| 초록 |
Angiogenesis is crucial in the treatment of various pathological conditions, and tissue engineering. Heparin is known to have binding affinities to angiogenic growth factors and has been commonly used in growth factor delivery. In this study, heparin was immobilized onto PLGA microspheres to improve its reversible binding capacities of growth factors. At first, porous PLGA microspheres were prepared using an O/W single emulsion method. Amine was conjugated onto the microspheres, and then heparin was immobilized onto surface amine. The amount of conjugated amine was 1.93 ± 0.01 nmol/mg-microspheres, and heparin 1.15 ± 0.03 μg/mg-microspheres. Conjugated amine and heparin was also visualized by using a fluorescent probe. bFGF was loaded onto the unmodified and heparin functionalized microspheres to examine in vitro release behaviors. For the unconjugated PLGA microspheres (MS), the total amount of protein released was 270 pg/mg-MS with an initial burst of 60% within a day. However, heparin immobilized MS released up to 1124 pg/mg-MS with a decrease in initial burst to about 40%. The therapeutic efficacy of this system was also investigated by subcutaneously injecting into nude mouse and observing blood vessel distributions. The presence of heparin on the PLGA surface greatly enhanced angiogenesis, resulting in formation of new microvessels. |
