Impacts of intentional mycoplasma contamination on CHO cell bioreactor cultures

Establishment and characterization of a kidney cell line from hybrid snakehead (male Channa argus × female Channa maculata) and its susceptibility to hybrid snakehead rhabdovirus (HSHRV)

Hybrid snakehead (male Channa argus × female Channa maculata) is an emerging fish breed with increasing production levels. However, infection with hybrid snakehead rhabdovirus (HSHRV) critically affects hybrid snakehead farming. In this study, a fish cell line called CAMK, derived from the kidneys of hybrid snakehead, was established and characterized. CAMK cells exhibited the maximum growth rate at 28 °C in Leibovitz's-15 medium supplemented with 10% fetal bovine serum(FBS). Karyotyping revealed diploid chromosomes in 54% of the cells at the 50th passage (2n = 66), and 16S rRNA sequencing validated that CAMK cells originated fromhybrid snakehead, and the detection of kidney-specific antibodies suggested that it originated from kidney. .The culture was free from mycoplasma contamination, and the green fluorescent protein gene was effectively transfected into CAMK cells, indicating their potential use for in vitro gene expression investigations. Furthermore, qRT-PCR and immunofluorescence analysis revealed that HSHRV could replicate in CAMK cells, indicating that the cells were susceptible to the virus. Transmission electron microscopy revealed that the viral particles had bullet-like morphology. The replication efficiency of HSHRV was 107.33 TCID50/mL. Altogether, we successfully established and characterized a kidney cell line susceptible to the virus. These findings provide a valuable reference for further genetic and virological studies.

Comparative genomic analysis of Mycoplasma related to cell culture for infB gene-based loop-mediated isothermal amplification

Mycoplasma contamination in cell culture affects the properties of cell lines. Gold standard detection by microbiological culture takes days and requires specialists. The polymerase chain reaction and loop-mediated isothermal amplification (LAMP) are fast molecular options, but LAMP only requires one heating block for DNA amplification. This study presents a comparative genomic analysis of Mycoplasma species to identify common target genes different from the rrsA gene, which encodes 16 S rRNA. The aim is to implement a LAMP assay to detect Mycoplasma species, reducing the time and specialized equipment required for detection. We performed a comparative genomic analysis through Mauve software and the GView server and selected infB and clpB genes as target candidates for designing LAMP primers. We evaluated both genes by multiple sequence alignment (MSA). The infB gene presented the best score MSA assessment with lower odd-log values (5,480,281) than other genes. We selected the infB gene to design LAMP primers specific to Mycoplasma spp. We used these primers to implement LAMP at 63 °C for 30 min, which showed 100% positive amplifications for detecting Mycoplasma spp. In conclusion, we present a methodology utilizing the infB gene-based LAMP assay to detect three of the six most prevalent Mycoplasma species in cell culture.

Sık Kullanılan Bazı Hücre Hatları için Kalite Kontrol: Mikoplazma Kontaminasyon Tespiti, Sitokrom B ve Sitokrom Oksidaz Alt Birim I Genlerinin DNA Dizi Analizlerinin Gerçekleştirilmesi

Amaç: Laboratuvarlarda sık kullanılan serviks epitelyal karsinom (HeLa), insan periferal kan promiyelösitik lösemi (HL-60), fare C3/bağ dokusu (L929), Madin Darby köpek böbrek (MDCK), fare nöroblastom (Neuro-2a) gibi bazı hücre hatlarının mikoplazma kontaminasyon kontrollerinin yapılması, kimlik doğrulamalarının gerçekleştirilmesi ve klonalitelerinin belirlenmesidir.Yöntem: Bu çalışmada üç farklı türe ait beş hücre hattı kullanılmıştır. Çalışılan tüm hatların Bisbenzimid (Hoechst 33258) ile deoksiribonükleik asit (DNA) floresan işaretlemesi yapılarak mikoplazma kontaminasyonu kontrolleri gerçekleştirilmiştir. Hücre hatlarından DNA izolasyonları yapılmış, elde edilen DNA örneklerinden sitokrom B (CYTB) geninin bölgesel amplifikasyonu için L14816 ve H15173 primerleri; sitokrom oksidaz alt birim I (COI) geni için ise LCO 1490 and HCO 2198 primerleri kullanılmıştır. İlgili amplifikasyonların DNA dizi analiz sonuçları, biyoinformatik araçlar kullanılarak referans dizilerle karşılaştırmalı olarak değerlendirilmiştir.Bulgular: Çalışmada ilgili hücrelerin, Bisbenzimid (Hoechst 33258) ile üretici firmanın protokollerine göre belirlenen konsantrasyon ve sürede yapılan boyama sonucunda mikoplazma kontaminasyonuna rastlanılmamıştır. Ayrıca CYTB gen bölgesi için veritabanında yer alan referans dizi ile yapılan karşılaştırma sonucu HL-60 için %97; "HeLa, L929, MDCK, Neuro-2a” hücre hatları için ise %98 oranında benzerlik bulunmuştur. COI gen bölgesi için ise bu benzerlik oranları “HeLa, HL-60, L929, MDCK ve Neuro-2a” hücre hatları için sırasıyla %95, %99, %96, %96 ve %98 olarak bulunmuştur.Sonuç: Bu bağlamda, çalışmadan elde edilen Bisbenzimid (Hoechst 33258) işaretleme ve DNA dizi analiz sonuçları, pek çok araştırmada kullanılan bu hücre hatlarının kalitesi konusunda kabul edilebilir bir belirteç ve güven sağlamıştır.   

Report of a clinical and laboratory management of cell therapy for knee cartilage in the face of mycoplasma contamination

To describe a case of autologous chondrocyte implantation after cell culture contamination by Mycoplasma pneumoniae and the measures taken to successfully complete cell therapy in a patient with focal chondral lesion. A 45-year-old male patient, complaining of chronic pain on the knee and no history of trauma. He had a chondral lesion in the trochlear region of the femur and clinical tests compatible with pain in the anterior compartment of the knee. Conservative treatment failed to alleviate symptoms. Surgical treatment was indicated, but due to the size of the lesion, membrane-assisted autologous chondrocyte implantation was the technique of choice. Cartilage biopsies were collected from the intercondylar region of the distal femur. After isolation, chondrocytes were expanded ex vivo in a trained laboratory, for three weeks, and seeded onto a commercially available collagen membrane prior to implantation in the knee. Two days before surgery, a cell culture sample tested positive for Mycoplasma pneumoniae. The source of contamination was found to be autologous blood serum, extracted from the patient´s peripheral vein, and used to supplement the cell culture medium. After treating the patient with antibiotics, all procedures were repeated and the new final cell product, free from contaminants, was successfully implanted. We discuss the strategies available to deal with this situation, and describe the results of this particular case, which led to modifications in the autologous chondrocyte implant protocol.

Low-molecular-weight impurity in Poloxamer 188 responsible for atypical cell culture performance for mAb production

During a recent manufacturing campaign for a monoclonal antibody using a fed-batch process, poor cell culture performance was observed across two manufacturing sites with similar scales and equipment. Root cause analysis indicated that the poor cell culture performance was linked to the production basal media. Genealogy of the precursor raw materials used in the media revealed that a particular lot of Poloxamer 188 (P188) was the common link to the poor-performing media lots. P188 serves a critical role in protecting cells against shear in cell culture bioprocesses. However, the small-scale studies suggested that the poor cell culture performance was cytostatic in nature rather than being caused due to lack of shear protection. Several P188 lots were tested analytically using SEC-MS and RP-LC-MS methods and a unique low molecular weight species was identified in the suspect lot of poloxamer. The impurity was identified to be polypropylene oxide (PPO), a reaction intermediate in P188 synthesis. Spiking studies with PPO further confirmed its cytostatic nature. This case study highlights yet another scenario where lot-to-lot variability continues to impact bioprocesses and re-emphasizes the need for robust analytical and cell-culture raw material screening methods.

Impacts on product quality attributes of monoclonal antibodies produced in CHO cell bioreactor cultures during intentional mycoplasma contamination events

A mycoplasma contamination event in a biomanufacturing facility can result in costly cleanups and potential drug shortages. Mycoplasma may survive in mammalian cell cultures with only subtle changes to the culture and penetrate the standard 0.2‐µm filters used in the clarification of harvested cell culture fluid. Previously, we reported a study regarding 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 G 1 (IgG1) antibody. Our previous 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. Careful evaluation of certain identified process parameters over time may be used to indicate mycoplasma contamination in CHO cell cultures in a bioreactor before detection from a traditional method. In this report, we studied the changes in the IgG1 product quality produced by CHO cells considered to be induced by the M. arginini contamination events. We observed changes in critical quality attributes correlated with the duration of contamination, including increased acidic charge variants and high mannose species, which were further modeled using principal component analysis to explore the relationships among M. arginini contamination, CHO cell growth and metabolites, and IgG1 product quality attributes. Finally, partial least square models using NIR spectral data were used to establish predictions of high levels (≥10⁴ colony‐forming unit [CFU/ml]) of M. arginini contamination, but prediction of levels below 10⁴ CFU/ml were not reliable. Contamination of CHO cells with M. arginini resulted in significant reduction of antibody product quality, highlighting the importance of rapid microbiological testing and mycoplasma testing during particularly long upstream bioprocesses to ensure product safety and quality.

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.