Evaluation of Angiogenic Factor Release from Thermosensitive Poly(N-Vinylcaprolactam)-g-Collagen: In Vitro and In Vivo Studies

Abstract

In this study, a thermosensitive poly(N-vinylcaprolactam)-g-collagen (PNVCL-g-Col)hybrid hydrogel was synthesized by conjugation using the NHS/EDC cross-linking system,and characterized. At first, the efficiency of in vitro sustained delivery of human vascularendothelial growth factor (VEGF) from the thermosensitive PNVCL-g-Col hydrogelmodified with heparin, was evaluated for duration of ten days under in vitro physiologicalconditions (37oC, pH 7.4). The results indicated that PNVCL-g-Col hydrogel preservedits stability and released ~90% of the loaded VEGF within this time period. In vitro studyshowed that PNVCL-g-Col was basically histocompatible. Then, the in vivo angiogenicactivity of the VEGF-releasing PNVCL-g-Col was investigated using a subcutaneous ratmodel. In vivo study confirmed that angiogenic-factor-loaded PNVCL-g-Col had the capacityto induce neovascularization indicating that the in vivo bioactivity of the VEGF waspreserved in the thermosensitive PNVCL-g-Col.