**6. Catheter-mediated local gene transfer**

Catheter delivery system is one of the devices used in vascular gene therapy. Several balloon catheters (porous and microporous catheters, hydrogel catheters, dispatch catheters, and infiltrator catheters) have been used for gene-based delivery. Rolland et al. [10] have investi‐ gated hydrogel-coated catheters for the delivery of interested drug and gene. In recent years, Saurer et al. [11] have designed ultrathin multilayered polyelectrolyte films fabricated on embolectomy catheter balloons by alternately adsorbing layers of a hydrolytically degradable poly (β-amino ester) for the localized delivery of plasmid DNA to vascular tissue. Although catheters seem to be a simple tool for gene delivery, several factors limit its efficiency. Most of the catheters cause localized vascular injury with increased inflammatory response and neointimal proliferation. Additionally, in direct injection method and catheter-based gene delivery, transgene expression is limited within the injection site and homogenous expression is not achieved. In point of fact, in stent-based gene delivery approach, a homogenous transgene expression is achieved in comparison to catheter-based gene delivery methods.
