A DNA CONTROLLED-RELEASE COATING FOR GENE-TRANSFER - TRANSFECTION IN SKELETAL AND CARDIAC-MUSCLE

In this paper we report a novel technique of DNA-polymer coating for g ene transfer. A proprietary DNA polymer solution was used for thin-lay er coating on a chromic gut suture as a model study. The coated suture s were characterized for physical properties such as coating thickness , mass of the DNA deposited on the suture, surface characteristics as determined by scanning electron microscopy, and in Vitro DNA release c haracteristics under simulated physiologic conditions. The in vivo gen e transfection using DNA-coated sutures was demonstrated in rat skelet al muscle and in canine atrial myocardium. A heat-stable human placent al alkaline phosphatase (AP) plasmid was used as a marker gene. Incisi ons of 1 to 1.5 cm were made in the rat skeletal muscles or the canine atrial myocardium. The sites were closed with either the DNA-coated s utures or control sutures. Two weeks after the surgery, the tissue sam ples adjacent to the suture lines were retrieved and analyzed for AP a ctivity. The DNA-coated sutures demonstrated a sustained release of th e DNA under in vitro conditions, with an similar to 84% cumulative DNA release occurring in 26 days. An agarose gel electrophoresis of the D NA samples released from the suture demonstrated two bands, with the t ower band corresponding to the input DNA (supercoiled). It seems that there was a partial transformation of the DNA from a supercoiled to an open circular form due to the polymer coating. The tissue sites, whic h received the DNA-coated sutures, demonstrated a significantly higher AP activity compared with the tissue sites that received control sutu res. In the rat studies, the mean AP activity (square root of cpm/mu g protein) was 43.6 +/- 3.3 vs 20.6 +/- 2.1 (p = 0.001) at the control sites. Similarly, in the canine studies, the AP activity was 73.6 +/- 7.4 Vs 21.6 +/- 1.4 (p = 0.0009) at the control sites. Thus, our studi es demonstrated a successful gene transfer using our DNA-polymer coati ng technique. This technique could be useful for coating sutures used in Vascular and general surgery, and also for coating medical devices, such as stents, catheters, or orthopedic devices, to achieve a site-s pecific gene delivery.