Localized in vivo genotypic and phenotypic correction of the albino mutation in skin by RNA-DNA oligonucleotide

We recently demonstrated that an RNA-DNA oligonucleotide corrected a point mutation in the mouse tyrosinase gene, resulting in permanent and inheritable restoration of tyrosinase enzymatic activity, melanin synthesis, and pigmentation changes in cultured melanocytes. In this study, we extended gene correction of melanocytes from tissue culture to live animals, using a chimeric oligonucleotide designed to correct a point mutation in the tyrosinase gene. Both topical application and intradermal injection of this oligonucleotide to albino BALB/c mouse skin resulted in dark pigmentation of several hairs in a localized area. The restored tyrosinase enzymatic activity was detected by dihydroxyphenylacetic acid (DOPA) staining of hair follicles in the treated skin. Tyrosinase gene correction was also confirmed by restriction fragment length polymorphism analysis and DNA sequencing from skin that was positive for DOPA staining and melanin synthesis. Localized gene correction was maintained three months after the last application of the chimeric oligonucleotides. These results demonstrated correction of the tyrosinase gene point mutation by chimeric oligonucleotides in vivo.