A pharmacokinetic analysis of molecular cardiac surgery with recirculation mediated delivery of βARKct gene therapy: developing a quantitative definition of the therapeutic window

J Card Fail. 2011 Aug;17(8):691-9. doi: 10.1016/j.cardfail.2011.03.011. Epub 2011 Jun 14.

Abstract

Background: Two major problems for translating gene therapy for heart failure therapy are: safe and efficient delivery and the inability to establish a relationship between vector exposure and in vivo effects. We present a pharmacokinetics (PK) analysis of molecular cardiac surgery with recirculating delivery (MCARD) of scAAV6-βARKct. MCARD's stable cardiac specific delivery profile was exploited to determine vector exposure, half-life, and systemic clearance.

Methods and results: Five naive sheep underwent MCARD with 10(14) genome copies of scAAV6-βARKct. Blood samples were collected over the recirculation interval time of 20 minutes and evaluated with quantitative polymerase chain reaction (qPCR). C(t) curves were generated and expressed on a log scale. The exposure, half-life, and clearance curves were generated for analysis. qPCR and Western blots were used to determine biodistribution. Finally, all in vivo transduction data was plotted against MCARD's PK to determine if a relationship existed. Vector concentrations at each time point were (cardiac and systemic, respectively): 5 minutes: 9.16 ± 0.15 and 3.21 ± 0.38; 10 minutes: 8.81 ± 0.19 and 3.62 ± 0.37; 15 minutes: 8.75 ± 0.12 and 3.69 ± 0.31; and 20 minutes: 8.66 ± 0.22 and 3.95 ± 0.26; P < .00001. The half life of the vector was 2.66 ± 0.24 minutes. PK model data revealed that only 0.61 ± 0.43% of the original dose remained in the blood after delivery, and complete clearance from the system was achieved at 1 week. A PK transfer function revealed a positive correlation between exposure and in vivo transduction. Robust βARKct expression was found in all cardiac regions with none in the liver.

Conclusion: MCARD may offer a viable method to establish a relationship between vector exposure and in vivo transduction. Using this methodology, it may be possible to address a critical need for establishing an effective therapeutic window.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cardiac Surgical Procedures / methods*
  • Coronary Circulation / physiology*
  • Gene Transfer Techniques*
  • Genetic Therapy / methods*
  • Peptides / administration & dosage
  • Peptides / blood*
  • Peptides / pharmacokinetics*
  • Recombinant Proteins / administration & dosage
  • Recombinant Proteins / blood*
  • Recombinant Proteins / pharmacokinetics*
  • Sheep
  • Tissue Distribution / physiology

Substances

  • Peptides
  • Recombinant Proteins
  • beta-adrenergic receptor kinase inhibitory peptide