Distinguishing the Metabolic Effect of Fetal and Adult Fibrinogen on Human Fibroblast Cell Culture by IR-MALDESI Mass Spectrometry Imaging.

Mass spectrometry imaging (MSI) of cells can elucidate metabolic changes with cellular and molecular specificity. Fibroblasts are mesenchymal cells that are important in tissue homeostasis and wound healing. During early wound healing, fibroblasts adhere to fibrinogen and migrate into fibrin clots, which are important interactions to stabilize early blood clots and promote subsequent tissue remodeling. It is understood that fibrinogen exists in distinct forms, fetal and adult, which have differing glycosylation and morphological effects on fibroblasts. Despite their importance to wound healing and the extracellular environment, fibroblasts are not commonly studied by MSI. While many MSI studies are conducted at the single-cell or subcellular level, there is still utility in accessing a broad view of the metabolic changes in a cell culture above single-cell spatial resolution. This enables imaging a wider area and larger number of cells directly from cell culture. In this work, dermal fibroblasts were imaged directly from cell culture chamber slides by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI). This method enabled treating the chambers with adult or fetal fibrinogen prior to cell culture and reduced sample preparation prior to MSI. Many metabolic effects of serum and fibrinogen type were elucidated, with changes in many membrane lipids such as cholesterol and ceramides potentially contributing to the observed morphological effects of fibrinogen types on fibroblasts.