Paraspinous muscle gene expression profiling following simulated staged endovascular repair of thoracoabdominal aortic aneurysm: exploring potential therapeutic pathways

OBJECTIVES Thoracic endovascular techniques for aneurysm repair offer less invasive alternatives to open strategies. Both approaches, however, are associated with the risk for neurological complications. Despite adjuncts to maintain spinal cord perfusion, ischaemia and paraplegia continue to occur during thoracoabdominal aortic aneurysm (TAAA) repair. Staging of such extensive procedures has been proven to decrease the risk for spinal cord injury. Archived biopsy specimens may offer insight into the molecular signature of the reorganization and expansion of the spinal collateral network during staged endovascular interventions in the setting of TAAA. METHODS Biological replicates of total RNA were isolated from existing paraspinous muscle samples from 22 Yorkshire pigs randomized to 1 of 3 simulated TAAA repair strategies as part of a previous study employing coil embolization of spinal segmental arteries within the thoracic and lumbar spine. Gene expression profiling was performed using the Affymetrix GeneChip Porcine array. RESULTS Microarray analysis identified 649 differentially expressed porcine genes (≥1.3-fold change, P ≤ 0.05) when comparing paralysed and non-paralysed subjects. Of these, 355 were available for further analysis. When mapped to the human genome, 169 Homo sapiens orthologues were identified. Integrated interpretation of gene expression profiles indicated the significant regulation of transcriptional regulators (such as nuclear factor кB), cytokine (including CXCL12) elements contributing to hypoxia signalling in the cardiovascular system (vascular endothelial growth factor and UBE2) and cytoskeletal elements (like dystrophin (DMD) and matrix metallopeptidase (MMP)). CONCLUSIONS This study demonstrates the ability of microarray-based platforms to detect the differential expression of genes in paraspinous muscle during staged TAAA repair. Pathway enrichment analysis detected subcellular actors accompanying the neuroprotective effects of staged endovascular coiling. These observations provide new insight into the potential prognostic and therapeutic value of gene expression profiling in monitoring and modulating the arteriolar remodelling in the collateral network.