Abstract Body: Background: Increased microtubule detyrosination by the tubulin carboxypeptidase Vasohibin (VASH) impairs cardiac mechanics in heart failure by increasing cytoplasmic viscosity. However, the role of VASH inhibition in maintaining Living Myocardial Slice (LMS) contractility under sustained mechanical stress remains poorly defined. We hypothesized that VASH inhibition to suppress the detyrosinated microtubules mitigates this "microtubule brake," preserving contractile performance under chronic high afterload.
Methods: Human LMS (7mm*7mm*300µm) were sectioned from normal human myocardium glued to a 3D printed anchor and cultured for 5 days in a 3D-printed platform (Fig 1) allowing precise preload and afterload control. LMS were paced at 0.25 Hz and subjected to three conditions: 1) Normal Afterload (10 mN/mm), 2) High Afterload (HA, 36 mN/mm), and 3) HA + VASH Inhibitor (HA+VASH-i) for the total duration of the culture. Contractility and force-length work loops were generated using the IonOptix system, followed by histological and molecular analysis of α-tubulin detyrosination and cell area.
Results: Exposure to 5 days of HA significantly reduced active force generation (Fig.2) and increased cell area by 17% compared to low afterload (P < 0.05). VASH inhibition prevented this accumulation and preserved contractility; HA+VASH-i slices maintained significantly higher active force generation than the HA group (Fig.3). Kinetic analysis revealed that VASH inhibition prevented the prolongation of the relaxation constant observed under HA. Despite 5 days of chronic load, the HA+VASH-i group exhibited preserved contractile forces, suggesting that mitigating microtubule-mediated drag maintains efficient cross-bridge cycling and mechanical performance even under pathological resistance.
Conclusion: Suppressing detyrosinated microtubules via VASH inhibition effectively preserves LMS contractility and kinetics during chronic high afterload. These findings identify the VASH-mediated "microtubule brake" as a viable therapeutic target to sustain cardiac function during persistent hypertensive or valvular stress.