A Metabolic Model of Human Erythrocytes: Practical Application of the E-Cell Simulation Environment
Figure 4
Modeling of metabolism in RBCs during long-term cold storage and model verification. (a) The work flow of developing and analyzing the “RC-MAP model”. (1) The values of external parameters in our E-Cell RBC model (basal model), which assumes normal circulating conditions, are modified to meet the conditions of the cold-MAP solution. (2) Adjustable parameters, which are thought to be changed by storage conditions, are determined. (3) Adjustable parameters are estimated using experimental data on metabolic alterations in RC-MAP. (4) The relevance and robustness of the parameter choices are checked. (5) The dynamics of metabolism are compared between the RC-MAP simulation and experimental treatment. (6) A sensitivity analysis of the model is conducted to find key reactions, metabolites, and parameters to maintain the energetics and oxygen-carrying capacity of stored RBCs. (7) Candidate components for optimized storage conditions are determined by computationally testing various combinations of factors that can be modified experimentally. (8) Finally, the candidate models are validated by a metabolome analysis. In (3), we employed the classical read number genetic algorithm within the E-Cell Simulation Environment to fit the model to the reported time-course data of ATP and 2,3-BPG concentration changes in RBCs held in cold RC-MAP for 49 days. (b) A comparison of time-related changes in ATP and 2,3-BPG levels between reported experiments (Shiba et al., 1991) and the “RC-MAP model” is presented. The time-course of ATP (solid black) and 2,3-BPG (broken black) in RC-MAP at C for 49 days in (a) previously reported data and (b) the prediction of the estimated model derived by the Genetic Algorithm. Experimental values are shown as the mean S.D. of 19 separate experiments. Values are percentages of the initial concentrations. (c) Measured (left) and simulated (right) time-dependent alterations in glycolytic intermediates. In CE-TOFMS measurements, the RBC samples were suspended in cold-MAP for 49 days under laboratory conditions. Data represent the means S.D. of five separate experiments. “G6P F6P” indicates the sum of the concentrations of G6P and F6P. Values are represented as percentages of the initial concentration of each metabolite.
