Incubation of tissue engineered blood vessels under pulsatile stress: a pilot study

Abstract

Objective To explore the feasibility of incubation of tissue engineered blood vessels (TEBV) subjected to pulsatile stress in a bioreactor.Methods The vascular smooth muscle cells (VSMCs) isolated from human umbilical artery were,following in vitro incubation,seeded on polyglycolic acid (PGA) scaffold and placed into the bioreactor for three-dimensional culture.The pulsatile stress was simulated by using a gas-driven left ventricular assisted pump mimicking the human cardiovascular internal environment (pressure:120 mm Hg,1 mm Hg=0.133 kPa,frequency:60 beats/min).The control group was cultured without pulsatile stress.This was followed by harvesting of TEBVs for subsequent scanning electron microscopy (SEM),HE staining and Masson staining at week 2.Results The TEBVs in the experimental group appeared bright-colored,with considerable thickness and flexibility sufficient to maintain the lumen architecture.As revealed by SEM,the internal wall lining the TEBV was smooth,with abundant extracellular matrix (ECM) that was evenly distributed and totally surrounded the PGA in the cross-section.HE staining showed a dense uniform vascular wall with well-oriented ECM and cells juxtaposed against undegraded PGA fragments.An abundance of collagen fibers lining the vascular wall was evidenced by Masson staining.In the control group,the dim-colored TEBV was characterized by its thin wall with poor flexibility that collapsed instantaneously following removal from the scaffold.SEM revealed a rough surface with little ECM by which PGA was not mostly surrounded.Histopathology staining showed a loose architecture characterized by unremarkable ECM and collagen fibers lining the vascular wall.Conclusion TEBV-like tissue with an ideal morphology can be cultured under the pulsatile stress in a bioreactor. Key words: Tissue engineering; blood vessels; stress; three-dimensional culture; bioreactor