Collaborative Research: GOALI: Exploiting metabolism-apoptosis interactions to enhance mammalian cell culture

Johns Hopkins University, Baltimore MD

Investigators

Abstract

Biopharmaceuticals encompassing monoclonal antibodies (mAbs) and other protein therapeutics are among the most expensive of all drugs to manufacture. Mammalian cell culture processes are responsible for producing the vast majority of these compounds, which represent a total market of more than 90 billion dollars annually. The accelerating demand for mAb therapeutics has led to a critical need for enhanced productivity in mammalian cell culture bioprocesses. However, the push toward higher cell and product concentrations has been accompanied by the accumulation of inhibitory metabolites and increased apoptotic cell death, both of which limit product yields. It has recently been shown that expressing anti-apoptosis genes in Chinese hamster ovary (CHO) cells causes a metabolic shift involving rapid lactate consumption during late exponential-phase growth. This opens the possibility of previously unforeseen strategies that can harness metabolism-apoptosis interactions to limit the accumulation of toxic by-products such as lactate and ammonia. The long-term goal of this project is therefore to understand the regulatory connections between metabolic and apoptotic pathways so that these processes can be modulated to enhance mammalian cell culture. The overall objective is to apply systems approaches to identify critical metabolic nodes that are strongly impacted by anti-apoptosis engineering and can be targeted to enhance mAb production in apoptotic-resistant (ApoR) CHO cells. The approach relies upon metabolic flux analysis (MFA) and quantitative cell imaging to map the dynamic flow of nutrients and signaling molecules through key intracellular pathways. The overall objective of this project will be accomplished by pursuing the following two specific aims. First, the mechanism by which overexpression of anti-apoptotic proteins causes reprogramming of lactate metabolism in CHO cells will be determined. Second, this understanding will be applied to optimize media and fed-batch culture conditions to maximize cell viability and mAb production of ApoR clones. The proposed research is innovative because it aims to develop integrated strategies for improving cell viability and antibody production while reducing by-product accumulation, rather than attempting to address these problems individually. This work is expected to fill a critical knowledge gap by contributing a quantitative understanding of metabolism-apoptosis interactions so that they can be exploited to enhance bioreactor performance. The research is significant because it will enable novel strategies for increasing productivity of mammalian cell bioprocesses, thus lowering drug development and production costs of therapeutic antibodies. This project will also provide the unique educational opportunity for a graduate student from the PI?s lab to engage in collaborative research with industry scientists. This will culminate in a 3-month internship in which the student will perform experiments in a Centocor bioprocessing facility, an experience that will provide ideal preparation for a career in the biotech industry, or alternatively to pursue industry-relevant research in a government or academic lab.