Microencapsulation of recombinant interferon a-2b into poly (D,L-lactide-co-glycolide) microspheres

Interferon-α2b (IFN-α2b) produced in Cuba by the Center for Genetic Engineering and Biotechnology was encapsulated into poly (D,L-lactide-co-glycolide) (PLGA) microspheres using the double emulsion-solvent evaporation method. Resulting microspheres showed smooth surfaces containing randomly distributed pores, a mean diameter of 28.1 ± 0.4 μm (using 14,000 rpm for the second emulsification step), PLGA recovery of 86 ± 1%, loading between 0.41 and 1.23% for interferon at 5-20 mg/mL in the inner aqueous phase, with the corresponding encapsulation efficiency of 79 and 56%. The encapsulated interferon was extracted by both passive diffusion and solvent extraction techniques and further characterized. No changes were detected in the physico-chemical and biological characteristics of the IFN-α2b recovered by diffusion-controlled release for 24 h at 37 oC. In contrast, the solvent-extracted fraction showed 43 ± 4% of immunorecognized IFN-α2b and 61% of its initial antiviral activity (1.7 x 10 IU/mg). These instabilities were due to the encapsulation method, and not to spontaneous IFN-α2b modifications. Consequently, IFN-α2b showed potential for encapsulation in PLGA microspheres for controlled release.