Abstract 603: Effective And Sustained ACE2 Delivery Using Minicircles Technology

Abstract

Chronic and sustained amplification of ACE2 activity in vivo has required the development of

transgenic mice or the use of viral vectors. Minicircle is a new gene delivery technology

which is resistant to gene silencing, and therefore represents an attractive

platform for gene replacement strategies in vivo. Here we cloned cDNA of

soluble mouse ACE2 into a circular expression cassette and the resulting ACE2

minicircle (MC) was injected to female FVB

mice using iv. hydrodynamic approach (10ug or 30ug/mouse). At 3-7d after MC

administration, serum ACE2 activity in mice that received 10ug ACE2MC (n=9) was

over 100-fold higher than in controls (n=9) (138±48 vs 0.7±0.2 RFU/uL/hr) and in

ACE2MC mice (30ug) (n=8) was almost 1000-fold higher than in controls (n=14) (480

±153 vs 0.5±0.1 RFU/uL/hr, respectively). Mice that received 10 ug ACE2MC were

followed for consecutive serum ACE2 activity monitoring, BP measurements and

plasma Ang levels. The increase in serum ACE2 activity was sustained until the

end of the study (up to 82 days) (Figure).

Despite such a marked increase in serum ACE2 activity in ACE2MC mice, conscious

SBP was not different from controls (137±8 vs 138±7 mmHg, respectively). At the

end of the study, when Ang II was infused acutely (0.2 ug/kg BW i.p.), the

increase in plasma Ang II in ACE2MC mice was significantly reduced compared to

control mice (915±154 vs 1420±131 fmoL/mL, p<0.05).

Mini-circle delivery of ACE2 results in a dose-dependent and sustained long-term

increase in serum ACE2 that efficiently degrades plasma Ang II. Extremely high

increases in serum ACE2 activity do not reduce BP probably due to activation of

non-ACE2 dependent compensatory Ang-hydrolyzing pathways.