Name: imaging metals in brain tissue by laser ablation - inductively coupled plasma - mass spectrometry (la-icp-ms)
Uploaded: 2017-01-22T14:00:00.000+00:00
Duration: 9 min 5 s
Description: Watch this Scientific Journal Video about Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry LA-ICP-MS at JoVE.com

DJH and PAD are supported by an Australian Research Council Linkage Project (LP120200081) with Agilent Technologies and ESI Ltd. The contribution of BK was supported by the Ruhr University Research School PLUS, funded by Germany&#39;s Excellence Initiative [DFG GSC 98/3]. DJH was partially supported by the Ramaciotti Foundation.&#160;&#160;KK is supported by the Sigrid Juselius Foundation.

<ol>
	<li>Barnham, K. J., Bush, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+metals+and+metal-targeting+compounds+in+major+neurodegenerative+diseases.">Biological metals and metal-targeting compounds in major neurodegenerative diseases.</a> Chem Soc Rev. 43 (19), 6727-6749 (2014).</li><li>Hare, D. J., Double, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+and+dopamine:+a+toxic+couple.">Iron and dopamine: a toxic couple.</a> Brain. 139 (4), 1026-1035 (2016).</li><li>Savory, J., Herman, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+instrumental+methods+for+the+measurement+and+speciation+of+trace+metals.">Advances in instrumental methods for the measurement and speciation of trace metals.</a> Ann Clin Lab Sci. 29 (2), 118-126 (1999).</li><li>New, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tools+to+study+distinct+metal+pools+in+biology.">Tools to study distinct metal pools in biology.</a> Dalton Trans. 42 (9), 3210-3219 (2013).</li><li>Hare, D. J., New, E. J., de Jonge, M. D., McColl, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+metals+in+biology:+balancing+sensitivity,+selectivity+and+spatial+resolution.">Imaging metals in biology: balancing sensitivity, selectivity and spatial resolution.</a> Chem Soc Rev. 44 (17), 5941-5958 (2015).</li><li>Pozebon, D., Scheffler, G. L., Dressler, V. L., Nunes, M. A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+the+applications+of+laser+ablation+inductively+coupled+plasma+mass+spectrometry+(LA-ICP-MS)+to+the+analysis+of+biological+samples.">Review of the applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to the analysis of biological samples.</a> J Anal At Spectrom. 29 (12), 2204-2228 (2014).</li><li>Becker, J. S., Zoriy, M. V., Dehnhardt, M., Pickhardt, C., Zilles, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Copper,+zinc,+phosphorus+and+sulfur+distribution+in+thin+section+of+rat+brain+tissues+measured+by+laser+ablation+inductively+coupled+plasma+mass+spectrometry:+possibility+for+small-size+tumor+analysis.">Copper, zinc, phosphorus and sulfur distribution in thin section of rat brain tissues measured by laser ablation inductively coupled plasma mass spectrometry: possibility for small-size tumor analysis.</a> J Anal At Spectrom. 20 (9), 912 (2005).</li><li>Hare, D. J., Austin, C., Doble, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+strategies+for+elemental+imaging+of+biological+samples+using+laser+ablation-inductively+coupled+plasma-mass+spectrometry.">Quantification strategies for elemental imaging of biological samples using laser ablation-inductively coupled plasma-mass spectrometry.</a> The Analyst. 137 (7), 1527-1537 (2012).</li><li>Hare, D. J., Lear, J., Bishop, D., Beavis, A., Doble, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protocol+for+production+of+matrix-matched+brain+tissue+standards+for+imaging+by+laser+ablation-inductively+coupled+plasma-mass+spectrometry.">Protocol for production of matrix-matched brain tissue standards for imaging by laser ablation-inductively coupled plasma-mass spectrometry.</a> Anal Meth. 5 (8), 1915-1921 (2013).</li><li>Hare, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+elemental+bio-imaging+of+Mn,+Fe,+Cu+and+Zn+in+6-hydroxydopamine+induced+Parkinsonism+mouse+models.">Quantitative elemental bio-imaging of Mn, Fe, Cu and Zn in 6-hydroxydopamine induced Parkinsonism mouse models.</a> Metallomics. 1 (1), 53 (2009).</li><li>Potter, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+commercial+perspective+on+the+growth+and+development+of+the+quadrupole+ICP-MS+market.">A commercial perspective on the growth and development of the quadrupole ICP-MS market.</a> J Anal At Spectrom. 23 (5), 690 (2008).</li><li>Lear, J., Hare, D. J., Adlard, P., Finkelstein, D., Doble, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+acquisition+times+of+elemental+bio-imaging+for+quadrupole-based+LA-ICP-MS.">Improving acquisition times of elemental bio-imaging for quadrupole-based LA-ICP-MS.</a> J Anal At Spectrom. 27 (1), 159 (2012).</li><li>Matusch, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+bioimaging+of+Cu,+Fe,+Zn,+and+Mn+in+the+MPTP+mouse+model+of+Parkinson's+disease+using+laser+ablation+inductively+coupled+plasma+mass+spectrometry+(LA-ICP-MS).">Cerebral bioimaging of Cu, Fe, Zn, and Mn in the MPTP mouse model of Parkinson's disease using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).</a> J Am Soc MAss Spectrom. 21 (1), 161-171 (2010).</li><li>Hare, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+iron-dopamine+index+predicts+risk+of+parkinsonian+neurodegeneration+in+the+substantia+nigra+pars+compacta.">An iron-dopamine index predicts risk of parkinsonian neurodegeneration in the substantia nigra pars compacta.</a> Chem Sci. 5 (6), 2160-2169 (2014).</li><li>Portbury, S. D., Hare, D. J., Sgambelloni, C., Finkelstein, D. I., Adlard, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+time-course+analysis+of+changes+in+cerebral+metal+levels+following+a+controlled+cortical+impact.">A time-course analysis of changes in cerebral metal levels following a controlled cortical impact.</a> Metallomics. 8 (2), 193-200 (2016).</li><li>Theiner, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LA-ICP-MS+imaging+in+multicellular+tumor+spheroids+-+a+novel+tool+in+the+preclinical+development+of+metal-based+anticancer+drugs.">LA-ICP-MS imaging in multicellular tumor spheroids - a novel tool in the preclinical development of metal-based anticancer drugs.</a> Metallomics. 8, 398-402 (2016).</li><li>Niedzwiecki, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multimodal+imaging+workflow+to+visualize+metal+mixtures+in+the+human+placenta+and+explore+colocalization+with+biological+response+markers.">A multimodal imaging workflow to visualize metal mixtures in the human placenta and explore colocalization with biological response markers.</a> Metallomics. 8, 444-452 (2016).</li><li>Austin, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Barium+distributions+in+teeth+reveal+early-life+dietary+transitions+in+primates.">Barium distributions in teeth reveal early-life dietary transitions in primates.</a> Nature. 498 (7453), 216-219 (2013).</li><li>Hare, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+paraformaldehyde+fixation+and+sucrose+cryoprotection+on+metal+concentration+in+murine+neurological+tissue.">The effect of paraformaldehyde fixation and sucrose cryoprotection on metal concentration in murine neurological tissue.</a> J Anal At Spectrom. 29, 565-570 (2014).</li><li>Dodt, H. -. U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultramicroscopy:+three-dimensional+visualization+of+neuronal+networks+in+the+whole+mouse+brain.">Ultramicroscopy: three-dimensional visualization of neuronal networks in the whole mouse brain.</a> Nat Meth. 4 (4), 331-336 (2007).</li><li>Hare, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+ablation-inductively+coupled+plasma-mass+spectrometry+imaging+of+white+and+gray+matter+iron+distribution+in+Alzheimer's+disease+frontal+cortex.">Laser ablation-inductively coupled plasma-mass spectrometry imaging of white and gray matter iron distribution in Alzheimer's disease frontal cortex.</a> NeuroImage. 137, 124-131 (2016).</li><li>G&#252;nther, D., Heinrich, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+sensitivity+in+laser+ablation-ICP+mass+spectrometry+using+helium-argon+mixtures+as+aerosol+carrier.">Enhanced sensitivity in laser ablation-ICP mass spectrometry using helium-argon mixtures as aerosol carrier.</a> J Anal At Spectrom. 14 (9), 1363-1368 (1999).</li><li>Austin, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+affecting+internal+standard+selection+for+quantitative+elemental+bio-imaging+of+soft+tissues+by+LA-ICP-MS.">Factors affecting internal standard selection for quantitative elemental bio-imaging of soft tissues by LA-ICP-MS.</a> J Anal At Spectrom. 26 (7), 1494-1501 (2011).</li><li>Hare, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+elemental+bio-imaging+of+Fe,+Zn,+Cu,+Mn+and+P+in+a+6-hydroxydopamine+lesioned+mouse+brain.">Three-dimensional elemental bio-imaging of Fe, Zn, Cu, Mn and P in a 6-hydroxydopamine lesioned mouse brain.</a> Metallomics. 2 (11), 745-753 (2010).</li><li>Osterholt, T., Salber, D., Matusch, A., Becker, J. S., Palm, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IMAGENA:+Image+Generation+and+Analysis+-+An+interactive+software+tool+handling+LA-ICP-MS+data.">IMAGENA: Image Generation and Analysis - An interactive software tool handling LA-ICP-MS data.</a> Int J Mass Spectrom. 307 (1-3), 232-239 (2011).</li><li>Uerlings, R., Matusch, A., Weiskirchen, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reconstruction+of+Laser+Ablation+Inductively+Coupled+Plasma+Mass+Spectrometry+(LA-ICP-MS)+Spatial+Distribution+Images+in+Microsoft+Excel+2007.">Reconstruction of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) Spatial Distribution Images in Microsoft Excel 2007.</a> Int J Mass Spectrom. 395, 27-35 (2015).</li><li>Paul, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualising+mouse+neuroanatomy+and+function+by+metal+distribution+using+laser+ablation-inductively+coupled+plasma-mass+spectrometry+imaging.">Visualising mouse neuroanatomy and function by metal distribution using laser ablation-inductively coupled plasma-mass spectrometry imaging.</a> Chem Sci. 6 (10), 5383-5393 (2015).</li><li>Paton, C., Hellstrom, J., Paul, B., Woodhead, J., Hergt, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iolite:+Freeware+for+the+visualisation+and+processing+of+mass+spectrometric+data.">Iolite: Freeware for the visualisation and processing of mass spectrometric data.</a> J Anal At Spectrom. 26 (12), 2508 (2011).</li><li>Lein, E. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-wide+atlas+of+gene+expression+in+the+adult+mouse+brain.">Genome-wide atlas of gene expression in the adult mouse brain.</a> Nature. 445 (7124), 168-176 (2007).</li><li>Hare, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+atlas+of+iron,+copper,+and+zinc+in+the+mouse+cerebrum+and+brainstem.">Three-dimensional atlas of iron, copper, and zinc in the mouse cerebrum and brainstem.</a> Anal Chem. 84 (9), 3990-3997 (2012).</li><li>Hjornevik, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+atlas+system+for+mouse+and+rat+brain+imaging+data.">Three-dimensional atlas system for mouse and rat brain imaging data.</a> Frontiers Neuroinform. 1, 4 (2007).</li><li>Bishop, D. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elemental+bio-imaging+using+laser+ablation-triple+quadrupole-ICP-MS.">Elemental bio-imaging using laser ablation-triple quadrupole-ICP-MS.</a> J Anal At Spectrom. 31 (1), 197-202 (2016).</li><li>Balcaen, L., Bolea-Fernandez, E., Resano, M., Vanhaecke, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inductively+coupled+plasma+-+tandem+mass+spectrometry+(ICP-MS/MS):+a+powerful+and+universal+tool+for+the+interference-free+determination+of+(ultra)trace+elements+-+a+tutorial+review.">Inductively coupled plasma - tandem mass spectrometry (ICP-MS/MS): a powerful and universal tool for the interference-free determination of (ultra)trace elements - a tutorial review.</a> Analytica Chimica Acta. 894, 7-19 (2015).</li><li>Van Malderen, S. J. M., Managh, A. J., Sharp, B. L., Vanhaecke, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+developments+in+the+design+of+rapid+response+cells+for+laser+ablation-inductively+coupled+plasma-mass+spectrometry+and+their+impact+on+bioimaging+applications.">Recent developments in the design of rapid response cells for laser ablation-inductively coupled plasma-mass spectrometry and their impact on bioimaging applications.</a> J Anal At Spectrom. 31, 423-439 (2016).</li></ol>

RWH and COC are paid employees of ESI Ltd. FF and TPH are paid employees of Agilent Technologies Australia.

Imaging metals in neurological tissue is just one example of how this protocol can provide useful information on the distribution and amounts of metals in any biological matrix. Although preparation of standard reference materials can be arduous, it is an experiment that can be performed once and archived for later use.
LA-ICP-MS has certain advantages over alternative methods, such as synchrotron-based X-ray fluorescence microscopy, mostly in terms of accessibility and sensitivity. However, there are certain disadvantages that should be considered when preparing an experiment using LA-ICP-MS, and as such it is often a useful complementary technique for chemical imaging that includes alternative metal analysis techniques, as well as comparative histochemistry5.
Alignment with known anatomical features of the mouse brain can provide useful information on the possible functional relationship between metal levels and spatial distribution. Previously, we have used the Allen Brain Atlas online resource,29 which is an open-access repository of both anatomical and gene expression data in the C57BL/6 mouse brain to examine spatial correlation of both metal-dependent enzyme expression14 and neuroanatomy27,30. Other resources, such as the Rodent Brain WorkBench31 are also available to assist with registration and alignment of metal images to assist in correct identification of metal distribution in often small anatomical regions.
Applications of this technique are useful in assessing how metal levels and distribution change at the microscale throughout both normal life events (e.g., aging) and in disease states; as well as studying the effects of both metal-containing compounds and drugs designed to target metal metabolism. The current major limitations of LA-ICP-MS as an imaging technique for spatially assessing metal distribution are throughput and sensitivity. There is a tradeoff between speed of analysis and spatial resolution5,12, with higher resolution images requiring longer analysis times. The technique is well suited to biological elements at higher concentrations, though elements such as manganese, cobalt and selenium are restricted due to their low abundance in normal tissue and/or limitations in their detection by conventional ICP-MS. New advances in ICP-MS technology, such as the introduction of triple-quadrupole mass analyzers, allow for targeted detection of difficult analytes, such as selenium32 at higher sensitivities33. As a technology-driven procedure, advances in both laser and mass spectrometry design will see this imaging technique continue to evolve, increasing the speed of analysis and sensitivity34.

The unique redox chemistry of metals facilitates a range of neurological functions, including signal transduction, energy production and neurotransmitter synthesis. In a number of major neurodegenerative diseases, dyshomeostasis of these metals have been both implicated in disease pathogenesis and identified as potential novel targets for therapeutic intervention1. To better understand how metals are involved in conditions such as Alzheimer&#39;s and Parkinson&#39;s disease (AD and PD, respectively), it is imperative to be able to measure how metal distribution and levels change within regions adversely affected by the disease process. These changes are often indicative of subtle shifts in the biochemical reactions that may be intimately linked to the processes that initiate cell death, such as our recently proposed mechanism of iron and dopamine neurotoxicity in PD2.
Traditionally, metal levels within defined anatomical regions has been achieved through careful excision, digestion and analysis using a range of analytical techniques3. However, such an approach loses spatial information, which can be critical when disease states being investigated involve small, well-defined regions or specific cell types. A number of analytical methods are available for visualizing metals in biological systems, from intact samples to tissue sections and in two and three dimensions, using emission spectroscopy, fluorescent probes and mass spectrometry4. Each technique has advantages and disadvantages regarding sensitivity, selectivity of chemical species, and the spatial resolution that can be achieved. For a comprehensive overview of the range of techniques available, see the review by Hare et al.5.
Mass spectrometry (MS)-based methods are the most sensitive of these techniques, capable of measuring most biologically relevant metals at their native concentration6. Laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) imaging employs a focused ultraviolet laser beam ranging in size from 1 to &#62;100 &#181;m in diameter (or width, when a quadrilateral beam shape is used), under which the sample is passed7. Quantitative information can be achieved through the representative ablation of standard reference materials, which can be produced using a variety of differing approaches8, each with varying degrees of technical difficulty and analytical practicality. The most common approach uses matrix-matching, where a standard with a predominant chemical makeup comparable to that of the sample is prepared by spiking with the target analyte and accurately assessed for homogeneity and absolute metal concentration by independent analytical means9,10. Ablation of prepared standards can then be used for external calibration purposes, allowing concentration data from the resultant sample image to be extracted per&#160;pixel.
Image resolution is determined by both the beam size and speed at which the sample is scanned. The standard quadrupole-design ICP-MS (which account for over 90% of all installed ICP-MS systems worldwide11) is a sequential mass analyzer, in that the mass detector cycles through all selected mass-to-charge ratio (m/z) rather than collecting data simultaneously. Thus, the acquisition time for each cycle of masses must equate to the time taken for the sample to traverse one width of the laser beam to ensure a pixel representative of the desired resolution is acquired12. Laser beam size selection is a crucial parameter that has significant effects on both sensitivity and total analysis time. As laser ablation physically removes material that is swept to the ICP-MS by an argon carrier gas, the amount of matter that can be physically detected by the mass analyzer follows the inverse square law. For example, reducing the laser beam diameter from 50 - 25 &#181;m results in a reduction of ablated material by a factor of four. Additionally, as a scanning method, smaller beam diameters increase the total time required to ablate a selected area. Therefore, experimental design is essential to balance the necessary spatial resolution with sensitivity needs and time constraints.
Imaging by LA-ICP-MS has been applied to a range of samples, matrices and disease states, including animal models of neurological disorders13,14, traumatic brain injury15, distribution of metal-containing anticancer drugs16, toxicant exposure in the placenta17 and metal distribution in teeth as a biomarker of early-life dietary transitions.18 In this protocol we describe a general method for imaging iron, copper and zinc in the WT mouse brain at a resolution of 30 &#181;m, though it can be easily adapted to a range of sample types and experimental outcomes, based on the needs of the analyst.

<table><tbody><tr><td>Soda glass microscope slides</td><td>n/a</td><td>n/a</td><td>Typical slides are suitable for all experiments</td></tr><tr><td>PTFE-coated microtome blades</td><td>C.L. Stuckey</td><td>DT315R50</td><td>Blade size depends on cryostat blade holder. Check before ordering.</td></tr><tr><td>Parafomaldehyde (PFA)</td><td>Sigma-Aldrich</td><td>16005</td><td>Any supplier suitable</td></tr><tr><td>Sucrose</td><td>n/a</td><td>n/a</td><td>Commercial grade white sugar is suitable</td></tr><tr><td>Phosphate-buffered Saline (PBS)</td><td>Sigma-Aldrich</td><td>P5368</td><td>Premixed sachets listed, can be prepared according to normal laboratory protocols</td></tr><tr><td>Xylene</td><td>Sigma-Aldrich</td><td>247624</td><td>Any supplier suitable</td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich</td><td>E7023</td><td>Any supplier suitable</td></tr><tr><td>Lamb brain</td><td>n/a</td><td>n/a</td><td>Available from most local butchers</td></tr><tr><td>Metal salts</td><td>n/a</td><td>n/a</td><td>Use water soluble metal salts containing desired analytes</td></tr><tr><td>Omni TH Tissue Homogeniser</td><td>Omni Inc</td><td>THP115</td><td>Alternative homogenizers are suitable</td></tr><tr><td>Polycarbonate homgenizer probes</td><td>Omni Inc</td><td>TH115-PCRH</td><td></td></tr><tr><td>Microwave digestion unit</td><td>n/a</td><td>n/a</td><td>Optional. See Section 2</td></tr><tr><td>1.5 mL microfuge tubes</td><td>TechnoPlas</td><td>P4010</td><td>Metal-free polypropylene tubes. Acid washed tubes are also suitable</td></tr><tr><td>65% nitric acid</td><td>Merk Millipore</td><td>100441</td><td>Trace analysis grade</td></tr><tr><td>30% hydrogen peroxide</td><td>Sigma-Aldrich</td><td>95321</td><td>Trace analysis grade</td></tr><tr><td>10 x 10 mm disposable cryomolds</td><td>Ted Pella</td><td>27181</td><td></td></tr><tr><td>Isopentane</td><td>Sigma-Aldrich</td><td>76871</td><td></td></tr><tr><td>Liquid nitrogen</td><td>n/a</td><td>n/a</td><td>Use local supplier</td></tr><tr><td>NWR213 Laser Ablation system</td><td>ESI Ltd</td><td>n/a</td><td>Used in these experiments. Other manufacturers suitable, may require modifications to protocol</td></tr><tr><td>Agilent 8800 Series ICP-MS</td><td>Agilent Technologies</td><td>n/a</td><td>Used in these experiments. Other manufacturers suitable, may require modifications to protocol</td></tr><tr><td>Iolite</td><td>Iolite Software</td><td>n/a</td><td>Available from http://iolite-software.com/. Other methods are available, see protocol</td></tr><tr><td>Excel</td><td>Microsoft</td><td>n/a</td><td></td></tr><tr><td>IGOR Pro</td><td>Wave Metrics</td><td>n/a</td><td>Avalable from https://www.wavemetrics.com/products/igorpro/igorpro.htm</td></tr></tbody></table>

imaging metals in brain tissue by laser ablation - inductively coupled plasma - mass spectrometry (la-icp-ms)

Metals are found ubiquitously throughout an organism, with their biological role dictated by both their chemical reactivity and abundance within a specific anatomical region. Within the brain, metals have a highly compartmentalized distribution, depending on the primary function they play within the central nervous system. Imaging the spatial distribution of metals has provided unique insight into the biochemical architecture of the brain, allowing direct correlation between neuroanatomical regions and their known function with regard to metal-dependent processes. In addition, several age-related neurological disorders feature disrupted metal homeostasis, which is often confined to small regions of the brain that are otherwise difficult to analyze. Here, we describe a comprehensive method for quantitatively imaging metals in the mouse brain, using laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) and specially designed image processing software. Focusing on iron, copper and zinc, which are three of the most abundant and disease-relevant metals within the brain, we describe the essential steps in sample preparation, analysis, quantitative measurements and image processing to produce maps of metal distribution within the low micrometer resolution range. This technique, applicable to any cut tissue section, is capable of demonstrating the highly variable distribution of metals within an organ or system, and can be used to identify changes in metal homeostasis and absolute levels within fine anatomical structures.

To demonstrate the capabilities of this LA-ICP-MS imaging approach, a simple experiment using a single section of a WT C57BL/6 mouse brain, bisected at the corpus callosum and sectioned in the coronal plane, is presented. A workflow for the analysis of data using Biolite (Figure 1), as described in Sections 6 and 7, as well as for providing a representative image of metal distribution in the section analyzed (Figure 2) is also described.
As can be seen, metal distribution in the mouse brain is variable according to anatomical region. This can be attributed to the variable roles metals, and more specifically the proteins to which they are bound, play in each brain region27. For instance, iron tends to have higher concentrations in the midbrain and along the dentate gyrus, whereas zinc is most abundant in the cortical areas. Carbon, which is a commonly used internal standard8, is homogenously distributed. Elemental maps (Figure 2) can be particularly useful when used in conjunction with existing anatomical and functional reference atlases29, where information on the colocalization of metals can the expression of specific metal-binding proteins can provide insight into the function of metals within a brain region, or changes in metal levels in line with an identified disease-related biomolecule. Using the approach described, which is optimized for a broader range of analytes, does preclude sensitivity for low abundance elements such as manganese, and methods can be adapted to focus primarily on this analyte by increasing dwell times at the expense of other measured masses.
The major advantage in using imaging by LA-ICP-MS is observing relative differences in metal concentration and distribution between experimental groups. We have previously used such a technique to demonstrate increased iron following a neurotoxin insult mimicking PD2,10, and changes in cortical iron levels in human Alzheimer&#39;s disease tissue21. Such a protocol as described here can be easily adapted to any other tissue type with minimal amendments to the listed methods.
<img alt="Figure 1" src="/files/ftp_upload/55042/55042fig1.jpg" /> 
Figure 1: Workflow for Image Processing. Workflow complementary to Sections 6 and 7, depicting conversion of raw time resolved data from the ICP-MS to quantitative images of metal distribution in the mouse brain. <a href="http://cloudflare.jove.com/files/ftp_upload/55042/55042fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/55042/55042fig2.jpg" /> 
Figure 2: Typical Elemental Distribution of Biometals within a Mouse Brain. Representative element maps of a 30 &#181;m-thick coronal section of a single mouse brain hemisphere analyzed with LA-ICP-MS. Images for carbon-13 (C13), magnesium-24 (Mg24) and phosphorus-31 (P31) displayed in Gold color scales (counts per second; CPS) (top row). Quantitative images (bottom row) for manganese-55 (Mn55), copper-63 (Cu63), iron-56 (Fe56) and zinc-66 (Zn66) displayed with corresponding BlueHot color scales (&#181;g g-1). Total analysis time for the brain section was approximately 5 h. Scale bar = 2 mm. <a href="http://cloudflare.jove.com/files/ftp_upload/55042/55042fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Supplementary Code File 1. Open-source Python code described in 6.1, which can be modified using an appropriate Python editor according to ICP-MS manufacturer&#39;s method of data output. <a href="http://cloudflare.jove.com/files/ftp_upload/55042/CopyFilesFromSubDirs_3.txt" target="_blank">Please click here to download this file.</a>

Watch this Scientific Journal Video about Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry LA-ICP-MS at JoVE.com

Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry LA-ICP-MS

Quantitatively mapping metals in tissue by laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) is a sensitive analytical technique that can provide new insight into how metals participate in normal function and disease processes. Here, we describe a protocol for quantitatively imaging metals in thin sections of mouse neurological tissue.

Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS)

Metals are found ubiquitously throughout an organism, with their biological role dictated by both their chemical reactivity and abundance within a ...

imaging-metals-brain-tissue-laser-ablation-inductively-coupled-plasma

Research

JoVE Journal

Medicine

21.5K Views.  University of Technology Sydney.  Kwantitatief afbeelden metalen weefsel door laserablatie - inductief gekoppeld plasma - massaspectrometrie (LA-ICP-MS) is een gevoelige analytische techniek die nieuw inzicht in hoe metalen deel aan normale functie en ziekteprocessen kunnen bieden. We beschrijven hier een protocol voor het kwantitatief beeldvorming metalen in dunne secties van muizen neurologisch weefsel. 

Video: Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry LA-ICP-MS

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) performed on thin sections of rodent tissues: kidneys and tumor, allows the detection of inorganic elements such as (i) Na, Ca, Cu, Mg, P, and Fe, naturally present in the body and (ii) Si and Gd, detected after the injection of gadolinium-based nanoparticles. The animals were euthanized 1&#160;to 24 hr&#160;after intravenous injection of particles. A two-dimensional scan of the sample, performed using a motorized micrometric 3D-stage, allowed the infrared laser beam exploring the surface with a lateral resolution less than 100 &#956;m. Quantitative chemical images of Gd element inside the organ were obtained with sub-mM sensitivity. LIBS offers a simple and robust method to study the distribution of inorganic materials without any specific labeling. Moreover, the compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of the same biological tissue with different types of response:&#160;elemental, molecular, or cellular.

Laser-induced breakdown spectroscopy performed on thin organ and tumor tissue successfully detected natural elements and artificially injected gadolinium (Gd), issued from Gd-based nanoparticles. Images of chemical elements reached a resolution of 100 &#956;m and quantitative sub-mM sensitivity. The compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of a same biological tissue.

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) ...

Engineering

Optimal Preparation of Formalin Fixed Samples for Peptide Based Matrix Assisted Laser Desorption/Ionization Mass Spectrometry Imaging Workflows

The use of matrix-assisted laser desorption/ionization, mass spectrometry imaging (MALDI MSI) has rapidly expanded, since this technique analyzes a host of biomolecules from drugs and lipids to N-glycans. Although various sample preparation techniques exist, detecting peptides from formaldehyde preserved tissues remains one of the most difficult challenges for this type of mass spectrometric analysis. For this reason, we have created and optimized a robust methodology that preserves the spatial information contained within the sample, while eliciting the greatest number of ionizable peptides. We have also aimed to achieve this in a cost effective and simple way, thereby eliminating potential bias or preparation error, which can occur when using automated instrumentation. The end result is a reproducible and inexpensive protocol.

This protocol describes a reproducible and reliable method for the sublimation-based preparation of formalin fixed tissue destined for imaging mass spectrometry.

The use of matrix-assisted laser desorption/ionization, mass spectrometry imaging (MALDI MSI) has rapidly expanded, since this technique analyzes a host ...

Biochemistry

Imaging of Biological Tissues by Desorption Electrospray Ionization Mass Spectrometry

Mass spectrometry imaging (MSI) provides untargeted molecular information with the highest specificity and spatial resolution for investigating biological tissues at the hundreds to tens of microns scale. When performed under ambient conditions, sample pre-treatment becomes unnecessary, thus simplifying the protocol while maintaining the high quality of information obtained. Desorption electrospray ionization (DESI) is a spray-based ambient MSI technique that allows for the direct sampling of surfaces in the open air, even in vivo. When used with a software-controlled sample stage, the sample is rastered underneath the DESI ionization probe, and through the time domain, m/z information is correlated with the chemical species' spatial distribution. The fidelity of the DESI-MSI output depends on the source orientation and positioning with respect to the sample surface and mass spectrometer inlet. Herein, we review how to prepare tissue sections for DESI imaging and additional experimental conditions that directly affect image quality. Specifically, we describe the protocol for the imaging of rat brain tissue sections by DESI-MSI.

Desorption electrospray ionization mass spectrometry (DESI-MS) is an ambient method by which samples, including biological tissues, can be imaged with minimal sample preparation. By rastering the sample below the ionization probe, this spray-based technique provides sufficient spatial resolution to discern molecular features of interest within tissue sections.

Mass spectrometry imaging (MSI) provides untargeted molecular information with the highest specificity and spatial resolution for investigating biological ...

Bioengineering

Quantitative Analysis of Vacuum Induction Melting by Laser-induced Breakdown Spectroscopy

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves several steps, include drawing samples, cooling, cutting, transport to the laboratory, and analysis. The whole analysis process requires more than 30 minutes, which hinders on-line process control. Laser-induced breakdown spectroscopy is an excellent on-line analysis method that can satisfy the requirements of vacuum induction melting because it is fast and noncontact and does not require sample preparation. The experimental facility uses a lamp-pumped Q-switched laser to ablate melted liquid steel with an output energy of 80 mJ, a frequency of 5 Hz, a FWHM pulse width of 20 ns, and a working wavelength of 1,064 nm. A multi-channel linear charge coupled device (CCD) spectrometer is used to measure the emission spectrum in real time, with a spectral range from 190 to 600 nm and a resolution of 0.06 nm at a wavelength of 200 nm. The protocol includes several steps: standard alloy sample preparation and an ingredient test, smelting of standard samples and determination of the laser breakdown spectrum, and construction of the elements concentration quantitative analysis curve of each element. To realize the concentration analysis of unknown samples, the spectrum of a sample also needs to be measured and disposed with the same process. The composition of all main elements in the melted alloy can be quantitatively analyzed with an internal standard method. The calibration curve shows that the limit of detection of most metal elements ranges from 20-250 ppm. The concentration of elements, such as Ti, Mo, Nb, V, and Cu, can be lower than 100 ppm, and the concentrations of Cr, Al, Co, Fe, Mn, C, and Si range from 100-200 ppm. The R2 of some calibration curves can exceed 0.94.

During vacuum induction melting, laser-induced breakdown spectroscopy is used to perform real-time quantitative analysis of the main-ingredient elements of a molten alloy.

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves ...

Expanding the Comprehension of the Tumor Microenvironment using Mass Spectrometry Imaging of Formalin-Fixed and Paraffin-Embedded Tissue Samples

Advances in immune-based therapies have revolutionized cancer treatment and research. This has triggered growing demand for the characterization of the tumor immune landscape. Although standard immunohistochemistry is suitable for studying tissue architecture, it is limited to the analysis of a small number of markers. Conversely, techniques such as flow cytometry can evaluate multiple markers simultaneously, although information about tissue morphology is lost. In recent years, multiplexed strategies that integrate phenotypic and spatial analysis have emerged as comprehensive approaches to the characterization of the tumor immune landscape. Herein, we discuss an innovative technology combining metal-labeled antibodies and secondary ion mass spectrometry focusing on the technical steps in assay development and optimization, tissue preparation, and image acquisition and processing. Before staining, a metal-labeled antibody panel must be developed and optimized. This hi-plex image system supports up to 40 metal-tagged antibodies in a single tissue section. Of note, the risk of signal interference increases with the number of markers included in the panel. After panel design, particular attention should be given to the metal isotope assignment to the antibody to minimize this interference. Preliminary panel testing is performed using a small subset of antibodies and subsequent testing of the entire panel in control tissues. Formalin-fixed, paraffin-embedded tissue sections are obtained and mounted on gold-coated slides and further stained. The staining takes 2 days and closely resembles standard immunohistochemical staining. Once samples are stained, they are placed in the image acquisition instrument. Fields of view are selected, and images are acquired, uploaded, and stored. The final stage is image preparation for the filtering and removal of interference using the system&#39;s image processing software. A disadvantage of this platform is the lack of analytical software. However, the images generated are supported by different computational pathology software.

In the era of cancer immunotherapy, interest in elucidating tumor microenvironment dynamics has increased strikingly. This protocol details a mass spectrometry imaging technique with respect to its staining and imaging steps, which allow for highly multiplexed spatial analysis.

Advances in immune-based therapies have revolutionized cancer treatment and research. This has triggered growing demand for the characterization of the ...

Cancer Research

Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI Mass Spectrometry

Ambient ionization methods in mass spectrometry allow analytical investigations to be performed directly on a tissue or biofilm under native-like experimental conditions. Laser ablation electrospray ionization (LAESI) is one such development and is particularly well-suited for the investigation of water-containing specimens. LAESI utilizes a mid-infrared laser beam (2.94 &mu;m wavelength) to excite the water molecules of the sample. When the ablation fluence threshold is exceeded, the sample material is expelled in the form of particulate matter and these projectiles travel to tens of millimeters above the sample surface. In LAESI, this ablation plume is intercepted by highly charged droplets to capture a fraction of the ejected sample material and convert its chemical constituents into gas-phase ions. A mass spectrometer equipped with an atmospheric-pressure ion source interface is employed to analyze and record the composition of the released ions originating from the probed area (pixel) of the sample. A systematic interrogation over an array of pixels opens a way for molecular imaging in the microprobe analysis mode. A unique aspect of LAESI mass spectrometric imaging is depth profiling that, in combination with lateral imaging, enables three-dimensional (3D) molecular imaging. With current lateral and depth resolutions of ~100 &mu;m and ~40 &mu;m, respectively, LAESI mass spectrometric imaging helps to explore the molecular structure of biological tissues. Herein, we review the major elements of a LAESI system and provide guidelines for a successful imaging experiment.

Laser ablation electrospray ionization (LAESI) is an atmospheric-pressure ion source for mass spectrometry. In the imaging mode, a mid-infrared laser probes the distributions of molecules across a tissue section or a biofilm. This technique presents a new approach for diverse bioanalytical studies carried out under native experimental conditions.

Ambient ionization methods in mass spectrometry allow analytical investigations to be performed directly on a tissue or biofilm under native-like ...

Biology

Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell types exhibit heterogeneous biochemical makeup depending on their physiological conditions and interactions with the environment. Conventional methods of mass spectrometry (MS) used for the analysis of biomolecules in single cells rely on extensive sample preparation. Removing the cells from their natural environment and extensive sample processing could lead to changes in the cellular composition. Ambient ionization methods enable the analysis of samples in their native environment and without extensive sample preparation.1 The techniques based on the mid infrared (mid-IR) laser ablation of biological materials at 2.94 &mu;m wavelength utilize the sudden excitation of water that results in phase explosion.2 Ambient ionization techniques based on mid-IR laser radiation, such as laser ablation electrospray ionization (LAESI) and atmospheric pressure infrared matrix-assisted laser desorption ionization (AP IR-MALDI), have successfully demonstrated the ability to directly analyze water-rich tissues and biofluids at atmospheric pressure.3-11 In LAESI the mid-IR laser ablation plume that mostly consists of neutral particulate matter from the sample coalesces with highly charged electrospray droplets to produce ions. Recently, mid-IR ablation of single cells was performed by delivering the mid-IR radiation through an etched fiber. The plume generated from this ablation was postionized by an electrospray enabling the analysis of diverse metabolites in single cells by LAESI-MS.12 This article describes the detailed protocol for single cell analysis using LAESI-MS. The presented video demonstrates the analysis of a single epidermal cell from the skin of an Allium cepa bulb. The schematic of the system is shown in Figure 1. A representative example of single cell ablation and a LAESI mass spectrum from the cell are provided in Figure 2.

Single cell analysis is performed by mass spectrometry on plant and animal cells at atmospheric pressure by using a sharpened optical fiber to sample the cells for laser ablation electrospray ionization (LAESI) mass spectrometry.

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell ...

Visualization of Amyloid &#946; Deposits in the Human Brain with Matrix-assisted Laser Desorption/Ionization Imaging Mass Spectrometry

The neuropathology of Alzheimer&#39;s disease (AD) is characterized by the accumulation and aggregation of amyloid &#946; (A&#946;) peptides into extracellular plaques of the brain. The A&#946; peptides, composed of 40 amino acids, are generated from amyloid precursor proteins (APP) by &#946;- and &#947;-secretases. A&#946; is deposited not only in cerebral parenchyma but also in leptomeningeal and cerebral vessel walls, known as cerebral amyloid angiopathy (CAA). While a variety of A&#946; peptides were identified, the detailed production and distribution of individual A&#946; peptides in pathological tissues of AD and CAA have not been fully addressed. Here, we develop a protocol of matrix-assisted laser desorption/ionization-based imaging mass spectrometry (MALDI-IMS) on human autopsy brain tissues to obtain comprehensive protein mapping. For this purpose, human cortical specimens were obtained from the Brain Bank at the Tokyo Metropolitan Institute of Gerontology. Frozen cryosections are cut and transferred to indium-tin-oxide (ITO)-coated glass slides. Spectra are acquired using the MALDI system with a spatial resolution up to 20 &#181;m. Sinapinic acid (SA) is uniformly deposited on the slide using either an automatic or a manual sprayer. With the current technical advantages of MALDI-IMS, a typical data set of various A&#946; species within the same sections of human autopsied brains can be obtained without specific probes. Furthermore, high-resolution (20 &#181;m) imaging of an AD brain and severe CAA sample clearly shows that A&#946;1-36 to A&#946;1-41 were deposited into leptomeningeal vessels, while A&#946;1-42 and A&#946;1-43 were deposited in cerebral parenchyma as senile plaque (SP). It is feasible to adopt MALDI-IMS as a standard approach in combination with clinical, genetic, and pathological observations in understanding the pathology of AD, CAA, and other neurological diseases based on the current strategy.

Molecular imaging with matrix-assisted laser desorption/ionization-based imaging mass spectrometry (MALDI-IMS) allows the simultaneous mapping of multiple analytes in biological samples. Here, we present a protocol for the detection and visualization of amyloid &#946; protein on brain tissues of Alzheimer&#39;s disease and cerebral amyloid angiopathy samples using MALDI-IMS.

The neuropathology of Alzheimer&#39;s disease (AD) is characterized by the accumulation and aggregation of amyloid &#946; (A&#946;) peptides into ...

Neuroscience

Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix&#160;assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has&#160;the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided.

Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging of small molecules; protocols for the use of DT for the MALDI imaging of endogenous lipids on the surface of tissue sections&#160;by positive-ion MALDI-MS on an ultrahigh-resolution quadrupole-FTICR instrument are provided here.

Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly ...

 Advanced MALDI-MSI Mapping of Metabolites in Brain Organoids

Molecular Imaging of Human Brain Organoids Using Mass Spectrometry 

Brain organoid models serve as a powerful tool for studying human brain development and function. Mass spectrometry imaging (MSI), a cutting-edge technology, allows us to map the spatial distribution of diverse molecules such as lipids, sugars, amino acids, drugs, and their metabolites within these organoids, all without the need for specific molecular probes. High-quality MSI data hinge on meticulous sample preparation. Fixatives play a pivotal role, but conventional options such as glutaraldehyde, paraformaldehyde, and cryopreserving such as sucrose may inadvertently impact tissue metabolites. Optimal fixation entails flash freezing in liquid nitrogen. However, for small organoids, a more suitable approach involves transitioning the organoids directly from the incubator into a warmed embedding solution, followed by freezing in dry ice-cooled ethanol. Another critical step is the embedding prior to cryosectioning, which also requires materials compatible with MSI, as traditional options can interfere with matrix deposition and ionization. Here, an optimized protocol for high resolution-MALDI-MSI of human brain organoids is presented, encompassing sample preparation, sectioning, and imaging using mass spectrometry. This method showcases the molecular distribution of small metabolites, such as amino acids, with high mass accuracy and sensitivity. As such, coupled with complementary studies of brain organoids, it can assist in illuminating complex processes governing early brain development, metabolic cell fate trajectories, and distinctive metabolite signatures. Furthermore, it provides insights into the precise locations of molecules within the organoid, enriching our understanding of the spatial organization of 3D brain organoid models. As the field continues to advance, a growing number of studies leveraging MSI to delve into brain organoids and complex biological systems is anticipated, thereby deepening the understanding of the metabolic aspects of human brain function and development.

Molecular Imaging of Human Brain Organoids Using Mass Spectrometry

An advanced method was developed for mass spectrometry imaging (MSI) of brain organoids that allows mapping metabolite distributions within these models. This technology offers insights into brain metabolic pathways and metabolite signatures during early development and in disease, promising a deeper understanding of the human brain function.

Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS)

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