A Novel Murine Model Enabling rAAV8-PC Gene Therapy for Severe Protein C Deficiency

Severe protein C deficiency (SPCD) is a rare inherited thrombotic disease associated with high morbidity and mortality. In the current study, we established a viable murine model of SPCD, enabling preclinical gene therapy studies. By creating SPCD mice with severe hemophilia A (PROC^-/-/F8^-), the multi-month survival of SPCD mice enabled the exploration of recombinant adeno-associated viral vector-PC (rAAV8-PC) gene therapy (GT). rAAV8- PC (10¹² vg/kg of AAV8-PC) was injected via the tail vein into 6-8-week-old PROC^-/-/F8^- mice. Their plasma PC antigen levels (median of 714 ng/mL, range 166-2488 ng/mL) and activity (303.5 ± 59%) significantly increased to the normal range after GT compared to untreated control animals. PC's presence in the liver after GT was also confirmed by immunofluorescence staining. Our translational research results provide the first proof of concept that an infusion of rAAV8-PC increases PC antigen and activity in mice and may contribute to future GT in SPCD. Further basic research of SPCD mice with prolonged survival due to the rebalancing of this disorder using severe hemophilia A may provide essential data regarding PC's contribution to specific tissues' development, local PC generation, and its regulation in inflammatory conditions.