Multiomics characterization of mesenchymal stromal cells cultured in monolayer and as aggregates.

Mesenchymal stromal cells (MSCs) have failed to consistently demonstrate their therapeutic efficacy in clinical trials, due in part to variability in culture conditions used for their production. Of various culture conditions used for MSC production, aggregate culture has been shown to improve secretory capacity (a putative mechanism of action in vivo) compared with standard monolayer culture. The purpose of this study was to perform multiomics characterization of MSCs cultured in monolayer and as aggregates to identify aspects of cell physiology that differ between these culture conditions to begin to understand cellular-level changes that might be related to secretory capacity. Targeted secretome characterization was performed on multiple batches of MSC-conditioned media, while nontargeted proteome and metabolome characterization was performed and integrated to identify cellular processes differentially regulated between culture conditions. Secretome characterization revealed a reduction in MSC batch variability when cultured as aggregates. Proteome and metabolome characterization showed upregulation of multiple protein and lipid metabolic pathways, downregulation of several cytoskeletal processes, and differential regulation of extracellular matrix synthesis. Integration of proteome and metabolome characterization revealed individual lipid metabolites and vesicle-trafficking proteins as key features for discriminating between culture conditions. Overall, this study identifies several aspects of MSC physiology that are altered by aggregate culture. Further exploration of these processes and pathways is needed to determine their potential role in regulating cell secretory capacity.