Cryogenic electrospinning has previously been demonstrated for controlling the pore sizes of electrospun scaffolds, which has been impossible with traditional electrospinning processes. This article describes the application of the cryogenic technique to fabricate a bilayered electrospun poly(D,L-lactide) scaffold (BLES) in a single uninterrupted process. The resulting BLES consisted of a traditional electrospun (ES) fibrous layer with a dense pore area of 17 +/- 3 microm(2) adjacent to a cryogenic electrospun layer (CES) with a pore area of 3300 +/- 500 microm(2). The significance of this bilayered scaffold was to mimic the anatomical structure of tissues with dense basement membrane followed by loose and highly porous connective tissue such as skin and blood vessels. Cell infiltration in the BLES was compared in vitro and in vivo. Both studies suggested the CES supported high cell infiltration, whereas the ES could serve as a physical barrier to prevent cell infiltration across the CES-ES boundary because of its size exclusion. The bilayered structure produced by this technique suggests a great potential for engineering tissues with similar architectures.

Decellularized xenografts have been identified as potential scaffolds for small-diameter vascular substitutes. This study aimed to develop and investigate a biomechanically functional and biocompatible acellular conduit using decellularized porcine saphenous arteries (DPSAs), through a modified decellularization process using Triton X-100/NH4 OH solution and serum-containing medium. Histological and biochemical analysis indicated a high degree of cellular removal and preservation of the extracellular matrix. Bursting pressure tests showed that the DPSAs could withstand a pressure of 1854 ± 164 mm Hg. Assessment of in vitro cell adhesion and biocompatibility showed that porcine pulmonary artery endothelial cells were able to adhere and proliferate on DPSAs in static and rotational culture. After interposition into rabbit carotid arteries in vivo, DPSAs showed patency rates of 60% at 1 month and 50% at 3 months. No aneurysm and intimal hyperplasia were observed in any DPSAs. All patent grafts showed regeneration of vascular elements, and thrombotic occlusion was found to be the main cause of graft failure, probably due to remaining xenoantigens. In conclusion, this study showed the development and evaluation of a decellularization process with the potential to be used as small-diameter grafts.

This study investigates the performance of surface modification of polycaprolactone (PCL) membrane on the binding and release behavior of basic fibroblast growth factor (bFGF) for in vitro proliferation of porcine eosophageal smooth muscle cells (PESMCs). The PCL membrane surfaceswere treated using UV/ozone and the surface modified PCL was characterized using water contact angle measurement, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The immobilization of bFGFs on the treated and non-treated PCL surfaces was also investigated using atomic force microscopy (AFM). It was found that the growth factor uptake on the PCL membrane was increased about 2-fold after treatment, which was attributed to significant contribution of oxygen containing polar groups resulting from UV/ozone treatment. Compared to non-treated PCL the treated PCL showed a prolonged bFGF release indicated by a linear increase over the first 3 days followed by a moderate and slow release profile. Moreover, the proliferation assay of PESMCs revealed that bFGF released from treated PCL had significantly higher proliferation than that of untreated PCL film. Thus, the UV/ozone-treated PCL membranes immobilized with bFGF accelerate the proliferation of PESMCs and may play an important role in soft tissue engineering.

The larger pores of CES add versatility to the use of electrospun scaffolds in tissue engineering applications.