title: Ambient ionization mass spectrometric analysis of human surgical specimens to distinguish renal cell carcinoma from healthy renal tissue.
abstract: Touch spray-mass spectrometry (TS-MS) is an ambient ionization technique (ionization of unprocessed samples in the open air) that may find intraoperative applications in quickly identifying the disease state of cancerous tissues and in defining surgical margins. In this study, TS-MS was performed on fresh kidney tissue (∼1-5 cm(3)), within 1 h of resection, from 21 human subjects afflicted by renal cell carcinoma (RCC). The preliminary diagnostic value of TS-MS data taken from freshly resected tissue was evaluated. Principal component analysis (PCA) of the negative ion mode (m/z 700-1000) data provided the separation between RCC (16 samples) and healthy renal tissue (13 samples). Linear discriminant analysis (LDA) on the PCA-compressed data estimated sensitivity (true positive rate) and specificity (true negative rate) of 98 and 95 %, respectively, based on histopathological evaluation. The results indicate that TS-MS might provide rapid diagnostic information in spite of the complexity of unprocessed kidney tissue and the presence of interferences such as urine and blood. Desorption electrospray ionization-MS imaging (DESI-MSI) in the negative ionization mode was performed on the tissue specimens after TS-MS analysis as a reference method. The DESI imaging experiments provided phospholipid profiles (m/z 700-1000) that also separated RCC and healthy tissue in the PCA space, with PCA-LDA sensitivity and specificity of 100 and 89 %, respectively. The TS and DESI loading plots indicated that different ions contributed most to the separation of RCC from healthy renal tissue (m/z 794 [PC 34:1 + Cl](-) and 844 [PC 38:4 + Cl](-) for TS vs. m/z 788 [PS 36:1 - H](-) and 810 [PS 38:4 - H](-) for DESI), while m/z 885 ([PI 38:4 - H](-)) was important in both TS and DESI. The prospect, remaining hurdles, and future work required for translating TS-MS into a method of intraoperative tissue diagnosis are discussed. Graphical abstract Touch spray-mass spectrometry used for lipid profiling of fresh human renal cell carcinoma. Left) Photograph of the touch spray probe pointed at the MS inlet. Right) Average mass spectra of healthy renal tissue (blue) and RCC (red).
authors.affiliation: Department of Chemistry, Center for Analytical Instrumentation Development and Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Clint M
authors.initials: CM
authors.lastname: Alfaro
authors.affiliation: Department of Chemistry, Center for Analytical Instrumentation Development and Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Alan K
authors.initials: AK
authors.lastname: Jarmusch
authors.affiliation: Department of Chemistry, Center for Analytical Instrumentation Development and Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Pirro
authors.affiliation: Department of Chemistry, Center for Analytical Instrumentation Development and Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Kerian
authors.affiliation: Department of Urology, Indiana University School of Medicine, Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, 46202, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Masterson
authors.affiliation: Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, 46202, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Department of Chemistry, Center for Analytical Instrumentation Development and Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA. cooks@purdue.edu.
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D000465:Algorithms; D014408:Biomarkers, Tumor / Q000032:analysis*; D002292:Carcinoma, Renal Cell / Q000737:chemistry* / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D006801:Humans; D007668:Kidney / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D007680:Kidney Neoplasms / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D010743:Phospholipids / Q000032:analysis*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014407:Tumor Cells, Cultured
chemical_list: D014408:Biomarkers, Tumor; D010743:Phospholipids
keywords: Cancer; Desorption electrospray ionization; Mass spectrometry; Multivariate statistics; Surgical tissue analysis; Touch spray ionization