Intra-arterial photodynamic therapy using 5-ALA in a swine model

Area of Science:

• Vascular Biology
• Photodynamic Therapy
• Medical Device Engineering

Background:

• Restenosis, the re-narrowing of arteries after angioplasty, remains a significant clinical challenge.
• Photodynamic therapy (PDT) utilizes light-activated compounds to induce cell death, offering a targeted therapeutic approach.
• Current PDT methods often face limitations in delivering light effectively to deep arterial tissues.

Purpose of the Study:

• To evaluate the feasibility of delivering intravascular light via a balloon catheter for arterial PDT.
• To assess the efficacy of this method in targeting vascular smooth muscle cells (VSMCs) within the arterial wall.
• To investigate the potential of intra-arterial PDT to prevent restenosis post-angioplasty.

Main Methods:

• A pig non-injury arterial model was utilized, employing clinical catheter equipment.
• Pigs were photosensitized with 5-aminolaevulinic acid (5-ALA) to induce protoporphyrin IX (PpIX) fluorescence.
• PDT was administered using a transparent-channel PTA balloon catheter, occluding arterial flow without distension.

Main Results:

• Fluorescence of PpIX peaked in arterial layers at specific time points (adventitia: 1.5h, intima: 4h, media: 6h).
• PDT consistently induced VSMC depletion across all tested time points.
• The extent of VSMC depletion correlated directly with the PpIX fluorescence profile.

Conclusions:

• Standard PTA balloon catheters with transparent channels can effectively deliver intravascular PDT.
• Intra-arterial PDT successfully depletes VSMC populations in the arterial wall without observed complications.
• This technique presents a promising therapeutic strategy for mitigating restenosis following angioplasty procedures.