Sustained Release of Vascular Endothelial Growth Factorfrom Poly(ε-caprolactone-PEG-ε-caprolactone)‑ b ‑Poly(l‑lactide) Multiblock CopolymerMicrospheres

Vascular endothelial growth factor (VEGF) is the major regulating factor for the formation of new blood vessels, also known as angiogenesis. VEGF is often incorporated in synthetic scaffolds to promote vascularization and to enhance the survival of cells that have been seeded in these devices. Such applications require sustained local delivery of VEGF of around 4 weeks for stable blood vessel formation. Most delivery systems for VEGF only provide short-term release for a couple of days, followed by a release phase with very low VEGF release. We now have developed VEGF-loaded polymeric microspheres that provide sustained release of bioactive VEGF for 4 weeks. Blends of two swellable poly(e-caprolactone)–poly(ethylene glycol)–poly(e-caprolactone)-b-poly(l-lactide) ([PCL–PEG–PCL]-b-[PLLA])-based multiblock copolymers with different PEG content and PEG molecular weight were used to prepare the microspheres. Loading of the microspheres was established by a solvent evaporation-based membrane emulsification meth...