Antibody production in plant cell suspension cultures : searching for new host species and identification of active genomic loci

Abstract

Plant suspension cells are considered as an interesting platform to produce monoclonal antibodies (mAb) and other pharmacological proteins. However, to date, the expression yields obtained are still relatively low in comparison with other expression platforms. So far suspension cells from very few plant species have been used as hosts. In this study, we screened cell suspension lines derived from the 13 following dicot species for their capacity to express an antibody: Ocimum basilicum, Lavandula angustifolia, Linum usitatissimum, Mentha x piperita, Brassica rapa, Dianthus caryophyllus, Citrus x sinensis, Phytolacca acinosa, Solanum tuberosum, Malus domestica, Phytolacca americana, Helianthus annuus, and Vitis vinifera. We succeeded in setting up Agrobacterium-mediated transformation and expressing intact mAbs in suspension cells derived from two of them, L. usitatissimum (flax) and L. angustifolia (lavender). We showed that, unlike the cauliflower mosaic virus 35S promoter, the constitutive promoter of Nicotiana plumaginifolia PMA4 was not able to efficiently drive gene transcription in L. usitatissimum cells. Mass spectrometry analysis of mAbs secreted from L. angustifolia cells revealed a high proportion of N-glycosylation with plant-specific glycans. In the second part, we sought to localize highly active genomic loci for heterologous expression. We screened 1595 Nicotiana tabacum and 430 Arabidopsis thaliana transformants expressing a fluorescent protein (mCherry) to select the highest expressing cell lines. The high mCherry expression observed in the selected lines seems to result from several T-DNA insertions among which active ones will have to be identified. The genomic environment of 20 insertion events was analyzed. In the last part, we showed that culture conditions (e.g. medium composition, culture vessel) influence plant cell growth as well as mAb accumulation in the extracellular medium of a transgenic cell line.(AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 201