Local Antitumor Effects of Intratumoral Delivery of RlL-2 Loaded Sustained-release Dextran/PLGA-PLA Core/shell Microspheres

In this study, we formulated a rIL-2 loaded sustained-release dextran/PLGA-PLA core/shell microsphere, mimicking the paracrine mechanisms of cytokine action, to investigate its local antitumor efficacy. The presented microspheres were formed in two steps: rIL-2 was firstly loaded into dextran particles to keep its bioactivity by a unique method of stabilizing aqueous-aqueous "emulsion"; subsequently, the particles were encapsulated into poly(dl-lactide-co-glycolide)/polylactic acid (PLGA/PLA). A stable sustained release behavior in vitro was achieved for a period of about 25 days. In the subcutaneous colon carcinoma BALB/c mice models, a single dose of microspheres was introtumorally administrated and compared with multiple doses of rIL-2 solution to investigate the long acting effect of microspheres on tumor. The animal experiments showed the local efficacy at tumor site mediated by rIL-2 from a single dose of microspheres was better than that of multiple rIL-2 solution injections. Based on the experimental results, we conclude that rlL-2 loaded sustained-release dextran/PLGA-PLA core/shell microspheres represent a promising approach for local cancer treatment in animals.