Quantified In Vitro Release of Interleukin-8 from Electrospun Bioresorbable Vascular Graft Materials

Abstract

Interleukin-8 (IL-8) is a chemokine from the CXC family that has been shown to have angiogenic properties through the activation of macrophages. Angiogenesis is a critical factor in tissue regeneration, specifically of implanted electrospun bioresorbable vascular grafts. The purpose of this study was to analyze the release of IL-8 from electrospun scaffolds of different materials to demonstrate these scaffolds can be used as a chemotactive agent for macrophages to promote increased tissue regeneration in vascular grafts. Polycaprolactone (PCL), poly(glycolic acid) (PGA), fibrinogen (FBG), and silk solutions were electrospun from 1,1,1,3,3,3 hexafluoro-2-propanol (HFP) with and without the addition of 3000 ng/ml human IL-8. High and low concentrations of polymer were used to form scaffolds of micro- to nano-sized fiber diameters, respectively. From these scaffolds, 6 mm discs were punched, placed in a 96 well plate, and incubated under standard conditions with the addition of complete media (200μl). Media was retained at days 1, 3, 5, and 7 for ELISA analysis of IL-8 release. Preliminary results of IL-8 release from electrospun constructs reveal a steady decrease of chemokine throughout the seven day time period from all scaffolds, with the exception of PGA. Silk scaffolds release the highest amount of IL-8 (0.07-0.21 ng/ml), whereas scaffolds of PCL exhibit the lowest amount of chemokine release (0.01-0.06 ng/ml). Although PGA scaffolds display a steady release of chemokine for days 1, 3, and 5 (0.03 ng/day), at day 7 there is an increase (0.06 ng/day and 0.04 ng/day for low and high concentrations, respectively) due to bulk degradation of the scaffold. Control scaffolds (those without IL-8) display undetectable amounts of IL-8. While these scaffolds seem to demonstrate the ability to enhance cell migration and promote increased tissue regeneration, future work, including analyzing the chemotactic property of scaffolds on macrophages and fibroblasts, will be necessary to verify these results.