Dataset Information

Protein Expression in Liver Tissue and Bile of Elderly Sprague-Dawley Rats after Normothermic Machine Perfusion

ABSTRACT: Liver are frequently declined for transplantation due to the donor age. It is still unclear how donor age affects the graft quality. Normothermic machine perfusion (NMP) has been proposed as a useful assessment tool prior to transplantation. We aimed to compare the performance of young and elderly rat liver grafts in a small animal NMP model. Grafts from 24 rats were procured, either 3 or 12 months old and perfused for 6 hours at 37°C or stored on ice as a reference group (n=6/group). Livers in both NMP groups cleared lactate and produced bile, with similar pressure, bile production, and pH levels. However, older rat livers showed higher peak transaminase and urea levels. Proteomic analysis revealed differences in protein composition, particularly higher levels of proteins related to oxidoreductase and catalytic activity in older livers. Older age appeared to increase susceptibility to oxidative stress in the livers.

INSTRUMENT(S): impact II

ORGANISM(S): Rattus Norvegicus (rat)

TISSUE(S): Liver, Bile

SUBMITTER: Simon Moosburner

LAB HEAD: Prof. Dr. Igor M. Sauer

PROVIDER: PXD045394 | Pride | 2024-08-09

REPOSITORIES: Pride

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Distinctive protein expression in elderly livers in a Sprague-Dawley rat model of normothermic ex vivo liver machine perfusion.

Zimmer Maximilian M Hillebrandt Karl Herbert KH Roschke Nathalie Nora NN Lippert Steffen S Klein Oliver O Nebrich Grit G Gassner Joseph Maria George Vernon JMGV Strobl Felix F Pratschke Johann J Krenzien Felix F Sauer Igor Maximilian IM Raschzok Nathanael N Moosburner Simon S

European journal of medical research 20240711 1

<h4>Background</h4>Liver grafts are frequently declined due to high donor age or age mismatch with the recipient. To improve the outcome of marginal grafts, we aimed to characterize the performance of elderly vs. young liver grafts in a standardized rat model of normothermic ex vivo liver machine perfusion (NMP).<h4>Methods</h4>Livers from Sprague-Dawley rats aged 3 or 12 months were procured and perfused for 6 h using a rat NMP system or collected as a reference group (n = 6/group). Tissue, bil ...[more]

PMID: 38992689

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Project description:There is a ever widening gap between the availability of donor livers suitable for transplantation and liver transplant demand of a growing waiting list. To expand the pool of liver grafts, donation after circulatory death is increasingly being used. Livers procured after circulatory death are exposed to a harmful period of warm Ischemia (WI) during the donation process, reducing post-transplant results significantly. Additionally, the conventional technique of static cold storage does not protect grafts that suffered WI. New dynamic preservation strategies by means of Normothermic Machine Perfusion (NMP) showed enhanced preservation of these type of grafts, but it is unknown how NMP influences liver cell biology during perfusion. Hepatocytes and cholnagiocytes have been shown to release Extracellular Vesicles (EVs) in the systemic circulation and bile, respectively. We hypothesized that EVs are released during liver NMP as well, in perfusate and bile. EVs have been separated from perfusate and bile during NMP of porcine livers, and the RNA cargo of the EVs has been sequenced to gain insights on liver cell biology during machine perfusion. Pigs were randomly allocated to undergo liver procurement either immediately after the start of surgery (no-WI, n=5) or after a period of WI of 60-minutes (clamping of thoracic aorta; WI-60, n=5). All livers (n=10) were cooled down and flushed out with ice-cold preservation solution, according to standard clinical practice. Porcine blood was collected and washed with a cell saver to obtain packed red blood cells for NMP. The hepatic artery, portal vein, and inferior vena cava were cannulated and after a period of about 2-hours of cold storage, NMP was started. All liver underwent NMP for 6-hours. Packed red blood-based perfusate samples were taken at 1, 3, and 6h of NMP; whereas, the bile produced the first 3-hours and the last 3-hours was pooled in 2 samples. Perfusate and bile samples were processed immediately for EVs separation with charge-based precipitation in a mixture of protamine and polyethylene glycol. The total RNA was extracted from EVs. Libraries of mRNA and of small RNA were prepared and analyzed for quality and size range, and sequenced on an Illumina HiSeq4000 instrument. Count-based differential expression analysis was done with R-based Bioconductor package DESeq2, and the following comparisons were performed: - Unpaired (between groups) comparison - perfusate samples WI-60 vs. no-WI - bile samples WI-60 vs. no-WI - Paired (withing group) comparison - no-WI - perfusate sample 1h vs. perfusate sample 3h - perfusate sample 1-3h vs. perfusate sample 6h - bile sample 1-3h vs. bile sample 3-6h - perfusate samples vs. bile samples - WI-60 - bile sample 1-3h vs. bile sample 3-6h - perfusate samples vs. bile samples Results were adjusted for multiple testing with the Benjamini-Hochberg procedure, to control for false discovery rate. Additionally, the function of the transcripts identified in the EVs of both groups and of the differentially expressed transcripts was investigated with gene ontology enrichment analysis for the domains \\"biological process\\" and \\"pathways\\".

Project description:Bile has gained increasing attention for its potential to reflect the overall health of the biliary system. Proteomic analysis of bile could deepen our understanding of the molecular pathophysiology of biliary disease and injury and provides a potential source of diagnostic biomarkers. With the emergence of normothermic machine perfusion (NMP) prior to liver transplantation, bile samples can be easily collected and analyzed. However, the unique composition of bile, including high concentrations of endogenous detergents and salts, can make application of proteomics challenging. In this study, we systematically evaluated a variety of available trypsin-digestion methods to optimize proteomics analysis of bile obtained from human NMP livers. Bile was collected from 12 human donor livers that were accepted for transplantation after NMP viability assessment. We performed tryptic digestion using 6 different methods: in-gel, in-solution, S-Trap, SMART, EasyPep, and filter-aided sample purification, with or without an additional precipitation step prior to digestion. Untargeted, data-independent acquisition proteomics was performed using an Exploris 480 mass spectrometer coupled with a FAIMS device. The methods were judged for total protein IDs, variation, and specific protein characteristics to determine the most optimal method. A total of 4650 unique proteins were identified across all samples and all methods. Methods involving precipitation identified substantially more proteins (4500 vs 3815, respectively). In-gel crude was the exception, identifying a comparable number of proteins to precipitated in-gel digest. We found minimal differences in the mass, cellular component, or hydrophobicity of identified proteins between methods. Intra-method variability was notably diverse, with in-gel, in-solution, and EasyPep outperforming other methods with considerably less variation. Age-related biological comparisons revealed significant disparities in protein abundances between methods, but younger donors consistently showed upregulation of metabolic-related processes compared to older donors. Older donors showed upregulation of immune response and cell cycle-related processes. The digestion method used for proteomic analysis of bile can heavily influence the results obtained. A method of protein purification appears to be essential for sufficient quality mass spectrometry runs and subsequent data. Sample processing speed, cost, cleanliness, and reproducibility should be carefully considered when selecting a protein digestion method for this difficult sample type.

			Action	DRS
	Legend.rtf	Other
	bile31.d.zip	Other
	bile31.mgf	Mgf
	bile31.xml	Xml
	bile32.d.zip	Other