Tissue Engineering Of Small-diameter Vessels Research Articles

The promotion of vascular reconstruction by hierarchical structures in biodegradable small-diameter vascular scaffolds

Tissue engineering of small-diameter vessels remains challenging due to the inadequate ability to promote endothelialization and infiltration of smooth muscle cells (SMCs). Ideal vascular graft is expected to provide the ability to support endothelial monolayer formation and SMCs infiltration. To achieve this, vascular scaffolds with both orientation and dimension hierarchies were prepared, including hierarchically random vascular scaffold (RVS) and aligned vascular scaffold (AVS), by utilizing degradable poly(ε-caprolactone)-co-poly(ethylene glycol) (PCE) and the blend of PCE/gelatin (PCEG) as raw materials. In addition to the orientation hierarchy, dimension hierarchy with small pores in the inner layer and large pores in the outer layer was also constructed in both RVS and AVS to further investigate the promotion of vascular reconstruction by hierarchical structures in vascular scaffolds. The results show that the AVS with an orientation hierarchy that consists with the natural vascular structure had better mechanical properties and promotion effect on the proliferation of vascular cells than RVS, and also exhibited excellent contact guidance effects on cells. While the dimension hierarchy in both RVS and AVS was favorable to the rapid infiltration of SMCs in a short culture time in vitro. Besides, the results of subcutaneous implantation further demonstrate that AVS achieved a fully infiltrated outer layer with wavy elastic fibers-mimic strips formation by day 14, ascribing to hierarchies of aligned orientation and porous dimension. The results further indicate that the scaffolds with both orientation and dimension hierarchical structures have great potential in the application of promoting the vascular reconstruction.

Suture-reinforced polydioxanone-elastin for tissue engineering of small-diameter vessels: a feasibility study

Objective To investigate the feasibility of constructing sutuze-reinforced polydioxanone(PDS)multilayer small-caliber artificial scaffolds and determine its biomechanical properties.Methods 7-0PDS fibers were woven into a stent with 4 mm inner diameter.The influence of different weaving angle and knitting structure on the mechanical properties were investigated.Multilayer scaffolds were constructed using the preparecl PDS stent as the middle elasticity layer and covering it with small intestinal submucosa(SIS).To reinforce the scaffold,the outer two lavers were continuously sutured with 8-0 PDS suture perpendicular to the longitudinal axis.The inner layer of scaffold was coated With collagen sponge which was added with 10%chondroitin sulfate(CS).The biomechanical properties of the scaffold such as burst strength,tensile strength and compliance were tested and compared to those of canine carotid artery.Results 65-degree weaving angle was chosen to construct stent with 4 mm inner diameter and 3 to 5 cm length.These scaffolds had(43.50±8.30)kPa burst strength,(19.10±1.56)N tensile strength,(42.88±3.16)% strain ratio and(5.96±0.87)%/100 mm Hg radial compliance.Conclusion The multilayer scaffolds have satisfactory biomechanical properties that meet the mechanical requirements for in vivo implantation as a tissue engineered blood vessel. Key words: Tissue engineering; Blood vessels; Biomechanics; Polydioxanone