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Abstract: PO1926

Human Kidney Mimetic Tissue Using Endogenous Lipids and Metabolites as Standards for Quantification and Quality Control

Session Information

Category: Pathology and Lab Medicine

  • 1600 Pathology and Lab Medicine

Authors

  • Pamreddy, Annapurna, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States
  • Zhang, Guanshi, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States
  • Ye, Hongping, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States

Group or Team Name

  • CRPM and KPMP
Background

Mass spectrometry imagine (MSI) determines the spatial localization of molecular species directly from the sample and has been heralded in tissue analysis. However, majority of studies have not been quantitative and reproducible. The presentation of a quantified tissue distribution has distinct benefits over the common approach of quantifying the tissue homogenate especially if tissue distribution is heterogeneous, making overcoming this limitation a top priority.

Methods

An improved mimetic tissue mold has been developed. Briefly, human kidney tissue was cut into small pieces and spiked with a normalization standard (lyso-PAF), an antioxidant, and a phospholipase A2 (PLA2) inhibitor to protect endogenous lipids and metabolites from the most common degradation. Lipidomic and metabolomic analyses of this mimetic tissue were performed, and the absolute amounts of various compounds were measured and used as standards for side by side MSI analysis of any tissue sample of interest. Since stabilizers are used, the quantitative data of the mimetic tissue are reliable and can be used as quality control (QC) tracers to tissue samples during storage and shipment.

Results

Mimetic tissue molds were prepared by spiking stable isotope labeled compounds at different concentrations layer by layer for validation. Initial validation experiments found that: a) MSI can detect the concentration differences with acceptable linearity, accuracy, and repeatability; b) Spiking of high concentrations affects the endogenous signals; c) It’s not practicable to spike each compound for its quantification due to signal suppression, high material and labor consumption; d) Using endogenous amounts as reference standards is a suitable approach. To use the homogenized mimetic tissue as a spatial quantitative and QC standard, the endogenous amounts of lipids and metabolites were measured with bulk omics. More than 200 lipids, 25 amino acids, and numinous organic acids were quantified.

Conclusion

Quantifying endogenous lipids and metabolites using bulk methods as MSI quantification standards is innovative in the field. The similarity of tissue matrix and targeting compounds between mimetic and sample tissues can provide more meaningful and reliable results.

Funding

  • NIDDK Support