Nature as blueprint: Global phenotype engineering of CHO production cells based on a multi-omics comparison with plasma cells

Especially for the production of artificial, difficult to express molecules a further development of the CHO production cell line is required to keep pace with the continuously increasing demands. However, the identification of novel targets for cell line engineering to improve CHO cells is a time and cost intensive process. Since plasma cells are evolutionary optimized for a high antibody expression in mammals, we performed a comprehensive multi-omics comparison between CHO and plasma cells to exploit optimized cellular production traits. Comparing the transcriptome, proteome, miRNome, surfaceome and secretome of both cell lines identified key differences including 392 potential overexpression targets for CHO cell engineering categorized in 15 functional classes like transcription factors, protein processing or secretory pathway. In addition, 3 protein classes including 209 potential knock-down/out targets for CHO engineering were determined likely to affect aggregation or proteolysis. For production phenotype engineering, several of these novel targets were successfully applied to transient and transposase mediated overexpression or knock-down strategies to efficiently improve productivity of CHO cells. Thus, substantial improvement of CHO productivity was achieved by taking nature as a blueprint for cell line engineering.

In pursuit of a minimal CHO genome: Establishment of large-scale genome deletions

Chinese hamster ovary (CHO) cells are the most commonly used mammalian cell line for the production of complex therapeutic glycoproteins. As CHO cells have evolved as part of a multicellular organism, they harbor many cellular functions irrelevant for their application as production hosts in industrial bioprocesses. Consequently, CHO cells have been the target for numerous genetic engineering efforts in the past, but a tailored host cell chassis holistically optimized for its specific task in a bioreactor is still missing. While the concept of genome reduction has already been successfully applied to bacterial production cells, attempts to create higher eukaryotic production hosts exhibiting reduced genomes have not been reported yet. Here, we present the establishment and application of a large-scale genome deletion strategy for targeted excision of large genomic regions in CHO cells. We demonstrate the feasibility of genome reduction in CHO cells using optimized CRISPR/Cas9 based experimental protocols targeting large non-essential genomic regions with high efficiency. Achieved genome deletions of non-essential genetic regions did not introduce negative effects on bioprocess relevant parameters, although we conducted the largest reported genomic excision of 864 kilobase pairs in CHO cells so far. The concept presented serves as a directive to accelerate the development of a significantly genome-reduced CHO host cell chassis paving the way for a next generation of CHO cell factories.

Multi-lipase gene knockdown in Chinese hamster ovary cells using artificial microRNAs to reduce host cell protein mediated polysorbate degradation

A large number of companies observe polysorbate (PS) degradation and associated (sub-)visible particle formation in biological drug formulations, which compromise the stability of the drug product, ultimately posing a risk toward delivering innovative medicines to patients. The main culprits of PS degradation are hydrolytic host cell proteins (HCPs) originating from the production cell lines, which are mostly Chinese hamster ovary (CHO) cell derived. Here, a small portion of particularly difficult-to-remove HCPs-mainly lipases-cause hydrolytic cleavage of PS resulting in the accumulation of free fatty acid aggregates/particles. One possible mitigation strategy is the removal of such critical HCPs in the production cell line. Multigene regulation can be achieved via microRNAs (miRNAs) thereby serving as a smart tool to reduce the expression of different target genes using a single miRNA. To enable a tailored gene regulation of multiple specific target lipases self-designed and non-naturally occurring artificial miRNAs (amiRNA) can be designed. Based on micro-conserved regions in the mRNA sequence of two sets of target HCPs, we provide a proof-of-concept for a simultaneous multi-lipase knockdown in CHO cells using single amiRNAs. By this, we were not only able to reduce PS degradation but laid the foundation to expand this tool to other areas of cell line phenotype engineering.

Transduction Enhancers Enable Efficient Human Adenovirus Type 5-Mediated Gene Transfer into Human Multipotent Mesenchymal Stromal Cells

Human multipotent mesenchymal stromal cells (hMSCs) are currently developed as cell therapeutics for different applications, including regenerative medicine, immune modulation, and cancer treatment. The biological properties of hMSCs can be further modulated by genetic engineering. Viral vectors based on human adenovirus type 5 (HAdV-5) belong to the most frequently used vector types for genetic modification of human cells in vitro and in vivo. However, due to a lack of the primary attachment receptor coxsackievirus and adenovirus receptor (CAR) in hMSCs, HAdV-5 vectors are currently not suitable for transduction of this cell type without capsid modification. Here we present several transduction enhancers that strongly enhance HAdV-5-mediated gene transfer into both bone marrow- and adipose tissue-derived hMSCs. Polybrene, poly-l-lysine, human lactoferrin, human blood coagulation factor X, spermine, and spermidine enabled high eGFP expression levels in hMSCs. Importantly, hMSCs treated with enhancers were not affected in their migration behavior, which is a key requisite for many therapeutic applications. Exemplary, strongly increased expression of tumor necrosis factor (TNF)-stimulated gene 6 (TSG-6) (a secreted model therapeutic protein) was achieved by enhancer-facilitated HAdV-5 transduction. Thus, enhancer-mediated HAdV-5 vector transduction is a valuable method for the engineering of hMSCs, which can be further exploited for the development of innovative hMSC therapeutics.

[Quality assurance in therapy of chronic pain. Results obtained by a taskforce of the German Section of the Association for the Study of Pain on psychological assessment of chronic pain. V. Instruments for the assessment of pain-related cognitions and coping with pain.]

The present paper is one of a series of publications, reviewing German instruments for psychological assessment of pain. Their main focus is on the results of a task force on quality testing for each subject. This paper describes and comments on methods regarding self-reporting of pain cognitions and both cognitive and behavioral strategies for coping with pain. Concerning pain cognitions one focus is on patients' attributions of causes of pain and the modes of controlling pain (subjective pain model). The other focus is on instruments recording "pain beliefs" in the sense of dysfunctional congitions associated with the experience of pain. Each instrument was examined with reference to approved psychometric criteria, empirical foundation and clinical relevance. It was noted that several instruments are deficient in their psychometric criteria and their empirical foundations. We used these data as a basis to elaborate a specific and differential recommendation. A similar procedure was followed with instruments for the assessment of pain-related coping strategies. According to our research there are two subgroups of coping instruments, one more specifically for cognitive coping with pain, and the other combined with behavioral coping strategies. Once again, we elaborated a specific and differential recommendation, giving priority to instruments taking account of both cognitive and behavioral dimensions of coping with pain.

[Quality assurance in therapy of chronic pain. Results obtained by a taskforce of the German Section of the Association for the Study of Pain on psychological assessment of chronic pain : VI. Instruments for the assessment of disability VII. Psychological instruments for the assessment of pain relevant aspects of social interaction and communication.]

Disability is a central aspect in the assessment of chronic pain patients. Disability questionnaires in German (developed or adapted) are examined and selected for different purposes. The "Funktionsfragebogen Hannover" and the "Pain Disability Index" are recommended for both research and clinicalapplication while the "Sickness Impact Profile" is suitable only for research purposes.Four different German questionnaires for the assessment of social interaction and communication in pain patients and their significant others are examined in part VII. There are some empirical data for three of them. Only the "Inventory of Familial Adaptability and Cohesion" has achieved a certain degree of empirical maturity. Further research and developmental activity in this area of pain assessment are urgently needed.