Mycoplasma Infection Alters Cancer Stem Cell Properties in Vitro

Effects and Eradication of Mycoplasma Contamination on Patient-derived Colorectal Cancer Organoid Cultures

Patient-derived organoids are a useful platform for identification and testing of novel precision oncology approaches. Patient-derived organoids are generated by direct culture of patient samples. However, prior to development into patient-derived organoids, these samples are often processed for clinical use, opening the potential for contamination by Mycoplasma and other microbes. While most microbes can be detected by visual inspection, Mycoplasma can go undetected and have substantial impacts on assay results. Given the increased use of patient-derived organoids, there is a growing need for a standardized protocol to detect and remove Mycoplasma from organoid models. In the current study, we report a procedure for Mycoplasma removal by passaging organoids through mice as patient-derived organoid xenografts. In vivo passage of patient-derived organoids followed by re-establishment was 100% effective at decontaminating colorectal patient-derived organoids (n = 9), based on testing with the Sigma LookOut Mycoplasma PCR Detection Kit. This process can serve as a method to re-establish contaminated patient-derived organoids, which represent precious models to study patient-specific genomic features and treatment responses.

SIGNIFICANCE

Organoids are valuable models of cancer. Mycoplasma contamination can alter organoid drug sensitivity, so there is a need for a standardized protocol to detect and remove Mycoplasma from organoids. We report a simple procedure for removing Mycoplasma from organoids via in vivo passaging through mice followed by re-establishment of organoids.

Mycoplasma genitalium infection in the female reproductive system: Diseases and treatment

Mycoplasma genitalium is a newly emerged sexually transmitted disease pathogen and an independent risk factor for female cervicitis and pelvic inflammatory disease. The clinical symptoms caused by M. genitalium infection are mild and easily ignored. If left untreated, M. genitalium can grow along the reproductive tract and cause salpingitis, leading to infertility and ectopic pregnancy. Additionally, M. genitalium infection in late pregnancy can increase the incidence of preterm birth. M. genitalium infections are often accompanied by co-infection with other sexually transmitted pathogens (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis) and viral infections (Human Papilloma Virus and Human Immunodeficiency Virus). A recent study suggested that M. genitalium plays a role in tumor development in the female reproductive system. However, few studies endorsed this finding. In recent years, M. genitalium has evolved into a new "superbug" due to the emergence of macrolide-and fluoroquinolone-resistant strains leading to frequent therapy failures. This review summarizes the pathogenic characteristics of M. genitalium and the female reproductive diseases caused by M. genitalium (cervicitis, pelvic inflammatory disease, ectopic pregnancy, infertility, premature birth, co-infection, reproductive tumors, etc.), as well as its potential relationship with reproductive tumors and clinical treatment.

Reverse phase protein arrays in acute leukemia: investigative and methodological challenges

INTRODUCTION

Acute leukemia results from a series of mutational events that alter cell growth and proliferation. Mutations result in protein changes that orchestrate growth alterations characteristic of leukemia. Proteomics is a methodology appropriate for study of protein changes found in leukemia. The high-throughput reverse phase protein array (RPPA) technology is particularly well-suited for the assessment of protein changes in samples derived from clinical trials.

AREAS COVERED

This review discusses the technical, methodological, and analytical issues related to the successful development of acute leukemia RPPAs.

EXPERT COMMENTARY

To obtain representative protein sample lysates, samples should be prepared from freshly collected blood or bone marrow material. Variables such as sample shipment, transit time, and holding temperature only have minimal effects on protein expression. CellSave preservation tubes are preferred for cells collected after exposure to chemotherapy, and incorporation of standardized guidelines for antibody validation is recommended. A more systematic biological approach to analyze protein expression is desired, searching for recurrent patterns of protein expression that allow classification of patients into risk groups, or groups of patients that may be treated similarly. Comparing RPPA protein analysis between cell lines and primary samples shows that cell lines are not representative of patient proteomic patterns.

Hemin activation abrogates Mycoplasma hyorhinis replication in chronically infected prostate cancer cells via heme oxygenase-1 induction

Mycoplasma hyorhinis (M. hyorhinis) lacks a cell wall and resists multiple antibiotics. We describe here the striking > 90% inhibitory effect of hemin, a natural inducer of the cytoprotective enzyme heme oxygenase‐1 (HO‐1), on M. hyorhinis replication in chronically infected LNCaP prostate cancer cells. The role of HO‐1 in interrupting M. hyorhinis replication was confirmed by HO‐1‐specific siRNA suppression of hemin‐induced HO‐1 protein expression, which increased intracellular M. hyorhinis DNA levels in LNCaP cells. Proteomic analysis and transmission electron microscopy of hemin‐treated cells confirmed the complete absence of M. hyorhinis proteins and intact microorganisms, respectively, strongly supporting these findings. Our study is the first to our knowledge suggesting therapeutic potential for activated HO‐1 in cellular innate responses against mycoplasma infection.

The Relationship between Mycoplasmas and Cancer: Is It Fact or Fiction ? Narrative Review and Update on the Situation

More than one million new cancer cases occur worldwide every year. Although many clinical trials are applied and recent diagnostic tools are employed, curing cancer disease is still a great challenge for mankind. Heredity and epigenetics are the main risk factors often related to cancer. Although, the infectious etiological role in carcinogenesis was also theorized. By establishing chronic infection and inflammation in their hosts, several microorganisms were suggested to cause cell transformation. Of these suspicious microorganisms, mycoplasmas were well regarded because of their intimate parasitism with host cells, as well as their silent and insidious role during infections. This assumption has opened many questions about the real role played by mycoplasmas in oncogenesis. Herein, we presented a sum up of many studies among the hundreds which had addressed the Mycoplasma-cancer topic over the past 50 years. Research studies in this field have first started by approving the mycoplasmas malignancy potential. Indeed, using animal models and in vitro experiments in various cell lines from human and other mammalians, many mycoplasmas were proven to cause varied modifications leading to cell transformation. Moreover, many studies have looked upon the Mycoplasma-cancer subject from an epidemiological point of view. Diverse techniques were used to assess the mycoplasmas prevalence in patients with cancer from different countries. Not less than 10 Mycoplasma species were detected in the context of at least 15 cancer types affecting the brain, the breast, the lymphatic system, and different organs in the genitourinary, respiratory, gastrointestinal, and urinary tracts. Based on these revelations, one should concede that detection of mycoplasmas often linked to ‘‘wolf in sheep's clothing” is not a coincidence and might have a role in cancer. Thorough investigations are needed to better elucidate this role. This would have a substantial impact on the improvement of cancer diagnosis and its prevention.

Progress of cationic gene delivery reagents for non-viral vector

Gene delivery systems play a vital role in gene therapy and recombinant protein production. The advantages of using gene delivery reagents for non-viral vector include the capacity to accommodate a large packaging load and their low or absent immunogenicity. Furthermore, they are easy to produce at a large scale and preserve. Gene delivery reagents for non-viral vector are commonly used for transfecting a variety of cells and tissues. It is mainly composed of liposomes and non-liposome cationic polymers. According to the different head structures used, the non-viral cationic transfection reagents include a quaternary ammonium salt, amine, amino acid or polypeptide, guanidine salt, and a heterocyclic ring. This article summarizes these approaches and developments of types and components of transfection reagents and optimization of gene delivery. The optimization of mammalian cell transient recombinant protein expression system and cationic reagents for clinical or clinical trials are also discussed.

FTIR Microspectroscopy for the Assessment of Mycoplasmas in HepG2 Cell Culture

To assess the presence and absence of mycoplasma contamination in cell culture, Fourier transform infrared (FTIR) microspectroscopy, coupled with multivariate analysis, was deployed to determine the biomolecular changes in hepatocellular carcinoma cells, HepG2, before and after mycoplasma contamination. The contaminated HepG2 cells were treated with antibiotic BM-Cyclin to decontaminate the mycoplasma, and polymerase chain reaction (PCR) was then performed to confirm the presence or the absence of mycoplasma contamination. The contaminated and decontaminated HepG2 cells were analyzed by FTIR microspectroscopy with principal component analysis (PCA) and peak integral area analysis. The results showed that the FTIR spectra of contaminated HepG2 cells demonstrated the alteration in the IR spectra corresponding to the lipid, protein, and nucleic acid regions. PCA analysis distinguished the spectral differences between the groups of mycoplasma-contaminated and -decontaminated cells. The PCA loading plots suggest that lipid and protein are the main contributed molecules for the difference between these two cell groups. Peak integral area analysis illustrated the increase of lipid and nucleic acid and the decrease of protein contents in the contaminated HepG2 cells. FTIR microspectroscopy is, therefore, proven to be a potential tool for assessing mycoplasma removal by monitoring biomolecular alterations in cell culture.

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.

The Lipocalin2 Gene is Regulated in Mammary Epithelial Cells by NFκB and C/EBP In Response to Mycoplasma

Lcn2 gene expression increases in response to cell stress signals, particularly in cells involved in the innate immune response. Human Lcn2 (NGAL) is increased in the blood and tissues in response to many stressors including microbial infection and in response to LPS in myeloid and epithelial cells. Here we extend the microbial activators of Lcn2 to mycoplasma and describe studies in which the mechanism of Lcn2 gene regulation by MALP-2 and mycoplasma infection was investigated in mouse mammary epithelial cells. As for the LPS response of myeloid cells, Lcn2 expression in epithelial cells is preceded by increased TNFα, IL-6 and IκBζ expression and selective reduction of IκBζ reduces Lcn2 promoter activity. Lcn2 promoter activation remains elevated well beyond the period of exposure to MALP-2 and is persistently elevated in mycoplasma infected cells. Activation of either the human or the mouse Lcn2 promoter requires both NFκB and C/EBP for activation. Thus, Lcn2 is strongly and enduringly activated by mycoplasma components that stimulate the innate immune response with the same basic regulatory mechanism for the human and mouse genes.

Non-Viral in Vitro Gene Delivery: It is Now Time to Set the Bar!

Transfection by means of non-viral gene delivery vectors is the cornerstone of modern gene delivery. Despite the resources poured into the development of ever more effective transfectants, improvement is still slow and limited. Of note, the performance of any gene delivery vector in vitro is strictly dependent on several experimental conditions specific to each laboratory. The lack of standard tests has thus largely contributed to the flood of inconsistent data underpinning the reproducibility crisis. A way researchers seek to address this issue is by gauging the effectiveness of newly synthesized gene delivery vectors with respect to benchmarks of seemingly well-known behavior. However, the performance of such reference molecules is also affected by the testing conditions. This survey points to non-standardized transfection settings and limited information on variables deemed relevant in this context as the major cause of such misalignments. This review provides a catalog of conditions optimized for the gold standard and internal reference, 25 kDa polyethyleneimine, that can be profitably replicated across studies for the sake of comparison. Overall, we wish to pave the way for the implementation of standardized protocols in order to make the evaluation of the effectiveness of transfectants as unbiased as possible.

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.

Conclusion

The 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.

Mycoplasma contamination of leukemic cell lines alters protein expression determined by reverse phase protein arrays

Mycoplasma contamination is a major problem in cell culturing, potentially altering the results of cell line-based experiments in largely uncharacterized ways. To define the consequences of mycoplasma infection at the level of protein expression we utilized the reverse phase protein array technology to analyze the expression of 235 proteins in mycoplasma infected, uninfected post treatment, and never-infected leukemic cell lines. Overall, protein profiles of cultured cells remained relatively stable after mycoplasma infection. However, paired comparisons for individual proteins identified that 18.7% of the proteins significantly changed between the infected and the never-infected cell line samples, and that 14.0% of the proteins significantly altered between the infected and the post treatment samples. Six percent of the proteins were affected in the post treatment samples compared to the never-infected samples, and 7.2% compared to treated cells that had never had mycoplasma infection before. Proteins that were significantly altered in the infected cells were enriched for apoptotic signaling processes and auto-phosphorylation, suggesting an increased cellular stress and a decreased growth rate. In conclusion, this study shows that mycoplasma infection of leukemic cell lines alters the proteins expression levels, potentially confounding experimental results. This reinforces the need for regular testing of mycoplasma.

Elimination of Mycoplasma Contamination from Infected Human Hepatocyte C3A Cells by Intraperitoneal Injection in BALB/c Mice

Background/Aims: The use of antibiotics to eliminate Mycoplasma contamination has some serious limitations. Mycoplasma contamination can be eliminated by intraperitoneal injection of BALB/c mice with contaminated cells combined with screening monoclonal cells. However, in vivo passage in mice after injection with contaminated cells requires a long duration (20-54 days). Furthermore, it is important to monitor for cross-contamination of mouse and human cells, xenotropic murine leukemia virus-related virus (XMRV) infection, and altered cell function after the in vivo treatment. The present study aimed to validate a reliable and simplified method to eliminate mycoplasma contamination from human hepatocytes. BALB/c mice were injected with paraffin oil prior to injection with cells, in order to shorten duration of intraperitoneal passage. Cross-contamination of mouse and human cells, XMRV infection and cell function-related genes and proteins were also evaluated. Methods: PCR and DNA sequencing were used to confirm Mycoplasma hyorhinis (M. hyorhinis) contamination in human hepatocyte C3A cells. Five BALB/c mice were intraperitoneally injected with 0.5 ml paraffin oil 1 week before injection of the cells. The mice were then intraperitoneally injected with C3A hepatocytes (5.0 × 10⁶/ml) contaminated with M. hyorhinis (6.2 ± 2.2 × 10⁸ CFU/ml). Ascites were collected for monoclonal cell screening on the 14th day after injection of contaminated cells. Elimination of mycoplasma from cells was determined by PCR and Transmission Electron Microscopy (TEM). Human-mouse cell and XMRV contamination were also detected by PCR. Quantitative reverse transcription PCR and western blotting were used to compare the expression of genes and proteins among treated cells, non-treated infected cells, and uninfected cells. Results: Fourteen days after injection with cells, 4 of the 5 mice had ascites. Hepatocyte colonies extracted from the ascites of four mice were all mycoplasma-free. There was no cell cross-contamination or XMRV infection in treated cell cultures. Elimination of Mycoplasma resulted in partial or complete recovery in the expression of ALB, TF, and CYP3A4 genes as well as proteins. Proliferation of the treated cells was not significantly affected by this management. Conclusion: The method of elimination of Mycoplasma contamination in this study was validated and reproducible. Success was achieved in four of five cases examined. Compared to the previous studies, the duration of intraperitoneal passage in this study was significantly shorter.