Identification and control of growth inhibitory metabolic products in Human Embryonic Kidney 293 cell fed-batch cultures

Human Embryonic Kidney (HEK) 293 is one of few cell lines of choice for production of AAV based viral vectors. HEK 293 cell line, being a fast-growing cell line, are known to consume significant amounts of nutrients and divert a large portion of them towards byproducts such as lactate, ammonia, and other novel byproducts. In fed-batch cultures, these compounds can inhibit cell proliferation. In this study, we show lactate and ammonia doesn’t explain the complete growth inhibition observed in fed-batch culture as controlling these two doesn’t fully alleviate growth inhibition. We show that the novel byproducts, large portion of which come from amino acid catabolism, have a growth inhibitory effect individually, and in combination. When residual concentrations of the source amino acids for these novel byproducts are kept low in HEK 293 fed-batch cultures, these growth-inhibitory byproducts accumulate to lower level in culture when compared to conditions with higher residual levels of amino acids. Lower byproduct accumulations also resulted in attaining and maintaining higher cell densities in the low amino acid conditions. Such strategies will allow developing processes with higher AAV titers.