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

通过质谱成像（MSI）检测寄生虫特别具有挑战性，需要亚细胞分辨率，目前只能通过西姆斯成像实现。已知T. Cruzi具有一些在哺乳动物宿主中不能复制的独特特征。具体地，已知糖肌醇磷脂（GIPL）和肌醇磷神经酰胺（IPC）是寄生虫特异性脂质，其可以证明适合于西姆斯成像。血浆磷脂酰乙醇胺也是寄生虫特异性的，并且将使其自身适合于+ve离子模式下的MS检测（726 Da是主要物质），IPC在-ve离子模式下。寄生虫也产生麦角固醇，同样在哺乳动物细胞中没有发现，这也可以适用于西姆斯成像，因为它可以成像胆固醇。切片的戊二醛树脂包埋将克服生物安全性，并充分适用于西姆斯。虽然已经实现了通过西姆斯检测药物，但它不能被描述为常规的，并且依赖于检测特定原子的片段。MALDI或DESI与合适的高分辨率MS的使用已被用于组织中药物浓度测量的许多研究中。虽然MALDI的空间分辨率（最多5- 10微米）不足以检测寄生虫，但可以使用脂质特征来确定寄生虫是否存在，并将其与确定药物浓度的能力相结合。使用西姆斯和MALDI/DESI将确定寄生虫负荷和药物浓度。项目提供定量和跨学科技能的培训。

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. Project provides training in Quantitative & Interdisciplinary Skills.