Project description:Background & Aims: Cellular responses induced by surgical procedure or ischemia-reperfusion injury (IRI) may severely alter transcriptome profiles. We have investigated this effect to obtain insight into molecular ischemia responses during surgical procedures and characterize pre-analytical effects impacting on molecular analyses. Methods: 143 non-malignant liver samples were obtained from 30 patients at different time points of ischemia during surgery from two individual cohorts, treated either with the Pringle maneuver or total vascular exclusion. Transcriptomics profiles were analyzed by Affymetrix microarrays and expression of selected mRNAs was validated by RT-qPCR. Results: Transcriptional profiles of both cohorts displayed 179 genes that were mutually deregulated confirming elevated cytokine signaling, and NFkB as the dominant pathways in ischemia response. Contrary to ischemia, reperfusion induced pro-apoptotic and pro-inflammatory cascades involving TNF, NFkB and MAPK pathways. FOS and JUN were down-regulated in steatosis compared to their up-regulation in normal livers. Surprisingly, molecular signatures of underlying primary and secondary cancers were clearly present in the non-tumor tissue. Conclusions: We identified transcripts mutually deregulated during ischemia and reperfusion injury in both cohorts that can be used to monitor ischemia during liver surgery and highlight the importance of pre-analytical quality control. The marked inter-patient variability might reflect differences in individual stress responses and impact of underlying disease conditions. Furthermore, we provide a comprehensive and pre-analytically highly standardized in vivo transcriptome profile of histologically normal liver and identified 230 genes with substantial pre-analytical robustness (<2 % covariation across both cohorts) that might serve as reference genes and could be particularly suited for future diagnostic applications. Conclusions: We identified transcripts mutually deregulated during ischemia and reperfusion injury in both cohorts that can be used to monitor ischemia during liver surgery and highlight the importance of pre-analytical quality control. The marked inter-patient variability might reflect differences in individual stress responses and impact of underlying disease conditions. Furthermore, we provide a comprehensive and pre-analytically highly standardized in vivo transcriptome profile of histologically normal liver and identified 230 genes with substantial pre-analytical robustness (<2 % covariation across both cohorts) that might serve as reference genes and could be particularly suited for future diagnostic applications.

Project description:Abstract Background: Gene transfer by electroporation (electro gene transfer) to muscle results in high level long term transgenic expression, showing great promise for treatment of e.g. protein deficiency syndromes. However little is known about the effects of electro gene transfer on muscle fibres. We have therefore investigated transcriptional changes through gene expression profile analyses, as well as morphological changes evaluated by histological analysis. Electro gene transfer was obtained using a combination of a short high voltage pulse (HV, 1000 V/cm, 100 @s) followed by a long low voltage pulse (LV, 100 V/cm, 400 ms); a pulse combination optimised for efficient and safe gene transfer. Muscles were transfected with green fluorescent protein (GFP) and excised at 4 hours, 48 hours or 3 weeks after treatment. Results: Differentially expressed genes were investigated by microarray analysis, and descriptive statistics were performed to evaluate the effects of 1) electroporation, 2) DNA injection, and 3) time after treatment. The biological significance of the results was assessed by gene annotation and supervised cluster analysis. Generally, electroporation caused down-regulation of structural proteins e.g. sarcospan and catalytic en-zymes such as phosphoenolpuryvate carboxykinase. Injection of DNA induced down-regulation of intracellular transport proteins e.g. sentrin. The effects on muscle fibres were transient as the expression profiles 3 weeks after treatment were closely related with the control muscles. Most interestingly, no changes in the expression of proteins involved in inflammatory responses or muscle regeneration was detected, indicating limited muscle damage and regeneration. Histological analysis revealed structural changes with loss of cell integrity and striation pattern in some fibres after DNA+HV+LV treatment, while electroporation alone caused minor loss of striation pattern but preservation of cell integrity. Conclusion: The small and transient changes found in the gene expression profiles are of great importance, as this demonstrates that electro gene transfer is safe with minor effects on the muscle host cells. These findings are essential for introducing the electro gene transfer to muscle for clinical use. Indeed the HV+LV pulse combination used have been optimised to ensure highly efficient and safe electro gene transfer. Keywords: Electro gene transfer, microarray, affymetrix, gene therapy, skeletal muscle, mouse, time course

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Expression data in Ischemia and Reperfusion during microsurgical tissue transfer

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