Scope: The Caco2/HT29-MTX co-culture system is widely used as a cell model of the intestinal epithelium. Although the gut epithelium plays an important role in the uptake of free fatty acids and the resynthesis of triglycerides the lipid distribution profile of the co-culture system is not well understood. Desorption electrospray ionization (DESI) is a mass spectrometry (MS) technique which has been widely used to study the main classes of lipid molecules on different tissue surfaces. This has been used to map lipid species and their distribution in Caco2 and HT29-MTX co-culture system.
Methods and results: Caco2 and HT29-MTX cells were seeded on coverslips either singly or as cocultures in ratios of 75:25 and 50:50. Cells were cultured for 21 days before MS imaging using a DESI source in both the positive and negative ionization modes. The identity of selected lipids was confirmed in negative and positive ionisation modes using tandem MS. Although many lipids were common to both cell lines, there were distinctive patterns in the lipidomes. Thus, the lipidome of Caco2 cells was more heterogeneous and rich in cholesterol esters and triglycerides whilst HT29-MTX cells has a distinctive lipidome relating to phosphatidylethanolamines, phosphatidylinositols and odd chain lipids, including C17 fatty acids.
Conclusion: DESI-MSI has shown that Caco2 and HT29-MTX cells have distinctive lipidomes which are still evident when the cells are cocultured. It has potential to both allow further validation of these widely used cell models and provide insights into how dietary components may modify lipid metabolism in future.