Systems analysis of metabolism in platelet concentrates during storage in platelet additive solution

Abstract

Platelets (PLTs) deteriorate over time when stored within blood banks through a biological process known as PLT storage lesion (PSL). Here, we describe the refinement of the biochemical model of PLT metabolism, iAT-PLT-636, and its application to describe and investigate changes in metabolism during PLT storage. Changes in extracellular acetate and citrate were measured in buffy coat and apheresis PLT units over 10 days of storage in the PLT additive solution T-Sol. Metabolic network analysis of these data was performed alongside our prior metabolomics data to describe the metabolism of fresh (days 1-3), intermediate (days 4-6), and expired (days 7-10) PLTs. Changes in metabolism were studied by comparing metabolic model flux predictions of iAT-PLT-636 between stages and between collection methods. Extracellular acetate and glucose contribute most to central carbon metabolism in PLTs. The anticoagulant citrate is metabolized in apheresis-stored PLTs and is converted into aconitate and, to a lesser degree, malate. The consumption of nutrients changes during storage and reflects altered PLT activation profiles following their collection. Irrespective of the collection method, a slowdown in oxidative phosphorylation takes place, consistent with mitochondrial dysfunction during PSL. Finally, the main contributors to intracellular ammonium and NADPH are highlighted. Future optimization of flux through these pathways provides opportunities to address intracellular pH changes and reactive oxygen species, which are both of importance to PSL. The metabolic models provide descriptions of PLT metabolism at steady state and represent a platform for future PLT metabolic research.

Temperature dependence of platelet metabolism

“…To estimate the flux states at each temperature, we used a modified version of the platelet metabolic reconstruction iAT-PLT-636 (31) following the same procedures as in (30). This modified version has previously been used for metabolic network analysis of buffy coat and apheresis derived PCs stored in PAS (30). Here, further modifications have been made to accommodate choline metabolism by adding the choline kinase reaction (CHOLK):…”

“…This reaction can be catalyzed by the choline/ethanolamine kinase CHKB, which has been detected in platelets by proteomics analysis (30). For each temperature, and each extracellular metabolite used to constrain the model, a regression line was fitted to the time-concentration profile.…”

“…The metabolism of stored PLTs has been extensively studied (18,25,26) (27)(28)(29)(30). Recently, we conducted a systems analysis of PLT metabolism during storage in PAS (30) using a modified version of a previously published PLT metabolic network reconstruction (31).…”

“…Recently, we conducted a systems analysis of PLT metabolism during storage in PAS (30) using a modified version of a previously published PLT metabolic network reconstruction (31). During storage, PLTs can utilize a variety of nutrients (18) and rely on both glycolytic and oxidative metabolic pathways for energy production (25,30). The temperature effects on platelet metabolism have mostly been investigated in the context of the glycolytic activity of PCs stored at 4°C by measuring the uptake and secretion rates of glucose and lactate, respectively (32)(33)(34).…”

“…Here, we used targeted time-course metabolomics analysis of PCs stored to assess the PLT metabolic network at four different temperatures (4°C, 13°C, 22°C and 37°C). We integrated these data into a cellscale computational model of PLT metabolism (15,30) to predict the metabolic flux of the entire metabolic network, allowing for the estimation of Q 10 values for individual metabolic reactions and pathways comparison of network-level responses to temperature changes.…”