The present study aimed at establishing feasibility of delivering
short interfering RNA (
siRNA) to target the coagulation cascade in rat and rabbit, two commonly used species for studying
thrombosis and hemostasis. siRNAs that produced over 90%
mRNA knockdown of rat plasma
prekallikrein and rabbit
Factor X (FX) were identified from in vitro screens. An ionizable amino
lipid based
lipid nanoparticle (LNP) formulation for
siRNA in vivo delivery was characterized as tolerable and exerting no appreciable effect on coagulability at day 7 postdosing in both species. Both
prekallikrein siRNA-LNP and FX
siRNA-LNP resulted in dose-dependent and selective knockdown of target gene
mRNA in the liver with maximum reduction of over 90% on day 7 following a single dose of
siRNA-LNP. Knockdown of plasma
prekallikrein was associated with modest clot
weight reduction in the rat arteriovenous shunt
thrombosis model and no increase in the cuticle bleeding time. Knockdown of FX in the rabbit was accompanied with prolongation in ex vivo clotting times. Results fit the expectations with both targets and demonstrate for the first time, the feasibility of targeting
coagulation factors in rat, and, more broadly, targeting a gene of interest in rabbit, via systemic delivery of ionizable LNP formulated
siRNA.