Biomechanical properties of veins cultured in vitro under elevated internal pressure

BACKGROUND: The venous response to elevated blood pressure (BP) is of major importance because it is closely related to the etiology of venous diseases and the competency of vein grafts. In vitro culture experiments may provide useful information on the phenomena and mechanisms of venou remodeling, because it is easier to separate mechanical and hemodynamic effects from other systemic influences compared to in vivo experiments. OBJECTIVE: To study the effects of BP elevation on wall dimensions and mechanical properties of in vitro cultured veins. METHODS: Rabbit femoral veins were cultured in vitro under internal pressures of 1 to 50 mmHg for 1 week, and their wall dimensions, biomechanical properties, and histology were determined. RESULTS: No significant differences were observed in internal vein diameter and wall thickness among vessels cultured at 10-50 mmHg and non-cultured control vessels. For an internal pressure of 10 mmHg applied to vessels during culture (equivalent to in vivo working BP), wall circumferential stress was maintained within control levels. There were no significant effects of pressure on basal tone and contractility of vascular smooth muscle and vascular compliance. CONCLUSIONS: The in vitro results were essentially similar to those obtained from previous in vivo animal experiments, indicating that in vitro tissue culture techniques are applicable to studies of venous remodeling.