The broader impact/commercial potential of this Small Business Technology Transfer (STTR) project is to develop the technology to power a more efficient platform for the most common method of production of biological therapeutics, the Chinese Hamster Ovary (CHO) cell line. Each batch production cycle of a given therapeutic is large and represents a significant investment and significant profit, and any methods to increase, even incrementally, the yield of such a batch would yield great profits. Currently, these cells split their metabolic energy into producing both the therapeutic, and a protein used to select for highest producers. The proposed system utilizes the transient expression of a different kind of selection marker - one that frees significant metabolic resources to focus solely on the production of the therapeutic once the selection phase is done. Increasing yields will drive down costs, and make these treatments available to a wider demographic. The biomanufacturing companies are searching for new methods to increase product yield, and are ready to spend significant time and resources to maintain their cutting edge status and profitability. This STTR Phase I project proposes to develop a selection method to significantly increase CHO cell biotherapeutic production. Current methods sacrifice yield because the cells must produce the selectable marker as well as the product, at a heavy burden to the cells. The proposed technology will use the transient expression of the selectable marker, glutamine synthase, tightly controlled by and active only in the presence of the gene of interest (GOI) through our structural interacting RNA (sxRNA) technology. Once the selection phase is complete, metabolic costs of selectable marker will cease and metabolic resources will go to GOI production. sxRNA links the expression of the selectable marker on an ectopic mRNA to a miRNA in the splicing product during GOI mRNA maturation. Stringency of selection is, therefore, directly proportional to GOI copy number and production. The plan is to optimize sxRNA technology through computational and empirical screens, and use the most suitable candidates in a side-by-side comparison with the traditional CHO cell glutamine synthetase system. Benchmarks for success will include assays for gene copy numbers by real-time PCR, and active product yield versus costs. Long-term stability of the GOI also will be monitored over many passages following the termination of the selection phase.
