Subcutaneous Implantation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly(ε-caprolactone) Scaffolds Modified with Growth Factors

The aim of the investigation was to assess the tissue response to subcutaneous implantation of nonwoven scaffolds fabricated from biodegradable polymers and further modified by growth factors.

Materials and Methods. Specimens were produced by two-phase electrospinning from poly(ε-caprolactone) and a blend of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ε-caprolactone) both unmodified (controls) and modified with growth factors VEGF, bFGF, and SDF-1α. The ratio of a polymer solution in chloroform and a water phase with a bioactive molecule was 20:1. To study the tissue response in vivo, nonwoven scaffolds were subcutaneously implanted in Wistar rats weighing 80–100 g for the periods of either 1, 2, 3, 6, 9, or 12 months.

Results. Incorporating growth factors into the scaffolds during electrospinning provided biofunctionalization, including enhanced vasculogenesis and angiogenesis and increased viability of endothelial cells. Histological examination showed that biomolecules incorporated into the matrix have been functionally active throughout the whole time of the implantation.

The tested specimens did not cause rejection and acute inflammatory reaction. A thin connective tissue capsule was formed around the implants. A full resorption of the scaffolds did not occur, and the polymers remained at the site of implantation for at least 12 months. Growth factors significantly improved performance of the implants during the first 3 months postimplantation: VEGF enhanced angiogenesis, bFGF stimulated a thick connective tissue capsule formation, while SDF-1α facilitated angiogenesis and cellular infiltration. From the 12^th month postimplantation, incomplete biodegradation of nonwoven scaffolds caused granulomatous inflammation.

Conclusion. Nonwoven scaffolds fabricated of biodegradable polymers and further modified with VEGF, bFGF, and SDF-1α represent a promising option for the fabrication of cardiovascular implants.

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