하이드로겔/마이크로스피어 복합시스템을 이용한 치료혈관형성용 이중 단백질 전달

Abstract

Ischemic disease has shown high mortality and morbidity rate to date, and therapeutic angiogenesis via systemic or local delivery of protein drugs is one potential approach to treat the disease. In this study, we hypothesized that two different protein drugs could be released from combination delivery systems in a controlled manner, which might enhance therapeutic effect for treatment of ischemic diseases. We first chose heat shock protein (HSP) and vascular endothelial factor (VEGF) as therapeutic angiogenic agents. Alginate hydrogels containing TAT-HSP27 as an anti-apoptotic agent were prepared and PLGA microspheres loaded with VEGF as an angiogenic molecule were incorporated into the hydrogels to prepare microsphere/hydrogel combination delivery systems. The sequential release of TAT-HSP27 and VEGF was achieved in vitro and the VEGF release rate was able to be controlled by varying the pore sizes of the microspheres. The release of TAT-HSP27 from hydrogels was completed within 7 days, while the release of VEGF from microspheres was monitored for 28 days. Sequential delivery of TAT-HSP27 and VEGF was useful to protect muscle degeneration and fibrosis and promoted new blood vessel formation in the ischemic site of a mouse model. We next chose VEGF and angiopoietin-1 (Ang-1) as therapeutic proteins, since Ang-1 plays an important role in the stabilization and maturation of blood vessels as well. We thus hypothesized that delivery of VEGF combined with Ang-1 could enhance mature and functional vessel formation as well as vasculogenesis. The combination systems composed of VEGF loaded alginate hydrogel and VEGF and Ang-1 loaded microspheres were prepared and the sustained delivery of VEGF and Ang-1 was also achieved in vitro. Controlled delivery of VEGF and Ang-1 significantly enhanced arteriole density and induced vessel enlargement in the ischemic site of a mouse model. This approach to controlling the release behavior of multiple drugs in a sequential manner could be useful for the design of novel drug delivery systems in many biomedical applications.