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UBC Theses and Dissertations

Selective laser arrest of antibody-producing cells to increase antibody production Chiu, Jeffrey


Monoclonal antibodies have become a dominant biopharmaceutical in recent years, with sales expected to exceed $125 billion by 2020. Antibody therapies have been used to treat a wide range of diseases including cancer, multiple sclerosis, and rheumatoid arthritis, with higher specificity and lower toxicity than other chemotherapeutics. The potential promise of antibody therapies has necessitated a significant need to develop improved production technologies in order to shorten the timelines for development, testing, and clinical trials. Modern methods of monoclonal antibody production involve transfecting an antibody gene expression cassette into a host cell line for production, where the cassette is randomly integrated into the genome. This random integration results in a heterogeneity between transduced cells, resulting in significant variability in antibody production rate within the cell population. Additional screening and selection processes are therefore needed to optimize the productivity of the antibody-producing cell line. While several strategies have been developed to select high-producing cell lines, each existing strategy suffers from problems such as long timelines, indirect selectivity, complex procedures, and proprietary processes. We developed a technology named Selective Laser Gelation (SLG) capable of selectively arresting the growth of individual target cells. This capability is enabled by localized gelation using an infrared laser to utilize the unique inverse solution-gel transition of methylcellulose solutions. Phase-transition hysteresis enables the retention of localized gels after the laser is removed. Methylcellulose solution limits the diffusion of secreted antibody from individual cells and small colonies, and when combined with a fluorescently-conjugated secondary antibody, the produced antibody can be visualized and quantified. This capability is then used to selectively preserve high antibody-producing cells while arresting the growth of low-producing cells. In this thesis, we first modeled the thermodynamics of laser heating on a methylcellulose solution. We then developed an experimental apparatus and software to test the SLG procedure, which we used to show that the SLG process can selectively inhibit the growth of selected cells. Finally, we use the SLG process to increase overall antibody productivity within a shorter timeline than current methods by selecting high-producing antibody-secreting cells.

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