Long-Term Expression of Human Factor Ⅸ cDNA in Rabbits

In this study, rabbits were used as a model for gene therapy for hemophilia B, Human factor Ⅸ cDNA was transferred to cultured normal rabbit skin fibroblasts (RSF) by a recombinant plasmid (pCMVIX) or retrovirus(XL-IX or N2CMVIX) constructed in our laboratoy. Infected fibroblasts capable of synthesizing and secreting high levels of biologically active human factor Ⅸ protein were selected and embedded in a collagen matrix. The latter was surgically implanted into rabbits as autografts or allografts. Human factor Ⅸ protein was detected in the plasma of all the grafted rabbits, and its expression has been maintained for more than 10 months at the time of writing. In addition, we have improved and simplified the method of implantation from surgically grafting the tissue-like matrix to the injection of the infected cell-collagen mixture subcutaneously. Using the latter method, human factor Ⅸ in rabbits injected with RSF-N2CMVIX reached a peak of 480 ng/ml plasma, and its expression has continued for more