Thrombospondin-4 regulates apoptosis of vascular smooth muscle cells after artery transplanted into vein
In the context of coronary artery bypass grafting (CABG), mechanical factors are pivotal;   however, the molecular underpinnings of vascular atrophy and remodeling subsequent to arterial transplantation into a venous hemodynamic milieu remain enigmatic.   Consequently, this study employed the vascular anastomosis wheel technique to graft the common carotid artery of New Zealand white rabbits into the external jugular vein, thereby establishing an innovative animal model of arterial mechanical unloading. The efficacy of the animal model was ascertained through ultrasound imaging. Immunohistochemical methodologies, transmission electron microscopy, and TUNEL staining were utilized to delineate alterations in vascular morphology. Advanced techniques such as gene transcriptomic analysis, proteomic profiling, iPathway guide (IPG) analysis, gene overexpression/silenced, flow cytometry, and stretch testing were applied to elucidate the potential molecular mechanisms. Comparative analysis between the arterial graft and the control group revealed the successful preparation of the mechanical unloading animal model in vitro. Morphological examination of the arterial vessels indicated that atrophy under venous flow mechanics is predominantly attributed to the apoptosis of vascular smooth muscle cells (VSMCs). Genomic and proteomic analyses revealed that thrombospondin-4 (THBS4) plays a pivotal role in vascular remodeling. IPG analysis suggested that THBS4 may modulate VSMCs apoptosis via the focal adhesion pathway. THBS4 gene overexpression/silence experiments and flow cytometry demonstrated the regulation of VSMCs apoptosis by THBS4. Furthermore, it was established that low stretch tension facilitates the expression of THBS4 and VSMCs apoptosis, thereby confirming the relationship between THBS4 and VSMCs apoptosis. This study was the first to introduce gene transcriptomics and proteomics into the arterial mechanical unloading animal model and the first to demonstrate the role of THBS4 in promoting VSMCs apoptosis. Consequently, THBS4 emerges as a promising therapeutic target for the prevention of intimal hyperplasia post-vascular transplantation in vascular surgery. Overall design: RNA-seq analysis was performed at 14 and 30 days after surgery in the control group (the artery of the contralateral group without operation) and the experimental group (the artery transplated into vein), respectively