Mathematical approach for the optimal expansion of erythroid progenitors in monolayer culture

The continuous production of large numbers of red blood cells (RBCs) ex vivo is a challenging task due to process economics and complex culture conditions. In any serial passaging process, the culture conditions and operation mode are important criteria for achieving high proliferation with optimal passage lengths. The optimal inoculation concentration for serial passaging is a factor that affects both the kinetics and the total expansion performance. As part of our attempt to develop a scalable, economical and reproducible system for production of RBCs we used mathematical expressions to define the growth curves of peripheral blood derived erythroid progenitors over the course of their expansion process. We used a Gompertz function to evaluate the specific growth rate for the optimisation of inoculation concentration and passage lengths to achieve optimal expansion. This led to values of 3 x 10(5) cells/ml as the optimum inoculation concentration and 36 h as the optimum passage length. Also the variations in growth curves confirmed the altered growth kinetics of erythroid progenitors during sequential passaging in expansion process. Cost analysis suggested a 60-h passage length at every passage, resulting in a 42.9% process-cost reduction. However, this has increased the process duration in achieving the similar expansion factor. This methodology for optimising the expansion process of peripheral derived erythroid progenitors based on optimum culture conditions could provide us with a direction and an improved performance for scale-up applications. (C) 2012 Elsevier B.V. All rights reserved.