A PRECLINICAL STUDY INVESTIGATING THE ROLE OF ASPIRIN IN ATTENUTATING NEUROLOGICAL DETERIORATION IN CERVICAL MYELOPATHY

Abstract

<p>​​​​​​​<strong>Introduction</strong></p><p>In addition to mechanical compression, hypoperfusion and inflammation are pathophysiological hallmarks of cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL). Aspirin has well-established effects on both pathological features in the management of cardiovascular and cerebrovascular conditions. Microglia have been highlighted as resident immune cells modulating neuroinflammation in CSM and may be particularly responsive to aspirin treatment. Our objective was to investigate the effect of aspirin treatment in the twy-twy mouse, which is a well-established OPLL disease model.</p><p><strong>Methods</strong></p><p>Twy-twy mice were administered aspirin via drinking water from weeks 4 – 12 of maturity. Cervical spine perfusion was assessed at week 12 using micro-CT imaging following transcardiac perfusion with MICROFIL®, and neurological function evaluated weekly with the rotarod test. Primary microglial cells isolated from adult mouse spinal cords were analysed for VEGF expression using flow cytometry, with and without aspirin treatment. An angiogenesis assay with microglia, human umbilical vein endothelial cells (HUVECs), with or without aspirin supplementation was conducted for the assessment of tube formation (branching length and mesh number), which was quantified using ImageJ.</p><p><strong>Results</strong></p><p>Micro-CT imaging at week 12 indicated increased cervical spinal cord perfusion in aspirin-treated mice, with vessel volume/total volume at 6.41±2.26% in the aspirin group versus 1.56±0.76% % in controls (p<0.01). Rotarod performance (balance on rod in seconds) also improved in aspirin-treated mice compared to non-treated controls, with significant differences observed at week 7 (19.34 ± 4.09s vs. 3.46 ± 1.42s, p<0.01) and week 11 (18.76 ± 8.12s vs. 5.50 ± 3.87s, p=0.04). For in vitro findings, aspirin exposure increased the proportion of VEGF+ microglia from 0.15% to 43.63%. In the tube formation assay, microglia culture with HUVEC and aspirin resulted in a marked increase in branch length (p < 0.01) and mesh number (p = 0.03), suggesting an angiogenic role orchestrated by VEGF+ microglia in vivo secondary to aspirin treatment.</p><p><strong>Conclusions</strong></p><p>We provide preclinical evidence for the effect of aspirin to attenuate neurological decline in an OPLL disease model. Upon consolidation of preclinical evidence and elucidating the mechanism of action, further evidence may be provided for in the prospective treatment of human subjects.</p>