Development and evaluation of axially aligned nanofibres for blood vessel tissue engineering

Biodegradable polymers have been extensively used as scaffolds to regenerate lost tissues. The geometry of the three-dimensional (3D) scaffolds has an influence on the cellular behaviour. In this study, we have developed 3D-scaffolds of axially aligned nanofibres of poly(lactic acid) (PLA), poly (caprolactone) (PCL) and PLA: CL (50:50) with diameters in the range 100-400 nm, internal diameter 4 mm, length 4 cm and wall thickness 0.2 mm, by using a dynamic collector. PCL and PLA: CL nanofibres were significantly less hydrophobic than PLA nanofibres. The porosity of PCL (16.23 +/- 9.88%) and PLA: CL nanofibres (14.77 +/- 3.41%) were comparable, while PLA (6.57 +/- 1.54%) nanofibres had lower porosity. The tensile strength and Young's modulus of PLA was significantly lower than PCL and PLA: CL nanofibres and the suture retention strengths of all three scaffolds were comparable. After 4 weeks, the molecular weight of PLA nanofibres was reduced by 53% compared to 44% and 41% for PCL and the PLA: CL nanofibres, respectively. However, the PLA: CL nanofibres maintained their structural integrity even after 28 days. Platelet adhesion studies showed that PCL nanofibres had least tendency to be thrombogenic, while PLA: CL blend nanofibres were highly thrombogenic. Further, in vitro responses such as cell adhesion, proliferation and gene expression of human umbilical vascular endothelial cells (HUVECs) were evaluated. After 6 days of culture, the surfaces of all the three scaffolds were completely covered with cells. Our results demonstrate that expression levels of elastin, angiopoietin, laminin-4 alpha and -5 alpha were upregulated in PCL and PLA:CL nanofibres without the addition of any exogenous factors. Copyright (C) 2012 John Wiley & Sons, Ltd.