Heritable non-genetic phenotypes are enriched for stress responses as a form of bet hedging
Ontology highlight
ABSTRACT: To produce humanized therapeutics, Chinese hamster ovary (CHO) cells have become the preferred host organism. During manufacturing batches, these cells encounter critical levels of environmental stressors such as ammonia, lactate, and osmolality accumulation that can significantly reduce cell health and productivity. It is therefore crucial that stress adaptation and resistance be factored into cell line development (CLD) considerations. An alternative to screening stress sensitivity during CLD, where the scaled-down micro-environment makes it difficult, is selecting for or engineering cell lines with a stress resistant phenotype. In this study, we employee population-based transcriptomic analysis and differential gene expression analysis on stress-induced CHO cells to identify biomarkers for engineering stress resistance. These biomarkers are identified as genes displaying heritable properties while being differentially expressed in the presence of manufacturing relevant stress levels. Using this workflow, 199 genes displayed transcriptional variability characteristic of a bistable system that formed six network communities of co-fluctuating genes. These communities were enriched in genes related to response to stimuli, regulation of apoptotic processes, and regulation of gene expression or metabolic pathways. Significant overlap with differentially expressed genes in stress-induced production fed-batch flasks reinforce the relevancy of these heritable genes states for stress adaptation. Assessing the overlap and the biological function, six genes were identified as promising biomarkers for engineering a stress-resistant phenotype. Cell line engineering methods may be employed in the future to bias clonal populations for higher stress tolerance and adaptability to manufacturing stress, therefore increasing cell health and productivity in at-scale bioreactors.
Project description:Small-scale bioreactors used in Chinese hamster ovary (CHO) cell line development allow transcriptomic studies on multiple cell lines. Here we define the CHO cell long non-coding RNA (lncRNA) transcriptome from cells grown in controlled miniature bioreactors under fed-batch conditions using RNA-Seq to identify lncRNAs and how the expression of these changes throughout growth and between IgG producers. We identify lncRNAs associated with productivity and growth characteristics, finding that Adapt15, linked to ER stress, GAS5, linked to mTOR signalling/growth arrest, and PVT1, linked to Myc expression, are differentially regulated during fed-batch culture and whose expression relates to productivity and growth. Changes in (non)-coding RNA expression between the seed train and the equivalent day of fed-batch culture are also reported, showing large differences in gene expression between these, and compared with existing datasets. Collectively, we present a comprehensive lncRNA CHO cell profiling and identify targets for engineering growth and productivity characteristics of CHO cells.
Project description:Small-scale bioreactors used in Chinese hamster ovary (CHO) cell line development allow transcriptomic studies on multiple cell lines. Here we define the CHO cell long non-coding RNA (lncRNA) transcriptome from cells grown in controlled miniature bioreactors under fed-batch conditions using RNA-Seq to identify lncRNAs and how the expression of these changes throughout growth and between IgG producers. We identify lncRNAs associated with productivity and growth characteristics, finding that Adapt15, linked to ER stress, GAS5, linked to mTOR signalling/growth arrest, and PVT1, linked to Myc expression, are differentially regulated during fed-batch culture and whose expression relates to productivity and growth. Changes in (non)-coding RNA expression between the seed train and the equivalent day of fed-batch culture are also reported, showing large differences in gene expression between these, and compared with existing datasets. Collectively, we present a comprehensive lncRNA CHO cell profiling and identify targets for engineering growth and productivity characteristics of CHO cells.
Project description:Fed-batch cultivation of recombinant Chinese hamster ovary (CHO) cell lines is one of the most widely used production mode for commercial manufacturing of recombinant protein therapeutics. Furthermore, fed-batch cultivations are often conducted as biphasic processes where culture temperature is decreased to maximize volumetric product yields. However, it still remains to be elucidated which intracellular regulatory elements actually control the observed pro-productive phenotypes. Recently, several studies have revealed microRNAs (miRNAs) to be important molecular switches of cell phenotypes since single miRNAs are capable of regulating entire physiological pathways. In this study, we analyzed miRNA profiles of two different recombinant CHO cell lines (high and low producer), and compared them to a non-producing CHO DG44 host cell line during fed-batch cultivation at 37 versus 30 °C culture temperature. Taking advantage of next-generation sequencing combined with cluster, correlation and differential expression analyses, we could identify 89 different miRNAs, which might be interesting for CHO cell engineering. Functional validation experiments using 19 validated target miRNAs confirmed that these miRNAs indeed induced changes in process relevant phenotypes such as recombinant protein production, apoptosis, necrosis and proliferation. Furthermore, computational miRNA target prediction combined with functional clustering identified putative target genes and cellular pathways, which might be regulated by these miRNAs. Taken together, our study systematically identified novel target miRNAs during different phases and conditions of a biphasic fed-batch process and functionally evaluated their potential for host cell engineering. 36 miRNA libraries from three different CHO cell lines and two process condition. In the control run temperature was maintained at 30°C, while temperature was reduced to 30°C after reaching mid exponential phase
Project description:In biopharmaceutical production, Chinese hamster ovary (CHO) cells derived from Cricetulus griseus remain the most commonly used host cell for recombinant protein production, especially antibodies. Over the last decade in-depth multi-omics characterization of these CHO cells provided data for extensive cell line engineering and corresponding increases in productivity. exosomes, extracellular vesicles containing proteins and nucleic acids, are barely researched at all in CHO cells. Exosomes have been proven to be an ubiquitous mediator of intercellular communication and are proposed as new biopharmaceutical format for drug delivery, indicator reflecting host cell condition and anti-apoptotic factor in spent media. Here we sequenced non-coding RNA of Exosomes (EXO) and whole cell lysate (WCL) isolated from CHO-K1 Cell Cultures at different growth phases (logarithmic/exponential phase (log/exp), stationary phase (stat), as well as death phase at 80 % viability (80 % ) and 60 % viability (60 %)) via Lexogen Small RNA-Seq Library Prep Kit for Illumina on the Illumina MiSeq platform in PE mode 2 x 36nt.
Project description:Gene expression is a key determinant of phenotypes that made Chinese Hamster Ovary (CHO) cells, with their human-like glycosylation profile and high protein titers, one of the most widely used cells for the production of therapeutic proteins and biopharmaceuticals. Engineering CHO gene expression thus holds a key to improve drug quality and cost effective production. However, the success of engineering gene expression or ectopic activation of silent genes to optimize desired pathways requires accurate annotation of the underlying regulatory elements and the transcription start site (TSS). Unfortunately, to date, most TSSs of CHO-expressed genes and the ~50% of hamster genes that are silent in CHO were computationally predicted and are frequently inaccurate. To oust this hurdle, we report revised TSSs annotations for 15,308 Chinese Hamster genes and 4,145 non-coding RNAs based on experimental data from CHO K1 cells and 10 hamster tissues. In the example of the glycosyltransferase gene Mgat3, we further demonstrate how accurate annotations readily facilitate activating silent genes by CRISPRa. Together, we envision that our annotation and data from the Chinese Hamster will provide a rich resource for the CHO community, improve genome engineering efforts and additionally aid comparative and evolutionary studies.
Project description:Fed-batch cultivation of recombinant Chinese hamster ovary (CHO) cell lines is one of the most widely used production mode for commercial manufacturing of recombinant protein therapeutics. Furthermore, fed-batch cultivations are often conducted as biphasic processes where culture temperature is decreased to maximize volumetric product yields. However, it still remains to be elucidated which intracellular regulatory elements actually control the observed pro-productive phenotypes. Recently, several studies have revealed microRNAs (miRNAs) to be important molecular switches of cell phenotypes since single miRNAs are capable of regulating entire physiological pathways. In this study, we analyzed miRNA profiles of two different recombinant CHO cell lines (high and low producer), and compared them to a non-producing CHO DG44 host cell line during fed-batch cultivation at 37 versus 30 °C culture temperature. Taking advantage of next-generation sequencing combined with cluster, correlation and differential expression analyses, we could identify 89 different miRNAs, which might be interesting for CHO cell engineering. Functional validation experiments using 19 validated target miRNAs confirmed that these miRNAs indeed induced changes in process relevant phenotypes such as recombinant protein production, apoptosis, necrosis and proliferation. Furthermore, computational miRNA target prediction combined with functional clustering identified putative target genes and cellular pathways, which might be regulated by these miRNAs. Taken together, our study systematically identified novel target miRNAs during different phases and conditions of a biphasic fed-batch process and functionally evaluated their potential for host cell engineering.
Project description:Viral contamination in biopharmaceutical manufacturing can lead to shortages in the supply of critical therapeutics. To facilitate the protection of bioprocesses, we explored the basis for the susceptibility of CHO cells, the most commonly used cell line in biomanufacturing, to RNA virus infection. Upon infection with certain ssRNA and dsRNA viruses, CHO cells fail to generate a significant interferon (IFN) response. Nonetheless, the downstream machinery for generating IFN responses and its antiviral activity is intact in these cells: treatment of cells with exogenously-added type I IFN or poly I:C prior to infection limited the cytopathic effect from Vesicular stomatitis virus (VSV), Encephalomyocarditis virus (EMCV), and Reovirus-3 virus (Reo) in a STAT1-dependent manner. To harness the intrinsic antiviral mechanism, we used RNA-Seq to identify two upstream repressors of STAT1: Gfi1 and Trim24. By knocking out these genes, the engineered CHO cells exhibited increased resistance to the prototype RNA viruses tested. Thus, omics-guided engineering of mammalian cell culture can be deployed to increase safety in biotherapeutic protein production.
Project description:Adeno-associated viral (AAV) vectors are widely used for gene therapy, providing treatment for diseases caused by absent or defective genes. Despite the success of gene therapy, AAV-manufacturing is still challenging, with production yields being limited. With increased patient demand, improvements in host cell productivity through various engineering strategies will be necessary. Here, we study the host cell proteome of AAV5 producing HEK293 cells using reversed phase nano liquid chromatography and tandem mass spectrometry (LC-MS/MS). Rela-tive label-free quantitation (LFQ) was performed allowing a comparison of transfected vs. un-transfected cells. Gene ontology enrichment and pathway analysis revealed differential expres-sion of proteins involved in fundamental cellular processes such as metabolism, proliferation and cell death. Furthermore, changes in expression of proteins involved in endocytosis and lysosomal degradation were observed. Our data provides highly valuable insights into cellular mechanisms involved during recombinant AAV production by HEK293 cells thus potentially enabling further improvements of gene therapy product manufacturing.
Project description:The field of tissue engineering aspires to provide clinically relevant solutions for patients through the integration of developmental engineering principles with a bottom up manufacturing approach. However, manufacturing of cell based advanced therapy medicinal products is hampered by protocol complexity, lack of non-invasive critical quality controls, and dependency on animal-derived components for tissue differentiation. We investigate a serum-free, chemically defined, xeno- and lipid-free chondrogenic differentiation medium to generate bone-forming callus organoids. Our results show an increase in microtissue homogeneity during prolonged differentiation and a high quality of in vivo bone forming organoids. The low protein content of the culture media potentially allows for monitoring of relevant secreted biomarkers as (critical) quality attributes . Together, we envisage that this xeno- and lipid-free chondrogenic medium is compatible with industrial scale-up and automation, while facilitating the implementation of non-invasive imaging and use of quality control parameters based on secreted biomarkers.
Project description:We performed a combination of metabolic engineering (deletion of ldh and poxB and overexpression of mmc) with evolutionary engineering (selection under oxygen stress, acid stress and osmotic stress) in Propionibacterium acidipropionici. The results indicated that the mutants had superior physiological activity, especially the mutant III obtained from P. acidipropionici-Δldh-ΔpoxB+mmc by evolutionary engineering, with 1.5-3.5 times higher growth rates, as well as a 37.1% increase of PA titer and a 37.8% increase PA productivity compared to the wild type. Moreover, the 5.5-fold upregulation of Dps, 2 to 4-fold upregulation of ABC-type glycine betaine transporter and 3-fold upregulation of SOD indicated that these genes were likely in key regulons for the adaptation to abiotic stresses. An approximately 2.5-fold upregulation of mmc was also found. The results showed the multidirectional variation tendency of P. acidipropionici under cross stress and provide in-depth insights into the mechanism of tolerance and high production of PA.