Heparin-Conjugated PCL Scaffolds Fabricated by Electrospinning and Loaded with Fibroblast Growth Factor 2

Abstract

A biodegradable poly(ε-caprolactone) (PCL) was synthesized by ring-opening polymerization of ε-caprolactone catalyzed by Sn(Oct)2/BDO, followed by the heparin conjugation using EDC/NHS chemistry. The structure of the heparin-PCL conjugate was characterized by (1)H-NMR and GPC. The results of static contact angle and water uptake ratio measurements also confirmed the conjugation of heparin with the polyester. Its in vitro anticoagulation time was substantially extended, as evidenced by activated partial thromboplastin time (APTT) testing. Afterwards the conjugate was electrospun into small-diameter tubular scaffolds and loaded with Fibroblast Growth Factor 2 (FGF2) in aqueous solution. The loading efficiency was assayed by enzyme-linked immunosorbent assay (ELISA); the results indicated that the conjugate holds a higher loading efficiency than the blank polyester. The viability of released FGF2 was evaluated by MTT and cell adhesion tests. The amount and morphology of cells were significantly improved after FGF2 loading onto the electrospun heparin-PCL vascular scaffolds.

Vascular Remodeling Process of Heparin-Conjugated Poly(ε-Caprolactone) Scaffold in a Rat Abdominal Aorta Replacement Model

“…As the stability and activity of heparin immobilized on vascular grafts are critical for blood compatibility in vivo, methods for heparin coating of vascular graft polymers have ranged from the adsorption of heparin from aqueous solution to covalent end-point immobilization [25]. It was reported that the hydrophilicity of PCL was improved after combination with heparin [18, 26]. In this study, we described a novel method for immobilizing heparin on PCL scaffolds via HMD, and PCL-HMD-H scaffold was successfully prepared by the electrospinning technique and surface modification.…”

“…In our previous study, a chemical method of immobilizing heparin on PCL scaffold was reported. The surface heparin content change was measured in an in vitro release experiment and heparin release was found to be stable after 21 days [18]. However, it was difficult to measure the heparin release of heparin-conjugated material in vivo.…”

“…In addition, the hydrophobic surface was less favorable for the EC adhesion and proliferation [30]. After combination with heparin, heparin-conjugated PCL scaffolds attained high positively charged amine groups and promotion of hydrophilicity [18, 21]. In the present study, anti-CD34 antibody and anti-vWF antibody were used for the markers of ECs.…”

“…The anticoagulant activity of the PCL-HMD-H scaffold was measured by APTT assay [18]. Five samples of heparin-conjugated PCL samples were cut into 0.5 × 0.3-cm rectangles and placed into the test tube.…”

“…As the antithrombin­city of implanted grafts are crucial for long-term patency, anticoagulant can be covalently coated on the surface of the polymer scaffold to inhibit thrombogenesis in vivo. Since heparin has been widely used in vascular grafts as reliable anticoagulant [16], covalently immobilizing heparin onto the electrospinning PCL scaffold can effectively improve the antithrombincity [17, 18]. Furthermore, the heparin peptide provides versatile coordinating capacity for a variety of angiogenic growth factors, such as vascular endothelial growth factor (VEGF), which could promote the growth of endothelial cells (ECs) [19, 20].…”