Using MS Imaging (MSI) to explore T.cruzi parasite and drug distribution

Detection of the parasites by Mass Spectrometry Imaging (MSI) is particularly challenging requiring sub-cellular resolution, currently only achievable by SIMS imaging. It is known that the lipid profile of T. cruzi has some unique features that are not replicated in the mammalian host. In particular Glycoinositol phospholipids (GIPL) and Inositiol phosphor ceramide (IPC) are known to be parasite specific lipids, which may prove amenable to SIMS imaging. Plasmenyl-phosphatidylethanolamines are also parasite specific and would lend themselves to MS detection in +ve ion mode (726Da is main species) with IPCs in -ve ion mode. The parasites also produce ergosterol, again not found in mammalian cells and this may also be amenable to SIMS imaging as it is possible to image cholesterol. Gluturaldehyde resin embedding of sections would overcome biosafety and lends itself adequately for SIMS. Although detection of drugs by SIMS has been achieved it cannot be described as routine and has relied on detection of a fragment of a particular atom. The use of either MALDI or DESI with a suitable high resolution MS has been used in a number of studies for drug concentration measurements in tissue. Although the spatial resolution in MALDI (5-10micronsM at best) is not sufficient for detection of the parasite it may be possible to use a lipid signature to determine whether the parasite is present and combine this with ability to determine drug concentration. Use of SIMS and MALDI/DESI will determine parasite load and drug concentration.
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