Developing Targeted Epigenetic Modifications to Induce a Biomanufacturing Stress Tolerance in CHO Cells


  • Kayla Wolf, Chemical Engineering, University of Delaware

Faculty Mentor(s)

  • Mark Blenner, Chemical & Biomolecular Engineering, University of Delaware


Chinese Hamster Ovary (CHO) cells are the cell of choice in many biomanufacturing processes for recombinant protein production due to their ability to complete human-like post translational modifications and superior efficiency at producing larger molecules when compared to prokaryotic cells. However, the biomanufacturing process at production scale invariably leads to an increase of toxins as cells grow. Ammonia and lactate accumulate as metabolic byproducts but accumulation can be toxic and lead to issues with glycosylation. Additionally, bioreactor conditions such as pH adjustment can also introduce stressors in the form of hyperosmolality as salts are introduced in buffers within the media. All of these stressors combined create an environment where cells that are in a stress response state exhibit increased fitness over other cells not engaged in that response. Previous work involving MemorySeq set out to identify biomarkers linked to this stress tolerant state. Hmox1 was identified as such a biomarker. Using CRISPRi/a like systems, dCas9 localized epigenetic domains to the Hmox1 gene. From here, we aimed to study how different modifications affect CHO cells’ ability to grow and proliferate within a stress-induced biomanufacturing environment. Both activating and repressing domains were initially screened for changes in Hmox1 expression in comparison to expression with a dCas9-eGFP integrated at the same site. VPR, a collection of activating domains, recruits transcription factors and displays the most upregulation of Hmox1 as indicated by RT-qPCR. KRAB, a chromatin remodeling domain, exhibited the most amount of downregulation of Hmox1. Development of stable cell lines with these domains is underway. Following successful development of cell lines, stress-induced fed batch flasks with each cell line will be investigated for potential effects on proliferation within a stressful, manufacturing-like environment.