Chondroitin sulfate (CsA) is an acidic mucopolysaccharide, which is able to form ionic complexes with positively charged
proteins. In this study, a
protein-CsA complex was constructed to nano-sized particles. Zeta potential measurements revealed that a CsA-to-
protein fraction of greater than 0.1 results in a neutralization of the positive charge on
lysozyme (Lys). Based on this preliminary study, we have prepared
poly(lactide-co-glycolide) (PLGA)
microspheres harboring Lys/CsA complexes via the multi-
emulsion method. Protein stability in the PLGA
microspheres was preserved during both
microsphere preparation and
protein release. The profiles of Lys release from the PLGA
microspheres evidenced nearly zero-order kinetics, depending on the quantity of CsA. An in vivo fluorescent image of experimental mouse tissue showed that the PLGA
microspheres with the Lys/CsA complex had released the entirety of their Lys without no residual amount after 23 days, but
microspheres without the complex harbored a great deal of residual Lys, which is attributable to its degradation by acidic PLGA degradates. The tissue reaction evidenced by the PLGA
microspheres stabilized with CsA showed minimal
foreign body reaction and little configuration of immune cells including neutrophils and macrophages, but the reactions of the PLGA
microspheres without CsA were characterized by a relatively elevated
inflammation. These results show that CsA is a viable candidate for long-acting micro-particular
protein delivery.