A modular ex vivo human vessel perfusion platform for studying vascular reconstruction

Vascular tissue responses to mechanical and biochemical stimuli are central to many vascular diseases and interventions, including maturation and failure of arteriovenous fistulas (AVF). Experimental systems that preserve native human vascular architecture while allowing controlled perfusion, surgical manipulation, and vascular interventions remain limited. We developed a modular ex vivo perfusion platform that supports pulsatile flow across multiple vascular configurations and enables controlled study of vessel architecture, hemodynamics, and cell biology ex vivo.

Deidentified human iliac arteries and veins discarded from liver transplantation were obtained under an Institutional Review Board-approved protocol and mounted in a closed-loop circuit driven by a pulsatile blood pump. Straight arterial vessels and surgically created ex vivo AVF were perfused with endothelial cell culture medium supplemented with 1× penicillin-streptomycin, maintained at 37 °C. Flow dynamics were assessed using Doppler ultrasound. Representative vessel segments were fixed for hematoxylin and eosin, Masson trichrome, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, and cleaved caspase-3 immunohistochemistry. TUNEL-positive area was quantified across whole vessel sections using Fiji (ImageJ) with Otsu automated thresholding, with manual counts of TUNEL- and cleaved caspase-3-positive nuclei performed as confirmatory analyses.

The platform accommodated straight arterial and surgically constructed AVF configurations during 2-hour pump perfusion. Pump settings of 40 strokes/min and 7 mL stroke volume generated pulsatile perfusion, confirmed by pressure transducers. In straight arterial runs, pulsed-wave Doppler confirmed measurable flow through the isolated human iliac artery, with velocities ranging from 4.81 to 25.18 cm/s and a mean velocity of 18.9 cm/s. In the AVF configuration, Doppler ultrasound demonstrated disturbed flow at the anastomosis, and venous outflow volume-flow rates ranged from 752.1 to 1442.5 mL/min, exceeding the 600 mL/min threshold commonly used to define functional fistula flow. Histology demonstrated close arteriovenous apposition in the constructed fistula. Pre- and postperfusion TUNEL quantification showed no increase in TUNEL-positive area after 2-hour perfusion, whereas in a separate time-course analysis, TUNEL-positive area increased with longer intervals from vessel acquisition to fixation.

We describe a modular human vessel perfusion platform that supports pulsatile flow and clinically relevant AVF conditions ex vivo. Histologic assessment demonstrated preserved vessel architecture and no increase in apoptotic burden after short-term pump perfusion. This system provides a biologically viable human tissue platform for studying mechanical, biochemical, and device-related contributors to vascular reconstruction.

Pathologic vascular remodeling contributes to critical vascular conditions, including peripheral arterial disease, adverse surgical reconstruction outcomes, restenosis, and arteriovenous fistula failure. Current models often lack intact adult human tissue under controlled flow. This modular ex vivo perfusion platform preserves native vessel architecture while supporting pulsatile perfusion, surgical manipulation, Doppler ultrasound assessment, and histologic analysis. By enabling controlled study of adult human iliac arteries and veins across multiple configurations, this system may support future investigation of vascular remodeling mechanisms, device testing, therapeutic delivery, and clinically relevant hemodynamic responses before translation to patient care.