A METHOD TO CODETECT INTRODUCED GENES AND THEIR PRODUCTS IN GENE-THERAPY PROTOCOLS

To monitor the presence of introduced genes and the distribution of th e encoded proteins in host tissues after gene transfer, we combined fl uorescence in situ hybridization (FISH) and immunohistochemistry in tw o separate gene therapy paradigms. In brain tissue sections from anima ls injected with pHSVlac vector, we localized nuclei containing vector DNA both in cells expressing and not expressing Beta-galactosidase (b eta-gal). This suggests that the efficiency of gene transfer is affect ed not only by gene delivery, but also by cellular controls on gene ex pression. In a second paradigm, following myoblast transplantation, we detected donor nuclei in the muscle of a patient with Duchenne's musc ular dystrophy. The donor nuclei were either surrounded by host nuclei or apparently fused in the patient's muscle fiber producing dystrophi n. The combined FISH and immunohistochemistry assay offers greater sen sitivity and more information than currently used polymerase chain rea ction and protein detection methods.