ABSTRACT
Thrombotic thrombocytopenic purpura (TTP) is primarily caused by deficiency of ADAMTS13 within the blood stream due to either genetic defects or presence of inhibitory autoantibodies. Preclinical and clinical studies suggest that enzyme replacement therapy with recombinant human ADAMTS13 protein (rhADAMTS13) is effective and safe in treatment of TTP. However, frequent dosing would be required due to the relatively short half-life of rhADAMTS13 in circulation as well as the presence of inhibitory autoantibodies that collectively result in the poor pharmacological profile of rhADAMTS13. With technical breakthroughs in exploring mRNA as therapeutics, we hypothesized that restoration of ADAMTS13 activity for a prolonged duration of time can be achieved through systemic dosing of mRNA, wherein the dosed mRNA would utilize hepatic cells as bioreactors for continuous production of ADAMTS13. To test this hypothesis, mRNA encoding human ADAMTS13 WT or an ADAMTS13 variant, that had demonstrated resistance to predominant clinical TTP autoantibodies, was formulated in lipid nano-particles for liver-targeted delivery. In both ADAMTS13-sufficient and -deficient mice, a single dose of the formulated mRNAs at 1 mg/kg resulted in expression of hADAMTS13 at or above therapeutically relevant levels in mice for up to five days. This proof-of-concept study suggests that mRNA therapy could provide a novel approach for TTP treatment.
Subject(s)
ADAMTS13 Protein/genetics , Genetic Therapy/methods , RNA, Messenger/genetics , ADAMTS13 Protein/blood , ADAMTS13 Protein/metabolism , Animals , Autoantibodies/blood , Drug Carriers/chemistry , HEK293 Cells , Humans , Lipids/chemistry , Liver/metabolism , Liver/pathology , Mice , Mice, Knockout , Mutagenesis , Nanoparticles/chemistry , Purpura, Thrombotic Thrombocytopenic/therapy , Purpura, Thrombotic Thrombocytopenic/veterinary , RNA, Messenger/blood , RNA, Messenger/chemistry , RNA, Messenger/therapeutic useABSTRACT
A 27-year-old male chimpanzee (Pan troglodytes verus) developed signs of thrombotic thrombocytopenic purpura (TTP). ADAMTS13 deficiency appeared to be the cause of disease. After treatment with high-dose prednisone, haematological values and clinical signs recovered. This is the first description of spontaneous TTP associated with ADAMTS13 deficiency in a non-human primate.
Subject(s)
ADAMTS13 Protein/deficiency , Anticoagulants/therapeutic use , Ape Diseases/drug therapy , Pan troglodytes , Prednisone/therapeutic use , Purpura, Thrombotic Thrombocytopenic/veterinary , Animals , Ape Diseases/genetics , Diagnosis, Differential , Male , Purpura, Thrombotic Thrombocytopenic/drug therapy , Purpura, Thrombotic Thrombocytopenic/geneticsABSTRACT
A disintegrin and metalloproteinase with thrombospondin type 1 motifs, number 13 (ADAMTS13) is a plasma zinc metalloprotease also known as von Willebrand factor (VWF)-cleaving protease. Deficiency of ADAMTS13 activity is known to cause thrombotic thrombocytopenic purpura (TTP) in humans. We isolated the canine ADAMTS13 cDNA, which encodes 1502 amino acids, and expressed the recombinant protein to evaluate VWF-cleaving ability. Although the propeptide domain was longer and the TSP1 repeat domain was shorter than those in other species, the overall structures were similar to human and mouse ADAMTS13. Recombinant canine ADAMTS13 cleaved the 250-kDa VWF monomer into two fragments of 150 kDa and 120 kDa. Furthermore, high molecular weight VWF multimers were abolished based on the activity of ADAMTS13. These results could facilitate research into hemostatic disorders such as TTP in dogs.
