reports of Aura virus isolation from mosquitoes in the scientific literature, and the existence of a vertebrate host is still unknown. The discovery of this new isolate was based on transmission electron microscopy and nucleic acid amplification through a non-specific RT-PCR amplification protocol followed by sequencing.ResultsGenetic analysis has shown that the new virus shares a high degree of identity with the previously described isolate (GenBank: AF126284.1). A major difference was observed in the nsP3 gene in which a 234-nucleotide duplication has been identified. Furthermore, a pronounced difference was observed in cell cultures compared to the data available for the previously described isolate. Cell permissiveness and phenotypic characteristics in C6/36, Vero and BHK-21 cells were found to differ from previous reports. This may be due to the genetic differences that have been observed.ConclusionsThe genetic and biological characteristics of the new Aura virus isolate are suggestive of viral adaptation to the cell substrate. The development of a cDNA clone will lend a perspective and better understanding of these results as well as open avenues for its use as a biotechnological tool, as seen for other alphaviruses.

A importância do controle de qualidade de culturas utilizadas em ensaios biológicos e no desenvolvimento de pesquisas na área de saúde

Introduction: Advances in scientific research are based on previously published findings. However,there is concern about the lack of reproducibility in the biological researches in basic and preclinical areas, due to the repercussion on the population´s health. Because in vitro cultured cells are the basis for many toxicological and therapeutic studies, concern about their quality becomes paramount. Regarding microbiological contaminants, although bacteria and fungi are easily recognized, viruses and mycoplasmas are invisible under light microscopy. Another delicate issue would be the results generated with cells with modified identity. Objective: To discuss the main methodologies for assuring the quality of cells used in in vitro assays and to demonstrate how some world collections are structured to address this issue. Method: The scientific literature in the PubMed and Scielo databases and the webpage of different biological collections until December 2017. Results: It is recommended to apply the following techniques to detect contaminants in cell cultures: 1) virus : PCR and viral isolation; 2) mycoplasmas: PCR,bioluminescence and staining of cells with DNA affinity fluorophore; 3) human cell identity: the STR; 4) non-human cell identity: the Barcode. Conclusions: Considering all the investment applied in scientific research worldwide, the development of new methodologies alternatives to the use of animals and the critical consensus of the concept of quality, it is concluded that any laboratory should guarantee the control of purity and authenticity of its lineages.

Molecular detection and characterization of sustainable intracellular contaminants in commercially used cell cultures for pre-clinical studies

Microbial contamination in cell and tissue culture is a constant problem, which can compromise development and applications of cell lines. An immediate consequence of cell culture contamination is loss of researcher time, money and effort spent developing cultures and setting up experiments. There are adverse effects detected on cultures suffering from undetected biological contamination. This hidden contamination can potentially achieve high densities altering the growth and characteristics of the cultures. The objective of this study was to assess the molecular detection and characterization of sustainable intracellular contaminants in commercially used cell cultures use for regulatory pre-clinical studies for developing new chemical entities. This study was prompted by a series of observations by multiple researchers that cell lines were harbouring visible black particulate contaminants, capable of intracellular mobility with secondary impacts on cell adherence and lyses. This was initially limited to human liver cells, HepG2, C3A and CaCO2 cell lines, but recently similar evidence has been found in a series of other cell lines as well. Giemsa staining did show many spore-like entities in the cytoplasm mainly of 0.5-1 μ diameter, rounded and transparent in colour. Electron microscope examination of C3A infected cell line revealed the presence of numerous intracellular bacteria located in vacuoles or free in the host cytoplasm. In addition, the interaction of this bacterium with epithelial cells was associated with the elongation of micro-villar extension that extruded from the host cell membranes and engulfed the bacteria. This internalization mechanism strongly resembles Salmonella- or Shigella-induced macro-pinocytosis. The strain was characterized using the 16S RNA sequence that amplified the gene from many genera. The closest phylogenetic relative was |HQ877772.1| Escherichia sp. A94 with 88% 16S ribosomal RNA gene sequence similarity. It was proposed that unidentified strain be assigned as type strain of species of the bacteria origin based on the 16S rRNA gene sequence search in Ribosomal Database project, small subunit rRNA and large subunit rRNA database together with the phylogenetic tree analysis.© 2017 International Formulae Group. All rights reserved.Keywords: Intracellular contaminants, cell cultures, bacteria culture, pre-clinical studies