Degradation and Healing Characteristics of Small-Diameter Poly(ε-Caprolactone) Vascular Grafts in the Rat Systemic Arterial Circulation

Abstract

Background-Long-term patency of conventional synthetic grafts is unsatisfactory below a 6-mm internal diameter.Poly(⑀-caprolactone) (PCL) is a promising biodegradable polymer with a longer degradation time. We aimed to evaluate in vivo healing and degradation characteristics of small-diameter vascular grafts made of PCL nanofibers compared with expanded polytetrafluoroethylene (ePTFE) grafts. Methods and Results-We prepared 2-mm-internal diameter grafts by electrospinning using PCL (M n ϭ80 000 g/mol).Either PCL (nϭ15) or ePTFE (nϭ15) grafts were implanted into 30 rats. Rats were followed up for 24 weeks. At the conclusion of the follow-up period, patency and structural integrity were evaluated by digital subtraction angiography. The abdominal aorta, including the graft, was harvested and investigated under light microscopy. Endothelial coverage, neointima formation, and transmural cellular ingrowth were measured by computed histomorphometry. All animals survived until the end of follow-up, and all grafts were patent in both groups. Digital subtraction angiography revealed no stenosis in the PCL group but stenotic lesions in 1 graft at 18 weeks (40%) and in another graft at 24 weeks (50%) in the ePTFE group. None of the grafts showed aneurysmal dilatation. Endothelial coverage was significantly better in the PCL group. Neointimal formation was comparable between the 2 groups. Macrophage and fibroblast ingrowth with extracellular matrix formation and neoangiogenesis were better in the PCL group. After 12 weeks, foci of chondroid metaplasia located in the neointima of PCL grafts were observed in all samples. Conclusions-Small-diameter PCL grafts represent a promising alternative for the future because of their better healing characteristics compared with ePTFE grafts. Faster endothelialization and extracellular matrix formation, accompanied by degradation of graft fibers, seem to be the major advantages. Further evaluation of degradation and graft healing characteristics may potentially lead to the clinical use of such grafts for revascularization procedures.

Morphology and Charge Transport Properties of Chemically Synthesized Polyaniline-poly(ε-caprolactone) Polymer Films

“…17,18 Due to its hydrophobic nature and high crystalline degree, PCL degrades slowly 19,20 by hydrolysis and has been considered in a wide range of applications, for example, biodegradable packaging materials, implantable biomaterials, scaffold, and micro-particles for drug delivery. [21][22][23] The crystallization behavior of PCL blends has been investigated in a number of studies. 24,25 Moreover, the effect of reinforcement materials such as starch, clay, and single-walled nanotubes, on the crystallization of PCL has been studied via isothermal and non-isothermal crystallization.…”

Influence of the fiber diameter and surface roughness of electrospun vascular grafts on blood activation

“…Electrospinning has been widely used as a processing method for the design of vascular grafts [12,13] with performances equal or superior to current standard, ePTFE [14]. This technique is quite popular as it allows easy production of fibrous tubular scaffolds with controllable composition, architecture, fiber diameter and mechanical properties [12,15,16].…”

Biodegradable Cell-Seeded Nanofiber Scaffolds for Neural Repair

“…Pektok et al were among the first to evaluate the in vivo degradation and healing features of small-diameter vascular grafts consisting of electrospun PCL fibers with a mean diameter of 1.90 µm in the rat systemic arterial circulation [176]. The major mechanism of PCL degradation is the breakup of ester linkages by nonenzymatic random hydrolysis [177].…”

“…The main cause for failure of graft using biodegradable polymers was aneurismal dilatation due to the premature loss of mechanical strength of the graft material [178]. Pektok et al examined the weight loss by assessing the molecular weight changes of the PCL grafts and discovered 20% loss for M w (weight average molecular weight, M w =∑ / ∑ , where N i is the number of moles of each polymer species and M i is the molar mess of the species) and 22% loss for M n (number average molecular weight, M n =∑ / ∑ 24 weeks after implantation, and observed no significant premature structural deformities and thus no aneurismal dilatation [176]. …”