Fabrication of burst pressure competent vascular grafts via electrospinning: Effects of microstructure

Abstract

In this work, electrospun tubes of interest for vascular tissue engineering were fabricated and evaluated for burst pressure and suture retention strength (SRS) in the same context as tensile strength providing a direct, novel comparison. Tubes could be fabricated displaying average burst pressures up to 4000 mmHg--well above the standard of 2000 mmHg--and SRS values matching those of relevant natural tissues. Surprisingly, highly oriented fiber and maximal tensile properties are not absolutely necessary to attain clinically adequate burst pressures. The ability to resist bursting is clearly related to both initial solution solids loading and electrospinning deposition time. We make novel in situ observations of the relative microstructural characteristics of failure during bursting, and connect this to the conditions used to fabricate the graft. Processes typically thought to promote fiber alignment are, in fact, highly condition-dependent and do not always provide superior properties. In fact, electrospun structures displaying no discernable alignment could achieve burst pressures regarded clinically sufficient. The properties of individual electrospun fiber clearly do not fully dictate macroscale properties. Normal background levels of point bonding are enhanced by increased rotational speeds, and can have effects on properties more dominant than those of alignment.

Evaluation of Mechanical Properties and Medical Applications of Polycaprolactone Small Diameter Artificial Blood Vessels

“…Therefore, they reported a moderate amount for this parameter equal to 4000 mm Hg, and by comparing the value of the parameter in natural vessels (2000 mm Hg) showed that the mechanical properties of PCL fibers were compatible with those of natural vessels. 36 According to the presented results, it can be concluded that by increasing the concentration, desirable mechanical properties such as tensile and stress can be achieved. However, in order to improve and modify PCL biomechanical properties, another group of researchers used thermal treatment method and did thermal operations at temperatures of 54 to 55°C, and observed that tensile, burst pressure, and suture retention significantly increased.…”

Recent Applications of Polymeric Biomaterials and Stem Cells in Tissue Engineering and Regenerative Medicine

“…Numerous reports have documented that synthetic biodegradable polymer-based materials can be electrospun to generate candidate vascular scaffolds with in vitro characteristics of strength and biological properties that appear consistent with clinical requirements. 113,[116][117][118][119] Many efforts attempted to develop a durable biomaterial capable of resisting physiological forces and maintaining structural integrity until mature vascular tissue forms in vivo. It is also important that engineered vessels should be compliant, resistant to kinking and compression, and possess sufficient tensile and shear strength to resist fraying at cut edges and tearing out of sutures.…”

Electrospun vascular graft properties following femtosecond laser ablation

“…Studies have shown that the scaffolds upon which cells are seeded are the most important factor for subsequent in vivo success. 7 In addition to possessing biocompatibility and antithrombogenicity, well-designed scaffolds must also meet specific mechanical requirements to be effective. The requirement of 2000 mmHg burst pressure is mandated by clinical concerns 6 as the arteries targeted for replacement typically have burst pressures above 2000 mmHg.…”

“…In recognition of the need for multiple extracellular environments and cell types to comprise such burst pressure resistant, biocompatible synthetic vessels, we utilize our previously developed expertise in both tubular electrospinning 7 and laser ablation of electrospun fiber. 10 A trilayer tissue engineered vessel mimicking the structure and the properties of the extracellular matrix found within innermost tunica intima, the middle tunica media, and the outermost tunica adventitia of a normal blood vessel is envisioned.…”