Engineered small-diameter vascular prostheses: A study in bioreactor

Vascular tissue engineering aims to the fabrication of biodegradable and bioadsorbable small-diameter vascular prostheses, bypassing the drawbacks that the common vascular scaffolds show after their implantation. Several strategies have been studied to obtain a good vascular substitute with good mechanical, biological and haematological properties. A depth study of the fabricated prostheses is always considered a fundamental step before any in vivo experimentation. These studies are necessary to obtain information regarding the behaviour of the vascular substitutes under dynamic conditions predicting many parameters (degradation, release of bioactive compounds etc.) that the vascular biodegradable scaffolds will show in vivo. In this work, electrospinning was used to fabricate vascular bioprostheses, made of poly (caprolactone) and poly (glycerol sebacate), both 20 % (w/v), at a ratio of 1:1 (v/v) and in the presence of quercetin (0.05 % w/v). They were electrospun on a collector of 2 mm in diameter and after coated with a layer of gelatin at 37°C for 1 h reducing their permeability. An ad hoc bioreactor consisting of a peristaltic pump, a manometer, a flow chamber for the scaffold, and a reservoir was used to test in dynamic conditions the electrospun scaffolds. were tested. In the bioreactor phosphate buffered saline (PBS) solution was flowed for 1, 2 and 3 months under physiological conditions. Daily, a part of PBS was collected to be analysed in terms of the quantity of the released gelatin and quercetin. Chemico-physical and mechanical properties of the vascular graft were studied at the end of the experiment. The permanence time in the bioreactor, as showed by scanning electron microscopy, influenced the randomized fibrous structure of the scaffold. The release of gelatin and quercetin was significantly different in comparison with those studies performed in static conditions (data previously presented). Mechanical properties were studied in terms of Young’s modulus, tensile strength and elongation percentage highlighting that the proposed engineered bioprostehes represent a promising tool for vascular tissue engineering. The obtained results proved the importance of studying electropsun graft in dynamic conditions with the aim of simulating an in vivo implant.