Electrospun Fibrous Scaffolds for Small-Diameter Blood Vessels: A Review

Abstract

Small-diameter blood vessels (SDBVs) are still a challenging task to prepare due to the occurrence of thrombosis formation, intimal hyperplasia, and aneurysmal dilation. Electrospinning technique, as a promising tissue engineering approach, can fabricate polymer fibrous scaffolds that satisfy requirements on the construction of extracellular matrix (ECM) of native blood vessel and promote the adhesion, proliferation, and growth of cells. In this review, we summarize the polymers that are deployed for the fabrication of SDBVs and classify them into three categories, synthetic polymers, natural polymers, and hybrid polymers. Furthermore, the biomechanical properties and the biological activities of the electrospun SBVs including anti-thrombogenic ability and cell response are discussed. Polymer blends seem to be a strategic way to fabricate SDBVs because it combines both suitable biomechanical properties coming from synthetic polymers and favorable sites to cell attachment coming from natural polymers.

Keywords: SDBVs; anti-thrombogenic agents; electrospinning; fibrous scaffold; thrombosis.

Figure 1

Schematic illustration of blood vessel structure (reprinted from Ref. [16]).

Figure 2

Electrospinning setups: (a) grounded flat collector is used to collect fibers; (b) tubular rotating mandrel is used to collect fibers to shape blood vessels.

Figure 3

SEM photographs of (a) synthetic poly(ε-caprolactone) (PCL)/Poly(l-lactic acid) (PLA) blood vessel of 6 mm diameter, (b) the randomly oriented PCL fiber inner layer, (c) the aligned PLA fiber outer layer (reprinted from Ref. [34]).

Figure 4

SEM image of polyurethane fibrous scaffold consists of micro-patterned internal layer and electrospun microfiber external layer; the ridge width, channel width and channel depth were 3.6 ± 0.2, 3.9 ± 0.1 and 0.9 ± 0.03 µm, respectively (reprinted from Ref. [40]).

Figure 5

Tubular blood vessels fabricated by melt electrospinning: (a,b) polypropylene (Moplen 462R PP); (c,d) polylactide (PLA 4060D) (reprinted from Ref. [42]).

Figure 6

SEM images of in vitro degradation of P (LLACL) fibrous scaffold in PBS at 37 °C after (a) 0 time, (b) 3 months (reprinted from Ref. [51]).

Figure 7

Endothelial cells cultured inside the micro-patterned polyurethane-based synthetic blood vessel after three days (reprinted from Ref. [40]).

Figure 8

PCL/PLA nanofibrous scaffold cultured in 3T3 mouse fibroblasts cells for 4 weeks (reprinted from Ref. [34]).

Figure 9

Expression of transgene eNOS protein in both MSCs seeded blood vessel (a,b) and eNOS-MSCs seeded blood vessel (c,d) (reprinted from Ref. [84]).

Figure 10

Histological analysis for PCL electrospun blood vessel implanted in an abdominal aortic rat for 12 weeks (a) 20 time, (b) 100 time, (c), and (d) 200 time magnification (reprinted from Ref. [31]).

Figure 11

Investigation of explanted (a) PCL graft and (b) PCL-arginine-glycine-aspartic acid (RGD) graft by stereomicroscope and (c,d) cross-section staining after four weeks of implantation. Acute thrombosis was observed in the lumen of PCL (reprinted from Ref. [89]).