Effects of high concentrations of energy sources and metabolites on suspension culture of Chinese hamster ovary cells producing tissue plasminogen activator

A high-concentration medium was developed for the high-density cultivation of Chinese hamster ovary (CHO) cells to produce tissue plasminogen activato r (WA). First, the effects of the concentrations of several medium componen ts on the growth and metabolism of CHO cells were studied particularly in r elation to the serum concentration, in order to develop a suitable concentr ated medium. High concentrations of serum, glucose, lactate, and glutamine and a low ammonia concentration increased the specific growth rate and decr eased the specific tPA production rate. Among these components, the effect of the serum concentration was the most significant. There was an inverse c orrelation between the specific rates of cell growth and tPA production. Us ing a medium containing glutamine at twice the concentration of the origina l medium (F-12) allowed the medium volume to be reduced to seven-ninths tha t of the original, without any reduction in tPA productivity. When the F-12 medium was supplemented five-fold with amino acids and vitamins, the total amount of tPA produced, specific rate of tPA production, and yield of tPA per unit volume of medium employed were respectively enhanced 1.7, 1.5, and 3.6 times. As a consequence, the frequency of medium exchange could be red uced. The results strongly indicate that the supplementation of nutrient am ino acids and vitamins to a medium with a low concentration of serum are th e most critical factors for cost-effective tPA production in high-density c ell cultivation.