Cutting Edge: Treatment of Complement Regulatory Protein Deficiency by Retroviral In Vivo Gene Therapy

Abstract

Gene therapy is an attractive means to replace a deficient or defective protein. Using a murine retroviral vector, we provide an example of reconstituting a C regulator by neonatal in vivo gene transfer. The fusion gene containing the mouse C receptor 1-related gene/protein y (Crry) and a single chain Ab fragment with specificity for mouse glycophorin A was placed under transcriptional control of a liver-specific promoter. Shortly after birth, Crry KO mice were injected with the retroviral vectors. Protein expression progressively increased over the next 6–8 wk after which an equilibrium was established. Coating levels on RBCs were obtained that inhibited C activation similar to wild-type cells and remained constant for >1 year. Thus, gene therapy with targeted regulators represents a treatment option to provide a long-term and sustained protein supply for the site-specific blockade of undesirable complement activation.