Publications

Delivery of Plasmid to the Myocardium Using Direct Injection Via Needle or Helical Needle-Catheter

Mehrdad Rezaee 1, Fiona MacLaughlin 2, Mary Thiesse 2, Jijun Wang 2, Dongming Hou 2, Keith March 4, Peter Altman 3, Michael Coleman 2

Delivery of gene therapies to the heart presents specific challenges because the procedure is typically invasive. A less invasive alternative using a steerable helical-needle catheter was assessed for delivery of formulated plasmid (encoding human developmental endothelial locus (Del-1)) to pig myocardium. Prior screening of plasmid formulations was performed by direct injection into mouse myocardium. Intramyocardial injection of 30 µg plasmid in mice produced peak luciferase expression levels at day 2 that decreased approximately 10-fold by day 7, and reached background levels by day 28. Murine Del-1 mRNA levels were quantified following administration of plasmid (30 µg) encoding the homologous murine Del-1. At day 2, 3 x 105 copies of Del-1mRNA/µg total RNA were measured with a similar log-fold reduction in expression at day 7. However, expression persisted through 56 days. Immunohistochemical analysis indicated that Del-1 expression was localized to myocytes (approximately 1% of cells). To assess percutaneous delivery using a helical needle catheter plasmid formulated with poloxamer 188 (3 mg plasmid/mL) was delivered via the helical needle catheter to 10 sites (200 µL/site) within the left ventricle of pigs (n = 4). PCR and rtPCR analysis of the myocardium and distal organs indicated that plasmid distribution and expression of Del-1 transgene was localized to the targeted myocardial region. Both plasmid and Del-1 mRNA were present in 30% of the samples within the LV. Half of the samples positive for Del-1 mRNA (average copy number 8.2 x 104/µg total RNA) were above the limit of quantitation. These results demonstrate the feasibility and specificity of gene delivery to the myocardium via a helical-needle catheter.

1 Cardiovascular Medicine, Stanford University, Stanford, CA, United States
2 Valentis, The Woodlands, TX, United States
3 Biocardia Inc., South San Francisco, CA, United States
4 Center for Vascular Biology and Medicine, Indianapolis, IN, United States

American Society of Gene Therapy, Boston, Massachusetts, June 7, 2002. Abstract No. 737