GELATIN MICROSPHERES AS A NEW APPROACH FOR THE CONTROLLED DELIVERY OF SYNTHETIC OLIGONUCLEOTIDES AND PCR-GENERATED DNA FRAGMENTS

The present paper reports the preparation and characterization of gelatin microspheres containing (a) a 44-mer single-stranded synthetic oligonucleotide, complementary to the HLA-DRA gene (ssDNA-44) and (b) a double-stranded fragment, 144 bp in length, prepared by the polymerase chain reaction (PCR) mimicking a region of the HIV-1 LTR (dsDNA-144). Spherical gelatin microspheres were obtained by a coacervation method, showing a high percentage of encapsulation yields (over 85%). Size distribution analysis of the microspheres produced resulted in an average diameter of 22 mum. In order to analyse the release profiles of both ssDNA-44 and dsDNA-144 from microspheres, in vitro studies were carried out by using a flow-through cell method. The chemical stability of dsDNA-144 to the encapsulation procedure steps was in addition demonstrated by. PCR amplification of the DNA eluted from the gelatin microspheres. The reported results indicate that gelatin-based microspheres offer excellent potential as carrier systems for the in vivo administration of both single- and double-stranded DNA molecules.