Therapeutic ultrasound: Increased HDL-Cholesterol following infusions of acoustic microspheres and apolipoprotein A-I plasmids.

BACKGROUND

Low levels of HDL-C are an independent cardiovascular risk factor associated with increased premature cardiovascular death. However, HDL-C therapies historically have been limited by issues relating to immunogenicity, hepatotoxicity and scalability, and have been ineffective in clinical trials.

OBJECTIVE

We examined the feasibility of using injectable acoustic microspheres to locally deliver human ApoA-I DNA plasmids in a pre-clinical model and quantify increased production of HDL-C in vivo.

METHODS

Our novel site-specific gene delivery system was examined in naïve rat model and comprised the following steps: (1) intravenous co-administration of a solution containing acoustically active microspheres (Optison™, GE Healthcare, Princeton, New Jersey) and human ApoA-I plasmids; (2) ultrasound verification of the presence of the microspheres within the liver vasculature; (3) External application of locally-directed acoustic energy, (4) induction of microsphere disruption and in situ sonoporation; (4) ApoA-I plasmid hepatic uptake; (5) transcription and expression of human ApoA-I protein; and (6) elevation of serum HDL-C.

RESULTS

Co-administration of ApoA-I plasmids and acoustic microspheres, activated by external ultrasound energy, resulted in transcription and production of human ApoA-I protein and elevated serum HDL-C in rats (up to 61%; p-value < 0.05).

CONCLUSIONS

HDL-C was increased in rats following ultrasound directed delivery of human ApoA-I plasmids by microsphere sonoporation. The present method provides a novel approach to promote ApoA-I synthesis and nascent HDL-C elevation, potentially permitting the use of a minimally-invasive ultrasound-based, gene delivery system for treating individuals with low HDL-C.