Production of human factor IX in animals by genetically modified skin fibroblasts: potential therapy for hemophilia B. lood 73

Inherited diseases might be treated by introducing normal genes into a patient’s somatic tissues to correct the genetic defects. In the case of hemophilia resulting from a missing clotting factor. the required gene could be intro-duced into any cell as long as active factor reached the circulation. We previously showed that retroviral vectors can efficiently transfer genes into normal skin fibroblasts and that the infected cells can produce high levels of a therapeutic product in vitro. In the current study. we examined the ability of skin fibroblasts to secrete active clotting factor after infection with different retroviral vec-tors encoding human clotting factor IX. Normal human H EMOPHILIA B is an inherited disease in which the clotting factor IX gene is inactive or produces a defective product. ’ Transfusion of clotting factor prepara